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Processes affecting the oceanic iron cycle and their interaction with marine biology and climate
Full text linkI present a model investigation on the complex marine iron (Fe) cycle. Attention is put on regional features, on the biological response to Fe availability, and on past and future climate. In a sequence of changes to the model, the main dFe features in the subtropical North Atlantic, such as a deep East-West gradient, a hydrothermal plume and a subsurface dFe minimum, could be better reproduced and explained. This was achieved by introducing scavenging on lithogenic particles and on phytoplankton, a new ligand parameterisation, a larger sinking velocity of particles and a hydrothermal source. In the Southern Ocean dFe is a limiting micro-nutrient for algee. The role of icebergs as a source of Fe was analysed, with respect to diatom and non-diatom net primary production, nutrient availability, carbon, nitrogen and silica export. The Fe Hypothesis suggests that the additional Fe input to the ocean contributed to lower atmospheric CO2 concentrations in the glacial. The results of a laboratory experiment indicated that high-Fe and low-pCO2 conditions (glacial ocean) were beneficial for the Southern Ocean bloom-forming diatom Pseudo-nitzschia subcurvata
Integrated mechanisms of cellular behavior : cell biology and biological physics of the slime mold Physarum polycephalum
Full text linkIn its natural habitat, the plasmodial slime mold Physarum polycephalum forms extensive transport networks that can reach up to square meters in surface area. Under laboratory conditions, small spherical microplasmodia can be produced, which are only several hundred micrometers in diameter. These fragments can be used to study the reorganization of the network, the morphology of which depends on environmental factors. When nutrients are scarce, P. polycephalum forms fan-shaped, polarized mesoplasmodia with an internal vein system instead of a stationary network with reticulated external tubes. Mesoplasmodia are migrating, autonomous and unconnected subunits, which represent a starvation-induced foraging strategy. This thesis demonstrates that the number of mitochondria correlates with the metabolic state of the cell: In the absence of glucose, the slime mold is forced to switch to different metabolic pathways, which occur inside the mitochondria. A catabolic cue which stimulates mitochondrial biogenesis is discussed. A detailed and quantitative ultrastructural description of the three main morphotypes, macro-, meso-, and microplasmodia, is provided in this thesis. These investigations provide the basis for physical models of the system. Furthermore, the present work discusses the unique motility mechanisms of mesoplasmodia: At the posterior end, lateral contraction waves pump endoplasm through the veins towards the extending front. The internal flow channel system forms a cascade of forks, which acts as a low-pass filter and causes the isotropic extension of the cellular front. This effect is analyzed by a lumped parameter model, based on the analogy of hydro-dynamic phenomena to electric circuits. The direction of locomotion is controlled via an asymmetry in the elasticity of the actin cortex. A softness gradient exists along the anterior-posterior axis, with the front being the most elastic. The slime mold is capable of constructing networks optimized for transport, and exhibits other sophisticated and complex behaviors such as decision-making, efficient foraging, and memory. The structure of the cell and its dynamics are strongly interconnected. Large-scale patterns and other phenomena, which can be observed on the entire network, are based on locally occurring cellular and molecular processes. The interplay of these mechanistic interactions, and especially the resulting intracellular fluid flow, is hypothesized to underlie the information processing which is the basis of complex behavior in P. polycephalum. The ultrastructure of the cell is the substrate on which cellular computing takes place. Therefore, an understanding of the unique cell biology of the slime mold is necessary to study emergent phenomena such as minimal cognition
Composition and Declassification in Possibilistic Information Flow Security
Full text linkFormal methods for security can rule out whole classes of security vulnerabilities, but applying them in practice remains challenging. This thesis develops formal verification techniques for information flow security that combine the expressivity and scalability strengths of existing frameworks. It builds upon Bounded Deducibility (BD) Security, which allows specifying and verifying fine-grained policies about what information may flow when to whom. Our main technical result is a compositionality theorem for BD Security, providing scalability by allowing us to verify security properties of a large system by verifying smaller components. Its practical utility is illustrated by a case study of verifying confidentiality properties of a distributed social media platform. Moreover, we discuss its use for the modular development of secure workflow systems, and for the security-preserving enforcement of safety and security properties other than information flow control
Digitalization of Maritime Transport Documents : a study of the interplay of public rules and private norms amid social changes
Full text linkThe digitalization of maritime transport documents has became the chokepoint of promoting the automation level of the shipping industry. The lack of stable expectation is, among other things, the main reason that preventing international seaborne trade participants to apply digitalization solution. A harmonized legal framework worldwide would be the first step towards achieving stable expectation of applying electronic maritime transport documents. By employing the doctrinal method and the functional method of comparative law, the book draws a landscape of electronic law today and examined the effect of public international legislation. The empirical study suggests that actors across branches have developed workable standards towards the use of electronic documents by introducing compatible bylaws. The interactions between these private actors and their bylaws provide a possibility to achieve legal unification and self-evolvement of law on the global sphere. Deducting from the empirical results, the book proposes a private regulatory system as an alternative for achieving legal unification for the digitalization of maritime transport documents
Firm-specific cluster effects - A meta-analysis
Full text linkThe tendency of industries to cluster in some areas and possible effects of this regional clustering have fascinated researchers from multiple disciplines alike. Driven by the success of some clusters, as for example Silicon Valley, the concept has also become quite popular among politicians. Despite the already substantial financial support, a positive cluster effect on the success of the corresponding companies has not been consistently asserted yet. In this context, recently it has been accentuated to further examine the role of contextual influences that might explain the ambiguous effect of clusters on firm s success. The aim of this paper is therefore to investigate the alleged effect of clusters on firm performance and the moderating influence of the specific context by conducting a meta-analysis of the relevant empirical literature. Therefor four different performance variables from four separate publication databases are considered. After the selection and exclusion process, the final sample of the meta-analysis consists of 168 empirical studies. The statistical integration of the corresponding results of these empirical studies indicate that there exists relatively weak evidence for a pure firm-specific cluster effect. Instead, it can be asserted that several variables from different levels of analysis directly or interactively moderate the relationship between clusters and firm s success. For example, it is pointed out that the probability for a positive firm-specific cluster effect is significantly higher in high-tech industries as well as for small and medium-sized companies. Depending on the specific conditions, clusters can therefore be blessing and curse at the same time
European Citizenship, Social Rights and Student Mobility : Cross-border Access to University Tuition and Study Finance in the European Union
No full textThis PhD dissertation traces domestic legislative and administrative reactions to case law by the European Court of Justice in the area of EU Citizenship, free movement and cross-border welfare rights. The empirical case study analyses EU studentsa free movement and cross-border welfare rights, based on an original data collection through semi-structured expert interviews, newspaper articles and policy documents, covering three case countries, namely Belgium, Germany and the UK. The findings of this PhD dissertation are exemplary for member statesa struggle in striking a delicate balance between open borders and sustainable public funds under EU non-discrimination provisions
Refining molecular stratigraphy through mass spectrometry imaging of sediments at sub-millimeter resolution
Full text linkThis dissertation focused on the implementation of a new, extraction-free approach to molecular stratigraphy by mass spectrometry imaging (MSI) that allows to increase the spatial and temporal resolution to the micrometer and subannual scale. With this novel technique, detailed insights into the drivers of lipid biomarker-derived proxies were gained by addressing the small-scale differences of the signal archived in the sedimentary record. Together with the improved understanding of the proxy signal, application of MSI to varved sediments from the Santa Barbara Basin, off Southern California revealed insights into the dynamics and interdependencies of ocean surface temperatures, upwelling strength, and bottom water oxygen content during the 20th century
Shifting the Rules of the Game : Institutional Change as a Barrier to MNE Investment Activity
Full text linkThis thesis argues that the country-specific instabilities of institutional change are of high relevance for multinational enterprises (MNEs) which operate in multiple national institutional environments. The International Business literature has long emphasized that underdeveloped institutional environments, mostly in developing and emerging economies, present significant barriers to the investment activity of MNEs in the form of foreign direct investment (FDI). While the link between FDI, uncertainty and institutional underdevelopment, e.g., in the form of deficient property rights, has been discussed in detail, the role of the dynamics of institutional environments has received little attention. However, the long-term nature of FDI is likely to require not only institutions that are developed, but also stable. The first part of the thesis develops a conceptual framework that engages with the potentially negative effects of disruptive institutional change processes on locational FDI attractiveness. This is followed by three independent essays that highlight the frameworka s different implications. The first essay discusses theoretical implications, while the second and third essay provide some supporting evidence for the central thesis. The conclusion provides some thoughts on how the developed arguments can support future research
Berücksichtigung der eingeschränkten Alltagskompetenz im Rahmen der Weiterentwicklung der Sozialen Pflegeversicherung
Full text linkIn 1995, long-term care insurance (LTCI) was introduced in Germany. The a need for long-term carea was tight and referred to people who needed help with basic ADL. The needs of people with dementia, mental disabilities or illnesses (PEA) were not included in the entitlement. Based on administrative data, partial linked with survey data, (1) a characterization of PEA and two cohort studies concerning (2) the utilization of relief services and (3) associated with institutionalization were conducted. These results were integrated in describing the development of entitlement rules for PEA within the LTCI. Within PEA, at least 60 % suffered from dementia. 75 % show medium cognitive impairment and more than half cannot perform any IADL anymore. The relief services were used more often when a nursing service conducted the care. The probability to be institutionalized is higher in women than in men and when cared for by a nursing service. Future research should focus on the analysis of the effectiveness of relief services, regional differences in supply and demand of these services and sex-specific differences concerning treatment, care and support of people with dementia
Supply Chain Management of Mass Customized Automobiles
Full text linkChallenges of mass customization has increase dependence upon supplier, disruptions from suppliers have resulted many times in stop of production from OEM. Keeping this in background, this study analyzed supply chain policies and practices with in the modern automotive industry. The study focused on three German automotive companies, Mercedes Benz, BMW and Volkswagen, all three companies are investigated through qualitative and quantitative analysis. Qualitative analysis showed outsourcing demands high level of managerial changes in supply chain structure. Moreover, OEM needs to manage not only Tier I supplier but Tier II supplier as well. A quantitative approach addresses the issues related to inventory management, distributional policies and downstream supply chain and their impact on supply chain efficiency under mass customization. The results suggests to increase raw material inventories and to decrease in-house operation. Furthermore, it is more profitable to keep production near the markets. The results also suggest that the issues of downstream supply chain have a strong and significant impact on supply chain efficiency under mass customization