@phdthesis{Simin2017, author = {Simin, Dmitrij}, title = {Quantum Sensing with Highly Coherent Spin Centers in Silicon Carbide}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-156199}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2017}, abstract = {In the present work, the energetic structure and coherence properties of the silicon vacancy point defect in the technologically important material silicon carbide are extensively studied by the optically detected magnetic resonance (ODMR) technique in order to verify its high potential for various quantum applications. In the spin vacancy, unique attributes are arising from the C3v symmetry and the spin-3/2 state, which are not fully described by the standard Hamiltonian of the uniaxial model. Therefore, an advanced Hamiltonian, describing well the appearing phenomena is established and the relevant parameters are experimentally determined. Utilizing these new accomplishments, several quantum metrology techniques are proposed. First, a vector magnetometry scheme, utilizing the appearance of four ODMR lines, allows for simultaneous detection of the magnetic field strength and the tilting angle of the magnetic field from the symmetry axis of the crystal. The second magnetometry protocol utilizes the appearance of energetic level anticrossings (LAC) in the ground state (GS) energy levels. Relying only on the change in photoluminescence in the vicinity of this GSLACs, this all-optical method does not require any radio waves and hence provides a much easier operation with less error sources as for the common magnetometry schemes utilizing quantum points. A similar all-optical method is applied for temperature sensing, utilizing the thermal shift of the zero field splitting and consequently the anticrossing in the excited state (ES). Since the GSLACs show no dependence on temperature, the all-optical magnetometry and thermometry (utilizing the ESLACs) can be conducted subsequently on the same defect. In order to quantify the achievable sensitivity of quantum metrology, as well as to prove the potential of the Si-vacancy in SiC for quantum processing, the coherence properties are investigated by the pulsed ODMR technique. The spin-lattice relaxation time T1 and the spin-spin relaxation time T2 are thoroughly analyzed for their dependence on the external magnetic field and temperature. For actual sensing implementations, it is crucial to obtain the best signal-to-noise ratio without loss in coherence time. Therefore, the irradiation process, by which the defects are created in the crystal, plays a decisive role in the device performance. In the present work, samples irradiated with electrons or neutrons with different fluences and energies, producing different defect densities, are analyzed in regard to their T1 and T2 times at room temperature. Last but not least, a scheme to substantially prolong the T2 coherence time by locking the spin polarization with the dynamic decoupling Carr-Purcell-Meiboom-Gill (CPMG) pulse sequence is applied.}, subject = {Siliciumcarbid}, language = {en} } @phdthesis{Hoffmann2017, author = {Hoffmann, Helene}, title = {Identifying regulators of tumor vascular morphology}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-142348}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2017}, abstract = {In contrast to normal vessels, tumor vasculature is structurally and functionally abnormal. Tumor vessels are highly disorganized, tortuous and dilated, with uneven diameter and excessive branching. Consequently, tumor blood flow is chaotic, which leads to hypoxic and acidic regions in tumors. These conditions lower the therapeutic effectiveness and select for cancer cells that are more malignant and metastatic. The therapeutic outcome could be improved by increasing the functionality and density of the tumor vasculature. Tumor angiogenesis also shows parallels to epithelial to mesenchymal transition (EMT), a process enabling metastasis. Metastasis is a multi-step process, during which tumor cells have to invade the surrounding host tissue to reach the circulation and to be transported to distant sites. We hypothesize that the variability in the phenotype of the tumor vasculature is controlled by the differential expression of key transcription factors. Inhibiting these transcription factors might be a promising way for angiogenic intervention and vascular re-engineering. Therefore, we investigated the interdependence of tumor-, stroma- and immune cell-derived angiogenic factors, transcription factors and resulting vessel phenotypes. Additionally, we evaluated whether transcription factors that regulate EMT are promising targets for vascular remodeling. We used formalin fixed paraffin embedded samples from breast cancer patients, classified according to estrogen-, progesterone- and human epidermal growth factor receptor (HER) 2 status. Establishing various techniques (CD34 staining, laser microdissection, RNA isolation and expression profiling) we systematically analyzed tumor and stroma-derived growths factors. In addition, vascular parameters such as microvessel size, area, circularity and density were assessed. Finally the established expression profiles were correlated with the observed vessel phenotype. As the SNAI1 transcriptional repressor is a key regulator of EMT, we examined the effect of vascular knockdown of Snai1 in murine cancer models (E0771, B16-F10 and lewis lung carcinoma). Among individual mammary carcinomas, but not among subtypes, strong differences of vascular parameters were observed. Also, little difference between lobular carcinomas and ductal carcinomas was found. Vessel phenotype of Her2 enriched carcinomas was similar to that of lobular carcinomas. Vessel morphology of luminal A and B and basal-like tumors resembled each other. Expression of angiogenic factors was variable across subtypes. We discovered an inverse correlation of PDGF-B and VEGF-A with vessel area in luminal A tumors. In these tumors expression of IL12A, an inhibitor of angiogenesis, was also correlated with vessel size. Treatment of endothelial cells with growth factors revealed an increased expression of transcription factors involved in the regulation of EMT. Knockdown of Snai1 in endothelial cells of mice increased tumor growth and decreased hypoxia in the E0771 and the B16-F10 models. In the lewis lung carcinomas, tumor vascularity and biodistribution of doxorubicin were improved. Here, doxorubicin treatment in combination with the endothelial cell-specific knockdown did slow tumor growth. This shows that SNAI1 is important for a tumor's vascularization, with the significance of its role depending on the tumor model. The methods established in this work open the way for the analysis of the expression of key transcription factors in vessels of formalin fixed paraffin embedded tumors. This research enables us to find novel targets for vascular intervention and to eventually design novel targeted drugs to inhibit these targets.}, subject = {Antiangiogenese}, language = {en} } @phdthesis{Danner2017, author = {Danner, Nadja}, title = {Honey bee foraging in agricultural landscapes}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-139322}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2017}, abstract = {1. Today honey bee colonies face a wide range of challenges in modern agricultural landscapes which entails the need for a comprehensive investigation of honey bees in a landscape context and the assessment of environmental risks. Within this dissertation the pollen foraging of honey bee colonies is studied in different agricultural landscapes to gain insight into the use of pollen resources and the influence of landscape structure across the season. General suggestions for landscape management to support honey bees and other pollinators are derived. 2. Decoding of waggle dances and a subsequent spatial foraging analysis are used as methods in Chapters 4 and 5 to study honey bee colonies in agricultural landscapes. The recently developed metabarcoding of mixed pollen samples was applied for the first time in honey bee foraging ecology and allowed for a detailed analysis of pollen, that was trapped from honey bees in front hive entrances (Chapter 6). 3. Pollen identification through molecular sequencing and DNA barcoding has been proposed as an alternative approach to light microscopy, which still is a tedious and error-prone task. In this study we assessed mixed pollen probes through next-generation sequencing and developed a bioinformatic workflow to analyse these high-throughput data with a newly created reference database. To evaluate the feasibility, we compared results from classical identification based on light microscopy from the same samples with our sequencing results. Abundance estimations from sequencing data were significantly correlated with counted abundances through light microscopy. Next-generation sequencing thus presents a useful and efficient workflow to identify pollen at the genus and species level without requiring specialized palynological expert knowledge. 4. During maize flowering, four observation hives were placed in and rotated between 11 landscapes covering a gradient in maize acreage. A higher foraging frequency on maize fields compared to other landuse types showed that maize is an intensively used pollen resource for honey bee colonies. Mean foraging distances were significantly shorter for maize pollen than for other pollen origins, indicating that effort is put into collecting a diverse pollen diet. The percentage of maize pollen foragers did not increase with maize acreage in the landscape and was not reduced by grassland area as an alternative pollen resource. Our findings allow estimating the distance-related exposure risk of honey bee colonies to pollen from surrounding maize fields treated with systemic insecticides. 5. It is unknown how an increasing area of mass-flowering crops like oilseed rape (OSR) or a decrease of semi-natural habitats (SNH) change the temporal and spatial availability of pollen resources for honey bee colonies, and thus foraging distances and frequency in different habitat types. Sixteen observation hives were placed in and rotated between 16 agricultural landscapes with independent gradients of OSR and SNH area within 2 km to analyze foraging distances and frequencies. SNH and OSR reduced foraging distance at different spatial scales and depending on season, with possible benefits for the performance of honey bee colonies. Frequency of pollen foragers per habitat type was equally high for SNH, grassland and OSR fields, but lower for other crops and forest. In landscapes with a small proportion of SNH a significantly higher density of pollen foragers on SNH was observed, indicating the limitation of pollen resources in simple agricultural landscapes and the importance of SNH. 6. Quantity and diversity of collected pollen can influence the growth and health of honey bee colonies, but little is known about the influence of landscape structure on pollen diet. In a field experiment we rotated 16 honey bee colonies across 16 agricultural landscapes (see also Chapter 5), used traps to get samples of collected pollen and observed the intra-colonial dance communication to gain information about foraging distances. Neither the amount of collected pollen nor pollen diversity were related to landscape diversity. The revealed increase of foraging distances with decreasing landscape diversity suggests that honey bees compensate for a lower landscape diversity by increasing their pollen foraging range in order to maintain pollen amount and diversity. 7. Our results show the importance of diverse pollen resources for honey bee colonies in agricultural landscapes. Beside the risk of exposure to pesticides honey bees face the risk of nutritional deficiency with implications for their health. By modifying landscape composition and therefore availability of resources we are able to contribute to the wellbeing of honey bees. Agri-environmental schemes aiming to support pollinators should focus on possible spatial and temporal gaps in pollen availability and diversity in agricultural landscapes.}, subject = {Apis mellifera}, language = {en} } @phdthesis{Kuen2017, author = {Kuen, Janina}, title = {Influence of 3D tumor cell/fibroblast co-culture on monocyte differentiation and tumor progression in pancreatic cancer}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-156226}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2017}, abstract = {Pancreatic cancer (PC) remains one of the most challenging solid tumors to treat with a high unmet medical need as patients poorly respond to standard-of-care-therapies. Prominent desmoplastic reaction involving cancer-associated fibroblasts (CAFs) and the immune cells in the tumor microenvironment (TME) and their cross-talk play a significant role in tumor immune escape and progression. To identify the key cellular mechanisms induce an immunosuppressive tumor microenvironment, we established 3D co-culture model with pancreatic cancer cells, CAFs, monocyte as well as T cells. Using this model, we analysed the influence of tumor cells and fibroblasts on monocytes and their immune suppressive phenotype. Phenotypic characterization of the monocytes after 3D co-culture with tumor/fibroblast spheroids was performed by analysing the expression of defined cell surface markers and soluble factors. Functionality of these monocytes and their ability to influence T cell phenotype and proliferation was investigated. 3D co-culture of monocytes with pancreatic cancer cells and fibroblasts induced the production of immunosuppressive cytokines which are known to promote polarization of M2 like macrophages and myeloid derived suppressive cells (MDSCs). These co-culture spheroid polarized monocyte derived macrophages (MDMs) were poorly differentiated and had an M2 phenotype. The immunosuppressive function of these co-culture spheroids polarized MDMs was demonstrated by their ability to inhibit autologous CD4+ and CD8+ T cell activation and proliferation in vitro, which we could partially reverse by 3D co-culture spheroid treatment with therapeutic molecules that are able to re-activate spheroid polarized MDMs or block immune suppressive factors such as Arginase-I. In conclusion, we generated a physiologically relevant 3D co-culture model, which can be used as a promising tool to study complex cell-cell interactions between different cell types within the tumor microenvironment and to support drug screening and development. In future, research focused on better understanding of resistance mechanisms to existing cancer immunotherapies will help to develop new therapeutic strategies in order to combat cancer.}, subject = {monocyte}, language = {en} } @phdthesis{Mahdiani2017, author = {Mahdiani, Maryam}, title = {Quantitative analysis of fatty acids, cholesterol and oxidation products thereof in human breast adipose tissues}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-156102}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2017}, abstract = {The aim of the present work was to determine the breast adipose tissue composition regarding fatty acids, cholesterol and (aut)oxidation products of cholesterol in women without breast cancer and to identify associated variables. Thus the necessary methods were optimized and validated where required and the breast adipose tissues of women without breast cancer were collected and analyzed. The gas chromatography with flame ionization detection was optimized for detection and separation of 37 relevant fatty acids. Fifty breast adipose tissues were analyzed using the optimized method. 26 fatty acids were detected in breast adipose tissues. The median proportion of saturated (sum of 11 fatty acids), monounsaturated (sum of 5 fatty acids), polyunsaturated (sum of 9 fatty acids) and one trans fatty acid were 34.6\%, 53.2\%, 12.1\% and 0.3\% respectively. Moreover, absolute levels of pentadecanoic acid (median: 0.37 mg/g, range: 0.08 - 1.31 mg/g), elaidic acid (median: 0.50 mg/g, range: 0.09 - 1.92 mg/g), linolenic acid (median: 0.88 mg/g, range: 0.10 - 3.06 mg/g) and docosahexaenoic acid (median: 0.31 mg/g, range: 0.04 - 1.80 mg/g) were determined in breast adipose tissues for the first time. These four fatty acids are indicative for consumption of dairy products, processed fats, vegetable oils such as flax seed oil and fish respectively. Furthermore, for the investigation of cholesterol in breast adipose tissues a gas chromatography was optimized and validated. The accuracies of the method in three independent spiked samples with low, medium and high levels of cholesterol were 99.1 ± 10.1\%, 87.0 ± 11.2\%, and 103.4 ± 4.6\% with precisions of 2.1, 2.1, and 0.8\% respectively. Using external calibration with internal standard cholesterol was quantified in samples (median: 1.1 mg/g, range: 0.7 - 1.5 mg/g). In order to detect (aut)oxidation products of cholesterol, gas chromatography coupled triple quadrupole mass spectrometry was optimized and validated. The accuracy was between 81.6\% and 115.7\% and precisions for low, medium and high oxy-cholesterols levels were below 10.0\%. The quantitative determination of (aut)oxidation products of cholesterol was established using external calibration with an internal standard. The most abundant oxy-cholesterol was 5,6β-Epoxy- (median: 147.2 ng/g, range: 25.7 - 624.2 ng/g), followed by 5,6α-Epoxy- (median: 34.6 ng/g, range: 9.9 - 124.7 ng/g), 7-Keto- (median: 19.1 ng/g, range: 7.9 - 220.6 ng/g), 7α-Hydroxy- (median: 10.2 ng/g, range: 3.8 - 111.3 ng/g) and 7β-Hydroxy-Cholesterol (median: 3.5 ng/g, range: 1.0 - 45.6 ng/g) respectively. Median oxy-cholesterol/cholesterol ratios ranged from 0.0001 (5,6β-Epoxy-Cholesterol) to 0.000003 (7β-Hydroxy-Cholesterol). Finally the associations between fatty acids, cholesterol and oxy-cholesterol were investigated using Spearman's rank correlation. Absolute levels of elaidic acid were positively correlated with levels of linolenic and docosahexaenoic acid (R = 0.79, 0.68, p < 0.01). Absolute levels of linolenic acid were positively associated with levels of docosahexaenoic acid (R = 0.81, p < 0.01). Moreover, relative proportions of saturated fatty acids capric, myristic, palmitic and stearic acid were negatively correlated with oleic acid (R = -0.36, -0.71, -0.65, -0.39, p < 0.05). Tissue levels of cholesterol were not correlated with levels of 5,6α/β-Epoxy-Cholesterols but were negatively associated with that of 7α-Hydroxy-, 7β-Hydroxy- and 7-Keto-Cholesterol (R = -0.29, -0.32, -0.29 p = 0.04, 0.02, 0.04). Levels of 7-Keto- and 7-Hydoxy-Cholesterol were strongly correlated with each other (R = 0.81, 0.91, p < 0.01) and, weaker, with 5,6α/β-Epoxy-Cholesterols (R = 0.60-0.70, p < 0.01). 5,6α/β-Epoxy-Cholesterols were associated positively with each other (R = 0.90, P < 0.01). Total oxy-cholesterol, 7β-Hydroxy-Cholesterol, and 5,6β-Epoxy-Cholesterol levels were correlated with relative proportions of elaidic acid (R = 0.30, 0.30, and 0.31 respectively, p = 0.04, 0.03, 0.03, respectively), whereas no correlation was observed between levels of oxy-cholesterols and relative proportion of pentadecanoic acid, linolenic acid and docosahexaenoic acid. Furthermore, Spearman's rank correlation was performed to investigate the relationship of fatty acids, cholesterol and oxy-cholesterol with age and body mass index. The relative proportions of total saturated fatty acids were negatively correlated with age (R = -0.47, p < 0.01) and body mass index (R = -0.29, p = 0.05). A positive significant correlation was observed between proportions of oleic acid and body mass index (R = 0.32, p = 0.02). There was no correlation between levels of cholesterol and body mass index or age. Likewise, no correlations of oxy-cholesterol levels with age or body mass index were observed. In sum, in this work the quantification methods of cholesterol and oxy-cholesterol were validated. The validation data met the criteria according to the FDA guideline. Using the validated methods the absolute levels of cholesterol and oxy-cholesterols were determined in breast adipose tissue of human females for the first time.}, subject = {Lebensmittelchemie}, language = {en} } @phdthesis{Karl2017, author = {Karl, Franziska}, title = {The role of miR-21 in the pathophysiology of neuropathic pain using the model of B7-H1 knockout mice}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-156004}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2017}, abstract = {The impact of microRNA (miRNA) as key players in the regulation of immune and neuronal gene expression and their role as master switches in the pathophysiology of neuropathic pain is increasingly recognized. miR-21 is a promising candidate that could be linked to the immune and the nociceptive system. To further investigate the pathophysiological role of miR-21 in neuropathic pain, we assesed mice deficient of B7 homolog 1 (B7-H1 ko), a protein with suppressive effect on inflammatory responses. B7-H1 ko mice and wildtype littermates (WT) of three different age-groups, young (8 weeks), middle-aged (6 months), and old (12 months) received a spared nerve injury (SNI). Thermal withdrawal latencies and mechanical withdrawal thresholds were determined. Further, we investigated anxiety-, depression-like and cognitive behavior. Quantitative real time PCR was used to determine miR-21 relative expression in peripheral nerves, dorsal root ganglia and white blood cells (WBC) at distinct time points after SNI. Na{\"i}ve B7-H1 ko mice showed mechanical hyposensitivity with increasing age. Young and middle-aged B7-H1 ko mice displayed lower mechanical withdrawal thresholds compared to WT mice. From day three after SNI both genotypes developed mechanical and heat hypersensitivity, without intergroup differences. As supported by the results of three behavioral tests, no relevant differences were found for anxiety-like behavior after SNI in B7-H1 ko and WT mice. Also, there was no indication of depression-like behavior after SNI or any effect of SNI on cognition in both genotypes. The injured nerves of B7-H1 ko and WT mice showed higher miR-21 expression and invasion of macrophages and T cells 7 days after SNI without intergroup differences. Perineurial miR-21 inhibitor injection reversed SNI-induced mechanical and heat hypersensitivity in old B7-H1 ko and WT mice. This study reveals that reduced mechanical thresholds and heat withdrawal latencies are associated with miR-21 induction in the tibial and common peroneal nerve after SNI, which can be reversed by perineurial injection of a miR-21 inhibitor. Contrary to expectations, miR-21 expression levels were not higher in B7-H1 ko compared to WT mice. Thus, the B7-H1 ko mouse may be of minor importance for the study of miR-21 related pain. However, these results spot the contribution of miR-21 in the pathophysiology of neuropathic pain and emphasize the crucial role of miRNA in the regulation of neuronal and immune circuits that contribute to neuropathic pain.}, subject = {neuropathic pain}, language = {en} } @phdthesis{Ritter2017, author = {Ritter, Cathrin}, title = {Scientific basics for new immunotherapeutic approaches towards Merkel cell carcinoma}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-124162}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2017}, abstract = {Merkel cell carcinoma (MCC) is an aggressive neuroendocrine skin cancer that has been associated with the Merkel cell polyomavirus (MCPyV). Indeed, MCC is one of the cancers with the best-established viral carcinogenesis. Despite persistence of the virus in MCC cells and the subsequent expression of viral antigens, the majority of MCC tumors are able to escape the surveillance of the immune system. Therefore the aim of the here presented thesis was to scrutinize immune escape mechanisms operative in MCC. A better understanding of their underlying molecular processes should allow to improve immunotherapeutic treatment strategies for MCC patients. The manuscripts included in this thesis characterize three novel immune evasion strategies of MCC. I) the epigenetic silencing of the NKG2D ligands MICA and MICB via histone H3 hypoacetylation II) reduced HLA class I surface expression via epigenetic silencing of the antigen processing machinery (APM) III) the activation of the PI3K-AKT pathway in a mutation independent manner as potential immune escape strategy MCC tumors and MCC cell lines were analyzed for their expression of MICA/B, HLA and components of the antigen processing machinery as well as for the activation of the PI3K-AKT pathway in situ and in vitro. These analysis reviled MICA and MICB, as well as HLA class I were not expressed or at least markedly reduced in ~80\% of MCCs in situ. The PI3K-AKT pathway, that had only recently been demonstrated to play a significant role in tumor immune escape, was activated in almost 90\% of MCCs in situ. To determine the underlying molecular mechanisms of these aberrations well characterized MCC cell lines were further analyzed in vitro. The fact that the PI3K-AKT pathway activation was due to oncogenic mutations in the PIK3CA or AKT1 gene in only 10\% of MCCs, suggested an epigenetic regulation of this pathway in MCC. In line with this MICA/B as well as components of the APM were indeed silenced epigenetically via histone hypoacetylation in their respective promoter region. Notably MICA/B and HLA class I expression on the cell surface of MCC cells could be restored after treatment with HDAC inhibitors in combination with the Sp1 inhibitor Mithramycin A in all analyzed MCC cell lines in vitro and in a xenotransplantation mouse model in vivo. Moreover inhibition of HDACs increased immune recognition of MCC cell lines in a MICA/B and HLA class I dependent manner. Several studies have accumulated evidence that immunotherapy is a promising treatment option for MCC patients due to the exquisite immunogenicity of this malignancy. However, current immunotherapeutic interventions towards solid tumors like MCC have to account for the plentitude of tumor immune escape strategies, in order to increase response rates. The immune escape mechanisms of MCC described in this thesis can be reverted by HDAC inhibition, thus providing the rationale to combine 'epigenetic priming' with currently tested immunotherapeutic regimens.}, subject = {Merkel-Zellkarzinom}, language = {en} } @phdthesis{Schmitt2017, author = {Schmitt, Franziska}, title = {Neuronal basis of temporal polyethism and sky-compass based navigation in \(Cataglyphis\) desert ants}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-142049}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2017}, abstract = {Desert ants of the genus Cataglyphis (Formicinae) are widely distributed in arid areas of the palearctic ecozone. Their habitats range from relatively cluttered environments in the Mediterranean area to almost landmark free deserts. Due to their sophisticated navigational toolkit, mainly based on the sky-compass, they were studied extensively for the last 4 decades and are an exceptional model organism for navigation. Cataglyphis ants exhibit a temporal polyethism: interior workers stay inside the dark nest and serve as repletes for the first ∼2 weeks of their adult life (interior I). They then switch to nursing and nest maintenance (interior II) until they transition to become day-active outdoor foragers after ∼4 weeks. The latter switch in tasks involves a transition phase of ∼2-3 days during which the ants perform learning and orientation walks. Only after this last phase do the ants start to scavenge for food as foragers. In this present thesis I address two main questions using Cataglyphis desert ants as a model organism: 1. What are the underlying mechanisms of temporal polyethism? 2. What is the neuronal basis of sky-compass based navigation in Cataglyphis ants? Neuropeptides are important regulators of insect physiology and behavior and as such are promising candidates regarding the regulation of temporal polyethism in Cataglyphis ants. Neuropeptides are processed from large precursor proteins and undergo substantial post-translational modifications. Therefore, it is crucial to biochemically identify annotated peptides. As hardly any peptide data are available for ants and no relevant genomic data has been recorded for Cataglyphis, I started out to identify the neuropeptidome of adult Camponotus floridanus (Formicinae) workers (manuscript 1). This resulted in the first neuropeptidome described in an ant species - 39 neuropeptides out of 18 peptide families. Employing a targeted approach, I identified allatostatin A (AstA), allatotropin (AT), short neuropeptide F (sNPF) and tachykinin (TK) using mass spectrometry and immunohistology to investigate the distribution of AstA, AT and TK in the brain (manuscript 2). All three peptides are localized in the central complex, a brain center for sensory integration and high-order control of locomotion behavior. In addition, AstA and TK were also found in visual and olfactory input regions and in the mushroom bodies, the centers for learning and memory formation. Comparing the TK immunostaining in the brain of 1, 7 and 14 days old dark kept animals revealed that the distribution in the central complex changes, most prominently in the 14 day old group. In the Drosophila central complex TK modulates locomotor activity levels. I therefore hypothesize that TK is involved in the internal regulation of the interior I-interior II transition which occurs after ∼2 weeks of age. I designed a behavioral setup to test the effect of neuropeptides on the two traits: 'locomotor activity level' and 'phototaxis' (manuscript 3). The test showed that interior I ants are less active than interior II ants, which again are less active than foragers. Furthermore, interior ants are negatively phototactic compared to a higher frequency of positive phototaxis in foragers. Testing the influence of AstA and AT on the ants' behavior revealed a stage-specific effect: while interior I behavior is not obviously influenced, foragers become positively phototactic and more active after AT injection and less active after AstA injection. I further tested the effect of light exposure on the two behavioral traits of interior workers and show that it rises locomotor activity and results in decreased negative phototaxis in interior ants. However, both interior stages are still more negatively phototactic than foragers and only the activity level of interior II ants is raised to the forager level. These results support the hypothesis that neuropeptides and light influence behavior in a stage-specific manner. The second objective of this thesis was to investigate the neuronal basis of skycompass navigation in Cataglyphis (manuscript 4). Anatomical localization of the sky-compass pathway revealed that its general organization is highly similar to other insect species. I further focused on giant synapses in the lateral complex, the last relay station before sky-compass information enters the central complex. A comparison of their numbers between newly eclosed ants and foragers discloses a rise in synapse numbers from indoor worker to forager, suggesting task-related synaptic plasticity in the sky-compass pathway. Subsequently I compared synapse numbers in light preexposed ants and in dark-kept, aged ants. This experiment showed that light as opposed to age is necessary and sufficient to trigger this rise in synapse number. The number of newly formed synapses further depends on the spectral properties of the light to which the ants were exposed to. Taken together, I described neuropeptides in C. floridanus and C. fortis, and provided first evidence that they influence temporal polyethism in Cataglyphis ants. I further showed that the extent to which neuropeptides and light can influence behavior depends on the animals' state, suggesting that the system is only responsive under certain circumstances. These results provided first insight into the neuronal regulation of temporal polyethism in Cataglyphis. Furthermore, I characterized the neuronal substrate for sky-compass navigation for the first time in Cataglyphis. The high level of structural synaptic plasticity in this pathway linked to the interior-forager transition might be particularly relevant for the initial calibration of the ants' compass system.}, subject = {Cataglyphis}, language = {en} } @phdthesis{Oesterreich2017, author = {Oesterreich, Babett}, title = {Preclinical development of an immunotherapy against antibiotic-resistant Staphylococcus aureus}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-123237}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2017}, abstract = {The Gram-positive bacterium Staphylococcus aureus is the leading cause of nosocomial infections. In particular, diseases caused by methicillin-resistant S. aureus (MRSA) are associated with higher morbidity, mortality and medical costs due to showing resistance to several classes of established antibiotics and their ability to develop resistance mechanisms against new antibiotics rapidly. Therefore, strategies based on immunotherapy approaches have the potential to close the gap for an efficient treatment of MRSA. In this thesis, a humanized antibody specific for the immunodominant staphylococcal antigen A (IsaA) was generated and thoroughly characterized as potential candidate for an antibody based therapy. A murine monoclonal antibody was selected for humanization based on its binding characteristics and the ability of efficient staphylococcal killing in mouse infection models. The murine antibody was humanized by CDR grafting and mouse and humanized scFv as well as scFv-Fc fragments were constructed for comparative binding studies to analyse the successful humanization. After these studies, the full antibody with the complete Fc region was constructed as isotype IgG1, IgG2 and IgG4, respectively to assess effector functions, including antibody-dependent killing of S. aureus. The biological activity of the humanized antibody designated hUK-66 was analysed in vitro with purified human PMNs and whole blood samples taken from healthy donors and patients at high risk of S. aureus infections, such as those with diabetes, end-stage renal disease, or artery occlusive disease (AOD). Results of the in vitro studies show, that hUK-66 was effective in antibody-dependent killing of S. aureus in blood from both healthy controls and patients vulnerable to S. aureus infections. Moreover, the biological activity of hUK-66 and hUK-66 combined with a humanized anti-alpha-toxin antibody (hUK-tox) was investigated in vivo using a mouse pneumonia model. The in vivo results revealed the therapeutic efficacy of hUK-66 and the antibody combination of hUK-66 and hUK-tox to prevent staphylococcal induced pneumonia in a prophylactic set up. Based on the experimental data, hUK-66 represents a promising candidate for an antibody-based therapy against antibiotic resistant MRSA.}, language = {en} } @phdthesis{ElBashir2017, author = {ElBashir, Rasha}, title = {Development of New Mass Spectrometry-based Methods for the Analysis of Posttranslational Modifications}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-153731}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2017}, abstract = {Posttranslational modifications (PTMs) play a crucial role in many cellular processes. They are reversible, dynamic, and highly regulated events that alter the properties of proteins and increase their functional diversity. The identification and quantification of PTMs are critical for deciphering the molecular mechanisms of PTMs-related biological processes and disease treatment and prevention. Two of the most common and important PTMs that regulate many protein functions are acetylation and phosphorylation. An important role of acetylation is the regulation of DNA/RNA-protein interactions. A prominent example for this are histones, whose tail regions are lysine-rich and can be highly acetylated at their N-terminal domain. In spite of the utmost importance of this PTM, methods that allow the accurate measuring the site-specific acetylation degree are missing. One of the challenges in quantifying the acetylation degree at an individual lysine residue of the histones N-termini is the occurrence of multiple lysines in close proximity. Herein, we describe the development of the "Fragment Ion Patchwork Quantification," a new mass spectrometry-based approach for the highly accurate quantification of sites-pecific acetylation degrees. This method combines 13C1-acetyl derivatization on the protein level, proteolysis by low-specificity proteases and quantification on the fragment ion level. Acetylation degrees are determined from the isotope patterns of acetylated b and y ions. We have shown that this approach allows determining the site-specific acetylation degrees of all lysine residues for all core histones of Trypanosoma brucei. In addition, we demonstrate the use of this approach to identify the substrate sites of histone acetyltransferases and to monitor the changes in acetylation of the histones of canonical nucleosome and transcription start site nucleosomes. Phosphorylation is one of the most common and most important PTMs. The analysis of the human genome showed that there are about 518 kinases and more than 500,000 phosphorylation sites are believed to exist in the cellular proteome. Protein phosphorylation plays a crucial role in signaling many different cell processes, such as intercellular communication, cell growth, differentiation of proliferation and apoptosis. Whereas MS-based identification and relative quantification of singly phosphorylated peptides have been greatly improved during the last decade, and large-scale analysis of thousands of phosphopeptides can now be performed on a routine-base, the analysis of multi-phosphorylated peptides is still lagging vastly behind. The low pKa value of phosphate group and the associated negative charge are considered the major source of the problems with the analysis of multi-phosphorylated peptides. These problems include the formation of phosphopeptide-metal complexes during liquid chromatography (e.g. Fe 3+), which leads to a drastic deterioration of the chromatographic properties of these peptides (peak tailing), the decreased ionization efficiencies of phosphorylated peptides compared to their unphosphorylated counterparts, the labile nature of phosphate during CID/HCD fragmentation, and the unsuitability of low-charged phosphopeptides for ETD fragmentation are the most important factors that hinder phosphorylation analysis by LC-MS/MS. Here we aimed to develop a method for improving the identification of multi-phosphorylated peptides as well as the localization of phosphorylation sites by charge-reversal derivatization of the phosphate groups. This method employs a carbodiimide-mediated phosphoramidation to converted the phosphates to stable aromatic phosphoramidates. This chemical modification of phosphosite(s) reversed the negative charge of the phosphate group(s) and increased the number of the positive charges within the phosphopeptide. This modification prevented the formation of phosphopeptide-metal ion complexes that dramatically decreases or completely diminishes the signal intensity of protonated phosphopeptides, specifically multi-phosphorylated peptides. Furthermore, the increased net charge the (phospho-)peptides made them suitable for ETD fragmentation, which generated a high number of fragment ions with high intensities that led to a better phosphopeptide identification and localization of phosphosite(s) with high confidence.}, subject = {LC-MS}, language = {en} } @phdthesis{Brueckner2017, author = {Br{\"u}ckner, Charlotte}, title = {The Electronic Structure and Optoelectronic Processes at the Interfaces in Organic Solar Cells Composed of Small Organic Molecules - A Computational Analysis of Molecular, Intermolecular, and Aggregate Aspects}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-141652}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2017}, abstract = {Describing the light-to-energy conversion in OSCs requires a multiscale understanding of the involved optoelectronic processes, i.e., an understanding from the molecular, intermolecular, and aggregate perspective. This thesis presents such a multiscale description to provide insight into the processes in the vicinity of the organic::organic interface, which are crucial for the overall performance of OSCs. Light absorption, exciton diffusion, photoinduced charge transfer at the donor-acceptor interface, and charge separation are included. In order to establish structure-property relationships, a variety of different molecular p-type semiconductors are combined at the organic donor-acceptor heterojunction with fullerene C60, one of the most common acceptors in OSCs. Starting with a comprehensive analysis of the accuracy of diverse ab initio, DFT, and semiempiric methods for the properties of the individual molecules, the intermolecular, and aggregate/device stage are subsequently addressed. At all stages, both methodological concepts and physical aspects in OSCs are discussed to extend the microscopic understanding of the charge generation processes.}, subject = {Benchmark}, language = {en} } @phdthesis{Spitznagel2017, author = {Spitznagel, Niko}, title = {Energy transfer during molten fuel coolant interaction}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-142891}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2017}, abstract = {The contact of hot melt with liquid water - called Molten Fuel Coolant Interaction (MFCI) - can result in vivid explosions. Such explosions can occur in different scenarios: in steel or powerplants but also in volcanoes. Because of the possible dramatic consequences of such explosions an investigation of the explosion process is necessary. Fundamental basics of this process are already discovered and explained, such as the frame conditions for these explosions. It has been shown that energy transfer during an MFCI-process can be very high because of the transfer of thermal energy caused by positive feedback mechanisms. Up to now the influence of several varying parameters on the energy transfer and the explosions is not yet investigated sufficiently. An important parameter is the melt temperature, because the amount of possibly transferable energy depends on it. The investigation of this influence is the main aim of this work. Therefor metallic tin melt was used, because of its nearly constant thermal material properties in a wide temperature range. With tin melt research in the temperature range from 400 °C up to 1000 °C are possible. One important result is the lower temperature limit for vapor film stability in the experiments. For low melt temperatures up to about 600 °C the vapor film is so unstable that it already can collapse before the mechanical trigger. As expected the transferred thermal energy all in all increases with higher temperatures. Although this effect sometimes is superposed by other influences such as the premix of melt and water, the result is confirmed after a consequent filtering of the remaining influences. This trend is not only recognizable in the amount of transferred energy, but also in the fragmentation of melt or the vaporizing water. But also the other influences on MFCI-explosions showed interesting results in the frame of this work. To perform the experiments the installation and preparation of the experimental Setup in the laboratory were necessary. In order to compare the results to volcanism and to get a better investigation of the brittle fragmentation of melt additional runs with magmatic melt were made. In the results the thermal power during energy transfer could be estimated. Furthermore the model of "cooling fragments " could be usefully applied.}, subject = {Vulkanologie}, language = {en} } @phdthesis{Borst2017, author = {Borst, Andreas}, title = {Apoptosis \& senescence: cell fate determination in inhibitor-treated melanoma cells}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-155085}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2017}, abstract = {Neoplasms of the skin represent the most frequent tumors worldwide; fortunately, most of them are benign or semi-malignant and well treatable. However, the two most aggressive and deadly forms of malignant skin-neoplasms are melanoma and Merkel cell carcinoma (MCC), being responsible for more than 90\% of skin-cancer related deaths. The last decade has yielded enormous progress in melanoma therapy with the advent of targeted therapies, like BRAF or MEK inhibitors, and immune-stimulating therapies, using checkpoint antibodies targeting CTLA- 4, PD-1 or PD-L1. Very recent studies suggest that also MCC patients benefit from a treatment with checkpoint antibodies. Nevertheless, in an advanced metastatic stage, a cure for both of these aggressive malignancies is still hard to achieve: while only a subset of patients experience durable benefit from the immune-based therapies, the widely applicable targeted therapies struggle with development of resistances that inevitably occur in most patients, and finally lead to their death. The four articles included in this thesis addressed current questions concerning therapy and carcinogenesis of melanoma and MCC. Moreover, they are discussed in the light of the up-to-date research regarding targeted and immune-based therapies. In article I we demonstrated that besides apoptosis, MAPK pathway inhibition in BRAF-mutated melanoma cells also induces senescence, a permanent cell cycle arrest. These cells may provide a source for relapse, as even permanently arrested cancer cells can contribute to a pro-tumorigenic milieu. To identify molecular factors determining the differential response, we established M14 melanoma cell line derived single cell clones that either undergo cell death or arrest when treated with BRAF/MEK inhibitors. Using these single cell clones, we demonstrated in article IV that downregulation of the pro-apoptotic BH3-only protein BIK via epigenetic silencing is involved in apoptosis deficiency, which can be overcome by HDAC inhibitors. These observations provide a possible explanation for the lack of a complete and durable response to MAPK inhibitor treatment in melanoma patients, and suggest the application of HDAC inhibitors as a complimentary therapy to MAPK pathway inhibition. Concerning MCC, we scrutinized the interactions between the Merkel cell polyomavirus' (MCV) T antigens (TA) and the tumor suppressors p53 and Rb in article II and III, respectively. In article III, we demonstrated that the cell cycle master regulator Rb is the crucial target of MCV large T (LT), while it - in contrast to other polyomavirus LTs - exhibits much lower affinity to the related proteins p107 and p130. Knockdown of MCV LT led to proliferation arrest in MCC cells, which can be rescued by knockdown of Rb, but not by knockdown of p107 and p130. Contrary to Rb, restriction of p53 in MCC seems to be independent of the MCV TAs, as we demonstrated in article II. In conclusion, the presented thesis has revealed new molecular details, regarding the response of melanoma cells towards an important treatment modality and the mechanisms of viral carcinogenesis in MCC.}, subject = {Melanom}, language = {en} } @phdthesis{Mann2017, author = {Mann, Daniel}, title = {"The smell of Ujamaa is still there" - Tanzania's Path of Development between Grassroots Socialism and Central State Control in Ruvuma}, edition = {1. Auflage}, publisher = {W{\"u}rzburg University Press}, address = {W{\"u}rzburg}, isbn = {978-3-95826-066-5 (print)}, issn = {0510-9833}, doi = {10.25972/WUP-978-3-95826-067-2}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-154079}, school = {W{\"u}rzburg University Press}, pages = {332}, year = {2017}, abstract = {In the 1960s, when most African nations gained their independence after the age of colonialism, several theories and strategies emerged with the goal of "developing" these apparently "underdeveloped" territories. One of the most influential approaches for this task was represented in Julius K. Nyerere´s idea of Ujamaa, the Tanzanian version of African socialism. Even before the Arusha Declaration established Ujamaa as a national development strategy in 1967, several groups of politicized young farmers took to the empty countryside of Tanzania to implement their own version of cooperative development. From one of these attempts emerged the Ruvuma Development Association (RDA), which organized up to 18 villages in southwestern Tanzania. The RDA became the inspiration for Nyerere´s concretization of Ujamaa and its implementation on national level. Yet, the central state could not replicate the success of the peasants, which was based on voluntariness and intrinsic motivation. In 2015, this exploratory study has revisited the Region of Ruvuma. Through a case study approach, relying mostly on qualitative methods, new insights into the local history of Ujamaa and its perception have been gathered. In particular, narrative interviews with contemporary witnesses and group interviews with the present-day farmers' groups have been conducted. Furthermore, NGOs active within the region, as well as regional and local government institutions were among the key stakeholders identified to concretize the local narrative of Ujamaa development. All interviews were analyzed according to the principles of qualitative content analysis. Additionally, individual villager questionnaires were used to achieve a more holistic picture of the local perception of development, challenges and the Ujamaa era. None of the original Ujamaa groups of the times of the RDA was still operational at the time of research and no case of village-wide organization of collective agriculture could be observed. Nevertheless, in all of the three case study villages, several farmers' groups (vikundi) were active in organizing development activities for their members. Furthermore, the perception of the Ujamaa era was generally positive throughout all of the case study sites. Yet, there have been significant differences in this perception, based on the village, age, gender and field size of the recipients. Overall, the period of Ujamaa was seen as an inspiration for present-day group activities, and the idea of such activities as a remedy for the developmental challenges of these villages was common among all stakeholders. This thesis concludes that the positive perception of group activities as a vehicle for village development and the perception of Ujamaa history as a positive asset for the inception and organization of farmers' groups would be highly beneficial to further attempts to support such development activities. However, the limitations in market access and capital availability for these highly-motivated group members have to be addressed by public and private development institutions. Otherwise, "the smell of Ujamaa" will be of little use for the progress of these villages.}, subject = {Ujamaa-Sozialismus}, language = {en} } @phdthesis{Schwab2017, author = {Schwab, Andrea}, title = {Development of an osteochondral cartilage defect model}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-155617}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2017}, abstract = {The limited intrinsic self-healing capability of articular cartilage requires treatment of cartilage defects. Material assisted and cell based therapies are in clinical practice but tend to result in formation of mechanical inferior fibro-cartilage in long term follow up. If a lesion has not been properly restored degenerative diseases are diagnosed as late sequela causing pain and loss in morbidity. Complex three dimensional tissue models mimicking physiological situation allow investigation of cartilage metabolism and mechanisms involved in repair. A standardized and reproducible model cultured under controllable conditions ex vivo to maintain tissue properties is of relevance for comparable studies. Topic of this thesis was the establishment of an cartilage defect model that allows for testing novel biomaterials and investigate the effect of defined defect depths on formation of repair tissue. In part I an ex vivo osteochondral defect model was established based on isolation of porcine osteochondral explants (OCE) from medial condyles, 8 mm in diameter and 5 mm in height. Full thickness cartilage defects with 1 mm to 4 mm in diameter were created to define ex vivo cartilage critical size after 28 days culture with custom developed static culture device. In part II of this thesis hydrogel materials, namely collagen I isolated from rat tail, commercially available fibrin glue, matrix-metalloproteinase clevable poly(ethylene glycol) polymerized with heparin (starPEGh), methacrylated poly(N-(2-hydroxypropyl) methacrylamide mono-dilactate-poly(ethylene glycol) triblock copolymer/methacrylated hyaluronic acid (MP/HA), thiol functionalized HA/allyl functionalized poly(glycidol) (P(AGE/G)-HA-SH), were tested cell free and chondrocyte loaded (20 mio/ml) as implant in 4 mm cartilage defects to investigate cartilage regeneration. Reproducible chondral defects, 8 mm in diameter and 1 mm in height, were generated with an artificial tissue cutter (ARTcut®) to investigate effect of defect depth on defect regeneration in part III. In all approaches OCE were analyzed by Safranin-O staining to visualize proteoglycans in cartilage and/or hydrogels. Immuno-histological and -fluorescent stainings (aggrecan, collagen II, VI and X, proCollagen I, SOX9, RUNX2), gene expression analysis (aggrecan, collagen II and X, SOX9, RUNX2) of chondrocyte loaded hydrogels (part II) and proteoglycan and DNA content (Part I \& II) were performed for detailed analysis of cartilage regeneration. Part I: The development of custom made static culture device, consisting of inserts in which OCE is fixed and deep well plate, allowed tissue specific media supply without supplementation of TGF � . Critical size diameter was defined to be 4 mm. Part II: Biomaterials revealed differences in cartilage regeneration. Collagen I and fibrin glue showed presence of cells migrated from OCE into cell free hydrogels with indication of fibrous tissue formation by presence of proCollagen I. In chondrocyte loaded study cartilage matrix proteins aggrecan, collagen II and VI and transcription factor SOX9 were detected after ex vivo culture throughout the two natural hydrogels collagen I and fibrin glue whereas markers were localized in pericellular matrix in starPEGh. Weak stainings resulted for MP/HA and P(AGE/G)-HA-SH in some cell clusters. Gene expression data and proteoglycan quantification supported histological findings with tendency of hypertrophy indicated by upregulation of collagen X and RunX2 in MP/HA and P(AGE/G)-HA-SH. Part III: In life-dead stainings recruitment of cells from OCE into empty or cell free collagen I treated chondral defects was seen. Separated and tissue specific media supply is critical to maintain ECM composition in cartilage. Presence of OCE stimulates cartilage matrix synthesis in chondrocyte loaded collagen I hydrogel and reduces hypertrophy compared to free swelling conditions and pellet cultures. Differences in cartilage repair tissue formation resulted in preference of natural derived polymers compared to synthetic based materials. The ex vivo cartilage defect model represents a platform for testing novel hydrogels as cartilage materials, but also to investigate the effect of cell seeding densities, cell gradients, cell co-cultures on defect regeneration dependent on defect depth. The separated media compartments allow for systematic analysis of pharmaceutics, media components or inflammatory cytokines on bone and cartilage metabolism and matrix stability.}, subject = {Hyaliner Knorpel}, language = {en} } @phdthesis{Pieger2017, author = {Pieger, Elisabeth}, title = {Metacognition and Disfluency - The Effects of Disfluency on Monitoring and Performance}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-155362}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2017}, abstract = {In this thesis, metacognition research is connected with fluency research. Thereby, the focus lies on how disfluency can be used to improve metacognitive monitoring (i.e., students` judgments during the learning process). Improving metacognitive monitoring is important in educational contexts in order to foster performance. Theories about metacognition and self-regulated learning suppose that monitoring affects control and performance. Accurate monitoring is necessary to initiate adequate control and better performance. However, previous research shows that students are often not able to accurately monitor their learning with meaningful text material. Inaccurate monitoring can result in inadequate control and low performance. One reason for inaccurate monitoring is that students use cues for their judgments that are not valid predictors of their performance. Because fluency might be such a cue, the first aim of this thesis is to investigate under which conditions fluency is used as a cue for judgments during the learning process. A fluent text is easy to process and, hence, it should be judged as easy to learn and as easy to remember. Inversely, a disfluent text is difficult to process, for example because of a disfluent font type (e.g., Mistral) or because of deleted letters (e.g., l_tt_rs). Hence, a disfluent text should be judged as difficult to learn and as difficult to remember. This assumption is confirmed when students learn with both fluent and disfluent material. When fluency is manipulated between persons, fluency seems to be less obvious as a cue for judgments. However, there are only a few studies that investigated the effects of fluency on judgments when fluency is manipulated between persons. Results from Experiment 1 (using deleted letters for disfluent text) and from Experiment 4 (using Mistral for disfluent text) in this thesis support the assumption that fluency is used as a cue for judgments in between-person designs. Thereby, however, the interplay with the type of judgment and the learning stage seems to matter. Another condition when fluency affects judgments was investigated in Experiment 2 and 3. The aim of these experiments was to investigate if disfluency leads to analytic monitoring and if analytic monitoring sustains for succeeding fluent material. If disfluency activates analytic monitoring that remains for succeeding fluent material, fluency should no longer be used as a cue for judgments. Results widely support this assumption for deleted letters (Experiment 2) as well as for the font type Mistral (Experiment 3). Thereby, again the interplay between the type of judgment and the learning stage matters. Besides the investigation of conditions when fluency is used as a cue for different types of judgments during the learning process, another aim of this thesis is to investigate if disfluency leads to accurate monitoring. Results from Experiment 3 and 4 support the assumption that Mistral can reduce overconfidence. This is the case when fluency is manipulated between persons or when students first learn with a fluent and then with a disfluent text. Dependent from the type of judgment and the learning stage, disfluency can lead even to underconfidence or to improved relative monitoring accuracy (Experiment 4). Improving monitoring accuracy is only useful when monitoring is implemented into better control and better performance. The effect of monitoring accuracy on control and performance was in the focus of Experiment 4. Results show that accurate monitoring does not result in improved control and performance. Thus, further research is required to develop interventions that do not only improve monitoring accuracy but that also help students to implement accurate monitoring into better control and performance. Summing up, the aim of this thesis is to investigate under which conditions fluency is used as a cue for judgments during the learning process, how disfluency can be used to improve monitoring accuracy, and if improved monitoring accuracy leads to improved performance. By connecting metacognition research and fluency research, further theories about metacognition and theories about fluency are specified. Results show that not only the type of fluency and the design, but also the type of judgment, the type of monitoring accuracy, and the learning stage should be taken into account. Understanding conditions that affect the interplay between metacognitive processes and performance as well as understanding the underlying mechanisms is necessary to enable systematic research and to apply findings into educational settings.}, subject = {Metakognition}, language = {en} } @phdthesis{Brendel2017, author = {Brendel, Michael}, title = {Correlation between Interface Energetics of Molecular Semiconductors and Opto-Electronic Properties of Planar Organic Solar Cells}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-155094}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2017}, abstract = {It was the scope of this work to gain a deeper understanding of the correlation between Interface energetics of molecular semiconductors in planar organic solar cells and the corresponding optoelectronic characteristics. For this aim, different approaches were followed. At first, a direct variation of donor/acceptor (D/A) interface energetics of bilayer cells was achieved by utilizing systematically modified donor compounds. This change could be correlated to the macroscopic device performance. At second, the impact of interface energetics was illustrated, employing a more extended device architecture. By introducing a thin interlayer between a planar D/A heterojunction, an energetic staircase was established. Exciton dissociation in such devices could be linked to the cascade energy level alignment of the photo-active materials. Finally, two different fullerene molecules C60 and C70 were employed in co-evaporated acceptor phases. The expected discrepancy in their electronic structure was related to the transport properties of the corresponding organic photovoltaic cells (OPVCs). The fullerenes are created simultaneously in common synthesis procedures. Next to the photo-physical relevance, the study was carried-out to judge on the necessity of separating the components from each other by purification which constitutes the cost-determining step in the total production costs.}, subject = {Organische Solarzelle}, language = {en} } @phdthesis{Nwaila2017, author = {Nwaila, Tsundukani Glen}, title = {Geochemistry of Palaeoarchaean to Palaeoproterozoic Kaapvaal Craton marine shales: Implications for sediment provenance and siderophile elements endowment}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-155326}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2017}, abstract = {The Kaapvaal Craton hosts a number of large gold deposits (e.g. Witwatersrand Supergroup) which mining companies have exploited at certain stratigraphic positions. It also hosts the largest platinum group element (PGE) deposits (e.g. Bushveld Igneous Complex) which mining companies have exploited in different mineralised layered magmatic zones. In spite of the extensive exploration history in the Kaapvaal Craton, the origin of the Witwatersrand gold deposits and Bushveld Igneous Complex PGE deposits has remained one of the most debated topics in economic geology. The goal of this study was to identify the geochemical characteristics of marine shales in the Barberton, Witwatersrand, and Transvaal supergroups in South Africa in order to make inferences on their sediment provenance and siderophile element endowments. Understanding why some of the Archaean and Proterozoic hinterlands are heavily mineralised, compared to others with similar geological characteristics, will aid in the development of more efficient exploration models. Fresh, unmineralised marine shales from the Barberton (Fig Tree and Moodies groups), Witwatersrand (West Rand and Central Rand groups), and Transvaal (Black Reef Formation and Pretoria Group) supergroups were sampled from drill core and underground mining exposures. Analytical methods, such as X-ray powder diffraction (XRD), optical microscopy, X-ray fluorescence (XRF), inductively coupled plasma optical emission spectroscopy (ICP-OES), inductively coupled plasma mass spectrometry (ICP-MS), and electron microprobe analysis (EMPA) were applied to comprehensively characterise the shales. All of the Au and PGE assays examined the newly collected shale samples. The Barberton Supergroup shales consist mainly of quartz, illite, chlorite, and albite, with diverse heavy minerals, including sulfides and oxides, representing the minor constituents. The regionally persistent Witwatersrand Supergroup shales consist mainly of quartz, muscovite, and chlorite, and also contain minor constituents of sulfides and oxides. The Transvaal Supergroup shales comprise quartz, chlorite, and carbonaceous material. Major, trace (including rare-earth element) concentrations were determined for shales from the above supergroups to constrain their source and post-depositional evolution. Chemical variations were observed in all the studied marine shales. Results obtained from this study revealed that post-depositional modification of shale chemistry was significant only near contacts with over- and underlying coarser-grained siliciclastic rocks and along cross-cutting faults, veins, and dykes. Away from such zones, the shale composition remained largely unaltered and can be used to draw inferences concerning sediment provenance and palaeoweathering in the source region and/or on intrabasinal erosion surfaces. Evaluation of weathering profiles through sections of the studied supergroups revealed that the shales therein are characterised by high chemical index of alteration (CIA), chemical index of weathering (CIW), and index of compositional variability (ICV), suggesting that the source area was lithologically complex and subject to intense chemical weathering. A progressive change in the chemical composition was identified, from a dominant ultramafic-mafic source for the Fig Tree Group to a progressively felsic-plutonic provenance for the Moodies Group. The West Rand Group of the Witwatersrand Supergroup shows a dominance of tonalite-trondhjemite-granodiorite and calcalkaline granite sources. Compositional profiles through the only major marine shale unit within the Central Rand Group indicate the progressive unroofing of a granitic source in an otherwise greenstone-dominated hinterland during the course of sedimentation. No plausible likely tectonic setting was obtained through geochemical modelling. However, the combination of the systematic shale chemistry, geochronology, and sedimentology in the Witwatersrand Supergroup supports the hypothesised passive margin setting for the >2.98 to 2.91 Ga West Rand Group, and an active continental margin source for the overlying >2.90 to 2.78 Ga Central Rand Group, along with a foreland basin setting for the latter. Ultra-low detection limit analyses of gold and PGE concentrations revealed a variable degree of gold accumulation within pristine unmineralised shales. All the studied shales contain elevated gold and PGE contents relative to the upper continental crust, with marine shales from the Central Rand Group showing the highest Au (±9.85 ppb) enrichment. Based on this variation in the provenance of contemporaneous sediments in different parts of the Kaapvaal Craton, one can infer that the siderophile elements were sourced from a fertile hinterland, but concentrated into the marine shales by a combination of different processes. It is proposed that accumulation of siderophile elements in the studied marine shales was mainly controlled by mechanical coagulation and aggregation. These processes involved suspended sediments, fine gold particles, and other trace elements being trapped in marine environments. Mechanical coagulation and aggregation resulted in gold enrichments by 2-3 orders of magnitude, whereas some of the gold in these marine shales can be reconciled by seawater adsorption into sedimentary pyrite. For the source of gold and PGEs in the studied marine shales in the Kaapvaal Craton, a genetic model is proposed that involves the following: (1) A highly siderophile elements enriched upper mantle domain, herein referred to as "geochemically anomalous mantle domain", from which the Kaapvaal crust was sourced. This mantle domain enriched in highly siderophile elements was formed either by inhomogeneous mixing with cosmic material that was added during intense meteorite bombardment of the Hadaean to Palaeoarchaean Earth or by plume-like ascent of relics from the core-mantle boundary. In both cases, elevated siderophile elements concentrations would be expected. The geochemically anomalous mantle domain is likely the ultimate source of the Witwatersrand modified palaeoplacer gold deposits and was tapped again ca. 2.054 Ga during the emplacement of the Bushveld Igneous Complex. Therefore, I propose that there is a genetic link (i.e. common geochemically anomalous mantle source) between the Witwatersrand gold deposits and the younger Bushveld Igneous Complex PGE deposits. (2) Scavenging of crustal gold by various surface processes such as trapping of gold from Archaean/Palaeoproterozoic river water on the surface of local photosynthesizing cyanobacterial or microbial mats, and reworking of these mats into erosion channels during flooding events. The above two models complement each other, with model (1) providing a common geological source for the Witwatersrand gold and Bushveld Igneous Complex PGE deposits, and model (2) explaining the processes responsible for Witwatersrand-type gold pre-concentration processes. In sequences such as the Transvaal Supergroup, a less fertile hinterland and/or less reworking of older sediments led to a correspondingly lower gold endowment. These findings indicate temporal distribution of siderophile elements in the upper crust (e.g. marine shales). The overall implications of these findings are that background concentrations of gold and PGEs can be used to target potential exploration areas in other cratons of similar age. This increases the likelihood of finding other Witwatersrand-type gold or Bushveld Igneous Complex-type PGE deposits in other cratons.}, subject = {Gold}, language = {en} } @phdthesis{Scholz2017, author = {Scholz, Nicole}, title = {Genetic analyses of sensory and motoneuron physiology in Drosophila melanogaster}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-123249}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2017}, abstract = {During my PhD I studied two principal biological aspects employing Drosophila melanogaster. Therefore, this study is divided into Part I and II. Part I: Bruchpilot and Complexin interact to regulate synaptic vesicle tethering to the active zone cytomatrix At the presynaptic active zone (AZ) synaptic vesicles (SVs) are often physically linked to an electron-dense cytomatrix - a process referred to as "SV tethering". This process serves to concentrate SVs in close proximity to their release sites before contacting the SNARE complex for subsequent fusion (Hallermann and Silver, 2013). In Drosophila, the AZ protein Bruchpilot (BRP) is part of the proteinous cytomatrix at which SVs accumulate (Kittel et al., 2006b; Wagh et al., 2006; Fouquet et al., 2009). Intriguingly, truncation of only 1\% of the C-terminal region of BRP results in a severe defect in SV tethering to this AZ scaffold (hence named brpnude; Hallermann et al., 2010b). Consistent with these findings, cell-specific overexpression of a C-terminal BRP fragment, named mBRPC-tip (corresponds to 1\% absent in brpnude; m = mobile) phenocopied the brpnude mutant in behavioral and functional experiments. These data indicate that mBRPC-tip suffices to saturate putative SV binding sites, which induced a functional tethering deficit at motoneuronal AZs. However, the molecular identity of the BRP complement to tether SVs to the presynaptic AZ scaffold remains unknown. Moreover, within larval motoneurons membrane-attached C-terminal portions of BRP were sufficient to tether SVs to sites outside of the AZ. Based on this finding a genetic screen was designed to identify BRP interactors in vivo. This screen identified Complexin (CPX), which is known to inhibit spontaneous SV fusion and to enhance stimulus evoked SV release (Huntwork and Littleton, 2007; Cho et al., 2010; Martin et al., 2011). However, so far CPX has not been associated with a function upstream of priming/docking and release of SVs. This work provides morphological and functional evidence, which suggests that CPX promotes recruitment of SVs to the AZ and thereby curtails synaptic short-term depression. Together, the presented findings indicate a functional interaction between BRP and CPX at Drosophila AZs. Part II: The Adhesion-GPCR Latrophilin/CIRL shapes mechanosensation The calcium independent receptor of α-latrotoxin (CIRL), also named Latrophilin, represents a prototypic Adhesion class G-protein coupled-receptor (aGPCR). Initially, Latrophilin was identified based on its capacity to bind the α-component of latrotoxin (α-LTX; Davletov et al., 1996; Krasnoperov et al., 1996), which triggers massive exocytotic activity from neurons of the peripheral nervous system (Scheer et al., 1984; Umbach et al., 1998; Orlova et al., 2000). As a result Latrophilin is considered to play a role in synaptic transmission. Later on, Latrophilins have been associated with other biological processes including tissue polarity (Langenhan et al., 2009), fertility (Pr{\"o}mel et al., 2012) and synaptogenesis (Silva et al., 2011). However, thus far its subcellular localization and the identity of endogenous ligands, two aspects crucial for the comprehension of Latrophilin's in vivo function, remain enigmatic. Drosophila contains only one latrophilin homolog, named dCirl, whose function has not been investigated thus far. This study demonstrates abundant dCirl expression throughout the nervous system of Drosophila larvae. dCirlKO animals are viable and display no defects in development and neuronal differentiation. However, dCirl appears to influence the dimension of the postsynaptic sub-synaptic reticulum (SSR), which was accompanied by an increase in the postsynaptic Discs-large abundance (DLG). In contrast, morphological and functional properties of presynaptic motoneurons were not compromised by the removal of dCirl. Instead, dCirl is required for the perception of mechanical challenges (acoustic-, tactile- and proprioceptive stimuli) through specialized mechanosensory devices, chordotonal organs (Eberl, 1999). The data indicate that dCirl modulates the sensitivity of chordotonal neurons towards mechanical stimulation and thereby adjusts their input-output relation. Genetic interaction analyses suggest that adaption of the molecular mechanotransduction machinery by dCirl may underlie this process. Together, these results uncover an unexpected function of Latrophilin/dCIRL in mechanosensation and imply general modulatory roles of aGPCR in mechanoception.}, subject = {Drosophila}, language = {en} } @phdthesis{Stritt2017, author = {Stritt, Simon}, title = {The role of the cytoskeleton in platelet production and the pathogenesis of platelet disorders in humans and mice}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-122662}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2017}, abstract = {Platelets are continuously produced from megakaryocytes (MK) in the bone marrow by a cytoskeleton-driven process of which the molecular regulation is not fully understood. As revealed in this thesis, MK/ platelet-specific Profilin1 (Pfn1) deficiency results in micro- thrombocytopenia, a hallmark of the Wiskott-Aldrich syndrome (WAS) in humans, due to accelerated platelet turnover and premature platelet release into the bone marrow. Both Pfn1-deficient mouse platelets and platelets isolated from WAS patients contained abnormally organized and hyper-stable microtubules. These results reveal an unexpected function of Pfn1 as a regulator of microtubule organization and point to a previously unrecognized mechanism underlying the platelet formation defect in WAS patients. In contrast, Twinfilin2a (Twf2a) was established as a central regulator of platelet reactivity and turnover. Twf2a-deficient mice revealed an age-dependent macrothrombocytopenia that could be explained by a markedly decreased platelet half-life, likely due to the pronounced hyper-reactivity of \(Twf2a^{-/-}\) platelets. The latter was characterized by sustained integrin acti- vation and thrombin generation in vitro that translated into accelerated thrombus formation in vivo. To further elucidate mechanisms of integrin activation, Rap1-GTP-interacting adaptor molecule (RIAM)-null mice were generated. Despite the proposed critical role of RIAM for platelet integrin activation, no alterations in this process could be found and it was concluded that RIAM is dispensable for the activation of β1 and β3 integrins, at least in platelets. These findings change the current mechanistic understanding of platelet integrin activation. Outside-in signaling by integrins and other surface receptors was supposed to regulate MK migration, but also the temporal and spatial formation of proplatelet protrusions. In this the- sis, phospholipase D (PLD) was revealed as critical regulator of actin dynamics and podo- some formation in MKs. Hence, the unaltered platelet counts and production in \(Pld1/2^{-/-}\) mice and the absence of a premature platelet release in the bone marrow of \(Itga2^{-/-}\) mice question the role of podosomes in platelet production and raise the need to reconsider the proposed inhibitory signaling by α2β1 integrins on proplatelet formation. Non-muscle myosin IIA (NMMIIA) has been implicated as a downstream effector of the in- hibitory signals transmitted via α2β1 integrins. Besides Rho-GTPase signaling, also \(Mg^{2+}\) and transient receptor potential melastatin-like 7 (TRPM7) channel α-kinase are known regulators of NMMIIA activity. In this thesis, TRPM7 was identified as major regulator of \(Mg^{2+}\) homeostasis in MKs and platelets. Furthermore, decreased \([Mg^{2+}]_i\) led to deregulated NMMIIA activity and altered cytoskeletal dynamics that impaired thrombopoiesis and resulted in macrothrombocytopenia in humans and mice.}, subject = {Thrombozytopoese}, language = {en} } @phdthesis{LyTung2017, author = {Ly Tung, Nam}, title = {Toward an Intelligent Long-Term Assistance for People with Dementia In the Context of Navigation in Indoor Environments}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-155235}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2017}, abstract = {Dementia is a complex neurodegenerative syndrome that by 2050 could affect about 135 Million people worldwide. People with dementia experience a progressive decline in their cognitive abilities and have serious problems coping with activities of daily living, including orientation and wayfinding tasks. They even experience difficulties in finding their way in a familiar environment. Being lost or fear of getting lost may consequently develop into other psychological deficits such as anxiety, suspicions, illusions, and aggression. Frequent results are social isolation and a reduced quality of life. Moreover, the lives of relatives and caregivers of people with dementia are also negatively affected. Regarding navigation and orientation, most existing approaches focus on outdoor environment and people with mild dementia, who have the capability to use mobile devices. However, Rasquin (2007) observe that even a device with three buttons may be too complicated for people with moderate to severe dementia. In addition, people who are living in care homes mainly perform indoor activities. Given this background, we decided to focus on designing a system for indoor environments for people with moderate to severe dementia, who are unable or reluctant to use smartphone technology. Adopting user-centered design approach, context and requirements of people with dementia were gathered as a first step to understand needs and difficulties (especially in spatial disorientation and wayfinding problems) experienced in dementia care facilities. Then, an "Implicit Interactive Intelligent (III) Environment" for people with dementia was proposed emphasizing implicit interaction and natural interface. The backbone of this III Environment is based on supporting orientation and navigation tasks with three systems: a Monitoring system, an intelligent system, and a guiding system. The monitoring system and intelligent system automatically detect and interpret the locations and activities performed by the users i.e. people with dementia. This approach (implicit input) reduces cognitive workload as well as physical workload on the user to provide input. The intelligent system is also aware of context, predicts next situations (location, activity), and decides when to provide an appropriate service to the users. The guiding system with intuitive and dynamic environmental cues (lighting with color) has the responsibility for guiding the users to the places they need to be. Overall, three types of a monitoring system with Ultra-Wideband and iBeacon technologies, different techniques and algorithms were implemented for different contexts of use. They showed a high user acceptance with a reasonable price as well as decent accuracy and precision. In the intelligent system, models were built to recognize the users' current activity, detect the erroneous activity, predict the next location and activity, and analyze the history data, detect issues, notify them and suggest solutions to caregivers via visualized web interfaces. About the guiding systems, five studies were conducted to test and evaluate the effect of lighting with color on people with dementia. The results were promising. Although several components of III Environment in general and three systems, in particular, are in place (implemented and tested separately), integrating them all together and employing this in the dementia context as a fully properly evaluation with formal stakeholders (people with dementia and caregivers) are needed for the future step.}, language = {en} } @phdthesis{Wirth2017, author = {Wirth, Robert}, title = {Consequences of bending and breaking the rules}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-155075}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2017}, abstract = {Social life is organized around rules and norms. The present experiments investigate the cognitive architecture of rule violations. To do so, a setting with arbitrary rules that had to be followed or broken was developed, and breaking these rules did not have any negative consequences. Removed from any social influences that might further encourage or hinder the rule breaker, results suggest that simply labeling a behavior as a rule violation comes with specific costs: They are more difficult to plan and come with specific behavioral markers during execution. In essence, rule violations resemble rule negations, but they also trigger additional processes. The question of what makes rule violations more difficult than rule inversions is the major focus of the remaining experiments. These experiments revealed negative affective consequences of rule violation and rule inversions alike, while rule violations additionally prime authority-related concepts, thus sensitizing towards authority related stimuli. Next, the question how these burdens of non-conformity can be mitigated was investigated, and the influence of having executed the behavior in question frequently and recently was tested in both negations and rule violations. The burdens of non-conformity can best be reduced by a combination of having violated/negated a rule very frequently and very recently. Transfer from another task, however, could not be identified. To conclude, a model that accounts for the data that is currently presented is proposed. As a variant of a task switching model, it describes the cognitive processes that were investigated and highlights unique processing steps that rule violations seem to require.}, subject = {Soziale Norm}, language = {en} } @phdthesis{Fuchs2017, author = {Fuchs, Benjamin Felix}, title = {Effects of timing and herbivory on a grass-endophyte association and its trophic interactions}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-141465}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2017}, abstract = {I.) Plant associated microorganisms can affect the plant`s interaction with herbivores and higher trophic levels. For instance, endophytic fungi infecting aerial plant parts of grass species produce bioactive alkaloids that can negatively affect species from higher trophic levels, indicating a defensive mutualism between the grass and the endophyte. However, beneficial insects can also be negatively affected by the endophyte, which might question the mutualistic effect of endophytic fungi. On the other hand, grass-endophytes are affected by environmental conditions and species interactions. Grazing can increase endophyte frequencies in natural habitats. Furthermore, endophyte mediated effects on herbivores are most pronounced during warm summers following rainy springs. In this study, we investigated whether endophyte derived alkaloids cascade up a food chain (chapter II) and whether their concentrations depend on plant age and season (chapter III). Further we analysed, whether altered herbivore phenology affects the endophytic fungus (chapter IV) and whether endophyte derived alkaloid production is induced by different herbivore species (chapter V). II.) In our first experimental study we analysed whether grass-endophyte derived alkaloids decreased the performance of two ladybird species feeding on aphids exclusively reared on endophyte infected grass (6 weeks young grass). Further, we screened species from three trophic levels (grass, herbivores and aphid predators) for their alkaloid content using two year old infected grass as diet for herbivores. We established an UPLC-MS method to detect and quantify the amount of the endophyte derived alkaloids peramine and lolitrem B extracted from the organic plant and insect material. Performance parameters of ladybirds revealed little differences between ladybirds fed on aphids reared on endophyte infected and non-infected grass, which probably resulted from low alkaloid concentrations in the young (6-weeks old) endophyte infected grass used in this part of the study. Alkaloid quantification of the two year old endophyte infected grass, herbivores and aphid predators revealed similar concentrations between grass and aphids, while aphid predators contained approximately half of that amount which still exceeded the bioactive threshold. We conclude that alkaloids produced by grass-endophytes cascade up the food chain and are responsible for fitness disadvantages of higher trophic levels. III.) In the second study we investigated the impact of plant age and seasonal timing on grass-endophyte growth and alkaloid production. Plants were sown in April of 2013 and sampled monthly over 30 consecutive months. Endophyte growth was quantified with real-time PCR (qPCR) and alkaloid concentrations with UPLC-MS. We showed that alkaloid concentrations and fungal growth followed a seasonal rhythmicity and that alkaloid concentrations increased with plant age. Alkaloid concentrations peak during summer, when also herbivore abundances are high. Consequently, we conclude that plant age and season contribute to the toxicity of endophytes on grass herbivores IV.) In the third study we simulated earlier spring arrival of aphids by enhancing aphid abundance on endophyte infected and endophyte-free grass in spring and analysed responses across three trophic levels. Enhanced aphid abundance in spring caused higher aphid abundances during the study period. Predators stayed unaffected by increased herbivore abundances; however they did level aphid numbers within two weeks after arrival on the plants, independent of aphid abundance. Grass-endophyte showed a time delayed growth, two weeks after aphid abundance peak and after predators already controlled aphid infestations on the plants. We conclude that phenology shifts of herbivorous insects can affect multi-trophic interactions leading to desynchronizations between phenologies of interacting species and mismatches in food-webs. V.) In the fourth study we analysed whether herbivores induce endophyte growth and alkaloid production and whether different types of herbivores induce specific alkaloid production. We applied three different herbivore treatments on endophyte infected grass over 18 weeks. Locust herbivory increased the insect deterring alkaloid peramine and clipping of plants (simulation of grazing livestock) increased the vertebrate toxic alkaloid lolitrem B. Aphid herbivory did not affect endophyte derived alkaloid concentrations. Endophyte responses to herbivory were species specific which indicates a primarily plant protecting role of alkaloid synthesis in endophyte infected plants and a close chemical crosstalk between interacting species. VI.) In summary, we showed that endophyte derived alkaloids affect higher trophic levels and that alkaloid concentrations in the plant depend on prevalent herbivore species, plant age and seasonal timing. Our results indicate a close chemical crosstalk between the host plant and the endophytic fungus which is susceptible to environmental changes altering the endophyte`s alkaloid production in plants. We gained insights into the grass-endophyte symbiosis in ecological contexts and conclude that several factors determine the herbivore toxic potential of endophytic fungi and thereby their plant mutualistic or parasitic character. Future studies should investigate the mechanisms behind the herbivore induced alkaloid concentration increase, shown in this thesis, especially whether plant signals mediate the endophyte response. Furthermore it would be interesting to study the induction of indirect endophyte mediated defence and how it affects multi-trophic level interactions.}, language = {en} } @phdthesis{Feichtner2017, author = {Feichtner, Thorsten}, title = {Optimal Design of Focusing Nanoantennas for Light : Novel Approaches: From Evolution to Mode-Matching}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-140604}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2017}, abstract = {Optische Antennen arbeiten {\"a}hnlich wie Antennen f{\"u}r Radiowellen und wandeln elektromagnetische Strahlung in elektrische Wechselstr{\"o}me um. Ladungsdichteansammlungen an der Antennen-Oberfl{\"a}che f{\"u}hren zu starken und lokalisierten Nahfeldern. Da die meisten optischen Antennen eine Ausdehnung von wenigen hundert Nanometern besitzen, erm{\"o}glichen es ihre Nahfelder, Licht auf ein Volumen weit unterhalb des Beugungslimits zu fokussieren, mit Intensit{\"a}ten, die mehrere Gr{\"o}ßenordnungen {\"u}ber dem liegen, was man mit klassischer beugender und reflektierender Optik erreichen kann. Die Aufgabe, die Abstrahlung eines Quantenemitters zu maximieren, eines punktf{\"o}rmigen Objektes, welches einzelne Photonen absorbieren und emittieren kann, ist identisch mit der Aufgabe, die Feldintensit{\"a}t am Ort des Quantenemitters zu maximieren. Darum ist es erstrebenswert, den Fokus optischer Antennen zu optimieren Optimierte Radiofrequenz-Antennen, welche auf Gr{\"o}ßenordnungen von wenigen 100 Nanometern herunterskaliert werden, zeigen bereits eine gute Funktionalit{\"a}t. Jedoch liegen optische Frequenzen in der N{\"a}he der Plasmafrequenz von den Metallen, die f{\"u}r optische Antennen genutzt werden und die Masse der Elektronen kann nicht mehr vernachl{\"a}ssigt werden. Dadurch treten neue physikalische Ph{\"a}nomene auf. Es entstehen gekoppelte Zust{\"a}nde aus Licht und Ladungsdichte-Schwingungen, die sogenannten Plasmonen. Daraus folgen Effekte wie Volumenstr{\"o}me und k{\"u}rzere effektive Wellenl{\"a}ngen. Zus{\"a}tzlich f{\"u}hrt die endliche Leitf{\"a}higkeit zu thermischen Verluste. Das macht eine Antwort auf die Frage nach der optimalen Geometrie f{\"u}r fokussierende optische Antennen schwer. Jedoch stand vor dieser Arbeit der Beweis noch aus, dass es f{\"u}r optische Antennen bessere Alternativen gibt als herunterskalierte Radiofrequenz-Konzepte. In dieser Arbeit werden optische Antennen auf eine bestm{\"o}gliche Fokussierung optimiert. Daf{\"u}r wird ein Ansatz gew{\"a}hlt, welcher bei Radiofrequenz-Antennen f{\"u}r komplexe Anwendungsfelder (z.B. isotroper Breitbandempfang) schon oft Erfolg hatte: evolution{\"a}re Algorithmen. Die hier eingef{\"u}hrte erste Implementierung erlaubt eine große Freiheit in Bezug auf Partikelform und Anzahl, da sie quadratische Voxel auf einem planaren, quadratischen Gitter beliebig anordnet. Die Geometrien werden in einer bin{\"a}ren Matrix codiert, welche als Genom dient und somit Methoden wie Mutation und Paarung als Verbesserungsmechanismus erlaubt. So optimierte Antennen-Geometrien {\"u}bertreffen vergleichbare klassische Dipol-Geometrien um einen Faktor von Zwei. Dar{\"u}ber hinaus l{\"a}sst sich aus den optimierten Antennen ein neues Funktionsprinzip ableiten: ein magnetische Split-Ring-Resonanz kann mit Dipol-Antennen leitend zu neuartigen und effektiveren Split-Ring-Antennen verbunden werden, da sich ihre Str{\"o}me nahe des Fokus konstruktiv {\"u}berlagern. Im n{\"a}chsten Schritt wird der evolution{\"a}re Algorithmus so angepasst, so die Genome real herstellbare Geometrien beschreiben. Zus{\"a}tzlich wird er um eine Art ''Druckertreiber'' erweitert, welcher aus den Genomen direkt Anweisungen zur fokussierten Ionenstrahl-Bearbeitung von einkristallinen Goldflocken erstellt. Mit Hilfe von konfokaler Mikroskopie der Zwei-Photonen-Photolumineszenz wird gezeigt, dass Antennen unterschiedlicher Effizienz reproduzierbar aus dem evolution{\"a}ren Algorithmus heraus hergestellt werden k{\"o}nnen. Außerdem wird das Prinzip der Split-Ring-Antenne verbessert, indem zwei Ring-Resonanzen zu einer Dipol-Resonanz hinzugef{\"u}gt werden. Zu guter Letzt dient die beste Antenne des zweiten evolution{\"a}re Algorithmus als Inspiration f{\"u}r einen neuen Formalismus zur Beschreibung des Leistungs{\"u}bertrages zwischen einer optischen Antenne und einem Punkt-Dipol, welcher sich als "dreidimensionaler Moden{\"u}berlapp" beschreiben l{\"a}sst. Damit k{\"o}nnen erstmals intuitive Regeln f{\"u}r die Form einer optischen Antenne aufgestellt werden. Die G{\"u}ltigkeit der Theorie wird analytisch f{\"u}r den Fall eines Dipols nahe einer metallischen Nano-Kugel gezeigt. Das vollst{\"a}ndige Problem, Licht mittels einer optischen Antenne zu fokussieren, l{\"a}sst sich so auf die Erf{\"u}llung zweier Moden{\"u}berlapp-Bedingungen reduzieren -- mit dem Feld eines Punktdipols, sowie mit einer ebenen Welle. Damit lassen sich zwei Arten idealer Antennenmoden identifizieren, welche sich von der bekannten Dipol-Antennen-Mode grundlegend unterscheiden. Zum einen l{\"a}sst sich dadurch die Funktionalit{\"a}t der evolution{\"a}ren und Split-Ring-Antennen erkl{\"a}ren, zum lassen sich neuartige plasmonische Hohlraum-Antennen entwerfen, welche zu besserer Fokussierung von Licht f{\"u}hren. Dies wird numerisch im direkten Vergleich mit einer klassischen Dipolantennen-Geometrie gezeigt.}, subject = {Physik}, language = {en} } @phdthesis{Ali2017, author = {Ali, Qasim}, title = {Distributed Control of Cooperating Mini UAVs}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-140686}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2017}, abstract = {Mini Unmanned Aerial Vehicles (MUAVs) werden immer beliebtere Forschungsplattformen. Vor allem in den letzten Jahren ziehen sie aufgrund ihrer Erschwinglichkeit und ihrer Flexibilit{\"a}t, die es erlaubt sie in fast allen Lebensbereichen einzusetzen, betr{\"a}chtliche Aufmerksamkeit auf sich. MUAVs haben offensichtliche Vorteile gegen{\"u}ber bemannten Plattformen einschließlich ihrer viel geringeren Herstellungs- und Betriebskosten, Risikovermeidung f{\"u}r den menschlichen Piloten, der M{\"o}glichkeit sicher niedrig und langsam fliegen zu k{\"o}nnen, und Realisierung von Operationen, die {\"u}ber die inh{\"a}renten Grenzen des menschlichen K{\"o}rpers hinausgehen. Der Fortschritt in der Micro Electro-Mechanical System (MEMS) Technologie, Avionik und Miniaturisierung von Sensoren spielte auch eine bedeutende Rolle bei der Entwicklung der MUAVs. Diese Flugger{\"a}te reichen von einfachem Spielzeug aus dem Elektrofachhandel bis zu hoch entwickelten, kommerziellen Plattformen, die die Durchf{\"u}hrung neuer Aufgaben wie Offshore-Windkraftwerk Inspektionen, 3D-Modellierung von Geb{\"a}uden usw. erlauben. MUAVs sind auch umweltfreundlich, da sie weniger Luftverschmutzung und L{\"a}rm verursachen. Unbemannt ist daher un{\"u}bertroffen. Aktuelle Forschung konzentriert sich auf die M{\"o}glichkeit mehrere kosteng{\"u}nstige Flugger{\"a}te zusammen fliegen zu lassen, w{\"a}hrend die erforderliche relative r{\"a}umliche Trennungen beibehalten wird. Dies erm{\"o}glicht es effizient Aufgaben zu erf{\"u}llen im Vergleich zu einem einzigen sehr teuren Flugger{\"a}t. Durch die Redundanz entf{\"a}llt auch das Risiko des Scheiterns der Mission durch den Verlust eines einzigen Flugger{\"a}ts. Wertvolle Aufgaben, die kooperative Flugger{\"a}te ausf{\"u}hren k{\"o}nnen, sind beispielsweise gemeinsame Lasttransporte, Such- und Rettungsmissionen, mobile Kommunikationsrelais, Spr{\"u}hen von Pestiziden und Wetterbeobachtung. Obwohl die Realisierung von Fl{\"u}gen mit mehreren, gekoppelten UAVs komplex ist, rechtfertigen dennoch offensichtliche Vorteile diese m{\"u}hsame und aufw{\"a}ndige Entwicklungsarbeit. Verteilte Steuerung von kooperierenden Einheiten ist ein multidisziplin{\"a}res Thema, das es erfordert in diversifizierten Bereichen zu arbeiten. Dazu geh{\"o}ren MUAV Hardware und Software, Kommunikationstechniken f{\"u}r den notwendigen Informationsaustausch, Flugdynamik, Regelungstechnik, insbesondere f{\"u}r verteilte / kooperative Steuerungstechniken, Graphentheorie f{\"u}r Kommunikationstopologie Modellierung und Sensoren-Technologie wie Differential GPS (DGPS). F{\"u}r eine Flotte von Agenten, die in unmittelbarer N{\"a}he fliegen, ist eine genaue Positionsbestimmung zwingend n{\"o}tig um Kollisionen zu vermeiden und die Anforderungen f{\"u}r die meisten Missionen wie Georeferenzierung zu erf{\"u}llen. F{\"u}r solche Szenarien ist DGPS ein potenzieller Kandidat. Ein Teil der Forschung konzentriert sich daher auf die Entwicklung von DGPS Code. Eines der Module dieser Forschung war Hardware-Implementierung. Ein einfacher Test-Aufbau zur Realisierung von Basisfunktionalit{\"a}ten f{\"u}r Formationsflug von Quadrocoptern wurde am Lehrstuhl f{\"u}r Informationstechnik in der Luft- und Raumfahrt der Universit{\"a}t W{\"u}rzburg entwickelt. Diese Testumgebung kann nicht nur zur Pr{\"u}fung und Validierung von Algorithmen f{\"u}r Formationsflug in realer Umgebung genutzt werden, sondern dient auch zur Ausbildung von Studenten. Ein bereits vorhandener Pr{\"u}fstand f{\"u}r einzelne Quadrocopter wurde mit den notwendigen Kommunikation und verteilten Steuerung erweitert, um Algorithmen f{\"u}r Formationsfl{\"u}ge in drei Freiheitsgraden (Roll / Nick / Gier) zu testen. Diese Studie umfasst die Bereiche der Kommunikation, Steuerungstechnik und Embedded-System-Programmierung. Das Bluetooth-Protokoll wurde f{\"u}r die gegenseitige Kommunikation zwischen zwei Quadrocoptern verwendet. Eine einfache Technik der Proportional-Integral-Differential (PID) Steuerung in Kombination mit Kalman-Filter wurde genutzt. Die MATLAB Instrument Control Toolbox wurde f{\"u}r die Datenanzeige, die Analyse und das Plotten verwendet. Plots k{\"o}nnen in Echtzeit gezeichnet werden und empfangene Daten k{\"o}nnen auch in Form von Dateien zur sp{\"a}teren Verwendung und Analyse gespeichert werden. Das System wurde preisg{\"u}nstig, unter Ber{\"u}cksichtigung eines einfachen Aufbaus, entwickelt. Der vorgeschlagene Aufbau ist sehr flexibel und kann einfach an ver{\"a}nderte Anforderungen angepasst werden. Als verteiltes Steuerungsschema wurde ein zentralisierter, heterogener Formationsflug Positionsregler formuliert, der einen „explicit model following Linear Quadratic Regulator Proportional Integral (LQR PI)" Regler verwendet. Der Anf{\"u}hrer Quadrocopter ist ein stabiles Referenzmodell mit der gew{\"u}nschten Dynamik, deren Ausgang vollkommen von den beiden Wingmen Quadrocopter verfolgt wird. Der Anf{\"u}hrer selbst wird durch Pole Placement Steuerverfahren mit den gew{\"u}nschten Stabilit{\"a}tseigenschaften gesteuert, w{\"a}hrend die beiden Anh{\"a}nger durch robuste und adaptive LQR PI Steuerverfahren geregelt werden. F{\"u}r diese Studie wird ein Vollzustandsvektor der Quadrocopter betrachtet w{\"a}hrend nur die resultierende Leistung verfolgt wird. Die ausgew{\"a}hlte 3D Formationsgeometrie und die statische Stabilit{\"a}t bleibt unter einer Vielzahl von m{\"o}glichen St{\"o}rungen erhalten. Bei Kommunikationsverlust zwischen Anf{\"u}hrer und einem der Anh{\"a}nger, leitet der andere Anh{\"a}nger die Daten, die er vom Anf{\"u}hrer erhalten hat, an den betroffenen Anh{\"a}nger weiter. Die Stabilit{\"a}t des Regelsystems wurde unter Verwendung von Singul{\"a}rwerten analysiert. Der vorgeschlagene Ansatz f{\"u}r eng gekoppelten Formationsflug von MUAVs wurde mit Hilfe von umfangreichen Simulationen unter MATLAB® / Simulink® validiert und ergab viel versprechende Ergebnisse. Auch die Tracking-Leistung wurde f{\"u}r zeitlich ver{\"a}nderliche Befehle gezeigt. Die vorgeschlagene Architektur ist skalierbar und kann problemlos erweitert werden. Dieser Ansatz ist f{\"u}r die Szenarien geeignet, die eng gekoppelte Formationsflug ben{\"o}tigen, wie kooperatives Greifen oder gemeinsame Lasttransporte. Ein innovatives Framework f{\"u}r die Teamarbeit von zwei Quadrocopter Flotten wurde entwickelt. Als Beispielmission wurde ein Szenario gew{\"a}hlt, bei dem ein Feuer auf einer gr{\"o}ßeren Fl{\"a}che gel{\"o}scht werden muss. Jede Formation hat ihre angegebene Formationsgeometrie und eine zugewiesene Aufgabe. Die Lageregelung f{\"u}r die Quadrocopter in einer der Formationen wurde durch ein LQR PI-Regelschema, das auf „explicit model following" basiert, umgesetzt. Die Quadrocopter in anderen Formation werden durch ein LQR PI Servomechanismus Regelsystem gesteuert. Die beiden Steuersysteme werden in Bezug auf ihre Leistung und ihren Steuerungsaufwand verglichen. Beide Formationen werden durch entsprechende Bodenstationen durch virtuelle Anf{\"u}hrer kommandiert. Die Bodenstationen tauschen die befohlene H{\"o}heninformation aus, um gegenseitig eine sichere Trennung zwischen den Formationen zu gew{\"a}hrleisten. Die Quadrocopter k{\"o}nnen kommandierte Solltrajektorien folgen und {\"u}ber erw{\"u}nschten Punkten f{\"u}r eine vorgegebene Zeit schweben. Bei Kommunikationsverlust zwischen Bodenstation und einem der Quadcopter leitet der benachbarte Quadrocopter die Befehlsdaten, die er von der Bodenstation erhalten hat, an die betroffene Einheit weiter. Das vorgeschlagene Framework wurde durch umfangreiche Simulationen mit Hilfe von MATLAB® / Simulink® validiert und liefert sehr brauchbare Ergebnisse. Cluster-Rekonfiguration von Agenten wird in unserer Arbeit ebenfalls gezeigt. Dies erlaubt es die Formationsgeometrie w{\"a}hrend des Fluges auf eine beliebige neue Form umzuschalten. F{\"u}r die genannten Anwendungen sind Konsens Algorithmen nicht erw{\"u}nscht, da wir von den Quadrocopter Flotten fordern, dass sie dem von uns gew{\"a}hlten Weg folgen, und nicht ihren Weg selbst w{\"a}hlen. Eine Reihe der praktischen Probleme von Kommunikationsnetzen kann in geeigneter Weise durch Graphen dargestellt werden. Dies erleichtert die Problemformulierung und den Analyseprozess. Kommunikationstopologien f{\"u}r Netzwerke mit einer großen Anzahl von Einheiten, wie zum Beispiel Schw{\"a}rme von Luftfahrzeugen, k{\"o}nnen durch einen graphentheoretischen Ansatz untersucht werden. Um die Bildung solcher Probleme zu erleichtern, wird der Graph mit Hilfe der Laplace-Matrix dargestellt. Eigenwerte der Laplace-Matrix wurden in unserer Studie angemessene Ber{\"u}cksichtigung gegeben einen Einblick in die Graphen / Subgraphen Eigenschaften zu verleihen. Der gleiche wurden genutzt um die bekannte Euler Formel zu verallgemeinern und somit auf Graphen und Subgraphen anwendbar zu machen. Eine modifizierte Euler-Formel wird ebenfalls vorgestellt. Die Verwendung der Graphentheorie in verteilten / kooperativen Regelsystemen wird auch durch Simulationen gezeigt. Kooperative Kontrolschemas, die auf auf Konsens-Algorithmen beruhenden, wurden f{\"u}r die Lageregelung von Quadrocopter-Flotten, in denen kein expliziter Anf{\"u}hrer existiert, verwendet. Konsens-Algorithmen wurden in Kombination mit verschiedenen Steuersystemen verwendet, was zur Autonomie von Quadrocoptern beitr{\"a}gt. Die Steuersysteme, die f{\"u}r diesen Zweck verwendet werden, umfassen LQR PI-Regelung basierend auf „model following" und LQR PI Servo-Mechanismus. Die Regelungen wurden unter verschiedenen Kommunikationstopologien untersucht, darunter voll verbundene ungerichtete Graphen, gerichteten Graphen und Zyklus-Topologie. Der Informationsfluss unter den Agenten in einem Cluster wurde durch Laplace-Matrix modelliert. Die Auswirkungen von Eingangs Verzerrungen auf Konsens Werte wurden ebenfalls untersucht. Quadrocopter k{\"o}nnen durch gegenseitigen Konsens Flugbahnen verfolgen und die Zielpunkte erreichen. Die vorgeschlagenen Regelungssysteme wurden unter verschiedenen Kommunikationstopologien in Matlab / Simulink-Umgebung durch umfangreiche Simulationen validiert. Die Ergebnisse bescheinigen die Wirksamkeit der pr{\"a}sentierten Schemata mit dem zus{\"a}tzlichen Vorteil der Einfachheit der Umsetzung. Das vorgeschlagene Regelungssystem ist skalierbar f{\"u}r große Gruppen von MUAVs. F{\"u}r Formationsflug sind die Anforderungen an die Positionsgenauigkeit sehr hoch. GPS-Signale allein bieten keine ausreichend hohe Positionsgenauigkeit um die Anforderung zu erf{\"u}llen; eine Technik f{\"u}r die genauere Positionsbestimmung ist daher erforderlich, beispielsweise DGPS. Es existiert eine Anzahl von {\"o}ffentlichen Codes f{\"u}r die GPS-Positionsbestimmung und Baseline-Bestimmung im Offline-Modus. Es existiert jedoch keine Software f{\"u}r DGPS, die Korrekturfaktoren der Basisstationen nutzt, ohne auf Doppel Differenz Informationen zu vertrauen. Um dies zu erreichen, wurde eine Methodik in MATLAB-Umgebung f{\"u}r DGPS mit C/A Pseudoranges nur auf einzelne Frequenz L1 eingef{\"u}hrt es machbar f{\"u}r Empf{\"a}nger kosteng{\"u}nstig GPS zu nutzen. Unsere Basisstation wird an einem genau vermessen Referenzpunkt aufgestellt. Pseudoranges und geometrische Abst{\"a}nde werden an der Basisstation verglichen, um die Korrekturfaktoren zu berechnen. Diese Korrekturfaktoren, f{\"u}r aller g{\"u}ltigen Satelliten w{\"a}hrend einer Epoche, werden dann an einen Rover {\"u}bergeben. Das Rover ber{\"u}cksichtigt innerhalb der entsprechenden Epoche diese f{\"u}r seine eigene wahre Positionsbestimmung. Zur Validierung der vorgeschlagenen Algorithmen wird unsere Rover ebenfalls an einer vorbestimmten Stelle platziert. Der vorgeschlagene Code ist ein geeignetes und einfaches Werkzeug f{\"u}r die Nachbearbeitung von GPS-Rohdaten f{\"u}r eine genaue Positionsbestimmung eines Rover, z.B. eines UAV w{\"a}hrend der Post-Missionsanalyse.}, subject = {Micro Air Vehicle}, language = {en} } @phdthesis{SchamelgebGeffers2017, author = {Schamel [geb. Geffers], Martha}, title = {Novel dual setting approaches for mechanically reinforced mineral biocements}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-154946}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2017}, abstract = {Calcium phosphate biocements are inherently brittle materials due to their ceramic nature. Hence, currently applied cement formulations are only indicated for non-load bearing application sites. An approach to reduce cement brittleness is based on the use of cement - polymer composites, which combine the flexibility of a polymeric phase with the hardness and compression strength of a cement matrix. Here, a relatively new strategy is the use of "dual-setting" cements, in which the polymeric phase is simultaneously build up from monomers or prepolymers during cement setting. This approach largely maintains basic properties of the fresh paste such as rheology or setting time. Previous works on such dual setting cements were dealing with a radical polymerization reaction to create the polymeric network. This type of reaction requires the addition of a suitable initiator system (e.g. a tertiary amine in conjunction with ammonium peroxosulfate), which are often cytotoxic and may interfere with the cement setting conditions. The current thesis dealt with alternative strategies, in which the cross-linking and gelation of the second (polymeric or inorganic) cement phase is initiated by the chemical conditions of the setting reaction such that no additional initiator has to be added to the cement paste. In a first approach a six armed star molecule functionalized with isocyanate groups as reactive termini (NCO-sP(EO-stat-PO)) was used to build up a hydrogel matrix, which was then subsequently mineralized with hydroxyapatite nanocrystals following the hydrolysis of incorporated -tricalcium phosphate particles. The stimulus to initiate hydrogel cross-linking are water molecules, which subsequently hydrolyzed isocyanate groups to amines, which then cross-linked with unreacted isocyanate to form urea-bonds. Here, it was possible to show the advantages features of a dual setting system in comparison to the simple combination of hydrogels with unreactive filler particles. By the formation of the cement matrix within the hydrogel a strength improvement by the factor of 30 could be observed. Furthermore, by applying a dual setting system higher mineral concentrations are realizable. The mechanical properties such as elasticity, compression strength and E-modulus of a composite with 30 wt\% NCO-sP(EO-stat-PO) were found to be similar to the properties of cancellous bone. With the motivation to develop a dual setting and resorbable cement, a brushite (CaHPO4·2H2O) forming cement was modified with a second inorganic silica based precursor. The latter was obtained by pre-hydrolysing tetraethyl orthosilicate (TEOS) under acidic conditions. This silica precursor was mixed with a cement powder composed of ß-tricalcium phosphate and monocalcium phosphate, whereas cement setting occurred by a dissolution-precipitation process to form a matrix of brushite. Simultaneously, the increase of the pH during setting from initially 1-2 to values > 4 initiated the condensation reaction of the hydrolysed TEOS. This resulted in an interpenetrating phase composite material in which the micropores of the cement were filled with the nanoporous silica gel. This resulted in a higher density and a compressive strength of 24 MPa, which is approximately 5-10 times higher than the CPC reference at the same powder to liquid ratio. The microporous character of the composites also altered the release of vancomycin as a model drug, whereby in contrast to the quantitative release from the CPC reference, approx. 25 \% of the immobilised drug remained in the composite matrix. It was also observed, that a variation of the TEOS content in the composite enabled a control over cement phase composition to form either brushite, anhydrous monetite or a biphasic mixture of both. Cytocompatibility tests revealed that composites with the highest silicate content showed an increased cell proliferation compared to the silica-free brushite reference. Proliferation was found to be similar to a hydroxyapatite reference with a significant higher activity per cell. Mechanistically, the improved biological response could not be attributed to the released silicate ions, but to a decreased release of phosphate and adsorption of magnesium ions from the cell culture medium. Finally, an investigated dual setting cement system was based on the combination of a brushite forming cement powder with an aqueous silk fibroin solution. Here, changes of both ion concentration and pH during cement setting were shown to build up an interpenetrating fibroin - brushite composite with combined properties of the elastic polymer and the rigid cement. Mechanistically, the low pH of the cement paste (2) as well as the free Ca2+ ions during setting resulted in a conformation change of the dissolved fibroin from random coil to ß-sheet structure. This leads to a rapid gelation and contraction of the fibroin phase with a self-densifying effect on the cement paste. The set composites showed typical ductile fracture behavior under dry testing conditions and a high elasticity under wet conditions with a mechanical strength nearly an order of magnitude higher than the fibroin free cement reference. Cell number and activity against MG63 cells were strongly increased on silk fibroin cement composite surfaces at later time points, which could be again attributed to a decreased ion release and adsorption compared to the fibroin free cements. This in turn slowed down the in vitro degradation of the CPC phase in such composites.}, subject = {Calciumphosphate}, language = {en} } @phdthesis{Lang2017, author = {Lang, Jean-Nicolas Olivier}, title = {Automation of electroweak NLO corrections in general models}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-154426}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2017}, abstract = {The thesis deals with the automated generation and efficient evaluation of scattering amplitudes in general relativistic quantum field theories at one-loop order in perturbation theory. At the present time we lack signals beyond the Standard Model which, in the past, have guided the high-energy physics community, and ultimately led to the discovery of new physics phenomena. In the future, precision tests could acquire this guiding role by systematically probing the Standard Model and constraining Beyond the Standard Model theories. As current experimental constraints strongly favour Standard Model-like theories, only small deviations with respect to the Standard Model are expected which need to be studied in detail. The required precision demands one-loop corrections in all future analyses, ideally in a fully automated way, allowing to test a variety of observables in different models and in an effective field theory approach. In the process of achieving this goal we have developed an enhanced version of the tool Recola and on this basis the generalization Recola2. These tools represent fully automated tree- and one-loop-amplitude providers for the Standard Model, or in the case of Recola2 for general models. Concerning the algorithm, we use a purely numerical and fully recursive approach allowing for extreme calculations of yet unmatched complexity. Recola has led to the first computation involving 9-point functions. Beyond the Standard Model theories and Effective Field theories are integrated into the Recola2 framework as model files. Renormalized model files are produced with the newly developed tool Rept1l, which can perform the renormalization in a fully automated way, starting from nothing but Feynman rules. In view of validation, we have extended Recola2 to new gauges such as the Background-Field Method and the class of Rxi gauges. In particular, the Background-Field Method formulation for new theories serves as an automated validation, and is very useful in practical calculations and the formulation of renormalization conditions. We have applied the system to produce the first results for Higgs-boson production in Higgs strahlung and vector-boson fusion in the Two-Higgs-Doublet Model and the Higgs-Singlet Extension of the Standard Model. All in all, we have laid the foundation for an automated generation and computation of one-loop amplitudes within a large class of phenomenologically interesting theories. Furthermore, we enable the use of our system via a very flexible and dynamic control which does not require any intermediate intervention.}, subject = {Standardmodell }, language = {en} } @phdthesis{Offner2017, author = {Offner, Kristin}, title = {SH3-mediated protein interactions of Mena and VASP}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-154481}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2017}, abstract = {Regulation of actin cytoskeletal turnover is necessary to coordinate cell movement and cell adhesion. Proteins of the Enabled/vasodilator-stimulated phosphoprotein (Ena/VASP) family are important mediators in cytoskeleton control, linking cyclic nucleotide signaling pathways to actin assembly. In mammals, the Ena/VASP family consists of mammalian Enabled (Mena), VASP, and Ena-VASP-like (EVL). The family members share a tripartite domain organization, consisting of an N-terminal Ena/VASP homology 1 (EVH1) domain, a central proline-rich region (PRR), and a C-terminal EVH2 domain. The EVH1 domain mediates binding to the focal adhesion proteins vinculin and zyxin, the PRR interacts with the actin-binding protein profilin and with Src homology 3 (SH3) domains, and the EVH2 domain mediates tetramerization and actin binding. Endothelial cells line vessel walls and form a semipermeable barrier between blood and the underlying tissue. Endothelial barrier function depends on the integrity of cell-cell junctions and defective sealing of cell-cell contacts results in vascular leakage and edema formation. In a previous study, we could identify a novel interaction of the PRR of VASP with αII-spectrin. VASP-targeting to endothelial cell-cell contacts by interaction with the αII-spectrin SH3 domain is sufficient to initiate perijunctional actin filament assembly, which in turn stabilizes cell-cell contacts and decreases endothelial permeability. Conversely, barrier function of VASP-deficient endothelial cells and microvessels of VASP- null mice is defective, demonstrating that αII-spectrin/VASP complexes regulate endothelial barrier function in vivo. The aim of the present study was to characterize the structural aspects of the binding of Ena/VASP proteins to αII-spectrin in more detail. These data are highly relevant to understand the cardiovascular function of VASP and its subcellular targeting. In the present study, the following points were experimentally addressed: 1. Comparison of the interaction between αII-spectrin and Mena, VASP, or EVL In contrast to the highly conserved EVH1/EVH2 domains, the PRR is the most divergent part within the Ena/VASP proteins and may differ in binding modes and mechanisms of regulation. More specifically, VASP contains a triple GP5 motif, whereas EVL and Mena contain one or more GP6 motifs or even longer proline stretches. In the present study, we used peptide scans and competitive αII-spectrin SH3 pull-down assays with the recombinant Mena, VASP, and VASP mutants to investigate the relative binding efficiency. Our results indicate that binding of the αII-spectrin SH3 domain to GP6 motifs is superior to GP5 motifs, giving a rationale for a stronger interaction of αII-spectrin with EVL and Mena than with VASP. 2. Interaction of SH3i with Ena/VASP proteins In the mammalian heart, an αII-spectrin splice variant exists (SH3i), which contains a 20 amino acid insertion C-terminal to the SH3 domain. We used GST-fusion proteins of αII-spectrin, comprising the SH3 domain with or without the alternatively spliced amino acids, to pull-down recombinant Mena, VASP or VASP mutants. The results demonstrate a substantially increased binding of the C-terminal extended SH3 domain as compared to the general αII-spectrin isoform without the 20 amino acid insertion. These findings were also confirmed in pull-down experiments with heart lysates and purified Mena from heart muscle. The increased binding was not due to an alternative, SH3-independent binding interface because a pointmutation of the SH3 domain (W1004R) in the alternatively spliced αII-spectrin isoform completely abrogated the interaction. To analyze the interaction of SH3i and Ena/VASP proteins in living cells, we expressed the extended SH3 domain as GFP fusion proteins in endothelial cells. Here, we observed an extensive co-localization with Mena and VASP at the leading edge of lamellipodia confirming the in vivo relevance of the interaction with potential impact on cell migration and angiogenesis. 3. Binding affinity and influence of the Ena/VASP tetramerization domain We also determined the binding affinity of the general and the alternatively spliced αII-spectrin SH3 with Ena/VASP proteins by isothermal titration calorimetry (ITC) using a peptide from the PRR of Mena (collaboration with Dr. Stephan Feller, University of Oxford). Surprisingly, the binding affinity of the general SH3 domain was low (~900 μM) as compared to other SH3 domain- mediated interactions, which commonly display binding constants in the low micromolar range. Furthermore and in contrast to the pull-down assays, we could not detect an increased binding affinity of the C-terminally extended SH3 domain. This could be either explained by the existence of a third protein, which "bridges" the Mena/αII-spectrin complex in the pull-down assays, or, more likely, by the small size of the Mena peptide, which lacks major parts of the Mena protein, including the tetramerization domain. Indeed, it has been previously shown that the tetramerization of Ena is crucial for the interaction with the Abl- SH3 domain, although no SH3 binding sites are found in the tetramerization domain. To address this point experimentally, we used a VASP mutant that lacks the tetramerization domain in pull-down assays. Neither the general nor the alternatively spliced SH3 domain bound to the monomeric VASP, demonstrating the crucial (indirect) impact of Ena/VASP tetramerization on the interaction with αII-spectrin. In summary, we conclude that the αII-spectrin SH3 domain binds to the proline- rich region of all Ena/VASP proteins. However, binding to EVL and Mena, which both possess one or more GP6 motifs, is substantially more efficient than VASP, which only contains GP5 motifs. The C-terminally extended SH3 domain, which is present in the αII-spectrin splice variant SH3i, binds stronger to the Ena/VASP proteins than the general isoform and expression of the isolated domain is sufficient for co-localization with Ena/VASP in living endothelial cells. Finally, the tetramerization of the Ena/VASP proteins is indispensable for the interaction with either isoform of αII-spectrin.}, language = {en} } @phdthesis{Dhara2017, author = {Dhara, Ayan}, title = {Stimuli-Responsive Self-Assembly and Spatial Functionalization of Organic Cages Based on Tribenzotriquinacenes}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-154762}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2017}, abstract = {Within this thesis, synthetic strategies for self-assembled organic cage compounds have been developed that allow for both stimuli-responsive control over assembly/disassembly processes and spatial control over functionalization. To purposefully operate the reversible assembly of organic cages, boron-nitrogen dative bonds have been exploited for the formation of a well-defined, discrete bipyramidal organic assembly in solution. Thermodynamic association equilibria for cage formation have been investigated by Isothermal Titration Calorimetry (ITC). Temperature-dependent NMR studies revealed a reversible cage opening upon heating and quantitative reassembly upon cooling. For the spatial functionalization of organic cages, two divergent molecular building units have been designed and synthesized, namely tribenzotriquinacene derivatives possessing a terminal alkyne moiety at the apical position and a meta-diboronic acid having a pyridyl group at the 2-position. Facile access to a variety of apically functionalized tribenzotriquinacenes has been illustrated by post-synthetic modifications at the terminal alkyne group by Sonogashira cross-coupling and azide-alkyne click reactions. Finally, these apically functionalized tribenzotriquinacene building blocks have been implemented into boronate ester-based organic cage compounds showing modular exohedral functionalities.}, subject = {Selbstorganisation}, language = {en} } @phdthesis{Leimbach2017, author = {Leimbach, Andreas}, title = {Genomics of pathogenic and commensal \(Escherichia\) \(coli\)}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-154539}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2017}, abstract = {High-throughput sequencing (HTS) has revolutionized bacterial genomics. Its unparalleled sensitivity has opened the door to analyzing bacterial evolution and population genomics, dispersion of mobile genetic elements (MGEs), and within-host adaptation of pathogens, such as Escherichia coli. One of the defining characteristics of intestinal pathogenic E. coli (IPEC) pathotypes is a specific repertoire of virulence factors (VFs). Many of these IPEC VFs are used as typing markers in public health laboratories to monitor outbreaks and guide treatment options. Instead, extraintestinal pathogenic E. coli (ExPEC) isolates are genotypically diverse and harbor a varied set of VFs -- the majority of which also function as fitness factors (FFs) for gastrointestinal colonization. The aim of this thesis was the genomic characterization of pathogenic and commensal E. coli with respect to their virulence- and antibiotic resistance-associated gene content as well as phylogenetic background. In order to conduct the comparative analyses, I created a database of E. coli VFs, ecoli_VF_collection, with a focus on ExPEC virulence-associated proteins (Leimbach, 2016b). Furthermore, I wrote a suite of scripts and pipelines, bac-genomics-scripts, that are useful for bacterial genomics (Leimbach, 2016a). This compilation includes tools for assembly and annotation as well as comparative genomics analyses, like multi-locus sequence typing (MLST), assignment of Clusters of Orthologous Groups (COG) categories, searching for protein homologs, detection of genomic regions of difference (RODs), and calculating pan-genome-wide association statistics. Using these tools we were able to determine the prevalence of 18 autotransporters (ATs) in a large, phylogenetically heterogeneous strain panel and demonstrate that many AT proteins are not associated with E. coli pathotypes. According to multivariate analyses and statistics the distribution of AT variants is instead significantly dependent on phylogenetic lineages. As a consequence, ATs are not suitable to serve as pathotype markers (Zude et al., 2014). During the German Shiga toxin-producing E. coli (STEC) outbreak in 2011, the largest to date, we were one of the teams capable of analyzing the genomic features of two isolates. Based on MLST and detection of orthologous proteins to known E. coli reference genomes the close phylogenetic relationship and overall genome similarity to enteroaggregative E. coli (EAEC) 55989 was revealed. In particular, we identified VFs of both STEC and EAEC pathotypes, most importantly the prophage-encoded Shiga toxin (Stx) and the pAA-type plasmid harboring aggregative adherence fimbriae. As a result, we could show that the epidemic was caused by an unusual hybrid pathotype of the O104:H4 serotype. Moreover, we detected the basis of the antibiotic multi-resistant phenotype on an extended-spectrum beta-lactamase (ESBL) plasmid through comparisons to reference plasmids. With this information we proposed an evolutionary horizontal gene transfer (HGT) model for the possible emergence of the pathogen (Brzuszkiewicz et al., 2011). Similarly to ExPEC, E. coli isolates of bovine mastitis are genotypically and phenotypically highly diverse and many studies struggled to determine a positive association of putative VFs. Instead the general E. coli pathogen-associated molecular pattern (PAMP), lipopolysaccharide (LPS), is implicated as a deciding factor for intramammary inflammation. Nevertheless, a mammary pathogenic E. coli (MPEC) pathotype was proposed presumably encompassing strains more adapted to elicit bovine mastitis with virulence traits differentiating them from commensals. We sequenced eight E. coli isolates from udder serous exudate and six fecal commensals (Leimbach et al., 2016). Two mastitis isolate genomes were closed to a finished-grade quality (Leimbach et al., 2015). The genomic sequence of mastitis-associated E. coli (MAEC) strain 1303 was used to elucidate the biosynthesis gene cluster of its O70 LPS O-antigen. We analyzed the phylogenetic genealogy of our strain panel plus eleven bovine-associated E. coli reference strains and found that commensal or MAEC could not be unambiguously allocated to specific phylogroups within a core genome tree of reference E. coli. A thorough gene content analysis could not identify functional convergence of either commensal or MAEC, instead both have only very few gene families enriched in either pathotype. Most importantly, gene content and ecoli_VF_collection analyses showed that no virulence determinants are significantly associated with MAEC in comparison to bovine fecal commensals, disproving the MPEC hypothesis. The genetic repertoire of bovine-associated E. coli, again, is dominated by phylogenetic background. This is also mostly the case for large virulence-associated E. coli gene cluster previously associated with mastitis. Correspondingly, MAEC are facultative and opportunistic pathogens recruited from the bovine commensal gastrointestinal microbiota (Leimbach et al., 2017). Thus, E. coli mastitis should be prevented rather than treated, as antibiotics and vaccines have not proven effective. Although traditional E. coli pathotypes serve a purpose for diagnostics and treatment, it is clear that the current typing system is an oversimplification of E. coli's genomic plasticity. Whole genome sequencing (WGS) revealed many nuances of pathogenic E. coli, including emerging hybrid or heteropathogenic pathotypes. Diagnostic and public health microbiology need to embrace the future by implementing HTS techniques to target patient care and infection control more efficiently.}, subject = {Escherichia coli}, language = {en} } @phdthesis{Steiger2017, author = {Steiger, Christoph}, title = {Drug delivery of therapeutic gases - strategies for controlled and local delivery of carbon monoxide}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-141054}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2017}, abstract = {The isoenzyme heme oxygenase 1 (HO-1) is a key element for maintaining cellular homeostasis. Upregulated in response to cellular stress, the HO-1 degrades heme into carbon monoxide (CO), biliverdin, and Fe2+. By means of a local cell-protective feedback loop the enzyme triggers numerous effects including anti-oxidative, anti-apoptotic, and anti-inflammatory events associated with complex signalling patterns which are largely orchestrated by CO. Various approaches to mimic this physiological HO-1 / CO system aiming for a treatment of medical conditions have been described [1]. These preclinical studies commonly applied CO systemically via (i) inhalation or (ii) using CO-Releasing Molecules (CORMs) [2]. The clinical use of these approaches, however, is challenged by a lack of practicability and substantial safety issues associated with the toxicity of high systemic doses of CO that are required for triggering therapeutic effects. Therefore, one rational of this thesis is to describe and evaluate strategies for the local delivery of CO aiming for safe and effective CO therapeutics of tomorrow.}, subject = {Targeted drug delivery}, language = {en} } @phdthesis{Iltzsche2017, author = {Iltzsche, Fabian}, title = {The Role of DREAM/MMB-mediated mitotic gene expression downstream of mutated K-Ras in lung cancer}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-154108}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2017}, abstract = {The evolutionary conserved Myb-MuvB (MMB) multiprotein complex has an essential role in transcriptional activation of mitotic genes. MMB target genes as well as the MMB associated transcription factor B-Myb and FoxM1 are highly expressed in a range of different cancer types. The elevated expression of these genes correlates with an advanced tumor state and a poor prognosis. This suggests that MMB could contribute to tumorigenesis by mediating overexpression of mitotic genes. Although MMB has been extensively characterized biochemically, the requirement for MMB to tumorigenesis in vivo remains largely unknown and has not been tested directly so far. In this study, conditional knockout of the MMB core member Lin9 inhibits tumor formation in vivo in a mouse model of lung cancer driven by oncogenic K-Ras and loss of p53. The incomplete recombination observed within tumors points towards an enormous selection pressure against the complete loss of Lin9. RNA interference (RNAi)-mediated depletion of Lin9 or the MMB associated subunit B-Myb provides evidence that MMB is required for the expression of mitotic genes in lung cancer cells. Moreover, it was demonstrated that proliferation of lung cancer cells strongly depends on MMB. Furthermore, in this study, the relationship of MMB to the p53 tumor suppressor was investigated in a primary lung cancer cell line with restorable p53 function. Expression analysis revealed that mitotic genes are downregulated after p53 re-expression. Moreover, activation of p53 induces formation of the repressive DREAM complex and results in enrichment of DREAM at mitotic gene promoters. Conversely, MMB is displaced at these promoters. Based on these findings the following model is proposed: In p53-negative cells, mitogenic stimuli foster the switch from DREAM to MMB. Thus, mitotic genes are overexpressed and may promote chromosomal instability and tumorigenesis. This study provides evidence that MMB contributes to the upregulation of G2/M phase-specific genes in p53-negative cells and suggests that inhibition of MMB (or its target genes) might be a strategy for treatment of lung cancer.}, subject = {Nicht-kleinzelliges Bronchialkarzinom (NSCLC)}, language = {en} } @phdthesis{Lyga2017, author = {Lyga, Sandra}, title = {Glycoprotein hormone receptor signaling in the endosomal compartment}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-139994}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2017}, abstract = {G protein-coupled receptors (GPCRs) are the major group of cell-surface receptors that transmit extracellular signals via classical, G protein-dependent pathways into the cell. Although GPCRs were long assumed to signal exclusively from the cell-surface, recent investigations have demonstrated a possibly completely new paradigm. In this new view, GPCR continues signaling via 3´,5´-cyclic adenosine monophosphate (cAMP) after their agonist-induced internalization of ligand/receptor complexes into an intracellular compartment, causing persistent cAMP elevation and apparently specific signaling outcomes. The thyroid stimulating hormone (TSH) receptor is one of the first GPCRs, which has been reported to show persistent signaling after ligand removal (Calebiro et al., 2009). In the meantime, signaling by internalized GPCR become a highly investigated topic and has been shown for several GPCRs, including the parathyroid hormone receptor (Ferrandon et al., 2009), D1 dopamine receptor (Kotowski et al., 2011) and beta2-adrenergic receptor (Irannejad et al., 2013). A recent study on the beta2-adrenergic receptor revealed that internalized receptor not only participates in cAMP signaling, but is also involved in gene transcription (Tsvetanova and von Zastrow, 2014). However, a biological effect of GPCR signaling at intracellular sites, which would demonstrate its physiological relevance, still remained to be shown. To investigate GPCR signaling from intracellular compartment under physiological condition, two different cellular models were utilized in the present study: intact ovarian follicles expressing luteinizing hormone (LH) receptors and primary thyroid cells expressing TSH receptors. Intact ovarian follicles were obtained from a transgenic mouse expressing, a F{\"o}rster/Fluorescence Resonance Energy Transfer (FRET) sensor for cAMP to monitor cAMP/LH receptor signaling. This study provides the first accurate spatiotemporal characterization of cAMP signaling, which is derived from different cell layers of an intact ovarian follicle. Additionally, it could be shown that cAMP diffusion via gap junctions is implicated in spreading the LH-induced cAMP signals from one the outermost (mural granulosa) to the innermost (cumulus oophorus) cell layer of an ovarian follicle. Interestingly, LH receptor stimulation was associated with persistent cAMP signaling after LH removal and negligible desensitization of the cAMP signal. Interfering with receptor internalization with a dynamin inhibitor dynasore did not only prevent persistent LH-induced cAMP signaling, but also impaired the resumption of meiosis in follicle-enclosed oocytes, a key biological effect of LH. In order to investigate the downstream activation of protein kinase A (PKA) in primary thyroid cells, FRET sensors with different subcellular localization (plasma membrane, cytosol and nucleus) were transiently transfected into primary thyroid cells of wild-type mice via electroporation. Interestingly, TSH stimulation causes at least two distinct phases of PKA activation in the global primary thyroid cell, which are temporally separated by approximately 2 min. In addition, PKA activation in different subcellular compartments are characterized by dissimilar kinetics and amplitudes. Pharmacological inhibition of TSH receptor internalization largely prevented the second (i.e. late) phase of PKA activation as well as the subsequent TSH-dependent phosphorylation of CREB and TSH-dependent induction of early genes. These results suggest that PKA activation and nuclear signaling require internalization of the TSH receptor. Taken together, the data of the present study provide strong evidence that GPCR signaling at intracellular sites is distinct from the one occurring at the cell-surface and is highly physiologically relevant.}, subject = {GPCR}, language = {en} } @phdthesis{Deppermann2017, author = {Deppermann, Carsten}, title = {The role of platelet granules in thrombosis, hemostasis, stroke and inflammation}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-121010}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2017}, abstract = {Platelets are small anucleate cell fragments derived from bone marrow megakaryocytes (MKs) and are important players in hemostasis and thrombosis. Platelet granules store factors which are released upon activation. There are three major types of platelet granules: alpha-granules, dense granules and lysosomes. While dense granules contain non-proteinacious factors which support platelet aggregation and adhesion, platelet alpha-granules contain more than 300 different proteins involved in various functions such as inflammation, wound healing and the maintenanceof vascular integrity, however, their functional significance in vivo remains unknown. This thesis summarizes analyses using three mouse models generated to investigate the role of platelet granules in thrombosis, hemostasis, stroke and inflammation. Unc13d-/- mice displayed defective platelet dense granule secretion, which resulted in abrogated thrombosis and hemostasis. Remarkably, Munc13-4-deficient mice were profoundly protected from infarct progression following transient middle cerebral artery occlusion (tMCAO) and this was not associated with increased intracranial bleeding indicating an essential involvementof dense granule secretion in infarct progression but not intracranial hemostasis during acute stroke with obvious therapeutic implications. In the second part of this thesis, the role of platelet alpha-granules was investigated using the Nbeal2-/- mouse. Mutations in NBEAL2 have been linked to the gray platelet syndrome (GPS), a rare inherited bleeding disorder. Nbeal2-/- mice displayed the characteristics of human GPS, with defective alpha-granule biogenesis in MKs and their absence from platelets. Nbeal2-deficiency did not affect MK differentiation and proplatelet formation in vitro or platelet life span in vivo. Nbeal2-/- platelets displayed impaired adhesion, aggregation, and coagulant activity ex vivo that translated into defective arterial thrombus formation and protection from thrombo-inflammatory brain infarction in vivo. In a model of skin wound repair, Nbeal2-/- mice exhibited impaired development of functional granulation tissue due to severely reduced differentiation of myofibroblasts. In the third part, the effects of combined deficiency of alpha- and dense granule secretion were analyzed using Unc13d-/-/Nbeal2-/- mice. Platelets of these mice showed impaired aggregation and adhesion to collagen under flow ex vivo, which translated into infinite tail bleeding times and severely defective arterial thrombus formation in vivo. When subjected to in vivo models of skin or lung inflammation, the double mutant mice showed no signs of hemorrhage. In contrast, lack of platelet granule release resulted in impaired vascular integrity in the ischemic brain following tMCAO leading to increased mortality. This indicates that while defective dense granule secretion or the paucity of alpha-granules alone have no effect on vascular integrity after stroke, the combination of both impairs vascular integrity and causes an increase in mortality.}, subject = {Thrombozyten}, language = {en} } @phdthesis{Saal2017, author = {Saal, Lena}, title = {Whole transcriptome profiling of compartmentalized motoneurons}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-140006}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2017}, abstract = {Spinal muscular atrophy and amyotrophic lateral sclerosis are the two most common devastating motoneuron diseases. The mechanisms leading to motoneuron degeneration are not resolved so far, although different hypotheses have been built on existing data. One possible mechanism is disturbed axonal transport of RNAs in the affected motoneurons. The underlying question of this study was therefore to characterize changes in transcript levels of distinct RNAs in cell culture models of spinal muscular atrophy and amyotrophic lateral sclerosis, especially in the axonal compartment of primary motoneurons. To investigate this in detail we first established compartmentalized cultures of Primary mouse motoneurons. Subsequently, total RNA of both compartments was extracted separately and either linearly amplified and subjected to microarray profiling or whole transcriptome amplification followed by RNA-Sequencing was performed. To make the whole transcriptome amplification method suitable for compartmentalized cultures, we adapted a double-random priming strategy. First, we applied this method for initial optimization onto serial dilutions of spinal cord RNA and later on to the compartmentalized motoneurons. Analysis of the data obtained from wildtype cultures already revealed interesting results. First, the RNA composition of axons turned out to be highly similar to the somatodendritic compartment. Second, axons seem to be particularly enriched for transcripts related to protein synthesis and energy production. In a next step we repeated the experiments by using knockdown cultures. The proteins depleted hereby are Smn, Tdp-43 and hnRNP R. Another experiment was performed by knocking down the non-coding RNA 7SK, the main interacting RNA of hnRNP R. Depletion of Smn led to a vast number of deregulated transcripts in the axonal and somatodendritic compartment. Transcripts downregulated in the axons upon Smn depletion were especially enriched for GOterms related to RNA processing and encode proteins located in neuron projections including axons and growth cones. Strinkingly, among the upregulated transcripts in the somatodendritic compartment we mainly found MHC class I transcripts suggesting a potential neuroprotective role. In contrast, although knockdown of Tdp-43 also revealed a large number of downregulated transcripts in the axonal compartment, these transcripts were mainly associated with functions in transcriptional regulation and RNA splicing. For the hnRNP R knockdown our results were again different. Here, we observed downregulated transcripts in the axonal compartment mainly associated with regulation of synaptic transmission and nerve impulses. Interestingly, a comparison between deregulated transcripts in the axonal compartment of both hnRNP R and 7SK knockdown presented a significant overlap of several transcripts suggesting some common mechanism for both knockdowns. Thus, our data indicate that a loss of disease-associated proteins involved in axonal RNA transport causes distinct transcriptome alterations in motor axons.}, subject = {Axon}, language = {en} } @phdthesis{Pakkayil2017, author = {Pakkayil, Shijin Babu}, title = {Towards ferromagnet/superconductor junctions on graphene}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-153863}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2017}, abstract = {This thesis reports a successful fabrication and characterisation of ferromagnetic/superconductor junction (F/S) on graphene. The thesis preposes a fabrication method to produce F/S junctions on graphene which make use of ALD grown Al2O3 as the tunnel barrier for the ferromagnetic contacts. Measurements done on F/G/S/G/F suggests that by injecting spin polarised current into the superconductor, a spin imbalance is created in the quasiparticle density of states of the superconductor which then diffuses through the graphene channel. The observed characteristic curves are similar to the ones which are already reported on metallic ferromagnet/superconductor junctions where the spin imbalance is created using Zeeman splitting. Further measurements also show that the curves loose their characteristic shapes when the temperature is increased above the critical temperature (Tc) or when the external magnetic field is higher then the critical field (Hc) of the superconducting contact. But to prove conclusively and doubtlessly the existence of spin imbalance in ferromagnet/superconductor junctions on graphene, more devices have to be made and characterised preferably in a dilution refrigerator.}, subject = {Graphen}, language = {en} } @phdthesis{Terveer2017, author = {Terveer, Nils}, title = {Springs and Parachutes - Development and Characterization of Novel Formulations for Poorly Water-Soluble Drugs}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-154311}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2017}, abstract = {Successful formulation development of novel, particularly organic APIs of low molecular weight as candidates for ground-breaking pharmaceutical products is a major challenge for the pharmaceutical industry because of the poor aqueous solubility of most of these compounds. The hit identification strategies of drug development in use today apply high throughput screening techniques for the investigation of thousands of substances. This approach led to a systematical increase in molecular weight and lipophilicity and a decrease of water solubility of lead compounds reaching market access. The high lipophilicity causes an excellent permeability of the compounds which favours the absorption process from the small intestine, but it causes a decrease of water-solubility. It becomes evident that an adequate aqueous solubility is necessary for absorption of the API from the gastrointestinal fluids into the systemic circulation and hence for efficacy of the pharmaceutical product. Only an dissolved API is getting absorbed and becomes efficacious. The precipitated proportion is resigned directly. Therefore, the development of an individual formulation aligning the physicochemical characteristics is necessary for every API to produce supersaturated solutions in the small intestine and to reach an adequate bioavailability after absorption into the systemic circulation. In this thesis a specific formulation development was investigated for two exemplary poorly water-soluble APIs to replace the empirical approach often used today. The basic tyrosine-kinase inhibitor imatinib and six different acetylated amino acids were transferred into ILs. As compared to the free base and the mesylate salt, which is marketed by Novartis AG as Gleevec®, the dissolution rate as well as the supersaturation time was increased significantly. By changing the mesylate anion with its potential genotoxic risks, the total toxicity of the drug product could be decreased. The amorphous ILs proved adequate stability under forcing conditions and there was no recrystallization of the free base observed. The amorphous character of the ILs caused an increased amount of water vapour sorption which can be compensated by special packaging materials. Taken together, the presentation of imatinib as an IL is intended for oral administration as a tablet and can cause a reduction of dose because of the increased solubility. Therefore, the occurrence of side effects can be reduced as compared to Gleevec®. If there is actually an increased bioavailability to observe, has to be proved by the execution of animal trials. The novel NOX inhibitor VAS3947 is intended for the treatment of endothelial dysfunctions causing diseases like heart failure and stroke. The compounds poor aqueous solubility hindered further clinical development so far and make the drug candidate to remain in a very early stage of the drug development process. Therefore, different formulation concepts were evaluated in this study: An amorphous solid dispersion prepared from VAS3947 and Eudragit® L100 by means of spray drying was able to increase the dissolution rate and solubility of the compound significantly, but with the accomplished kinetic solubility being in the low µM range it is not possible to reach therapeutic plasma concentrations. In contrast, the incorporation into cyclodextrins resulted in an 760-fold increased solubility. Different cyclodextrins were evaluated. Especially the lipophilic derivatives of the β-cyclodextrin showed to be the most adequate excipients. The incorporation of the API into the cyclodextrin cavity was proved by means of NMR spectroscopy. Additionally, a formulation of VAS3947 and hydroxypropyl-β-cyclodextrin was prepared. This formulation is intended for the intravenous application during animal trials, which have to be conducted to get to know the pharmacokinetics of VAS3947. This formulation reached a concentration of 1 mg/mL spending striking protection of VAS3947 against degradation. Presentation of VAS3947 as a microemulsion system led also to increase the aqueous solubility of the compound, but not in the same extent as the cyclodextrin formulation. Beside the formulation development a physicochemical characterization was performed to get to know important parameters such as log P and pKa values of VAS3947. An HPLC method was developed and validated to analyse the extent of solubility improvement. A major issue of the compound VAS3947 and all related triazolopyrimidine derivatives, developed by Vasopharm GmbH, is the insufficient chemical stability because of presence of a hemiaminal moiety in the chemical structure. Stability investigations and an extensive biopharmaceutical characterization confirm the hindering of further clinical development by insufficient drug stability and high cytotoxicity. Poor aqueous solubility is an additional disadvantage which can be handled by a concerted formulation development.}, language = {en} } @phdthesis{Seufert2017, author = {Seufert, Michael Thomas}, title = {Quality of Experience and Access Network Traffic Management of HTTP Adaptive Video Streaming}, issn = {1432-8801}, doi = {10.25972/OPUS-15413}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-154131}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2017}, abstract = {The thesis focuses on Quality of Experience (QoE) of HTTP adaptive video streaming (HAS) and traffic management in access networks to improve the QoE of HAS. First, the QoE impact of adaptation parameters and time on layer was investigated with subjective crowdsourcing studies. The results were used to compute a QoE-optimal adaptation strategy for given video and network conditions. This allows video service providers to develop and benchmark improved adaptation logics for HAS. Furthermore, the thesis investigated concepts to monitor video QoE on application and network layer, which can be used by network providers in the QoE-aware traffic management cycle. Moreover, an analytic and simulative performance evaluation of QoE-aware traffic management on a bottleneck link was conducted. Finally, the thesis investigated socially-aware traffic management for HAS via Wi-Fi offloading of mobile HAS flows. A model for the distribution of public Wi-Fi hotspots and a platform for socially-aware traffic management on private home routers was presented. A simulative performance evaluation investigated the impact of Wi-Fi offloading on the QoE and energy consumption of mobile HAS.}, subject = {Quality of Experience}, language = {en} } @phdthesis{Kurz2017, author = {Kurz, Julian Frederick}, title = {Capacity Planning and Control with Advanced Information}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-154097}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2017}, abstract = {Die Dissertation „Capacity Planning and Control with Advanced Information" besteht aus drei inhaltlich abgeschlossenen Teilen, die ein {\"u}bergeordnetes Thema zur Grundlage haben: Wie k{\"o}nnen Daten {\"u}ber zuk{\"u}nftige Bedarfe zur Kapazit{\"a}tsplanung und -steuerung genutzt werden? Im Rahmen von Industrie 4.0 werden zunehmend Daten erzeugt und f{\"u}r pr{\"a}dikative Analysen genutzt. Zum Beispiel werden Flugzeugtriebwerke mit Sensoren ausgestattet, die verschiedene Parameter in Echtzeit ermitteln und {\"u}bertragen. In Kombination mit Flugpl{\"a}nen k{\"o}nnen diese Daten, unter Einsatz geeigneter Machine Learning Algorithmen, zur Vorhersage des Zeitpunkts der n{\"a}chsten Wartung und des Wartungsbedarfs genutzt werden. In dieser Arbeit werden diese Vorhersagedaten zur optimalen Planung und Steuerung der Kapazit{\"a}t eines MRO (Maintenance, Repair and Overhaul) Dienstleisters genutzt. Im ersten Artikel, "Capacity Planning for a Maintenance Service Provider with Advanced Information", wird die aus mehreren Stationen bestehende Produktionsst{\"a}tte des MRO Dienstleisters mit Hilfe eines Netzwerks aus GI/G/1 Warteschlagen beschrieben. Durch L{\"o}sung eines Optimierungsproblems werden die Kapazit{\"a}ten der einzelnen Stationen so ermittelt, dass Kapazit{\"a}ts- und Strafkosten f{\"u}r eine zu lange Durchlaufzeit minimiert werden. Dar{\"u}berhinaus wird untersucht, wie Vorhersagedaten bez{\"u}glich des Eintreffens und Wartungsaufwands zuk{\"u}nftiger Auftr{\"a}ge genutzt werden k{\"o}nnen, um die Gesamtkosten zu reduzieren. Der Artikel "Flexible Capacity Management with Future Information" nutzt Informationen hinsichtlich zuk{\"u}nftigerWartungsbedarfe f{\"u}r die Steuerung einer flexiblen Kapazit{\"a}t. Die Produktionsst{\"a}tte des MRO Dienstleisters wird als M/M/1 Warteschlange beschrieben, die zwischen einer Basiskapazit{\"a}t und einer erh{\"o}hten Kapazit{\"a}t wechseln kann. Allerdings kann die hohe Kapazit{\"a}t nur einen definierten Zeitanteil genutzt werden. In dem Artikel werden Politiken entwickelt, welche die erwartete Warteschlangenl{\"a}ge minimieren, falls keine Informationen bez{\"u}glich des Eintreffens zuk{\"u}nftiger Auftr{\"a}ge verf{\"u}gbar sind beziehungsweise alle Informationen in einem unendlich langen Zeitfenster vorliegen. Es zeigt sich, dass die erwartete Warteschlangenl{\"a}nge drastisch reduziert werden kann, falls Informationen {\"u}ber zuk{\"u}nftige Bedarfe genutzt werden k{\"o}nnen. Im dritten Artikel, "Queueing with Limited Future Information", wird neben der Steuerung einer flexiblen Kapazit{\"a}t auch die Zulassungskontrolle behandelt: Welche Auftr{\"a}ge sollten umgeleitet werden, zum Beispiel an einen Subdienstleister, falls ein definierter Anteil aller ankommenden Triebwerke nicht angenommen werden muss? Es werden Politiken zur Steuerung der flexiblen Kapazit{\"a}t und f{\"u}r die Zulassungskontrolle entwickelt, die zuk{\"u}nftige Informationen in verschieden langen Zeitfenstern ber{\"u}cksichtigen: keine Informationen, endlich und unendlich lange Zeitfenster. Numerische Analysen zeigen, dass die Ber{\"u}cksichtigung von Informationen {\"u}ber die Zukunft im Vergleich zu reaktiven Politiken zu einer Verringerung der mittleren Warteschlangenl{\"a}nge f{\"u}hrt. Andererseits wird ersichtlich, dass die Nutzung von k{\"u}rzeren Zeitfenstern unter bestimmten Umst{\"a}nden vorteilhaft sein kann. Den inhaltlichen Rahmen der Dissertation bilden die Einleitung im ersten Kapitel sowie ein Ausblick in Kapitel 5. Beweise werden im Anhang zusammengefasst.}, language = {en} } @phdthesis{Reichert2017, author = {Reichert, Thorsten}, title = {Classification and Reduction of Equivariant Star Products on Symplectic Manifolds}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-153623}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2017}, abstract = {This doctoral thesis provides a classification of equivariant star products (star products together with quantum momentum maps) in terms of equivariant de Rham cohomology. This classification result is then used to construct an analogon of the Kirwan map from which one can directly obtain the characteristic class of certain reduced star products on Marsden-Weinstein reduced symplectic manifolds from the equivariant characteristic class of their corresponding unreduced equivariant star product. From the surjectivity of this map one can conclude that every star product on Marsden-Weinstein reduced symplectic manifolds can (up to equivalence) be obtained as a reduced equivariant star product.}, subject = {Homologische Algebra}, language = {en} } @phdthesis{Gupta2017, author = {Gupta, Sanjay Kumar}, title = {The human CCHC-type Zinc Finger Nucleic Acid Binding Protein (CNBP) binds to the G-rich elements in target mRNA coding sequences and promotes translation}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-142917}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2017}, abstract = {The genetic information encoded with in the genes are transcribed and translated to give rise to the functional proteins, which are building block of a cell. At first, it was thought that the regulation of gene expression particularly occurs at the level of transcription by various transcription factors. Recent discoveries have shown the vital role of gene regulation at the level of RNA also known as post-transcriptional gene regulation (PTGR). Apart from non-coding RNAs e.g. micro RNAs, various RNA binding proteins (RBPs) play essential role in PTGR. RBPs have been implicated in different stages of mRNA life cycle ranging from splicing, processing, transport, localization and decay. In last 20 years studies have shown the presence of hundreds of RBPs across eukaryotic systems many of which are widely conserved. Given the rising number of RBPs and their link to human diseases it is quite evident that RBPs have major role in cellular processes and their regulation. The current study is aimed to describe the so far unknown molecular mechanism of CCHC-type Zinc Finger Nucleic Acid Binding Protein (CNBP/ZNF9) function in vivo. CNBP is ubiquitously expressed across various human tissues and is a highly conserved RBP in eukaryotes. It is required for embryonic development in mammals and has been implicated in transcriptional as well as post-transcriptional gene regulation; however, its molecular function and direct target genes remain elusive. Here, we use multiple systems-wide approaches to identify CNBP targets and document the consequences of CNBP binding. We established CNBP as a cytoplasmic RNA-binding-protein and used Photoactivatable Ribonucleoside Enhanced Crosslinking and Immunoprecipitation (PAR-CLIP) to identify direct interactions of CNBP with 4178 mRNAs. CNBP preferentially bound a G-rich motif in the target mRNA coding sequences. Functional analyses, including ribosome profiling, RNA sequencing, and luciferase assays revealed the CNBP mode of action on target transcripts. CNBP binding was found to increase the translational efficiency of its target genes. We hypothesize that this is consistent with an RNA chaperone function of CNBP helping to resolve secondary structures, thus promoting translation. Altogether this study provides a novel mechanism of CNBP function in vivo and acts as a step-stone to study the individual CNBP targets that will bring us closer to understand the disease onset.}, subject = {CNBP}, language = {en} } @phdthesis{YazdaniRashvanlouei2017, author = {Yazdani Rashvanlouei, Kourosh}, title = {Developing a Framework for International Projects of ERP Implementation}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-154000}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2017}, abstract = {Enterprise Systeme werden immer mehr von Bedeutung, was sie in die Mitte der Aufmerksamkeit und der Ber{\"u}cksichtigung durch Organisationen in verschiedensten Formen r{\"u}ckt - seien es Unternehmen oder Industrien von riesigen {\"o}ffentlichen oder privaten Organisationen bis hin zu mittleren und kleinen Dienstleistungsunternehmen. Diese Systeme verbessern sich st{\"a}ndig, sowohl funktionell, als auch technologisch und sie sind unumg{\"a}nglich f{\"u}r Unternehmen, um ihre Produktivit{\"a}t zu vergr{\"o}ßern und um in dem nationalen und globalen Wettbewerb mitzuhalten. Da lokale Softwarel{\"o}sungen die Bedingungen, speziell von großen Betrieben, funktionell und technologisch nicht erf{\"u}llen konnten und da riesige globale Softwarehersteller, wie SAP, Oracle und Microsoft ihre L{\"o}sungen rapide verbessern und sie ihren Markt immer mehr {\"u}ber den Globus expandieren, nimmt die Nachfrage f{\"u}r diese globalen Marken und deren nahezu einwandfreien Softwarel{\"o}sungen t{\"a}glich zu. Die Zustimmung f{\"u}r internationale ERP Unternehmensberatungsanwendungen nimmt deswegen exponentiell zu, w{\"a}hrend die Forschung der beeinflussenden Faktoren und des Fachwissens wenig verbreitet ist. Deswegen ist es so dringlich, dieses Gebiet zu erforschen. Das schlussendliche f{\"u}nf-in-f{\"u}nf Framework dieser Studie sammelt zum ersten Mal in der Geschichte alle historisch erw{\"a}hnten, kritischen Erfolgsfaktoren und Projektaktivit{\"a}ten. Diese wurden in f{\"u}nf Phasen unterteilt und nach den f{\"u}nf Schwerpunkten der internationalen ERP Projektdurchf{\"u}hrung kategorisiert. Dieses Framework bietet einen {\"U}berblick und bildet einen umfassenden Fahrplan f{\"u}r solche Projekte.}, subject = {ERP}, language = {en} } @phdthesis{Wolf2017, author = {Wolf, Beat}, title = {Reducing the complexity of OMICS data analysis}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-153687}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2017}, abstract = {The field of genetics faces a lot of challenges and opportunities in both research and diagnostics due to the rise of next generation sequencing (NGS), a technology that allows to sequence DNA increasingly fast and cheap. NGS is not only used to analyze DNA, but also RNA, which is a very similar molecule also present in the cell, in both cases producing large amounts of data. The big amount of data raises both infrastructure and usability problems, as powerful computing infrastructures are required and there are many manual steps in the data analysis which are complicated to execute. Both of those problems limit the use of NGS in the clinic and research, by producing a bottleneck both computationally and in terms of manpower, as for many analyses geneticists lack the required computing skills. Over the course of this thesis we investigated how computer science can help to improve this situation to reduce the complexity of this type of analysis. We looked at how to make the analysis more accessible to increase the number of people that can perform OMICS data analysis (OMICS groups various genomics data-sources). To approach this problem, we developed a graphical NGS data analysis pipeline aimed at a diagnostics environment while still being useful in research in close collaboration with the Human Genetics Department at the University of W{\"u}rzburg. The pipeline has been used in various research papers on covering subjects, including works with direct author participation in genomics, transcriptomics as well as epigenomics. To further validate the graphical pipeline, a user survey was carried out which confirmed that it lowers the complexity of OMICS data analysis. We also studied how the data analysis can be improved in terms of computing infrastructure by improving the performance of certain analysis steps. We did this both in terms of speed improvements on a single computer (with notably variant calling being faster by up to 18 times), as well as with distributed computing to better use an existing infrastructure. The improvements were integrated into the previously described graphical pipeline, which itself also was focused on low resource usage. As a major contribution and to help with future development of parallel and distributed applications, for the usage in genetics or otherwise, we also looked at how to make it easier to develop such applications. Based on the parallel object programming model (POP), we created a Java language extension called POP-Java, which allows for easy and transparent distribution of objects. Through this development, we brought the POP model to the cloud, Hadoop clusters and present a new collaborative distributed computing model called FriendComputing. The advances made in the different domains of this thesis have been published in various works specified in this document.}, subject = {Bioinformatik}, language = {en} } @phdthesis{Stockinger2017, author = {Stockinger, Bastian}, title = {Causes and effects of worker mobility between firms: empirical studies for Germany}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-153894}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2017}, abstract = {This dissertation investigates selected causes and effects of worker mobility between firms in three empirical studies for Germany. Chapter 2 investigates the productivity effects of worker inflows to manufacturing establishments, distinguishing inflows by their previous employers' wage level, as a proxy for productivity. The chapter is motivated by several empirical studies which find that worker inflows from more productive or higher-paying firms increase hiring firms' productivity. The analyses in chapter 2 are based on a unique linked employer-employee data set. The findings indicate that inflows from higher-paying establishments do not increase hiring establishments' productivity, but inflows from lower-paying establishments do. Further analyses suggest that this effect is due to a positive selectivity of such inflows from their sending establishments. These findings can be interpreted as evidence of a reallocation process by which the best employees of lower-paying establishments become hired by higher-paying establishments. This process reflects the assortative pattern of worker mobility in Germany documented by Card et al. (2013) for the past decades. The chapter thus contributes to the literature by linking establishment-level productivity analysis to the assortative pattern of inter-firm worker mobility, thereby providing a micro-foundation for the latter. Chapter 3 focuses on a positive selection of workers moving between firms from another, more specific perspective. The analysis focuses on the importance of regional labor market competition for establishments' apprentice training and poaching of apprenticeship completers. Previous studies have found that firms provide less training if they are located in regions with strong labor market competition. This finding is usually interpreted as evidence of a higher risk of poaching in these regions. Yet, there is no direct evidence that regional competition is positively correlated with poaching. Building on a recently established approach to ex-post identify poaching of apprenticeship completers, this chapter is the first to directly investigate the correlation between regional labor market competition and poaching. Using German administrative data, it is found that competition indeed increases training establishments' probability of becoming poaching victims. However, poaching victims do not change their apprenticeship training activity in reaction to poaching. Instead, the findings indicate that the lower training activity in competitive regions can be attributed to lower retention rates, as well as a less adverse selection and lower labor and hiring costs of apprenticeship completers hired from rivals. Chapter 4 investigates the effects of local broadband internet availability on establishment-level employment growth. The analysis uses data for Germany in the years 2005-2009, when broadband was introduced in rural regions of Western Germany and in large parts of Eastern Germany. Technical frictions in broadband rollout are exploited to obtain exogenous variation in local broadband availability. The results suggest that broadband expansion had a positive effect on employment growth in the Western German service sector and a negative effect in Western German manufacturing, suggesting that broadband expansion has accelerated the reallocation of workers from manufacturing to services. Furthermore, this pattern of results is driven by pronounced positive effects in knowledge- and computer-intensive industries, suggesting that it is the actual use of broadband in the production process that leads to complementary hiring, respectively a slowdown of employment growth, in the respective sectors. For Eastern Germany, no significant employment growth effects are found.}, subject = {Arbeitsmarkt}, language = {en} } @phdthesis{Schmitt2017, author = {Schmitt, Dominik}, title = {Structural Characterization of the TFIIH Subunits p34 and p44 from C. thermophilum}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-104851}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2017}, abstract = {Several important cellular processes, including transcription, nucleotide excision repair and cell cycle control are mediated by the multifaceted interplay of subunits within the general transcription factor II H (TFIIH). A better understanding of the molecular structure of TFIIH is the key to unravel the mechanism of action of this versatile protein complex within these pathways. This becomes especially important in the context of severe diseases like xeroderma pigmentosum, Cockayne syndrome and trichothiodystrophy, that arise from single point mutations in some of the TFIIH subunits. In an attempt to structurally characterize the TFIIH complex, we harnessed the qualities of the eukaryotic thermophile Chaetomium thermophilum, a remarkable fungus, which has only recently been recognized as a novel model organism. Homologues of TFIIH from C. thermophilum were expressed in E. coli, purified to homogeneity and subsequently utilized for crystallization trials and biochemical studies. The results of the present work include the first crystal structure of the p34 subunit of TFIIH, comprising the N-terminal domain of the protein. The structure revealed a von Willebrand Factor A (vWA) like fold, which is generally known to be involved in a multitude of protein-protein interactions. Structural comparison allowed to delineate similarities as well as differences to already known vWA domains, providing insight into the role of p34 within TFIIH. These results indicate that p34 assumes the role of a structural scaffold for other TFIIH subunits via its vWA domain, while likely serving additional functions, which are mediated through its C-terminal zinc binding domain and are so far unknown. Within TFIIH p34 interacts strongly with the p44 subunit, a positive regulator of the XPD helicase, which is required for regulation of RNA Polymerase II mediated transcription and essential for eukaryotic nucleotide excision repair. Based on the p34 vWA structure putative protein-protein interfaces were analyzed and binding sites for the p34 p44 interaction suggested. Continuous crystallization efforts then led to the first structure of a p34 p44 minimal complex, comprising the N-terminal vWA domain of p34 and the C-terminal C4C4 RING domain of p44. The structure of the p34 p44 minimal complex verified the previous hypothesis regarding the involved binding sites. In addition, careful analysis of the complex interface allowed to identify critical residues, which were subsequently mutated and analyzed with respect to their significance in mediating the p34 p44 interaction, by analytical size exclusion chromatography, electrophoretic mobility shift assays and isothermal titration calorimetry. The structure of the p34 p44 complex also revealed a binding mode of the p44 C4C4 RING domain, which differed from that of other known RING domains in several aspects, supporting the hypothesis that p44 contains a novel variation of this domain.}, subject = {DNA-Reparatur}, language = {en} } @phdthesis{Hagen2017, author = {Hagen, Franziska}, title = {Sphingolipids in gonococcal infection}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-153852}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2017}, abstract = {Neisseria gonorrhoeae, the causative agent of the sexually transmitted disease gonorrhea, has the potential to spread in the human host and cause a severe complication called disseminated gonococcal infection (DGI). The expression of the major outer membrane porin PorBIA is a characteristic of most gonococci associated with DGI. PorBIA binds to the scavenger receptor expressed on endothelial cells (SREC-I), which mediates the so-called low phosphate-dependent invasion (LPDI). This uptake mechanism enables N. gonorrhoeae to rapidly invade epithelial and endothelial cells in a phosphate-sensitive manner. We recently demonstrated that the neutral sphingomyelinase, which catalyses the hydrolysis of sphingomyelin to ceramide and phosphorylcholine, is required for the LPDI of gonococci in non-phagocytic cells. Neutral sphingomyelinase 2 (NSM2) plays a key role in the early PorBIA signaling by recruiting the PI3 kinase to caveolin. The following activation of the PI3 kinase-dependent downstream signaling leads to the engulfment of the bacteria. As a part of this work, I could confirm the involvement of the NSM2. The role of the enzyme was further elucidated by the generation of antibodies directed against NSM2 and the construction of an epithelium-based NSM2 knockout cell line using CRISPR/Cas9. The knockout of the NSM2 strongly inhibits the LPDI. The invasion could be, however, restored by the complementation of the knockout using an NSM2-GFP construct. However, the results could not be reproduced. In this work, I could show the involvement of further members of the sphingolipid pathway in the PorBIA-mediated invasion. Lipidome analysis revealed an increase of the bioactive molecules ceramide and sphingosine due to gonococcal infection. Both molecules do not only affect the host cell, but seem to influence the bacteria as well: while ceramide seems to be incorporated by the gonococci, sphingosine is toxic for the bacteria. Furthermore, the sphingosine kinase 2 (SPHK2) plays an important role in invasion, since the inhibition and knockdown of the enzyme revealed a negative effect on gonococcal invasion. To elucidate the role of the sphingosine kinases in invasion in more detail, an activity assay was established in this study. Additionally, the impact of the sphingosine-1-phosphate lyase (S1PL) on invasion was investigated. Inhibitor studies and infection experiments conducted with a CRISPR/Cas9 HeLa S1PL knockout cell line revealed a role of the enzyme not only in the PorBIA-mediated invasion, but also in the Opa50/HSPG-mediated gonococcal invasion. The signaling experiments allowed the categorization of the SPHK and S1PL activation in the context of infection. Like the NSM2, both enzymes play a role in the early PorBIA signaling events leading to the uptake of the bacteria. All those findings indicate an important role of sphingolipids in the invasion and survival of N. gonorrhoeae. In the last part of this work, the role of the NSM2 in the inhibition of apoptosis in neutrophils due to gonococcal infection was investigated. It could be demonstrated that the delayed onset of apoptosis is independent of neisserial porin and Opa proteins. Furthermore, the influence of neisserial peptidoglycan on PMN apoptosis was analysed using mutant strains, but no connection could be determined. Since the NSM2 is the most prominent sphingomyelinase in PMNs, fulfils manifold cell physiological functions and has already been connected to apoptosis, the impact of the enzyme on apoptosis inhibition due to gonococcal infection was investigated using inhibitors, with no positive results.}, subject = {gonococcal}, language = {en} } @phdthesis{Muthers2017, author = {Muthers, Johannes}, title = {Essays in Industrial Organization}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-141671}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2017}, abstract = {The dissertation deals with the market and welfare effects of different business practices and the firm's incentives to use them: resale price maintenance, revenue sharing of a platform operator, membership fees to buyers using a platform and patent licensing. In the second chapter we investigate the incentives of two manufacturers with common retailers to use resale price maintenance (RPM). Retailers provide product specific services that increase demand and manufacturers use minimum RPM to compete for favorable services for their products. Minimum RPM increases consumer pricesby voiding retailer price competition and can create a prisoner's dilemma for manufacturers without increasing, and possibly even decreasing the overall service level. If manufacturer market power is asymmetric, minimum RPM tends to distort the allocation of sales services towards the high-priced products of the manufacturer with more market power. These results challenge the service argument as an efficiency defense for minimum RPM. The third chapter deals with trade platforms whose operators not only allow third party sellers to offer their products to consumers, but also offer products themselves. In this context, the platform operator faces a hold-up problem if he uses classical two-part tariffs only (which previous literature on two-sided markets has focused on) as potential competition between the platform operator and sellers reduces platform attractiveness. Since some sellers refuse to join the platform, some products that are not known to the platform operator will not be offered at all. We discuss the effects of different platform tariffs on this hold-up problem. We find that revenue-based fees lower the platform operator's incentives to compete with sellers, increasing platform attractiveness. Therefore, charging such proportional fees can be profitable, what may explain why several trade platforms indeed charge proportional fees. The fourth chapter investigates the optimal tariff system in a model in which buyers are heterogeneous. A platform model is presented in which transactions are modeled explicitly and buyers can differ in their expected valuations when they decide to join the platform. The main effect that the model identifies is that the participation decision sorts buyers according to their expected valuations. This affects the pricing of sellers. Furthermore diffing form the usual approach, in which buyers are ex-ante homogeneous, the platform does not internalize the full transaction surplus. Hence it does not implement the socially efficient price on the platform, also it has control of the price with the transaction fee. The fifth chapter investigates the effects of licensing on the market outcome after the patent has expired. In a setting with endogenous entry, a licensee has a head start over the competition which translated into a first mover advantage if strategies are strategic substitutes. As competitive strategies quantities and informative advertising are considered explicitly. We find that although licensing increases the joint profit of the patentee and licensee, this does not necessarily come from a reduction in consumer surplus or other firms profits. For the case of quantity competition we show that licensing is welfare improving. For the case of informative advertising, however, we show that licensing increases prices and is thus detrimental to consumer surplus.}, subject = {Wettbewerbsverhalten}, language = {en} } @phdthesis{Spinner2017, author = {Spinner, Simon}, title = {Self-Aware Resource Management in Virtualized Data Centers}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-153754}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2017}, abstract = {Enterprise applications in virtualized data centers are often subject to time-varying workloads, i.e., the load intensity and request mix change over time, due to seasonal patterns and trends, or unpredictable bursts in user requests. Varying workloads result in frequently changing resource demands to the underlying hardware infrastructure. Virtualization technologies enable sharing and on-demand allocation of hardware resources between multiple applications. In this context, the resource allocations to virtualized applications should be continuously adapted in an elastic fashion, so that "at each point in time the available resources match the current demand as closely as possible" (Herbst el al., 2013). Autonomic approaches to resource management promise significant increases in resource efficiency while avoiding violations of performance and availability requirements during peak workloads. Traditional approaches for autonomic resource management use threshold-based rules (e.g., Amazon EC2) that execute pre-defined reconfiguration actions when a metric reaches a certain threshold (e.g., high resource utilization or load imbalance). However, many business-critical applications are subject to Service-Level-Objectives defined on an application performance metric (e.g., response time or throughput). To determine thresholds so that the end-to-end application SLO is fulfilled poses a major challenge due to the complex relationship between the resource allocation to an application and the application performance. Furthermore, threshold-based approaches are inherently prone to an oscillating behavior resulting in unnecessary reconfigurations. In order to overcome the deficiencies of threshold-based approaches and enable a fully automated approach to dynamically control the resource allocations of virtualized applications, model-based approaches are required that can predict the impact of a reconfiguration on the application performance in advance. However, existing model-based approaches are severely limited in their learning capabilities. They either require complete performance models of the application as input, or use a pre-identified model structure and only learn certain model parameters from empirical data at run-time. The former requires high manual efforts and deep system knowledge to create the performance models. The latter does not provide the flexibility to capture the specifics of complex and heterogeneous system architectures. This thesis presents a self-aware approach to the resource management in virtualized data centers. In this context, self-aware means that it automatically learns performance models of the application and the virtualized infrastructure and reasons based on these models to autonomically adapt the resource allocations in accordance with given application SLOs. Learning a performance model requires the extraction of the model structure representing the system architecture as well as the estimation of model parameters, such as resource demands. The estimation of resource demands is a key challenge as they cannot be observed directly in most systems. The major scientific contributions of this thesis are: - A reference architecture for online model learning in virtualized systems. Our reference architecture is based on a set of model extraction agents. Each agent focuses on specific tasks to automatically create and update model skeletons capturing its local knowledge of the system and collaborates with other agents to extract the structural parts of a global performance model of the system. We define different agent roles in the reference architecture and propose a model-based collaboration mechanism for the agents. The agents may be bundled within virtual appliances and may be tailored to include knowledge about the software stack deployed in a specific virtual appliance. - An online method for the statistical estimation of resource demands. For a given request processed by an application, the resource time consumed for a specified resource within the system (e.g., CPU or I/O device), referred to as resource demand, is the total average time the resource is busy processing the request. A request could be any unit of work (e.g., web page request, database transaction, batch job) processed by the system. We provide a systematization of existing statistical approaches to resource demand estimation and conduct an extensive experimental comparison to evaluate the accuracy of these approaches. We propose a novel method to automatically select estimation approaches and demonstrate that it increases the robustness and accuracy of the estimated resource demands significantly. - Model-based controllers for autonomic vertical scaling of virtualized applications. We design two controllers based on online model-based reasoning techniques in order to vertically scale applications at run-time in accordance with application SLOs. The controllers exploit the knowledge from the automatically extracted performance models when determining necessary reconfigurations. The first controller adds and removes virtual CPUs to an application depending on the current demand. It uses a layered performance model to also consider the physical resource contention when determining the required resources. The second controller adapts the resource allocations proactively to ensure the availability of the application during workload peaks and avoid reconfiguration during phases of high workload. We demonstrate the applicability of our approach in current virtualized environments and show its effectiveness leading to significant increases in resource efficiency and improvements of the application performance and availability under time-varying workloads. The evaluation of our approach is based on two case studies representative of widely used enterprise applications in virtualized data centers. In our case studies, we were able to reduce the amount of required CPU resources by up to 23\% and the number of reconfigurations by up to 95\% compared to a rule-based approach while ensuring full compliance with application SLO. Furthermore, using workload forecasting techniques we were able to schedule expensive reconfigurations (e.g., changes to the memory size) during phases of load load and thus were able to reduce their impact on application availability by over 80\% while significantly improving application performance compared to a reactive controller. The methods and techniques for resource demand estimation and vertical application scaling were developed and evaluated in close collaboration with VMware and Google.}, subject = {Cloud Computing}, language = {en} } @phdthesis{Cherpokova2017, author = {Cherpokova, Deya}, title = {Studies on modulators of platelet (hem)ITAM signaling and platelet production in genetically modified mice}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-120068}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2017}, abstract = {Summary Platelet activation and aggregation at sites of vascular injury is critical to prevent excessive blood loss, but may also lead to life-threatening ischemic disease states, such as myocardial infarction and stroke. Glycoprotein (GP) VI and C type lectin-like receptor 2 (CLEC-2) are essential platelet activating receptors in hemostasis and thrombo-inflammatory disease which signal through a (hem)immunoreceptor tyrosine-based activation motif (ITAM)-dependent pathway. The adapter molecules Src-like adapter protein (SLAP) and SLAP2 are involved in the regulation of immune cell receptor surface expression and signaling, but their function in platelets is unknown. As revealed in this thesis, single deficiency of SLAP or SLAP2 in mice had only moderate effects on platelet function, while SLAP/SLAP2 double deficiency resulted in markedly increased signal transduction, integrin activation, granule release, aggregation, procoagulant activity and thrombin generation following (hem)ITAM-coupled, but not G protein-coupled receptor activation. Slap-/-/Slap2-/- mice displayed accelerated occlusive arterial thrombus formation and a dramatically worsened outcome after focal cerebral ischemia. These results establish SLAP and SLAP2 as critical inhibitors of platelet (hem)ITAM signaling in the setting of arterial thrombosis and ischemic stroke. GPVI has emerged as a promising novel pharmacological target for treatment of thrombotic and inflammatory disease states, but the exact mechanisms of its immunodepletion in vivo are incompletely understood. It was hypothesized that SLAP and SLAP2 may be involved in the control of GPVI down-regulation because of their role in the internalization of immune cell receptors. As demonstrated in the second part of the thesis, SLAP and SLAP2 were dispensable for antibody-induced GPVI down-regulation, but anti-GPVI treatment resulted in prolonged strong thrombocytopenia in Slap-/-/Slap2-/- mice. The profound thrombocytopenia likely resulted from the powerful platelet activation which the anti-GPVI antibody induced in Slap-/-/Slap2-/- platelets, but importantly, not in wild-type platelets. These data indicate that the expression and activation state of key modulators of the GPVI signaling cascade may have important implications for the safety profile and efficacy of anti-GPVI agents. Small GTPases of the Rho family, such as RhoA and Cdc42, are critically involved in the regulation of cytoskeletal rearrangements during platelet activation, but little is known about the specific roles and functional redundancy of both proteins in platelet biogenesis. As shown in the final part of the thesis, combined deficiency of RhoA and Cdc42 led to marked alterations in megakaryocyte morphology and the generation of platelets of heterogeneous size and granule content. Despite severe hemostatic defects and profound thrombo¬cytopenia, circulating RhoA-/-/Cdc42-/- platelets were still capable of granule secretion and the formation of occlusive thrombi. These results implicate the existence of both distinct and overlapping roles of RhoA and Cdc42 in platelet production and function.}, subject = {Thrombozyt}, language = {en} } @phdthesis{Loeffler2017, author = {L{\"o}ffler, Diana}, title = {Color, Metaphor and Culture - Empirical Foundations for User Interface Design}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-153782}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2017}, abstract = {Using color in user interface design is both art and science. Often, designers focus on aesthetic properties of color, but neglect that it also carries meaning and entails profound psychological consequences. Color psychology, filling this gap, is in its infancy, and lacks a theoretical approach that predicts and explains color-meaning associations shared by a large group of people in a large variety of contexts. To amend this situation, this work develops Conceptual Metaphor Theory of Color (CMToC), which predicts and explains cross-cultural and experience-based semantic color associations. The theory is based on the idea from cognitive linguistics that the study of metaphorical language provides valuable insights into our mental models involving color. A discussion of three types of metaphors that cover associations with physical and abstract concepts in light of existing empirical evidence provides the basis for deriving empirical research questions. The first research question addresses the use of color for conveying physical information like weight in user interfaces. The results of four online surveys involving a total of 295 German and Japanese participants show the relative impact of hue, saturation and brightness for associations with 16 physical properties. Two thirds of these color associations were correctly predicted by CMToC. Participants frequently matched physical properties to colors based on sensorimotor correspondences and participants of both cultures did not considerably vary in their performance. The second research question addresses the use of color for conveying abstract information like importance in user interfaces. In one experimental study, a total of 75 German and Japanese participants validated color-to-abstract mappings in form of color population stereotypes like important is dark. The majority of these color associations (86\%) were correctly predicted by CMToC. Again, participants of both cultures did not considerably vary in their performance. The third research question addresses whether predicted color associations with physical and abstract information are processed automatically as a precondition for intuitive use. The results of three studies involving a total of 85 German and Japanese participants show on the example of temperature that color automatically influences the identification speed of related physical properties, but not vice versa. Color and abstract information were not automatically associated. As a result of these studies it can be concluded that predictions of CMToC are cross-culturally valid for user interface design. Derived implicit associations with physical properties and explicit associations with abstract concepts can inform design decisions in both hard- and software user interface design.}, subject = {Softwareergonomie}, language = {en} }