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Inverse Modelling at Recovery Glacier, Antarctica
Get PDFThe future ice loss of Recovery Glacier will probably be the largest of the East Antarctic Ice Sheet over the next millennia. Its evolution can be predicted by models solving the equations of the momentum and mass balance. Ice dynamics are fundamentally driven by bedrock conditions underneath the ice, but these can not simply be measured yet. This thesis utilizes an inverse method implemented in the Ice Sheet System Model (ISSM) to acquire basal parameters. The technique minimizes the difference between horizontal surface velocities derived from remote sensing and computed by the model. False values in the observations can lead to uncertainties in basal parameters. In order to remove such false values, this thesis presents a new filtering method. Data gaps are filled comparing four different interpolation methods. A sensitivity analysis shows that the influence of filtering outliers and interpolation on basal parameters derived from inverse modelling is large in specific regions. The resulting basal parameters do not indicate the existence of the previously proposed subglacial lakes at the onset of Recovery Glacier
Interview with Deyfou-lah Sani Bah-Traore on the Togolese game Origin - the Rise of Dzitri
No full textIn the Togelese game Origin - the Rise of Dzitri that was developed in Lome, the character Edoh takes you on a journey to historic places in the city to revive the spirit of Dzitri. Deyfou-lah Sani Bah-Traore, programmer and game developer, spoke with Lisa Kienzl about his and his Teammate s work on Origin - the Rise of Dzitr
Investigation of diatom-bacteria interactions with the model organism Thalassiosira rotula
Get PDFMarine microalgae are key primary producers responsible for more than 45% of global net primary production, fixing billions of tons of inorganic carbon each year. Diatoms constitute one of the most diverse and ecologically important group of microalgae. While diatom productivity and health are likely to be strongly governed by the structure and function of the diatom microbiome, we have little understanding which factors contribute to the microbiome assembly. In order to investigate the microbiome establishment on diatoms, an in vitro model system for reproducible laboratory studies was developed with the marine diatom Thalassiosira rotula. Thus, this thesis describes the isolation of diatoms and bacteria from the environment and the development of an in vitro model system for reproducible laboratory studies followed by the investigation of the microbiome assembling on the diatom T. rotula using co-culture experiments. In Chapter 2 diatoms and bacteria were co-isolated from a spring bloom in the German Bight of the North Sea. The isolation resulted in four different diatom species and 200 morphological different bacteria in culture. The marine diatom Thalassiosira rotula was selected as the model organism for the in vitro studies with diatoms and bacteria. Chapter 3 focused on the development of a co-culture to study mutualistic interactions between the diatom T. rotula and bacteria as well as the generation of an axenic (bacteria-free) culture of the diatom T. rotula. The experiments revealed that the diatom T. rotula is auxotroph for B-vitamins and that the bacterial community of T. rotula is able to maintain the growth of the vitamin-free diatom with the provision of vitamins. In Chapter 4 and 5 the microbiome assembling was investigated by exposing the vitamin-free and axenic diatom T. rotula to several bacterial source communities obtained from different diatom species. The co-culture experiments revealed that each of the newly established microbiomes on the T. rotula acceptor supports the growth of the diatom under vitamin absence, indicating that all microbiomes comprise bacteria capable for B-vitamin synthesis. To investigate the factors that contribute to the microbiome assembling, the bacterial community compositions of the different inoculated bacterial source communities and newly assembled acceptor microbiomes were analysed. The analysis revealed that the different inoculated bacterial source communities were highly different in their bacterial community composition and contained up to 4406 different operational taxonomic units (OTUs). On the contrary, the analysis of the newly established acceptor microbiomes revealed that all acceptor microbiomes were similar to each other in respect to their bacterial community composition and that they were more similar to the original T. rotula bacterial source community than to the donor cultures where the bacterial source communities were obtained from. The similarity of the acceptor microbiomes was most likely caused by 10 OTUs, which constituted for more than 80% of the total relative abundance of all acceptor microbiomes. Furthermore, these 10 OTUs were shown to be most responsible for the differences between acceptor microbiomes and bacterial source communities and were thus described as the core microbiome of the diatom T. rotula. Consequently, it was shown for the first time that the ecologically relevant diatom T. rotula establishes a robust and reproducible bacterial core microbiome of 10 OTUs if it is offered highly diverse and compositionally different bacterial source communities with up to 4406 OTUs. The results of the robust and reproducible microbiome composition on the diatom T. rotula suggest that host factors contribute more than the bacterial diversity in the environment to the shaping of the microbiome composition
Friction reduction in dry forming by using tetrahedral amorphous carbon coatings and laser micro-structuring
Get PDFFriction has a dominant influence on manufacturing processes. In deep drawing of sheet metals, lubricants are regularly used to reduce friction forces. However, significant production costs originate from their supply, application, removal and disposal. The negative environmental consequences of using lubricants promote extended research on lubricant free deep drawing processes and tools. A combination of macro-structuring in the flange area and micro-structuring of ta-C layers at the pulling edge radius of deep drawing tools is identified to compensate the loss of tribological functions. Surface texturing of semi-finished sheet metals also supports friction reduction by minimizing the contact area to the deep drawing tool. In this study, a variation of ta-C coating iterations with several coating and decoating steps, as well as microstructuring of the ta-C coatings using Direct Laser Interference Patterning was used on cylinders in draw bend test rigs. The resulting friction coefficients between the cylinders and steel stripes show minimal friction for ta-C covered draw bend tools
Chinesische Pflegekräfte in Deutschland : Literaturanalyse und Expertenbefragungen zu Möglichkeiten und Grenzen der Beschäftigung von chinesischen Pflegefachkräften in Deutschland
Get PDFThe shortage of nurses is not only a problem in Germany, but also in many other western and eastern countries in and outside of Europe. One approach to coping with the already existing skills shortage in nursing, which is expected to aggrevate in the future, is to recruit care personnel from other countries, from so-called third countries, including China. So far, there have been many individual references to the potential of and possible issues with recruiting skilled nurses from China, but there is no systematic overview of the opportunities of employing Chinese nursing staff in Germany. In order to be able to better assess the benefits of recruiting nursing staff from China, the author systematically compiled an empirical record of the associated risks and potentials in her paper on the basis of guided expert interviews
Die Theorie der Hebammenidentitäts-Konstruktion im Kontext von interprofessioneller Zusammenarbeit und Medikalisierung der Geburt
Get PDFMidwifery care is provided by several health professions, but is not always successful. Up to now research on collaboration in obstetrical care is limited. Aim of this research is to explore the working conditions of interprofessional work in the clinical setting and examine the subjective perspective of midwives on collaboration. Data from 20 participant observations and 14 interviews in the clinical setting are part of the analysis. The a Theory of midwifery-professional identity-construction in the context of interprofessional collaboration and medicalization of birtha stresses the influence of professional identity in the collaboration with others. The professional identity of midwives is characterized by several parts of identity. They are built in a process of identity-construction. Different parts of the identity can include contrasting believes. Midwifery-professional identity-construction is shown on a range of autonomous to subordinated work. In this way midwives cope with the heterogeneous demands of the work situation in the clinical setting
Evaluation und Implementierung von Interventionen zur Förderung von körperlicher Aktivität bei älteren Erwachsenen unter besonderer Berücksichtigung von eHealth-Ansätzen
Get PDFDespite the known positive effects of regular physical activity on physical, psychological, and cognitive health, only about one fifth of adults aged 65 years and above living in Germany meets the physical activity recommendations of the World Health Organization. The increasing digitalization opens new opportunities for the promotion of physical activity. Interventions which are delivered via the internet or mobile devices are defined as electronic health (eHealth) interventions. The aim of this dissertation was to investigate various aspects of the evaluation and implementation of interventions promoting physical activity in older adults, particularly focusing on eHealth interventions. The objective of this dissertation was examined in three parts, using a combination of quantitative and qualitative methods: 1) A systematic review was conducted to examine the effectiveness of eHealth interventions promoting physical activity in adults aged 55 years and above compared to either a non-eHealth physical activity intervention or a no intervention control group. 2) In a randomized controlled trial, the effectiveness of two ten-week web-based interventions promoting physical activity in adults aged 65 years and above on objectively measured physical activity was evaluated in comparison to a delayed intervention control group. 3) In qualitative case studies, facilitating factors for the implementation and maintenance of interventions and policies promoting physical activity were examined. The review showed that eHealth interventions can effectively promote physical activity in older adults compared to a no intervention control group, at least in the short-term. Compared to more traditional intervention modalities (e.g., print interventions), eHealth interventions were not more effective in promoting physical activity in older adults. Participants of the two web-based physical activity interventions did not increase moderate-to-vigorous physical activity or decrease sedentary behaviour after ten weeks, compared to a delayed intervention control group. Facilitating factors for the implementation and maintenance of interventions and policies promoting physical activity were active involvement of relevant stakeholders, standardized training for staff, tailoring of intervention materials to the needs of the target group, embedding in existing or newly created organisational structures, and continuous funding. eHealth interventions have the potential to promote physical activity in older adults. However, older adults are a very heterogeneous group. Future intervention studies promoting physical activity of older adults should hence be designed as individually as possible (e.g., with regards to the use of technical components). In addition, the target group and stakeholders should be involved more in the development and implementation of future physical activity studies targeting older adults. More time, personnel, and financial resources should be invested in the development of interventions to promote physical activity, particularly to encourage physically inactive persons to participate
Ontology-Mediated Querying with Horn Description Logics
Get PDFAn ontology-mediated query (OMQ) consists of a database query paired with an ontology. When evaluated on a database, an OMQ returns not only the answers that are already in the database, but also those answers that can be obtained via logical reasoning using rules from ontology. There are many open questions regarding the complexities of problems related to OMQs. Motivated by the use of ontologies in practice, new reasoning problems which have never been considered in the context of ontologies become relevant, since they can improve the usability of ontology enriched systems. This thesis deals with various reasoning problems that occur when working with OMQs and it investigates the computational complexity of these problems. We focus on ontologies formulated in Horn description logics, which are a popular choice for ontologies in practice
The Promises of a Naturalistic Approach: How Cultural Evolution Theory Can Inform (Evolutionary) Economics
Get PDFHumans are an ecologically extremely successful species. Underlying this achievement is our evolved unique adaptation for culture. Moreover, humans cultural capacity initiated a process of gene-culture coevolution that lead to a plethora of behavioral and cognitive dispositions on which cultural adaptation to challenging environments via cultural evolution rests. These characteristics of human cognition are highly relevant to any discipline dealing with human behavior. This article presents these outcomes of human phylogeny and discusses this naturalistic perspective s implications for (evolutionary) economics. Moreover, some fruitful applications of cultural evolution theory to the explanation of economic phenomena are provided
How do fragmented seascapes influence fish movement behaviour? Insights from an individual-based model (IBM) using potential fields
Get PDFAnalysing movement is essential for understanding population dynamics and spatial distributions and has strong implications for the design of natural reserves. In coral reef systems movement patterns of fishes are particularly important as they are an essential part of the ecosystem and many fish species undertake diel migrations using different habitats. However, guidance mechanisms of these movements are not yet well understood. In this study we thus aim to elucidate potential causal mechanisms and spatiotemporal patterns of reef fish movements. To this end, we simulate the movement decision-making of the parrotfish Chlorurus sordidus by linking it with two main functional landscape features (food availability and predation risk) in a novel approach combining individual-based modelling (IBM) with potential field methods. Model results indicate that populations are more irregularly distributed among coral reef patches the more the coral reef habitat becomes fragmented and reduced. The spatial configuration of the seascape thus influences spatial exploitation of microhabitats, which may have far-reaching consequences on the ecosystem. By shaping individual space use patterns, the physical features of the environment may also impact encounter rates between individuals and thus the overall social structure of a population. Based on our findings we believe our model can provide valuable insights into the spatio-temporal variability of local herbivore fish populations. Moreover, the integration of potential field methods into IBMs seems a promising strategy to represent the complexity of dynamic decision-making of animals in applied models