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Variations in surface and thermocline conditions of the Western Pacific Warm Pool : Insights from Mg/Ca and stable isotopes in foraminifera tests
Get PDFThe Western Pacific Warm Pool (WPWP) is a major source of heat and moisture to the global atmosphere and thus plays a major role in the global climate system. This thesis deals with the reconstruction of past variations in WPWP surface and thermocline conditions with the overarching goal to better understand the regional ocean and climate variability over the last (two) glaciala interglacial cycle(s). The reconstruction is mainly based on records of stable oxygen isotopes (I 18O) and Mg/Ca in planktic foraminifera from marine sediment cores. First, the proxies are calibrated against modern water column data. Then, these calibrations are applied to records from the southern WPWP off Papua New Guinea. The records illustrate the interplay of local and remote forcing on the WPWP on glacial-interglacial and orbital timescales by indicating that (I) variations in the Pacific Walker circulation affect the WPWP on glacial-interglacial timescales, (II) climate variations in the extratropics influence the WPWP thermocline in response to astronomical forcing and (III) precession is the main driver for precipitation over the WPWP
Paleo-ice sheet dynamics on the northwest Greenland continental shelf
Get PDFIncreasing temperatures in the ocean and atmosphere result in the decline of the modern ice sheets in both hemispheres, causing global sea-level rise. Direct records on these ice-sheet dynamics are sparse as most observations were first initiated in the last century. Although ice-core analyses and satellite data from the polar regions increase our knowledge of modern ice flow and ice-sheet dynamics, the reconstruction and investigation of these dynamics during past glacial cycles is required to predict future scenarios for ice-sheet dynamics. Erosional and depositional glacial landforms that developed under the paleo-ice sheet and at its margin are used to reconstruct past ice-sheet extends and dynamics. These glacial landforms indicate the flow direction of past ice-streams that drained the former ice-sheet. They indicate the maximum ice-sheet extent as well as ice-sheet stabilizations or re-advances during ice-sheet retreat. This thesis focuses on the analysis of the Greenland ice-sheet dynamics since the last glacial maximum (LGM, 26.5-19 ka BP). The analysis is based on the identification and investigation of glacial landforms on the seabed of Melville Bay, on the northwest Greenland continental shelf. This region in northeast Baffin Bay hosts three large crossshelf troughs. They were formed by ice-streams advancing to the shelf edge during past glacial cycles. They are among the widest and deepest cross-shelf troughs of the continental shelf of Greenland. High-resolution bathymetry, which is necessary for identification of glacial landforms at the seabed in and adjacent to these troughs is limited in this remote region due to harsh sea-ice conditions. Thus, detailed reconstructions of LGM ice-sheet dynamics and their timing in Melville Bay are incomplete. In this thesis, I present new high-resolution bathymetry data from the northeast Baffin Bay that I investigated for submarine glacial landforms. The data have been recorded in 2010 with RV Polarstern and in 2015 with RV Maria S. Merian. This study aims to reconstruct the Greenland Ice Sheet dynamics since the LGM by inferring glacial processes and their relative chronology from the distribution and configuration of glacial landforms. The presented results show that the ice streams extended to the shelf edge and subsequent retreat of the ice streams varied between the glacial cross-shelf troughs in Melville Bay. Local ice domes on the shallow banks between the cross-shelf troughs are inferred from the distribution of glacial landforms. A newly discovered trough network on the inner continental shelf extends from the large cross-shelf troughs towards the fjords under the modern ice sheet. It was likely formed by a former ice sheet. Steep ridges in the north of Melville Bay are likely related to Proterozoic volcanic dyke swarms that to some extent confined former meltwater and ice-stream pathways. The results of this thesis improve our understanding of the northwest Greenland ice-sheet dynamics during past glacials and indicate that at least some glacial processes are related to underlying bedrock morphology
FoldWatch: Using Origami-Inspired Paper Prototypes to Explore the Extension of Output Space in Smartwatches
Get PDFSmartwatches are highly portable, ubiquitous devices, allowing rich interaction at a small scale. However, the display size can hinder user engagement, limit information display, and presentation style. Most research focuses on exploring ways in which the interaction area of smartwatches can be ex- tended, although this mainly entails simple fold-out displays or additional screens. Conversely, added weight and size can hinder the wearable experience. In response, we took inspiration from origami and explored the design space for new types of lightweight, highly foldable smartwatch, by developing complex paper-prototypes which demonstrate novel ways of extending screen space. We collected data on potential input and output interaction with complex folded smartwatch displays during workshops with expert and non-expert users, discovering application ideas and additional input/output functionality. These insights were used to produce and evaluate a concept video for the FoldWatch prototype
Trust in Sharing Resources in Logistics Collaboration
Get PDFCollaboration on resource sharing advocates a joint usage of resources by multiple parties (actors) to attain mutual benefits. Resource sharing becomes vital when resources under consideration are scarce, challenging, and expensive to attain; as well when they are idle or underutilized. In collaborative logistics, resource sharing entails the joint usage of the physical and non-physical assets. Shared assets include the transportation vehicles (trucks), warehouses, distribution centers, information, on-demand staffing, and logistics services offered under cloud computing. Through sharing, collaborating partners in logistics can reduce costs and harms to the environment, but also improve the efficiency of logistical functions. Although collaborative sharing is beneficial, still many difficulties impede its uptake. The difficulties include how to choose partners, establish and maintain trust among partners involved. Indeed, in both academia and industry, low-level trust inhibits the collaboration critically on sharing logistics resources. To this end, the present dissertation addresses the trust problem encountered by collaborating partners when they are sharing logistics resources. It deals with the trust problem by developing the Trust Mechanism (TrustMech) concept. The primary role of the TrustMech is to help logistics stakeholders acquire the far-reaching understanding about the trustworthiness of prospective networks of sharing they configure, before advancing them to an implementation stage. The TrustMech stands on a mitigation approach that focuses on estimating outcomes of trust uncertainties a rather than a their sources. Henceforth, this dissertation advances on estimating outcomes of trust uncertainties to answer the following central Research Question (RQ): how can collaborating partners acquire the far-reaching understanding about the trustworthiness of prospective networks of sharing they configure? An approach to the research problem, which as well answers the RQ proceeds as follows. The first steps involve establishing behavioral factors and parameters, which influence trust in collaborative sharing of logistics resources. The second stage entails establishing a conceptual framework that depicts and guides trust-based interaction of collaborating partners. The third step comprises developing the TrustMech concept, validating it in both the conceptual and operational aspects, and demonstrating its application by carrying out controlled (simulation) experiments in Multi-Agent Systems. In particular, the proposed TrustMech concept characterizes fundamental logical processes that account for trusting decisions, actions, and reactions of collaborating partners to reinforce emergent trusting outcomes The core contributions of this dissertation are the general-purpose TrustMech and the operational TrustMech. The operational TrustMech is customary for collaborative sharing of logistics resources. Regarding its application, the operational TrustMech provides logistics managers and stakeholders the ability to forecast how a configured network of sharing may, in respect of trustworthiness, function upon its implementation. To clarify further, the operational TrustMech scrutinizes many issues. For example, it scrutinizes trustworthiness of the configured network regarding possible strengths and pitfalls and provides pathway explanations underlying such foreseen strengths and pitfalls. Secondly, the operational TrustMech scrutinizes effects which such strengths and pitfalls can generate. Moreover, the operational TrustMech estimates an extent to which behavioral factors influence the trustworthiness of the individual partner and entire resource sharing network. Future research works include extending the TrustMech and replicating the study using system data. Additional future work consists of adjusting the design and settings used, as well as incorporating additional predictor and response variables into the operational TrustMech
Der Nachlass Hinrich Knittermeyer (1891-1958) in der Staats- und Universitätsbibliothek Bremen
Get PDFDer Nachlass von Hinrich Knittermeyer (1891-1958) gehört mit annähernd 5000 Dokumenten zu den umfangreicheren in der Staats- und Universitätsbibliothek Bremen. Er besteht zum größten Teil aus Korrespondenzen, daneben aus Manuskripten von Vorlesungen, Vorträgen und Veröffentlichungen von Hinrich Knittermeyer. Knittermeyer war von 1923 bis 1945 Direktor der Vorläuferinstitution der SuUB Bremen und prägte darüber hinaus mit Vorträgen und Veröffentlichungen das kulturelle Leben der Freien Hansestadt Bremen. Das vorliegende Verzeichnis beinhaltet eine Lebensbeschreibung sowie eine formale und inhaltliche Beschreibung jedes der im Nachlass enthaltenen ca. 5.000 Schriftstücke
Disabled, but at What Cost? An Examination of Wheelchair Routing Algorithms
Get PDFPlatforms like Google Maps or Bing Maps are used by a large number of users to find the shortest path to their destinations. While these services mainly focus on supporting drivers and pedestrians, first services exist that support wheelchair users. Routing algorithms for wheelchair users try to avoid obstacles like stairs or bollards and optimize on criteria like surface properties and slope of the route. In this study, we undertake the first controlled examination of wheelchair routing approaches. By analyzing three routing platforms, including two wheelchair routing algorithms and three pedestrian routing algorithms, across fifteen major cities in Germany, our results highlight that the routes for wheelchair users are significantly longer and partially also more complex than those for pedestrians. In addition, we show that today s pedestrian routing algorithms also output very diverse routes
Ectomycorrhiza Development : Investigation of Selected Ectomycorrhiza Induced Poplar Genes
Get PDFMutualistic interaction such as ectomycorrhiza (ECM) is important for forest ecosystem function. Here two kingdoms, plant and fungi, form a symbiosis and exchanges nutrients and carbohydrates. A bottle neck in ectomycorrhizal research is the time demand for transgenic plant generation. Formation of so-called composite plants, where transgenic roots are formed on non-transgenic shoots, is an alternative strategy. An Agrobacterium rhizogenes-mediated root transformation protocol was developed in this work using axenic Populus tremula A tremuloides and P. tremula A alba cuttings. Out of four different A. rhizogenes strains, K599 was found to be the most suitable one. Roots of composite poplars were able to form ectomycorrhiza when inoculated with Amanita muscaria. By using real time quantitative PCR a comparative analysis of transcript levels was done for selected genes in mycorrhized and non-mycorrhized poplar fine roots. A total of 50 ectomycorrhiza-induced genes were chosen based on a genome wide microarray analysis (Nehls, unpublished). As the array oligomers were designed based on Populus trichocarpa genome but the array hybridization was performed using P. tremula x tremuloides cDNA, cross hybridization leading to misinterpretation is feasible. Therefore, the first step was to screen P. tremula/P. tremuloides datasets for the best matching homologs. After primer design and first qRT-PCR tests 14 candidate genes remained. Finally, expression analysis with several independent batches of poplar fine roots and mycorrhizas were obtained for six genes. Two genes, a transcription factor (TF- Potri.008G071100) belonging to the AP2/ERF superfamily and a potential glycosyltransferase (GT- Potri.007G095000) revealing the highest gene expression difference, were selected for further analysis. Fusion with super yellow fluorescent protein revealed a probable subcellular localization of Potri.007G095000 in nucleus and cytoplasm and Potri.008G071100 in nucleus. Following their establishment, composite poplars were used for promoter analysis of the selected genes. For this purpose, around 3 kb promoter fragments were amplified from genomic DNA of P. tremula x tremuloides, successively shortened from the 5' end and the resulting fragments were cloned in front of the coding sequence of a peroxisomal located yellow fluorescent protein. The longest promoter-reporter constructs were used for generation of composite poplars. No reliable ECM induced expression was found for the TF and the GT indicating the need for longer promoter fragments. Furthermore, as the best Arabidopsis TF homolog is known to be auto-regulated, the identification of potential cis-elements in the promoter region was planned. Therefore, protein overexpression in E. coli was initiated. However, all attempts of receiving a natively folded protein in soluble form were unsuccessful
Clinical epidemiology of vaccines and vaccine-preventable diseases using administrative healthcare data
Get PDFFor centuries, infectious diseases have been among the top 10 leading causes of death. In 2015, they accounted for about 11% of 56.4 million deaths worldwide indicating a global public health relevance. Vaccines provide an opportunity to eliminate or even eradicate infectious diseases. In order to maximize the benefit of vaccines while minimizing their risks, it is important to investigate infectious disease etiology as well as to continuously monitor and evaluate direct vaccination effects as well as indirect vaccination effects through herd immunity. Since vaccines are usually administered to healthy people to prevent infectious diseases, the monitoring of the safety of vaccines is of high importance. For their evaluation, there is usually no trade-off between risk of disease and risk of its treatment as is usually the case for the treatment of severe diseases. Vaccine safety is also essential for the acceptance of vaccines in the population and thus for high vaccine uptake to enable herd immunity. Epidemiological observational studies are a powerful tool to investigate the burden of vaccine-preventable diseases, direct and indirect vaccination effects as well as the safety of vaccines in a real-world setting, meaning they provide important data as they includea often in contrast to randomized controlled trialsa older or immunocompromised people as well as children or pregnant women, which are most often the target population groups for vaccinations. Administrative data are a valuable data source for epidemiological observational studies and are increasingly used for studies on vaccines and vaccine-preventable diseases. However, a comprehensive knowledge of the healthcare system itself, including reimbursement policies, but also of the data source and the containing information depth is required. This thesis investigates different aspects of vaccines and vaccine-preventable diseases. Thus, in a first study, the burden of the vaccine-preventable disease of herpes zoster (HZ) and its complications is investigated and in a separate study, the risk of stroke complication after HZ infection. Vaccine uptake of the human papillomavirus (HPV) vaccine at the population level as well as its indirect impact after vaccine recommendation is assessed. Furthermore, this thesis discusses the nested case-control design with respect to its potential use for direct effectiveness and safety studies of vaccines. Relevant methodological challenges when using different observational study designs based on administrative healthcare data as well as methods to control confounding or to reduce bias are elucidated and discussed. Finally, this thesis gives outlook on potential challenges of future studies on vaccines and vaccine-preventable diseases, especially with regard to newly developed therapeutic vaccines for chronic diseases
Social Dimensions and Participation in Vocational Education and Training - An Introduction in the Special Issue
Get PDFThis is the introduction of the IJRVET's special edition in 2013 Social Dimension and Participation in VET-System
Organic carbon fluxes in polar oceans: Subject to changing ice conditions and related secondary effects
Get PDFPrimary production and mineralization are key processes and living organisms key components of the biological carbon cycle. Their dynamics are controlled by abiotic and biotic factors, which can also be inter-dependently linked with each other. Changes in the polar cryosphere and related secondary effects, associated with global temperature increase, can have a great impact on processes and components of the biological carbon cycle. For example, nutrients and particles are released into the marine realm by glacial and permafrost soil melt, while thinning, diminishing, and retreating sea ice leads to increased light availability but suppresses nutrient upwelling. These secondary effects are known to influence primary productivity, organismal community structures and mineralization rates. The investigation of how changes in polar ice conditions alter primary production, the benthic biota, and benthic mineralization is the overall aim of this thesis and was addressed in three manuscripts