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Sea-ice thickness and porosity from multi-frequency electromagnetic induction sounding: Application to the sub-ice platelet layer in Atka Bay, Antarctica
No full textCharacterization of the sea-ice cover is of great importance for understanding processes and feedback mechanisms and predicting the evolution of the polar-climate system. One important climate relevant parameter, which can be used for this characterization, is sea-ice thickness. It can be retrieved by a variety of methods, where the majority is based on indirect determination from related parameters such as sea-ice draft or freeboard. A direct method that can be applied on the ground or from airborne platforms is electromagnetic (EM) induction sounding. In this thesis, the potential of EM sensors with multiple frequencies was investigated in designated case studies for the retrieval of sea-ice thickness, but also for the porosity of sea ice. A unique EM dataset over fast ice at Atka Bay, Antarctica was analyzed with a laterally-constrained Marquardt-Levenberg inversion. The results provide evidence that in addition to sea-ice, also platelet-layer thickness retrieval is possible using a non-destructive method, a finding which is expected to significantly facilitate its volume estimation in the future. The developed methodology is a crucial step in determining the relative contribution of sub-ice shelf processes to sea-ice mass balance in the Southern Ocean, and hence a valuable tool to better understand ocean/ice-shelf interaction
Phytochemical Analysis of Rhododendron Species
No full textThis research was successful in creating a polyphenolic profile of the leaves of 100 Rhododendron species from six subgenera. The polyphenolic profile of the fruits and flowers of a few Rhododendron species was also studied. This was achieved by using the technique of liquid chromatography coupled to mass spectrometry. Compounds were identified based on their retention time, UV absorption, fragmentation pattern and high resolution mass data.
The leaves of Rhododendron species were determined to be a good source of polyphenolic secondary metabolites with a total of 348 polyphenols identified. Out of 348 compounds, 221 compounds were novel in Rhododendron species and 7 compounds were novel in nature. The most abundant compounds included quercetin derivatives, protocatechuic acid-O-hexoside, catechin, epicatechin, procyanidin A and B dimers, kaempferol-O-rhamnoside, p-coumaric acid-O-hexoside, 3-O-caffeoylquinic acid and 5-O-caffeoylquinic acid.
From the identified secondary metabolites in Rhododendron species, a few marker compounds were identified for some individual Rhododendron species and also for the six subgenera. The use of polyphenolic secondary metabolites as chemotaxonomic markers needs to be assessed.
Multivariate statistical analysis was carried out to investigate whether phytochemistry, phylogeny and biological activity showed any correlation. The relative quantities of polyphenolic compounds were compared using box plots. Some compounds were found in higher intensity in certain subgenus. Some isomers of these compounds were found to be relatively more abundant than others. PCA plots and hierarchical clustering plot were generated using LC-TOF-MS data and it was determined that the genetically similar Rhododendron species produces a diverse variety of secondary metabolites. The number of compounds present in Rhododendron species was found to have no correlation to the ploidy level or their anti-bacterial activity against Bacillus subtilis
Complex Connections: How Self-Esteem and Group Identity Relate to Well-Being and Out-Group Negativity
No full textSocial identity theory suggests that when studying ‘the self’, both personal identity and social identity should be considered. Within the frame of social identity theory, the dissertation analyzes the role of personal self-esteem (PSE) and in-group attitudes in well-being and out-group negativity. Developments in implicit measures have demonstrated that people can hold different attitudes both at the explicit and implicit level. Therefore, the dissertation examines not only explicit, but also implicit attitudes towards the self and the in-group.
Chapter 1 provides a theoretical background to the empirical studies and emphasizes the research gaps and inconsistent results in the literature. Chapter 2, Article 1, which focuses on the link between PSE and well-being as well as in-group attitudes and well-being, presents the results of a study conducted with a Turkish majority (Turks in Turkey) and a minority group members (Turks in Germany and Bulgaria) in different contexts. The study draws conclusions regarding the consistent positive relation of explicit PSE to well-being across the three samples and the beneficial effect of in-group attitudes only for the well-being of the majority group. The study does not indicate a consistent relation of implicit attitudes to well-being across the groups. Chapter 3, Article 2 analyzes the main effects and intervening roles of immigrant (minority) and national citizenship identities for the relationship between perceived discrimination and well-being. The research, which was conducted with a peculiar immigrant group -Turkish immigrants from Bulgaria- who migrated to a country where their ethnic group is the majority, indicates the negative influence of perceived discrimination on well-being and the positive relationship of citizenship identification, rather than immigrant group identification, and well-being.
Chapter 4, Article 3, analyzes the interrelation of PSE and in-group attitudes with out-group negativity for a majority (Turks in Turkey) and minority groups (Turks in Germany and Bulgaria). Additionally, this research investigates the interaction of explicit and implicit PSE and the interaction of explicit and implicit in-group attitudes as predictors of out-group negativity. The findings suggest that while the increases in positive in-group attitudes predict out-group negativity for majority group members, increases in PSE associate with lower out-group negativity for the minority group members (Turks in Germany). Besides, the study highlights the negativity of people with damaged PSE: Among the majority group, people with damaged PSE direct their negativity toward out-group members, however, among the minority group (Turks in Bulgaria), people with damaged PSE are more negative toward in-group members.
Chapter 5, Article 4 analyzes the roles of in-group identification and implicit in-group attitudes in predicting out-group negativity in a sport context by considering the possible effect of identity threat. This study, which was conducted with the supporters of Werder Bremen, examines the explicit evaluations and physiological reactions towards both the stimuli representing in-group (Werder Bremen) and the stimuli shown in the neutral and identity threat conditions. Results demonstrate that people who are highly identified with Werder Bremen evaluate stimuli representing in-group more positively and they evaluate stimuli inducing identity threat more negatively.
Chapter 6, the discussion, provides a summary of the empirical chapters (chapters 2, 3, 4 and 5). In this section, theoretical and methodological contributions of the dissertation are highlighted and the findings of the studies are discussed within the frame of the research goals of the dissertation. This section also includes limitations and implications for further research that are the outcomes of the dissertation
Synthesis, Characterization and Properties of Polyoxopalladates and Organoantimony(III)-Substituted Heteropolytungstates
No full textPolyoxometalates (POMs) are discrete, polynuclear metal-oxides featured by an unmatched versatility in terms of structure and composition, giving rise to a broad range of applications in science and technology. The work presented in this dissertation comprises two research projects, polyoxopalladates(II) and organoantimony(III)-substituted heteropolytungstates. The obtained 24 novel compounds have been structurally characterized by a combination of solid-state techniques, such as single-crystal XRD, FT-IR spectroscopy, thermogravimetric and elemental analyses, and their solution stability was validated by multinuclear (e.g., 1H, 13C, 31P, 71Ga, 113Cd, 115In, 183W, and 205Tl) NMR, ESI-MS, and UV-vis spectroscopy
The Representation of American Visual Art in the USSR during the Cold War (1950s to the late 1960s)
No full textDuring the first two decades of the Cold War, Soviet institutions hosted dozens of exhibitions of American art. These exhibitions introduced works of a variety of styles, from figurative to abstract, to millions of Soviet citizens. Based on unique original materials from American and Russian archives, my thesis examines this extensive showcasing of American art. In my thesis, I argue that American visual art in the Soviet Union was subject to two distinct approaches to representation. The first approach was epitomized by Soviet-organized exhibitions of American leftist figurative artists such as Rockwell Kent. When promoting Kent, hardly a leading artist in the postwar United States, Soviet propaganda maintained that Kent’s art was underappreciated in America because of the artist’s sympathies for socialism and adherence to figurativeness. Soviet propaganda further argued that American bourgeois society preferred abstract art and was unable to appreciate genuine realist art. Ultimately, by representing Kent as a marginalized artist suffering under capitalism, the Soviet Union accused America's capitalist society of suppressing Kent—a genuine and genius artist from the Soviet point of view. As a result, Soviet discussions of Kent became intertwined with criticism of the United States and served as anti-American propaganda. The intersection of the Soviet discourse on American art with Soviet anti-Americanism was not limited to the case of Kent but was also relevant to other figurative and abstract artists, among them Anton Refregier, Emmy Lou Packard, Jackson Pollock and many others, whom I examine in my thesis.
The second approach was that of American institutions such as the United States Information Agency (USIA) which organized exhibitions showcasing contemporary American art, from figurative painting such as those by William Glackens to abstract expressionist painting such as by Willem de Kooning. (For the complete abstract, please see the thesis.
On the feasibility to engage heterogeneous communities in data gathering, sharing and enrichment
No full textMarine microbes play critical roles in the well being of the planet Earth and all its inhabitants. Not only do they influence chemical cycles, the marine food chain, but also the whole atmosphere and climate of our planet. However, the field of marine microbiology is still in its infancy and there is much more waiting to be explored. Here, I present a new approach to investigate global marine microbial diversity and function on a single day of the year, the 21st of June 2014/2015: the Ocean Sampling Day (OSD). The collection of a simultaneous, global dataset, required marine researchers, worldwide, to be connected. The aim was not only to create a snap shot of the marine microbial diversity fixed in time, but also to raise awareness amongst the general public of the important role these tiny organisms play in our daily lives. Therefore, professional scientists as well as the non-scientific public were invited to join the corresponding citizen science project, MyOSD. They supported OSD by providing oceanographic measurements and even microbial samples. Data collected by citizen scientists were validated and show that citizen science can contribute valuable data to marine research. A special focus was set on additional environmental measurements such as water temperature. This contextual data is important for the interpretation of microbial diversity in any given sample; however, it is still not common practice in marine microbial research to measure or report contextual data; OSD aims to make scientists more aware of this problem.
Extracting contextual data after a dataset or article has been published, is onerous work. Hence, I present two new tools to extract environmental information and geographic locations from scientific literature. The text mining tool, ENVIRONMENTS, automatically annotates scientific text with terms from the Environmental Ontology (EnvO). The PubMap application utilizes the power of the crowd to enable the creation of a manually curated database of georeferenced scientific publications.
Overall, this thesis shows that enabling collaboration within the scientific community as well as the non-scientific public, leads to achievements not only in gathering of new datasets, but also in enhancing present and historic scientific literature
The Malleability of Bias: Finding, Measuring, and Connecting Plural Rationalities
No full textPreferences and ways of life have in the literature been described as both stable and forever malleable. The Theory of Socio-Cultural Viability, of cultural theory for short, is approaching the puzzle from the angle of Anthropology and is commonly used in Political Science. In order to not only test the theory’s value and reliability, but also to develop new ways of employing it in assessing individuals’ and groups’ biases, the present dissertation is structured into three co-dependent papers.
The first study, Four Angles to Every Issue, investigates in how far an open-ended discussion of wicked problems leads to an emergence of all four cultures, as predicted by the theory, and supports the assumption of clustering and polarization of preferences in open debates. The second paper, Measuring the Malleable, then takes the analysis to the individual level. The results show that they do in fact remain the same within one context, but do not across life domains. This supports the assumption of multiple selves in the theory and is in line with much of psychological research. The third article then builds on this idea by illuminating cultural theory’s overlap with multiple theories from the field of Psychology. By identifying overlaps and potential links, the paper is able to explain the underlying processes and mechanisms of cultural theory with psychological findings.
The last chapter is the general discussion, which offers a synthesis of the presented findings, as well as options for further research. Continuing in the direction that this thesis has shown would allow a better understanding of human interaction and bias formation, as well as transmissions. The focus should from here on out lie on the mechanisms that enable the identified processes and thereby allow a better and more holistic understanding of how biases come about and change malleably
Induced pluripotent stem cells in a marmoset model for Parkinson's disease
No full textHuman ESC research raises ethical and political controversies. The reprogramming of already differentiated somatic cells to generate iPS cells avoids the ethical problems specific to ESC research. iPS cells can be efficiently differentiated into clinically relevant cell types. Hence, severe and currently incurable diseases like Parkinson could be cured in the future. Prior to clinical application in humans the safety and efficacy of the reprogrammed cells need to be tested long-term in animal models. In the present study, the common marmoset monkey(Callithrix jacchus) was used as a non-human primate model. In general, iPS cells could easily be generated by lentivirus-mediated introduction of a specific set of pluripotency-associated factors. However, approaches based on viruses stably integrating into the host cell DNA bear an increased risk of insertional mutagenesis and tumor formation. Substantial progress in cell replacement therapies may be achieved by generating autologous iPS cells with non-integrating and non-viral vector systems. For that reason, we used for the first time a non-integrating and non-viral episomal vector pEPI. Vector constructs with four marmoset monkey reprogramming factors (SOX2, OCT4, KLF4, cMYC (=SOKM)) and six factors (SOKM + LIN28 and NANOG (=SOKMLN)) were cloned. It could be shown that SOKMLN, which are expressed under the control of the constitutively active CAG promoter, were properly transcribed into mRNA. Furthermore, the expression of proteins encoded by the reprogramming construct could also be demonstrated. Finally, colony-like structures, properly representing putative primary integration-free iPS cell colonies, could be generated. The final characterization and differentiation of these colony-like structures are still pending. Nevertheless, the vector pEPI seems a promising tool for the generation of integration-free iPS cells, which may be used in preclinical testing of cell replacement therapies in marmoset monkeys
Exploiting nuclear quantum effects for hydrogen isotopologues separation in metal-organic frameworks
No full textThe thesis is devoted to the understanding of the nuclear quantum effects and the underlying mechanism of the hydrogen isotopologues (D2/HD/H2) separation in metal-organic frameworks, which involves fundamentals of quantum mechanics.
The thesis highlights the concept of nanoporous materials and specifically the relatively new class of crystalline compounds called metal-organic frameworks (MOFs). The accent is on the two types of MOFs. One type incorporates strongly unsaturated (also known as open) metal centers and the other possesses geometrically restricted, strongly confined pores. The metal centers and the defined pores are proven to be excellent sieves for the gas molecules. When exploiting the sieving in MOFs, we refer to the two main selective mechanisms for hydrogen isotopologues: Chemical Affinity Quantum Sieving (CAQS), which takes place when the highly attractive unsaturated metal centers are present and Kinetic Quantum Sieving (KQS), which occurs due to the strongly confined pores. The CAQS process is most pronounced at relatively high temperatures (100 K and above) while KQS manifest itself at nearly cryogenic temperature.
The theoretical background of this work is based on the approximate solutions of the complex quantum-mechanical systems e.g. the adsorption of D2/HD/H2 and their separation in MOFs. This involves Born-Oppenheimer approximation of the time independent non-relativistic Schrödinger equation, the solutions to the electronic and nuclear parts of the Schrödinger equation incorporating ab initio quantum-mechanical calculations for electronic structure and the methods for treating nuclear quantum effects
Structural and Functional relationship of OprP and OprO mutants of Pseudomonas aeruginosa and genome annotation of Dietzia maris
No full textPorins are water-filled pores across the outer cell membrane of Gram-negative bacteria, Gram-positive (mycolata) bacteria, mitochondria and chloroplast which allows diffusion of hydrophilic molecules across the membrane. This thesis focuses on the study of pores from the Gram-negative bacteria, Pseudomonas aeruginosa and the Gram-positive bacteria, Dietzia maris and Rhodococcus ruber.Pseudomonas aeruginosa can be found in a very vast environment such as soil, water, humans, animals, plants, sewage, and hospitals. Outer membrane of Pseudomonas aeruginosa consists of many specific porins. Out of these specific porins, OprP and OprO are phosphate specific porins, regulated at phosphate deficiency, which is an essential component for various biochemical activities inside the cell. For understanding the function of various amino acids in the lumen of these pores, two specific amino-acid were selected in OprP and OprO and they were interchanged. Two tyrosine at position62 and 114 positions in OprP were mutated to phenylalanine and aspartic acid of OprO. The double mutant of OprP behaved similar to OprO in single channel conductance and substrate specificity. Similarly, we also mutated phenylalanine at position 62 and aspartic acid at position 114 in OprO with two tyrosines. In this case also OprO double mutant behaved similar to OprP in substrate specificity but the single channel varied conductance.Dietzia maris and Rhodococcus ruber are mycolic acid containing Gram-positive bacteria. They have high G+C content. Whole genome of Dietzia maris was sequenced and annotated with automatic annotation by Rapid Annotations using Subsystems Technology (RAST) server and Prokaryotic Genomes Automatic Annotation Pipeline (PGAAP) and manual annotation by NCBI-Basic Local Alignment Search Tool (BLAST). Different species of Rhodococcus were searched to find homologous porins of MspA, which is a major porin in Mycobacterium smegmatis. This porin is used for nanopore–based DNA sequencing