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Computer-Aided Analysis of PCMRI Flow Data
No full textMagnetic resonance imaging (MRI) has firmly established itself as one of the leading tools in clinical diagnostics and radiology. However, its full potential still remains to be utilized in clinical routine. Apart from imaging the anatomy, MRI can also be used for obtaining functional and even molecular information in vivo. One such functional technique is phase contrast MRI (PCMRI). With PCMRI, it is possible to capture time-resolved three-dimensional velocity information. This is especially useful for quantifying cardiac function and hemodynamics of larger vessels, as PCMRI can reconstruct a full velocity field v(x,t) during one heart cycle along with morphological information. Velocity-encoded 4D PCMRI flow measurements have revealed a wealth of in vivo flow patterns in healthy volunteers as well as in patients. There are strong hints that hemodynamic flow patterns are correlated to various vascular pathological phenomena like atherosclerosis, plaques and aneurysms. This motivates the computer-aided characterization, detection, and quantification of flow patterns from 4D PCMRI flow measurements. This thesis explores the possibilities of a comprehensive characterization of in vivo hemodynamics from PCMRI data. The focus is on the hemodynamic parameters influencing the genesis, progression, and rupture of aortic plaques. Such plaques develop as the thickening of the vessel wall; they contain lipids (cholesterol etc.) and are prone to calcification and rupture. The rupture of an aortic plaque may finally result in a stroke. Further applications of 4D PCMRI velocity mapping are aneurysms and their risk assessment, planning and follow up of surgery for congenital heart defects, analysis of flow through artificial heart valves, and stenosis, among others
Object Understanding Through Abstraction Inspired by Compositionality and Connectionism – From Noisy Scene Point Clouds to Objects and Shape Reasoning
No full textThis thesis focuses on object perception. Particularly we focus on the description and representation of object shape information for detection and reasoning purposes by considering spatial information in form of RGBD data. Such RGBD data can be expressed by point clouds in which points are independently organized, but a subset or as a whole, may contain relevant information on different semantic levels and granularity. Inspired
by visuoperceptual principles such as compositionality and connectionism, i.e. complex structures can be expressed by the relation and interplay of simpler ones, the presented work proposes a hierarchical and data-driven abstraction process to reveal visual patterns and persistent structures: from generating building blocks of our surroundings over detecting potential object candidates to reasoning about the semantics of object shapes. In the course of our work, we aim on generic approaches such as detection of unknown objects in unstructured environments or the classification of object shape types instead of the recognition of individual object instances. Our eventual goal is a data-driven unsupervised conceptualization of shape commonalities regarding object appearance. Therein we aim to reduce supervision in form of handcrafted labeled data and to learn machine-centric prediction models that are solely based on the given data without incorporating knowledge that is not inferable from given data or is biased by supervision.
Further on, we specifically aim on the applicability in real-world scenarios coping with challenging conditions as in form of noisy sensor data to partial observations and occlusions. The presented work showed its applicability in autonomous unloading of goods from shipping containers or in shelf replenishment in retail scenarios. Additionally, our work was applied to a tool substitution framework
Synthesis and Characterization of Polyoxopalladates and Organoantimony-Containing Heteropolytungstates
No full textPolyoxometalates (POMs) are discrete, polynuclear metal-oxides with a negative charge and a multitude of shapes, sizes and compositions. Here we report on the synthesis and structural as well as physicochemical characterization of two fundamentally different classes of POM-based materials.
Part I: In 2008 the Kortz group discovered the class of polyoxopalladates (POPs) and hence this is a young research field. The synthesis of novel POPs is of interest due to their structural diversity combined with multiple interesting properties including catalysis. Here the synthesis of 20 novel POPs is reported, which were structurally characterized in the solid state and in solution.
Part II: Hybrid inorganic-organic POMs contain organic functionalities covalently attached to the metal-oxo framework. Such compounds, if soluble and stable at physiological conditions, are of interest for biomedical applications, e.g. as inhibitors of enzymes or as antibacterial agents. In this section three novel organoantimony(III)-containing heteropolytungstates and their biomedical properties are reported
Motion Compensation for Minimally Invasive Liver Interventions
No full textMinimal invasive therapies for treating liver tumors heavily depend on imaging. Motion in between the acquisition of different images and in between image acquisition and therapy action needs to be compensated to reach the therapy goal. This thesis presents motion compensation techniques for liver tumor therapies and addresses unsolved problems in their transfer to clinical practice.
A first problem is motion in between the time-points of dynamic contrast-enhanced (DCE)
magnetic resonance imaging time series, which is a prominent tool for imaging liver anatomies in therapy planning and assessment. We present a motion compensation employing a pipeline of liver segmentation, rigid preregistration and deformable registration to robustly compensate large differences in the respiratory state. The transfer of DCE motion compensations to clinical practice is hampered by the lack of homogeneous, direct, quantitative measures for motion compensation quality. We address this problem with a novel landmark annotation scheme that allows for direct sampling of ground truth on numerous cases with comparably low effort.
In a second part, we address motion compensation problems during the intervention at the example of a novel, motion-compensated focused ultrasound (FUS) treatment system.
We present a ready-to-use treatment system employing clinically approved hardware, in which motion-compensation is realized by observing motion several times per second, predicting the target motion, and finally adopting the treatment plan accordingly. Monitoring of treatment effect in the moving liver and in real-time is enabled by a multi-baseline thermometry approach employing a novel fast lookup. To prepare for regulatory approval of the use in a clinical study, clinical requirements for safety and efficacy are defined and their fulfillment is tested via a dedicated suite of experiments. The results suggest that safe and effective motion-compensated FUS is possible with the proposed system
Gender Differences in Career Success and Satisfaction - Investigations among German Managers and Employees of a German Car Manufacturer
No full textManagerial positions in Germany are still dominated by men, and even in comparable jobs, women earn less money than men. Striving for a gender balance in these positions and aligning women’s and men’s salaries is the goal of many people. But women not only experience less objective career success than men; they also experience less subjective success once they reached a managerial level. Previous studies have shown that women with managerial careers in Germany are significantly less satisfied with their jobs and lives than their male counterparts. As career decisions are based on satisfaction-seeking strategies, it is fundamental to find the reasons for gender differences in satisfaction in order to reach an equal distribution of women and men in management positions. Therefore, the present dissertation investigates the reasons why managerial women may be less satisfied than managerial men, and why women may have less objective career success than men. The empirical endeavor is a set of studies on samples from Germany. Based on data of a representative German panel (the Socio-Economic Panel, SOEP), the first study explores how money, spare time, preferences, and biological differences may influence the life satisfaction of female and male managers. Using the same database, a second study examines how personality traits and job characteristics may explain gender differences in managers’ job satisfaction. Finally, a third study investigates if and to what extent human capital, the organizational culture, and gender discrimination may explain differences in the salary group development of male and female employees of a German car manufacturer by the analysis of personnel data and qualitative interviews
Myths, Curious Incidents and Obstacles—Becoming an Artist in Portugal. The Early Career of German Sculptor Hein Semke
No full textThe Hamburg native Hein Semke (1899-1995) travelled to Portugal for the first time in 1929. Inspired by his stay, he decided to study arts. In 1932, he returned to Lisbon, where he started his career as an artist and developed into a solid parameter in the country’s art scene: as Expressionist sculptor and ceramic artist, he participated in almost all important art exhibitions until 1975.
Concurrently with Semke’s relocation, major changes in both countries were taking place and, in each case, the situation of Modern Art was precarious. In Portugal, António de Oliveira Salazar (1889-1970) established the corporatist authoritarian right-wing regime of Estado Novo. Artists revolted after years of suffering from declining sales figures due to the severe financial crisis affecting the country. In Germany, Adolf Hitler's (1889-945) Nazi Party gained power, and, since 1933, the Reichskammer der Bildenden Künste restricted artistic freedom by implementing an ideological selection. Despite this situation, Semke was included into a major project: the design of a Commemorative Courtyard at the newly built German Protestant Church in Lisbon. When the influence of the recently elected German authorities reached out for the German community of Portugal, Semke lost the support of his patrons and found his work in a bitter controversy, resulting in the removal of one of his sculptures.
In my Ph.D. thesis, I examine the life and career of the Hein Semke, with a main focus on the years between 1899 and 1960. The difficulties the artist had to face in the early years of Estado Novo are evaluated in detail, as well as the legal situation for foreigners in the 1930s and 1940s. Moreover, the in-depth analysis of the controversy around Semke’s artistic work for the German Protestant Church in Lisbon, the artist’s selfconcept and his self-created image stand in the center of attention of this examination and offer a multi-layered discussion reflecting the zeitgeist of the era
The Role and the Nature of Repetition in Jasper Johns’s Paintings in the Context of Postwar American Art
No full textFrom the beginning of his artistic career, American artist Jasper Johns (b. 1930) has used various repetitive means in his paintings. Their significance in his work has not been sufficiently discussed; hence this thesis is an exploration of the role and the nature of repetition in Johns’s paintings, which is essential to better understand his artistic production.
Following a thorough review of his paintings, it is possible to broadly classify his use of repetition into three types: repeating images and gestures, using the logic of printing, and quoting and returning to past artists. I examine each of these in relation to three major art theory elements: abstraction, autonomy, and originality. When Johns repeats images and gestures, he also reconsiders abstraction in painting; using the logic of printing enables him to follow the logic of another medium and to challenge the autonomy of painting; by quoting other artists, Johns is reexamining originality in painting. These types of repetition are distinct in their features but complementary in their mission to expand the boundaries of painting. The proposed classification system enables a better understanding of the role and the nature of repetition in the specific case of Johns’s paintings, and it enriches our understanding of the use of repetition and its perception in art in general
Biodiesel production from Microalgae: Towards a sustainable closed loop through residual waste biodegradation
No full textNo doubt that the whole world facing energy crisis problems, therefore, three different biofuel generations have been developed to overcome fossil fuel depletion. As first generation biofuels have been shown to be unsustainable and insufficient to meet the increasing energy demands, due to the competition for arable lands and second generation biofuels have potential negative effects on carbon balances and biodiversity, Algal-based “third generation” biofuels, typically based on microalgae can overcome the drawbacks of the two others biofuel generations. To make the biofuel (biodiesel and biogas) production process from microalgae sustainable, it is essential that further cost reductions are applied to all steps and to make use of all the process waste and convert it to energy positive outcomes. Three scientific papers have been developed in the framework of my PhD thesis contributing process sustainability.
In the first paper (published) “Isolation and Screening of Non-toxic Thermo-tolerant Microalgae Strains Cultivated in Different Growth Media for Further Outdoor Applications”, we focused on robust strains selection which is the major bottleneck towards the process sustainability. Fresh water samples from Nile River / Egypt were investigated to select the most robust strains which have high growth rate and high lipid content at 40°C. Afterword the promising strains were cultivated in different growth media for further outdoor cultivation. Seven unicellular strains were able to grow fast with high lipid accumulation at 40°C; two from them can grow in synthetic human urine (SHU) as a synthetic wastewater. Lipid quantification has been done using Nile red stain method. Toxicity experiment carried out using Artemia salina shrimps to avoid using any toxic strains in outdoor cultivation. In addition, the promising strains were identified at molecular level by 18S and 16S rDNA sequencing
Simulation-Aided Continuous System Integration and Autonomous Knowledge Expansion in Real-World Robotic Systems
No full textAutonomous robotics in the real world is based on complex, interacting systems which demand for major integration efforts. In particular, the validation of such systems in order to reach production state raises the stakes in terms of parallelized testing and inter-workgroup interfacing. This thesis proposes to make use of a comprehensive simulation framework in order to increase the validation efficiency of such systems. Seamless integration into the testing pipeline allows for rapid development of components and validation under controlled conditions. This Continuous System Integration paradigm can be utilized to replace missing parts of the system, nevertheless ensuring realistic conditions, during the software development phase. Moreover, it is applicable during deployment in field trials as well where business logic can be replaced by simulated components with no overhead.
Additionally, with the foundations of a simulation framework being described and embedded into the context of system integration, this framework can further on be utilized for various knowledge expansion tasks, including benchmarking, optimization and autonomous reasoning needs. To open up these use cases, an abstract Simulation-Aided Knowledge Expansion concept is presented to run specified tasks in a loop within the simulation environment, making use of high-fidelity alignment with sensor data recorded in field trials. This concept allows for generating and expanding knowledge using the simulation in the sense that every iteration yields results which are supportive for use cases like benchmarking algorithms, optimizing parameters or increasing the basis of facts used in autonomous reasoning. For each of these use cases, an implementation of the concept is introduced and evaluated in detail
Investigations on the Chemistry of Coffee Processing
No full textThe International Coffee Organization announced that coffee consumption has increased for 4 years consecutively by 1.9 % every year from 2013/14 to 2016/17. The economic importance of coffee is continuously increasing, so that research on coffee becomes more and more important. Chlorogenic acids (CGAs) and caffeine are the best investigated components among all the coffee compounds after Clifford group developed easy identification method by using novel LC-MSn at 2003. They have been identified as the most health-affecting compounds in coffee.
A lot of coffee research has investigated the chemical composition of green or roasted coffee beans and the final cups of coffee by academics and industries, respectively. However, still there is little research studying the role of composition changes caused by each individual coffee processes. Furthermore, increasing demands of specialty coffee promotes new developments of coffee processes but the inventors need scientific input for analyzing the component with bioactivities to support and market their innovations.
In this thesis, the different stages of coffee processing have been investigated using suitable experiments in those stages; cultivating, grading, roasting and brewing steps were investigated. Additionally, those methods were applied to analyze Korean traditional green tea samples.
The different grades of Jamaican Blue Mountain coffee, a product of high price and rarity, were analyzed by LC-MSn together with different originated common coffees. The relative ratios of regioisomers of caffeoylquinic acids (CQAs) were determined as the possible specialty flavor for the first time from this source.
A new coffee product marketed as fermented coffee, obtained by a consecutive steaming and drying process was also investigated. This product, which is marketed as a roasting substitute for coffee, showed the highest antioxidant property if compared to the green coffee bean and two roasted coffee beans with different de