TY - THES A1 - Wenk, Sebastian T1 - Engineering formatotrophic growth in Escherichia coli N2 - To meet the demands of a growing world population while reducing carbon dioxide (CO2) emissions, it is necessary to capture CO2 and convert it into value-added compounds. In recent years, metabolic engineering of microbes has gained strong momentum as a strategy for the production of valuable chemicals. As common microbial feedstocks like glucose directly compete with human consumption, the one carbon (C1) compound formate was suggested as an alternative feedstock. Formate can be easily produced by various means including electrochemical reduction of CO2 and could serve as a feedstock for microbial production, hence presenting a novel entry point for CO2 to the biosphere and a storage option for excess electricity. Compared to the gaseous molecule CO2, formate is a highly soluble compound that can be easily handled and stored. It can serve as a carbon and energy source for natural formatotrophs, but these microbes are difficult to cultivate and engineer. In this work, I present the results of several projects that aim to establish efficient formatotrophic growth of E. coli – which cannot naturally grow on formate – via synthetic formate assimilation pathways. In the first study, I establish a workflow for growth-coupled metabolic engineering of E. coli. I demonstrate this approach by presenting an engineering scheme for the PFL-threonine cycle, a synthetic pathway for anaerobic formate assimilation in E. coli. The described methods are intended to create a standardized toolbox for engineers that aim to establish novel metabolic routes in E. coli and related organisms. The second chapter presents a study on the catalytic efficiency of C1-oxidizing enzymes in vivo. As formatotrophic growth requires generation of both energy and biomass from formate, the engineered E. coli strains need to be equipped with a highly efficient formate dehydrogenase, which provides reduction equivalents and ATP for formate assimilation. I engineered a strain that cannot generate reducing power and energy for cellular growth, when fed on acetate. Under this condition, the strain depends on the introduction of an enzymatic system for NADH regeneration, which could further produce ATP via oxidative phosphorylation. I show that the strain presents a valuable testing platform for C1-oxidizing enzymes by testing different NAD-dependent formate and methanol dehydrogenases in the energy auxotroph strain. Using this platform, several candidate enzymes with high in vivo activity, were identified and characterized as potential energy-generating systems for synthetic formatotrophic or methylotrophic growth in E. coli.   In the third chapter, I present the establishment of the serine threonine cycle (STC) – a synthetic formate assimilation pathway – in E. coli. In this pathway, formate is assimilated via formate tetrahydrofolate ligase (FtfL) from Methylobacterium extorquens (M. extorquens). The carbon from formate is attached to glycine to produce serine, which is converted into pyruvate entering central metabolism. Via the natural threonine synthesis and cleavage route, glycine is regenerated and acetyl-CoA is produced as the pathway product. I engineered several selection strains that depend on different STC modules for growth and determined key enzymes that enable high flux through threonine synthesis and cleavage. I could show that expression of an auxiliary formate dehydrogenase was required to achieve growth via threonine synthesis and cleavage on pyruvate. By overexpressing most of the pathway enzymes from the genome, and applying adaptive laboratory evolution, growth on glycine and formate was achieved, indicating the activity of the complete cycle. The fourth chapter shows the establishment of the reductive glycine pathway (rGP) – a short, linear formate assimilation route – in E. coli. As in the STC, formate is assimilated via M. extorquens FtfL. The C1 from formate is condensed with CO2 via the reverse reaction of the glycine cleavage system to produce glycine. Another carbon from formate is attached to glycine to form serine, which is assimilated into central metabolism via pyruvate. The engineered E. coli strain, expressing most of the pathway genes from the genome, can grow via the rGP with formate or methanol as a sole carbon and energy source. N2 - Um den steigenden Bedarf einer wachsenden Weltbevölkerung zu decken und gleichzeitig die CO2-Emissionen zu reduzieren, ist es notwendig, CO2 aufzufangen und zu recyceln. Durch gentechnische Veränderungen von Mikroorganismen ist es möglich diese zur Produktion wertvoller organischer Verbindungen zu nutzen. Da mikrobielle Kulturen primär mit Glucose gefüttert werden und somit mit menschlicher Nahrungsversorgung konkurrieren, wurde die C1-Verbindung Formiat als alternativer bakterieller Nährstoff vorgeschlagen.. Formiat kann durch unterschiedliche Verfahren hergestellt werden, unter anderem durch elektrochemische Reduktion von CO2. Dieses Verfahren ermöglicht das Recycling von CO2 und weiterhin eine Speichermöglichkeit für überschüssige Elektrizität. Formiat ist im Vergleich zum gasförmigen CO2 gut wasserlöslich, was den Transport und die Verwendung als mikrobiellen Nährstoff erleichtert. Natürlich vorkommende formatotrophe Mikroorganismen nutzen Formiat als Kohlenstoff- und Energiequelle. Diese lassen sich allerdings meist schwierig kultivieren und genetisch verändern. In dieser Arbeit stelle ich die Ergebnisse verschiedener Projekte vor, die gemeinsam darauf abzielen, effizientes formatotrophes Wachstum von E. coli – welches natürlicherweise nicht auf Formiat wachsen kann – mittels synthetischer Formiat-Assimilierungswege zu ermöglichen. In der ersten Studie stelle ich eine Strategie für wachstumsgekoppeltes Stoffwechsel-Engineering in E. coli vor. Ich erläutere diese Strategie anhand eines Beispiels, der schrittweisen Etablierung eines synthetischen Formiat- Assimilierungswegs, des PFL-Threonin-Zyklus. Die in diesem Kapitel beschriebenen Methoden sollen einen Leitfaden für Ingenieure bereitstellen, die neue Stoffwechselwege in E. coli und verwandten Organismen etablieren wollen. Im zweiten Kapitel stelle ich eine Studie über die katalytische Effizienz von C1-oxidierenden Enzymen vor. Da formatotrophes Wachstum sowohl die Erzeugung von Energie als auch von Biomasse aus Formiat erfordert, müssen synthetisch formatotrophe E. coli Stämme mit einer hocheffizienten Formiat-Dehydrogenase ausgestattet werden, welche Reduktionsäquivalente und ATP für die Assimilierung von Formiat liefert. Um die Effizienz verschiedener Enzyme testen und vergleichen zu können, entwickelte ich einen E. coli Stamm, der aus Acetat weder Reduktionsäquivalente noch Energie für das Zellwachstum erzeugen kann. Dieser „energie-auxotrophe“ Stamm benötigt eines zusätzlichen enzymatischen Systems zur NADH-Regenerierung, um auf Acetat wachsen zu können. Ich testete verschiedene NAD-abhängige Formiat- und Methanol-Dehydrogenasen in diesem Stamm und konnte zeigen, dass Wachstum auf Acetat durch Zugabe von Formiat oder Methanol ermöglicht wurde. Dies zeigt, dass der Stamm eine zuverlässige Testplattform für C1-oxidierende Enzyme darstellt. Unter Verwendung dieser Plattform wurden mehrere Kandidatenenzyme mit hoher in vivo-Aktivität identifiziert und als Kandidatenenzyme für synthetisches formatotrophes oder methylotrophes Wachstum in E. coli charakterisiert.   Im dritten Kapitel stelle ich die Etablierung des Serin-Threonin-Zyklus (STZ) – eines synthetischen Formiat-Assimilationswegs – in E. coli vor. In diesem Stoffwechselweg wird Formiat über die Formiat-Tetrahydrofolat-Ligase (FtfL) aus Methylobacterium extorquens (M. extorquens) assimiliert. Der Kohlenstoff aus Formiat wird an Glycin gebunden, um Serin zu produzieren, welches im nächsten Schritt in Pyruvat umgewandelt wird und so in den zentralen Kohlenstoffmetabolismus gelangt. Über den natürlichen Threonin-Synthese- und Spaltweg wird Glycin regeneriert und Acetyl-CoA als Produkt des Stoffwechselwegs generiert. Ich entwickelte mehrere E. coli Selektionsstämme, deren Wachstum von verschiedenen STZ-Modulen abhängt, und konnte Schlüsselenzyme bestimmen, die einen hohen Reaktionsfluss durch die Threonin-Synthese und -Spaltung ermöglichen. Ich konnte zeigen, dass die Expression einer Formiat-Dehydrogenase erforderlich ist, um Wachstum auf Pyruvat über Threonin zu erreichen. Durch Integration und Überexpression der meisten Enzyme des STZ auf Genomebene und Anwendung adaptiver Laborevolution wurde Wachstum auf Glycin und Formiat erreicht, was bedeutet, dass der gesamte Serin-Threonin-Zyklus in E. coli aktiv ist. Das vierte Kapitel zeigt die Etablierung des reduktiven Glycinwegs (rGW) – eines kurzen, linearen Formiat-Assimilierungswegs – in E. coli. Wie im STZ wird Formiat über M. extorquens FtfL assimiliert. Dabei wird das Kohlenstoffatom aus Formiat mit CO2 über die umgekehrte Reaktion des Glycin-Spaltungssystems zu Glycin kondensiert. Ein weiteres Kohlenstoffatom aus Formiat wird an Glycin gebunden, um Serin zu bilden, welches über Pyruvat in den Zentralstoffwechsel gelangt. Durch Expression der rGW Enzyme auf Genomebene und adaptive Laborevolution wurde ein E. coli Stamm erzeugt welcher über den rGW auf Formiat oder Methanol als einziger Kohlenstoff- und Energiequelle wachsen kann. KW - metabolic engineering KW - E. coli KW - formate assimilation KW - methanol assimilation KW - energy metabolism Y1 - 2020 ER - TY - JOUR A1 - Tofelde, Stefanie A1 - Bufe, Aaron A1 - Turowski, Jens M. T1 - Hillslope Sediment Supply Limits Alluvial Valley Width JF - AGU Advances N2 - River-valley morphology preserves information on tectonic and climatic conditions that shape landscapes. Observations suggest that river discharge and valley-wall lithology are the main controls on valley width. Yet, current models based on these observations fail to explain the full range of cross-sectional valley shapes in nature, suggesting hitherto unquantified controls on valley width. In particular, current models cannot explain the existence of paired terrace sequences that form under cyclic climate forcing. Paired river terraces are staircases of abandoned floodplains on both valley sides, and hence preserve past valley widths. Their formation requires alternating phases of predominantly river incision and predominantly lateral planation, plus progressive valley narrowing. While cyclic Quaternary climate changes can explain shifts between incision and lateral erosion, the driving mechanism of valley narrowing is unknown. Here, we extract valley geometries from climatically formed, alluvial river-terrace sequences and show that across our dataset, the total cumulative terrace height (here: total valley height) explains 90%–99% of the variance in valley width at the terrace sites. This finding suggests that valley height, or a parameter that scales linearly with valley height, controls valley width in addition to river discharge and lithology. To explain this valley-width-height relationship, we reformulate existing valley-width models and suggest that, when adjusting to new boundary conditions, alluvial valleys evolve to a width at which sediment removal from valley walls matches lateral sediment supply from hillslope erosion. Such a hillslope-channel coupling is not captured in current valley-evolution models. Our model can explain the existence of paired terrace sequences under cyclic climate forcing and relates valley width to measurable field parameters. Therefore, it facilitates the reconstruction of past climatic and tectonic conditions from valley topography. Y1 - 2022 U6 - https://doi.org/10.1029/2021AV000641 SN - 2576-604X PB - American Geophysical Union (AGU); Wiley CY - Hoboken, New Jersey, USA ER - TY - JOUR A1 - Miklashevsky, Alex A1 - Fischer, Martin H. A1 - Lindemann, Oliver T1 - Spatial-numerical associations without a motor response? Grip force says ‘Yes’ JF - Acta Psychologica N2 - In numerical processing, the functional role of Spatial-Numerical Associations (SNAs, such as the association of smaller numbers with left space and larger numbers with right space, the Mental Number Line hypothesis) is debated. Most studies demonstrate SNAs with lateralized responses, and there is little evidence that SNAs appear when no response is required. We recorded passive holding grip forces in no-go trials during number processing. In Experiment 1, participants performed a surface numerical decision task (“Is it a number or a letter?”). In Experiment 2, we used a deeper semantic task (“Is this number larger or smaller than five?”). Despite instruction to keep their grip force constant, participants' spontaneous grip force changed in both experiments: Smaller numbers led to larger force increase in the left than in the right hand in the numerical decision task (500–700 ms after stimulus onset). In the semantic task, smaller numbers again led to larger force increase in the left hand, and larger numbers increased the right-hand holding force. This effect appeared earlier (180 ms) and lasted longer (until 580 ms after stimulus onset). This is the first demonstration of SNAs with passive holding force. Our result suggests that (1) explicit motor response is not a prerequisite for SNAs to appear, and (2) the timing and strength of SNAs are task-dependent. (216 words). KW - SNARC KW - Mental number line KW - Number processing KW - Embodied cognition KW - Grip force KW - Motor system Y1 - 2022 U6 - https://doi.org/10.1016/j.actpsy.2022.103791 SN - 1873-6297 VL - 231 SP - 1 EP - 17 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Lindner, Nadja A1 - Moeller, Korbinian A1 - Hildebrandt, Frauke A1 - Hasselhorn, Marcus A1 - Lonnemann, Jan T1 - Children's use of egocentric reference frames in spatial language is related to their numerical magnitude understanding JF - Frontiers in Psychology N2 - Numerical magnitude information is assumed to be spatially represented in the form of a mental number line defined with respect to a body-centred, egocentric frame of reference. In this context, spatial language skills such as mastery of verbal descriptions of spatial position (e.g., in front of, behind, to the right/left) have been proposed to be relevant for grasping spatial relations between numerical magnitudes on the mental number line. We examined 4- to 5-year-old’s spatial language skills in tasks that allow responses in egocentric and allocentric frames of reference, as well as their relative understanding of numerical magnitude (assessed by a number word comparison task). In addition, we evaluated influences of children’s absolute understanding of numerical magnitude assessed by their number word comprehension (montring different numbers using their fingers) and of their knowledge on numerical sequences (determining predecessors and successors as well as identifying missing dice patterns of a series). Results indicated that when considering responses that corresponded to the egocentric perspective, children’s spatial language was associated significantly with their relative numerical magnitude understanding, even after controlling for covariates, such as children’s SES, mental rotation skills, and also absolute magnitude understanding or knowledge on numerical sequences. This suggests that the use of egocentric reference frames in spatial language may facilitate spatial representation of numbers along a mental number line and thus seem important for preschoolers’ relative understanding of numerical magnitude. KW - spatial language KW - frames of reference KW - numerical development KW - mental number line KW - preschool children Y1 - 2022 U6 - https://doi.org/10.3389/fpsyg.2022.943191 SN - 1664-1078 SP - 1 EP - 13 PB - Frontiers CY - Lausanne, Schweiz ER - TY - CHAP A1 - Curzon, Paul A1 - Kalas, Ivan A1 - Schubert, Sigrid A1 - Schaper, Niclas A1 - Barnes, Jan A1 - Kennewell, Steve A1 - Bröker, Kathrin A1 - Kastens, Uwe A1 - Magenheim, Johannes A1 - Dagiene, Valentina A1 - Stupuriene, Gabriele A1 - Ellis, Jason Brent A1 - Abreu-Ellis, Carla Reis A1 - Grillenberger, Andreas A1 - Romeike, Ralf A1 - Haugsbakken, Halvdan A1 - Jones, Anthony A1 - Lewin, Cathy A1 - McNicol, Sarah A1 - Nelles, Wolfgang A1 - Neugebauer, Jonas A1 - Ohrndorf, Laura A1 - Schaper, Niclas A1 - Schubert, Sigrid A1 - Opel, Simone A1 - Kramer, Matthias A1 - Trommen, Michael A1 - Pottbäcker, Florian A1 - Ilaghef, Youssef A1 - Passig, David A1 - Tzuriel, David A1 - Kedmi, Ganit Eshel A1 - Saito, Toshinori A1 - Webb, Mary A1 - Weigend, Michael A1 - Bottino, Rosa A1 - Chioccariello, Augusto A1 - Christensen, Rhonda A1 - Knezek, Gerald A1 - Gioko, Anthony Maina A1 - Angondi, Enos Kiforo A1 - Waga, Rosemary A1 - Ohrndorf, Laura A1 - Or-Bach, Rachel A1 - Preston, Christina A1 - Younie, Sarah A1 - Przybylla, Mareen A1 - Romeike, Ralf A1 - Reynolds, Nicholas A1 - Swainston, Andrew A1 - Bendrups, Faye A1 - Sysło, Maciej M. A1 - Kwiatkowska, Anna Beata A1 - Zieris, Holger A1 - Gerstberger, Herbert A1 - Müller, Wolfgang A1 - Büchner, Steffen A1 - Opel, Simone A1 - Schiller, Thomas A1 - Wegner, Christian A1 - Zender, Raphael A1 - Lucke, Ulrike A1 - Diethelm, Ira A1 - Syrbe, Jörn A1 - Lai, Kwok-Wing A1 - Davis, Niki A1 - Eickelmann, Birgit A1 - Erstad, Ola A1 - Fisser, Petra A1 - Gibson, David A1 - Khaddage, Ferial A1 - Knezek, Gerald A1 - Micheuz, Peter A1 - Kloos, Carlos Delgado ED - Brinda, Torsten ED - Reynolds, Nicholas ED - Romeike, Ralf ED - Schwill, Andreas T1 - KEYCIT 2014 BT - key competencies in informatics and ICT N2 - In our rapidly changing world it is increasingly important not only to be an expert in a chosen field of study but also to be able to respond to developments, master new approaches to solving problems, and fulfil changing requirements in the modern world and in the job market. In response to these needs key competencies in understanding, developing and using new digital technologies are being brought into focus in school and university programmes. The IFIP TC3 conference "KEYCIT – Key Competences in Informatics and ICT (KEYCIT 2014)" was held at the University of Potsdam in Germany from July 1st to 4th, 2014 and addressed the combination of key competencies, Informatics and ICT in detail. The conference was organized into strands focusing on secondary education, university education and teacher education (organized by IFIP WGs 3.1 and 3.3) and provided a forum to present and to discuss research, case studies, positions, and national perspectives in this field. T3 - Commentarii informaticae didacticae (CID) - 7 KW - Schlüsselkompetenzen KW - Informatik KW - Bildung KW - ICT KW - Informatikdidaktik KW - Key Competencies KW - Informatics KW - education KW - ICT KW - Computer Science Education Y1 - 2015 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-70325 SN - 978-3-86956-292-6 PB - Universitätsverlag Potsdam CY - Potsdam ER - TY - JOUR A1 - Ogunkola, Moses Olalekan A1 - Guiraudie-Capraz, Gaelle A1 - Féron, François A1 - Leimkühler, Silke T1 - The Human Mercaptopyruvate Sulfurtransferase TUM1 Is Involved in Moco Biosynthesis, Cytosolic tRNA Thiolation and Cellular Bioenergetics in Human Embryonic Kidney Cells JF - Biomolecules N2 - Sulfur is an important element that is incorporated into many biomolecules in humans. The incorporation and transfer of sulfur into biomolecules is, however, facilitated by a series of different sulfurtransferases. Among these sulfurtransferases is the human mercaptopyruvate sulfurtransferase (MPST) also designated as tRNA thiouridine modification protein (TUM1). The role of the human TUM1 protein has been suggested in a wide range of physiological processes in the cell among which are but not limited to involvement in Molybdenum cofactor (Moco) biosynthesis, cytosolic tRNA thiolation and generation of H2S as signaling molecule both in mitochondria and the cytosol. Previous interaction studies showed that TUM1 interacts with the L-cysteine desulfurase NFS1 and the Molybdenum cofactor biosynthesis protein 3 (MOCS3). Here, we show the roles of TUM1 in human cells using CRISPR/Cas9 genetically modified Human Embryonic Kidney cells. Here, we show that TUM1 is involved in the sulfur transfer for Molybdenum cofactor synthesis and tRNA thiomodification by spectrophotometric measurement of the activity of sulfite oxidase and liquid chromatography quantification of the level of sulfur-modified tRNA. Further, we show that TUM1 has a role in hydrogen sulfide production and cellular bioenergetics. KW - Moco biosynthesis KW - sulfite oxidase KW - cytosolic tRNA thiolation KW - 5-methoxycarbonylmethyl-2-thiouridine KW - H2S biosynthesis KW - cellular bioenergetics Y1 - 2023 U6 - https://doi.org/10.3390/biom13010144 SN - 2218-273X VL - 13 SP - 1 EP - 23 PB - MDPI CY - Basel, Schweiz ET - 1 ER - TY - JOUR A1 - Marggraf, Lara Christin A1 - Lindecke, Oliver A1 - Voigt, Christian C. A1 - Pētersons, Gunārs A1 - Voigt-Heucke, Silke Luise T1 - Nathusius’ bats, Pipistrellus nathusii, bypass mating opportunities of their own species, but respond to foraging heterospecifics on migratory transit flights JF - Frontiers in Ecology and Evolution N2 - In late summer, migratory bats of the temperate zone face the challenge of accomplishing two energy-demanding tasks almost at the same time: migration and mating. Both require information and involve search efforts, such as localizing prey or finding potential mates. In non-migrating bat species, playback studies showed that listening to vocalizations of other bats, both con-and heterospecifics, may help a recipient bat to find foraging patches and mating sites. However, we are still unaware of the degree to which migrating bats depend on con-or heterospecific vocalizations for identifying potential feeding or mating opportunities during nightly transit flights. Here, we investigated the vocal responses of Nathusius’ pipistrelle bats, Pipistrellus nathusii, to simulated feeding and courtship aggregations at a coastal migration corridor. We presented migrating bats either feeding buzzes or courtship calls of their own or a heterospecific migratory species, the common noctule, Nyctalus noctula. We expected that during migratory transit flights, simulated feeding opportunities would be particularly attractive to bats, as well as simulated mating opportunities which may indicate suitable roosts for a stopover. However, we found that when compared to the natural silence of both pre-and post-playback phases, bats called indifferently during the playback of conspecific feeding sounds, whereas P. nathusii echolocation call activity increased during simulated feeding of N. noctula. In contrast, the call activity of P. nathusii decreased during the playback of conspecific courtship calls, while no response could be detected when heterospecific call types were broadcasted. Our results suggest that while on migratory transits, P. nathusii circumnavigate conspecific mating aggregations, possibly to save time or to reduce the risks associated with social interactions where aggression due to territoriality might be expected. This avoidance behavior could be a result of optimization strategies by P. nathusii when performing long-distance migratory flights, and it could also explain the lack of a response to simulated conspecific feeding. However, the observed increase of activity in response to simulated feeding of N. noctula, suggests that P. nathusii individuals may be eavesdropping on other aerial hawking insectivorous species during migration, especially if these occupy a slightly different foraging niche. KW - playback KW - phonotaxis KW - bats KW - acoustic communication KW - animal migration KW - eavesdropping KW - echolocation KW - Pipistrellus nathusii Y1 - 2023 U6 - https://doi.org/10.3389/fevo.2022.908560 SN - 2296-701X SP - 1 EP - 10 PB - Frontiers CY - Lausanne, Schweiz ER - TY - JOUR A1 - Kühne, Franziska A1 - Fauth, Henriette A1 - Destina Sevde, Ay-Bryson A1 - Visser, Leonie N.C. A1 - Weck, Florian T1 - Communicating the diagnosis of cancer or depression: Results of a randomized controlled online study using video vignettes JF - Cancer Medicine N2 - Background Communicating a diagnosis is highly important, yet complex, especially in the context of cancer and mental disorders. The aim was to explore the communication style of an oncologist vs. psychotherapist in an online study. Methods Patients (N = 136: 65 cancer, 71 depression) were randomly assigned to watch a standardized video vignette with one of two communication styles (empathic vs. unempathic). Outcome measures of affectivity, information recall, communication skills, empathy and trust were applied. Results Regardless of diagnosis, empathic communication was associated with the perception of a significantly more empathic (p < 0.001, η2partial = 0.08) and trustworthy practitioner (p = 0.014, η2partial = 0.04) with better communication skills (p = 0.013, η2partial = 0.05). Cancer patients reported a larger decrease in positive affect (p < 0.001, η2partial = 0.15) and a larger increase in negative affect (p < 0.001, η2partial = 0.14) from pre- to post-video than depressive patients. Highly relevant information was recalled better in both groups (p < 0.001, d = 0.61–1.06). Conclusions The results highlight the importance of empathy while communicating both a diagnosis of cancer and a mental disorder. Further research should focus on the communication of a mental disorder in association with cancer. KW - consultation KW - mental health KW - oncology KW - psycho-oncology KW - skills Y1 - 2021 U6 - https://doi.org/10.1002/cam4.4396 SN - 2045-7634 VL - 10 SP - 9012 EP - 9021 PB - Wiley CY - Hoboken, New Jersey, USA ET - 24 ER - TY - JOUR A1 - Reeg, Jette A1 - Strigl, Lea A1 - Jeltsch, Florian T1 - Agricultural buffer zone thresholds to safeguard functional bee diversity BT - Insights from a community modeling approach JF - Ecology and Evolution N2 - Wild bee species are important pollinators in agricultural landscapes. However, population decline was reported over the last decades and is still ongoing. While agricultural intensification is a major driver of the rapid loss of pollinating species, transition zones between arable fields and forest or grassland patches, i.e., agricultural buffer zones, are frequently mentioned as suitable mitigation measures to support wild bee populations and other pollinator species. Despite the reported general positive effect, it remains unclear which amount of buffer zones is needed to ensure a sustainable and permanent impact for enhancing bee diversity and abundance. To address this question at a pollinator community level, we implemented a process-based, spatially explicit simulation model of functional bee diversity dynamics in an agricultural landscape. More specifically, we introduced a variable amount of agricultural buffer zones (ABZs) at the transition of arable to grassland, or arable to forest patches to analyze the impact on bee functional diversity and functional richness. We focused our study on solitary bees in a typical agricultural area in the Northeast of Germany. Our results showed positive effects with at least 25% of virtually implemented agricultural buffer zones. However, higher amounts of ABZs of at least 75% should be considered to ensure a sufficient increase in Shannon diversity and decrease in quasi-extinction risks. These high amounts of ABZs represent effective conservation measures to safeguard the stability of pollination services provided by solitary bee species. As the model structure can be easily adapted to other mobile species in agricultural landscapes, our community approach offers the chance to compare the effectiveness of conservation measures also for other pollinator communities in future. KW - agricultural landscape KW - buffer zones KW - community model KW - functional traits KW - solitary bees KW - spatially explicit Y1 - 2022 U6 - https://doi.org/10.1002/ece3.8748 SN - 2045-7758 VL - 12 SP - 1 EP - 17 PB - Wiley Online Library CY - Hoboken, New Jersey, USA ET - 3 ER - TY - JOUR A1 - Liebe, Thomas A1 - Dordevic, Milos A1 - Kaufmann, Jörn A1 - Avetisyan, Araks A1 - Skalej, Martin A1 - Müller, Notger Germar T1 - Investigation of the functional pathogenesis of mild cognitive impairment by localisation-based locus coeruleus resting-state fMRI JF - Human Brain Mapping N2 - Dementia as one of the most prevalent diseases urges for a better understanding of the central mechanisms responsible for clinical symptoms, and necessitates improvement of actual diagnostic capabilities. The brainstem nucleus locus coeruleus (LC) is a promising target for early diagnosis because of its early structural alterations and its relationship to the functional disturbances in the patients. In this study, we applied our improved method of localisation-based LC resting-state fMRI to investigate the differences in central sensory signal processing when comparing functional connectivity (fc) of a patient group with mild cognitive impairment (MCI, n = 28) and an age-matched healthy control group (n = 29). MCI and control participants could be differentiated in their Mini-Mental-State-Examination (MMSE) scores (p < .001) and LC intensity ratio (p = .010). In the fMRI, LC fc to anterior cingulate cortex (FDR p < .001) and left anterior insula (FDR p = .012) was elevated, and LC fc to right temporoparietal junction (rTPJ, FDR p = .012) and posterior cingulate cortex (PCC, FDR p = .021) was decreased in the patient group. Importantly, LC to rTPJ connectivity was also positively correlated to MMSE scores in MCI patients (p = .017). Furthermore, we found a hyperactivation of the left-insula salience network in the MCI patients. Our results and our proposed disease model shed new light on the functional pathogenesis of MCI by directing to attentional network disturbances, which could aid new therapeutic strategies and provide a marker for diagnosis and prediction of disease progression. KW - attention KW - locus coeruleus KW - mild cognitive impairment KW - resting-state fMRI Y1 - 2022 U6 - https://doi.org/10.1002/hbm.26039 SN - 1097-0193 VL - 43 SP - 5630 EP - 5642 PB - Wiley CY - New York, NY, USA ET - 18 ER - TY - JOUR A1 - Hauffe, Robert A1 - Rath, Michaela A1 - Agyapong, Wilson A1 - Jonas, Wenke A1 - Vogel, Heike A1 - Schulz, Tim Julius A1 - Schwarz, Maria A1 - Kipp, Anna Patricia A1 - Blüher, Matthias A1 - Kleinridders, André T1 - Obesity Hinders the Protective Effect of Selenite Supplementation on Insulin Signaling JF - Antioxidants N2 - The intake of high-fat diets (HFDs) containing large amounts of saturated long-chain fatty acids leads to obesity, oxidative stress, inflammation, and insulin resistance. The trace element selenium, as a crucial part of antioxidative selenoproteins, can protect against the development of diet-induced insulin resistance in white adipose tissue (WAT) by increasing glutathione peroxidase 3 (GPx3) and insulin receptor (IR) expression. Whether selenite (Se) can attenuate insulin resistance in established lipotoxic and obese conditions is unclear. We confirm that GPX3 mRNA expression in adipose tissue correlates with BMI in humans. Cultivating 3T3-L1 pre-adipocytes in palmitate-containing medium followed by Se treatment attenuates insulin resistance with enhanced GPx3 and IR expression and adipocyte differentiation. However, feeding obese mice a selenium-enriched high-fat diet (SRHFD) only resulted in a modest increase in overall selenoprotein gene expression in WAT in mice with unaltered body weight development, glucose tolerance, and insulin resistance. While Se supplementation improved adipocyte morphology, it did not alter WAT insulin sensitivity. However, mice fed a SRHFD exhibited increased insulin content in the pancreas. Overall, while selenite protects against palmitate-induced insulin resistance in vitro, obesity impedes the effect of selenite on insulin action and adipose tissue metabolism in vivo. KW - selenite KW - insulin KW - adipose tissue KW - obesity KW - insulin resistance Y1 - 2022 U6 - https://doi.org/10.3390/antiox11050862 SN - 2076-3921 VL - 11 SP - 1 EP - 16 PB - MDPI CY - Basel, Schweiz ET - 5 ER - TY - JOUR A1 - Kayhan, Ezgi A1 - Matthes, Daniel A1 - Marriott Haresign, Ira A1 - Bánki, Anna A1 - Michel, Christine A1 - Langeloh, Miriam A1 - Wass, Sam A1 - Hoehl, Stefanie T1 - DEEP: A dual EEG pipeline for developmental hyperscanning studies JF - Developmental Cognitive Neuroscience N2 - Cutting-edge hyperscanning methods led to a paradigm shift in social neuroscience. It allowed researchers to measure dynamic mutual alignment of neural processes between two or more individuals in naturalistic contexts. The ever-growing interest in hyperscanning research calls for the development of transparent and validated data analysis methods to further advance the field. We have developed and tested a dual electroencephalography (EEG) analysis pipeline, namely DEEP. Following the preprocessing of the data, DEEP allows users to calculate Phase Locking Values (PLVs) and cross-frequency PLVs as indices of inter-brain phase alignment of dyads as well as time-frequency responses and EEG power for each participant. The pipeline also includes scripts to control for spurious correlations. Our goal is to contribute to open and reproducible science practices by making DEEP publicly available together with an example mother-infant EEG hyperscanning dataset. KW - Developmental hyperscanning KW - Dual EEG analysis KW - Adult-child interaction KW - Phase Locking Value KW - PLV KW - Cross-frequency PLV KW - FieldTrip Y1 - 2022 U6 - https://doi.org/10.1016/j.dcn.2022.101104 SN - 1878-9307 VL - 54 SP - 1 EP - 11 PB - Elsevier CY - Amsterdam, Niederlande ER - TY - JOUR A1 - Tiedemann, Kim A1 - Iobbi-Nivol, Chantal A1 - Leimkühler, Silke T1 - The Role of the Nucleotides in the Insertion of the bis-Molybdopterin Guanine Dinucleotide Cofactor into apo-Molybdoenzymes JF - Molecules N2 - The role of the GMP nucleotides of the bis-molybdopterin guanine dinucleotide (bis-MGD) cofactor of the DMSO reductase family has long been a subject of discussion. The recent characterization of the bis-molybdopterin (bis-Mo-MPT) cofactor present in the E. coli YdhV protein, which differs from bis-MGD solely by the absence of the nucleotides, now enables studying the role of the nucleotides of bis-MGD and bis-MPT cofactors in Moco insertion and the activity of molybdoenzymes in direct comparison. Using the well-known E. coli TMAO reductase TorA as a model enzyme for cofactor insertion, we were able to show that the GMP nucleotides of bis-MGD are crucial for the insertion of the bis-MGD cofactor into apo-TorA. KW - bis-MGD KW - chaperone KW - molybdenum cofactor KW - TMAO reductase Y1 - 2022 U6 - https://doi.org/10.3390/molecules27092993 SN - 1420-3049 VL - 27 SP - 1 EP - 15 PB - MDPI CY - Basel, Schweiz ET - 9 ER - TY - JOUR A1 - Weithoff, Guntram A1 - Bell, Elanor Margaret T1 - Complex Trophic Interactions in an Acidophilic Microbial Community JF - Microorganisms N2 - Extreme habitats often harbor specific communities that differ substantially from non-extreme habitats. In many cases, these communities are characterized by archaea, bacteria and protists, whereas the number of species of metazoa and higher plants is relatively low. In extremely acidic habitats, mostly prokaryotes and protists thrive, and only very few metazoa thrive, for example, rotifers. Since many studies have investigated the physiology and ecology of individual species, there is still a gap in research on direct, trophic interactions among extremophiles. To fill this gap, we experimentally studied the trophic interactions between a predatory protist (Actinophrys sol, Heliozoa) and its prey, the rotifers Elosa woralli and Cephalodella sp., the ciliate Urosomoida sp. and the mixotrophic protist Chlamydomonas acidophila (a green phytoflagellate, Chlorophyta). We found substantial predation pressure on all animal prey. High densities of Chlamydomonas acidophila reduced the predation impact on the rotifers by interfering with the feeding behaviour of A. sol. These trophic relations represent a natural case of intraguild predation, with Chlamydomonas acidophila being the common prey and the rotifers/ciliate and A. sol being the intraguild prey and predator, respectively. We further studied this intraguild predation along a resource gradient using Cephalodella sp. as the intraguild prey. The interactions among the three species led to an increase in relative rotifer abundance with increasing resource (Chlamydomonas) densities. By applying a series of laboratory experiments, we revealed the complexity of trophic interactions within a natural extremophilic community. KW - acid mine drainage KW - extremophiles KW - food web KW - heliozoa KW - intraguild predation KW - mining lakes KW - Rotifera Y1 - 2022 U6 - https://doi.org/10.3390/microorganisms10071340 SN - 2076-2607 VL - 10 SP - 1 EP - 10 PB - MDPI CY - Basel, Schweiz ET - 7 ER - TY - BOOK A1 - Weiß, Norman A1 - Verlaan, Stephanie A1 - Vasquez Carruthers, Juan Francisco A1 - Mair, Theresa A1 - Conner, Sean A1 - Maaser, Lucas A1 - Röthlisberger, Livia ED - Weiß, Norman T1 - Transitional Justice BT - Theoretical and Practical Approaches T3 - Potsdamer Studien zu Staat, Recht und Politik N2 - This publication deals with the topic of transitional justice. In six case studies, the authors link theoretical and practical implications in order to develop some innovative approaches. Their proposals might help to deal more effectively with the transition of societies, legal orders and political systems. Young academics from various backgrounds provide fresh insights and demonstrate the relevance of the topic. The chapters analyse transitions and conflicts in Sierra Leone, Argentina, Nicaragua, Nepal, and South Sudan as well as Germany’s colonial genocide in Namibia. Thus, the book provides the reader with new insights and contributes to the ongoing debate about transitional justice. N2 - Gegenstand dieser Publikation ist das Thema „Transitional Justice“. In sechs Fallstudien verknüpfen die Autoren theoretische und praktische Implikationen, um innovative Ansätze zu entwickeln. Ihre Vorschläge wollen dazu beitragen, den Übergangsprozess von Gesellschaften, Rechtsordnungen und politischen Systemen effektiver zu gestalten. Nachwuchswissenschaftler mit unterschiedlichem fachlichem Hintergrund geben hier neue Einblicke und zeigen die fortdauernde Relevanz des Themas. Die Kapitel analysieren Übergänge und Konflikte in Sierra Leone, Argentinien, Nicaragua, Nepal und Süd-Sudan sowie den kolonialen Völkermord in Namibia. So liefert das Buch dem Leser neue Erkenntnisse und trägt zur laufenden Debatte über das Thema „Transitional Justice“ bei. T3 - Potsdamer Studien zu Staat, Recht und Politik - 7 KW - transitional justice KW - transformation KW - transformative justice KW - reconciliation KW - political opportunism KW - Übergangsjustiz KW - Transformation KW - Versöhnung KW - Demokratisierung Y1 - 2022 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-431711 SN - 978-3-86956-473-9 SN - 1869-2443 SN - 1867-2663 IS - 7 PB - Universitätsverlag Potsdam CY - Potsdam ER - TY - JOUR A1 - Prasse, Paul A1 - Iversen, Pascal A1 - Lienhard, Matthias A1 - Thedinga, Kristina A1 - Herwig, Ralf A1 - Scheffer, Tobias T1 - Pre-Training on In Vitro and Fine-Tuning on Patient-Derived Data Improves Deep Neural Networks for Anti-Cancer Drug-Sensitivity Prediction JF - MDPI N2 - Large-scale databases that report the inhibitory capacities of many combinations of candidate drug compounds and cultivated cancer cell lines have driven the development of preclinical drug-sensitivity models based on machine learning. However, cultivated cell lines have devolved from human cancer cells over years or even decades under selective pressure in culture conditions. Moreover, models that have been trained on in vitro data cannot account for interactions with other types of cells. Drug-response data that are based on patient-derived cell cultures, xenografts, and organoids, on the other hand, are not available in the quantities that are needed to train high-capacity machine-learning models. We found that pre-training deep neural network models of drug sensitivity on in vitro drug-sensitivity databases before fine-tuning the model parameters on patient-derived data improves the models’ accuracy and improves the biological plausibility of the features, compared to training only on patient-derived data. From our experiments, we can conclude that pre-trained models outperform models that have been trained on the target domains in the vast majority of cases. KW - deep neural networks KW - drug-sensitivity prediction KW - anti-cancer drugs Y1 - 2022 U6 - https://doi.org/10.3390/cancers14163950 SN - 2072-6694 VL - 14 SP - 1 EP - 14 PB - MDPI CY - Basel, Schweiz ET - 16 ER - TY - JOUR A1 - Omane, Paul Okyere A1 - Höhle, Barbara T1 - Acquiring syntactic variability BT - The production of Wh-questions in children and adults speaking Akan JF - Frontiers in communication N2 - This paper investigates the predictions of the Derivational Complexity Hypothesis by studying the acquisition of wh-questions in 4- and 5-year-old Akan-speaking children in an experimental approach using an elicited production and an elicited imitation task. Akan has two types of wh-question structures (wh-in-situ and wh-ex-situ questions), which allows an investigation of children’s acquisition of these two question structures and their preferences for one or the other. Our results show that adults prefer to use wh-ex-situ questions over wh-in-situ questions. The results from the children show that both age groups have the two question structures in their linguistic repertoire. However, they differ in their preferences in usage in the elicited production task: while the 5-year-olds preferred the wh-in-situ structure over the wh-ex-situ structure, the 4-year-olds showed a selective preference for the wh-in-situ structure in who-questions. These findings suggest a developmental change in wh-question preferences in Akan-learning children between 4 and 5 years of age with a so far unobserved u-shaped developmental pattern. In the elicited imitation task, all groups showed a strong tendency to maintain the structure of in-situ and ex-situ questions in repeating grammatical questions. When repairing ungrammatical ex-situ questions, structural changes to grammatical in-situ questions were hardly observed but the insertion of missing morphemes while keeping the ex-situ structure. Together, our findings provide only partial support for the Derivational Complexity Hypothesis. KW - Akan KW - wh-questions KW - wh-in-situ KW - wh-ex-situ KW - derivational complexity KW - language acquisition Y1 - 2021 U6 - https://doi.org/10.3389/fcomm.2021.604951 SN - 2297-900X VL - 2021 PB - Frontiers Media CY - Lausanne, Schweiz ER - TY - THES A1 - Müller, Melanie J. I. T1 - Bidirectional transport by molecular motors T1 - Bidirektionaler Transport durch molekulare Motoren N2 - In biological cells, the long-range intracellular traffic is powered by molecular motors which transport various cargos along microtubule filaments. The microtubules possess an intrinsic direction, having a 'plus' and a 'minus' end. Some molecular motors such as cytoplasmic dynein walk to the minus end, while others such as conventional kinesin walk to the plus end. Cells typically have an isopolar microtubule network. This is most pronounced in neuronal axons or fungal hyphae. In these long and thin tubular protrusions, the microtubules are arranged parallel to the tube axis with the minus ends pointing to the cell body and the plus ends pointing to the tip. In such a tubular compartment, transport by only one motor type leads to 'motor traffic jams'. Kinesin-driven cargos accumulate at the tip, while dynein-driven cargos accumulate near the cell body. We identify the relevant length scales and characterize the jamming behaviour in these tube geometries by using both Monte Carlo simulations and analytical calculations. A possible solution to this jamming problem is to transport cargos with a team of plus and a team of minus motors simultaneously, so that they can travel bidirectionally, as observed in cells. The presumably simplest mechanism for such bidirectional transport is provided by a 'tug-of-war' between the two motor teams which is governed by mechanical motor interactions only. We develop a stochastic tug-of-war model and study it with numerical and analytical calculations. We find a surprisingly complex cooperative motility behaviour. We compare our results to the available experimental data, which we reproduce qualitatively and quantitatively. N2 - In biologischen Zellen transportieren molekulare Motoren verschiedenste Frachtteilchen entlang von Mikrotubuli-Filamenten. Die Mikrotubuli-Filamente besitzen eine intrinsische Richtung: sie haben ein "Plus-" und ein "Minus-"Ende. Einige molekulare Motoren wie Dynein laufen zum Minus-Ende, während andere wie Kinesin zum Plus-Ende laufen. Zellen haben typischerweise ein isopolares Mikrotubuli-Netzwerk. Dies ist besonders ausgeprägt in neuronalen Axonen oder Pilz-Hyphen. In diesen langen röhrenförmigen Ausstülpungen liegen die Mikrotubuli parallel zur Achse mit dem Minus-Ende zum Zellkörper und dem Plus-Ende zur Zellspitze gerichtet. In einer solchen Röhre führt Transport durch nur einen Motor-Typ zu "Motor-Staus". Kinesin-getriebene Frachten akkumulieren an der Spitze, während Dynein-getriebene Frachten am Zellkörper akkumulieren. Wir identifizieren die relevanten Längenskalen und charakterisieren das Stauverhalten in diesen Röhrengeometrien mit Hilfe von Monte-Carlo-Simulationen und analytischen Rechnungen. Eine mögliche Lösung für das Stauproblem ist der Transport mit einem Team von Plus- und einem Team von Minus-Motoren gleichzeitig, so dass die Fracht sich in beide Richtungen bewegen kann. Dies wird in Zellen tatsächlich beobachtet. Der einfachste Mechanismus für solchen bidirektionalen Transport ist ein "Tauziehen" zwischen den beiden Motor-Teams, das nur mit mechanischer Interaktion funktioniert. Wir entwickeln ein stochastisches Tauzieh-Modell, das wir mit numerischen und analytischen Rechnungen untersuchen. Es ergibt sich ein erstaunlich komplexes Motilitätsverhalten. Wir vergleichen unsere Resultate mit den vorhandenen experimentellen Daten, die wir qualitativ und quantitativ reproduzieren. KW - molekulare Motoren KW - bidirektionaler intrazellulärer Transport KW - Tauziehen KW - stochastische Prozesse KW - kooperative Phänomene KW - molecular motors KW - bidirectional intracellular transport KW - tug-of-war KW - stochastic processes KW - cooperative phenomena Y1 - 2008 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-18715 ER - TY - JOUR A1 - Rose, Robert A1 - Groeger, Lars A1 - Hölzle, Katharina T1 - The Emergence of Shared Leadership in Innovation Labs JF - Frontiers in Psychology N2 - Implementing innovation laboratories to leverage intrapreneurship are an increasingly popular organizational practice. A typical feature in these creative environments are semi-autonomous teams in which multiple members collectively exert leadership influence, thereby challenging traditional command-and-control conceptions of leadership. An extensive body of research on the team-centric concept of shared leadership has recognized the potential for pluralized leadership structures in enhancing team effectiveness; however, little empirical work has been conducted in organizational contexts in which creativity is key. This study set out to explore antecedents of shared leadership and its influence on team creativity in an innovation lab. Building on extant shared leadership and innovation research, we propose antecedents customary to creative teamwork, that is, experimental culture, task reflexivity, and voice. Multisource data were collected from 104 team members and 49 evaluations of 29 coaches nested in 21 teams working in a prototypical innovation lab. We identify factors specific to creative teamwork that facilitate the emergence of shared leadership by providing room for experimentation, encouraging team members to speak up in the creative process, and cultivating a reflective application of entrepreneurial thinking. We provide specific exemplary activities for innovation lab teams to increase levels of shared leadership. KW - innovation laboratories KW - intrapreneurship KW - team creativity KW - shared leadership KW - social network analysis Y1 - 2021 U6 - https://doi.org/10.3389/fpsyg.2021.685167 SN - 1664-1078 VL - 12 SP - 1 EP - 13 PB - Frontiers in psychology CY - Lausanne, Schweiz ER - TY - JOUR A1 - Dordevic, Milos A1 - Hölzer, Sonja A1 - Russo, Augusta A1 - García Alanis, José Carlos A1 - Müller, Notger Germar T1 - The Role of the Precuneus in Human Spatial Updating in a Real Environment Setting—A cTBS Study JF - Life N2 - As we move through an environment, we update positions of our body relative to other objects, even when some objects temporarily or permanently leave our field of view—this ability is termed egocentric spatial updating and plays an important role in everyday life. Still, our knowledge about its representation in the brain is still scarce, with previous studies using virtual movements in virtual environments or patients with brain lesions suggesting that the precuneus might play an important role. However, whether this assumption is also true when healthy humans move in real environments where full body-based cues are available in addition to the visual cues typically used in many VR studies is unclear. Therefore, in this study we investigated the role of the precuneus in egocentric spatial updating in a real environment setting in 20 healthy young participants who underwent two conditions in a cross-over design: (a) stimulation, achieved through applying continuous theta-burst stimulation (cTBS) to inhibit the precuneus and (b) sham condition (activated coil turned upside down). In both conditions, participants had to walk back with blindfolded eyes to objects they had previously memorized while walking with open eyes. Simplified trials (without spatial updating) were used as control condition, to make sure the participants were not affected by factors such as walking blindfolded, vestibular or working memory deficits. A significant interaction was found, with participants performing better in the sham condition compared to real stimulation, showing smaller errors both in distance and angle. The results of our study reveal evidence of an important role of the precuneus in a real-environment egocentric spatial updating; studies on larger samples are necessary to confirm and further investigate this finding. KW - precuneus KW - spatial updating KW - TMS KW - cTBS Y1 - 2022 U6 - https://doi.org/10.3390/life12081239 SN - 2075-1729 VL - 12 SP - 1 EP - 13 PB - MDPI CY - Basel, Schweiz ET - 8 ER - TY - JOUR A1 - Westphal, Andrea A1 - Kalinowski, Eva A1 - Hoferichter, Clara Josepha A1 - Vock, Miriam T1 - K−12 teachers' stress and burnout during the COVID-19 pandemic: A systematic review JF - Frontiers in Psychology N2 - We present the first systematic literature review on stress and burnout in K−12 teachers during the COVID-19 pandemic. Based on a systematic literature search, we identified 17 studies that included 9,874 K−12 teachers from around the world. These studies showed some indication that burnout did increase during the COVID-19 pandemic. There were, however, almost no differences in the levels of stress and burnout experienced by K−12 teachers compared to individuals employed in other occupational fields. School principals' leadership styles emerged as an organizational characteristic that is highly relevant for K−12 teachers' levels of stress and burnout. Individual teacher characteristics associated with burnout were K−12 teachers' personality, self-efficacy in online teaching, and perceived vulnerability to COVID-19. In order to reduce stress, there was an indication that stress-management training in combination with training in technology use for teaching may be superior to stress-management training alone. Future research needs to adopt more longitudinal designs and examine the interplay between individual and organizational characteristics in the development of teacher stress and burnout during the COVID-19 pandemic and beyond. KW - burnout KW - stress KW - COVID-19 KW - pandemic KW - K−12 teachers KW - remote teaching Y1 - 2022 U6 - https://doi.org/10.3389/fpsyg.2022.920326 SN - 1664-1078 SP - 1 EP - 29 PB - Frontiers CY - Lausanne, Schweiz ER - TY - JOUR A1 - Spikes, Montrai A1 - Rodríguez-Silva, Rodet A1 - Bennett, Kerri-Ann A1 - Bräger, Stefan A1 - Josaphat, James A1 - Torres-Pineda, Patricia A1 - Ernst, Anja A1 - Havenstein, Katja A1 - Schlupp, Ingo A1 - Tiedemann, Ralph T1 - A phylogeny of the genus Limia (Teleostei: Poeciliidae) suggests a single-lake radiation nested in a Caribbean-wide allopatric speciation scenario JF - BMC Research Notes N2 - Objective The Caribbean is an important global biodiversity hotspot. Adaptive radiations there lead to many speciation events within a limited period and hence are particularly prominent biodiversity generators. A prime example are freshwater fish of the genus Limia, endemic to the Greater Antilles. Within Hispaniola, nine species have been described from a single isolated site, Lake Miragoâne, pointing towards extraordinary sympatric speciation. This study examines the evolutionary history of the Limia species in Lake Miragoâne, relative to their congeners throughout the Caribbean. Results For 12 Limia species, we obtained almost complete sequences of the mitochondrial cytochrome b gene, a well-established marker for lower-level taxonomic relationships. We included sequences of six further Limia species from GenBank (total N  = 18 species). Our phylogenies are in concordance with other published phylogenies of Limia. There is strong support that the species found in Lake Miragoâne in Haiti are monophyletic, confirming a recent local radiation. Within Lake Miragoâne, speciation is likely extremely recent, leading to incomplete lineage sorting in the mtDNA. Future studies using multiple unlinked genetic markers are needed to disentangle the relationships within the Lake Miragoâne clade. KW - Cytochrome b KW - Island biogeography KW - Fresh water fish KW - Phylogeny Y1 - 2021 U6 - https://doi.org/10.1186/s13104-021-05843-x SN - 1756-0500 VL - 14 SP - 1 EP - 8 PB - BMC Research Notes / Biomed Central CY - London ER - TY - JOUR A1 - Krüger, Johanna A1 - Foerster, Verena Elisabeth A1 - Trauth, Martin H. A1 - Hofreiter, Michael A1 - Tiedemann, Ralph T1 - Exploring the Past Biosphere of Chew Bahir/Southern Ethiopia: Cross-Species Hybridization Capture of Ancient Sedimentary DNA from a Deep Drill Core JF - Frontiers in Earth Science N2 - Eastern Africa has been a prime target for scientific drilling because it is rich in key paleoanthropological sites as well as in paleolakes, containing valuable paleoclimatic information on evolutionary time scales. The Hominin Sites and Paleolakes Drilling Project (HSPDP) explores these paleolakes with the aim of reconstructing environmental conditions around critical episodes of hominin evolution. Identification of biological taxa based on their sedimentary ancient DNA (sedaDNA) traces can contribute to understand past ecological and climatological conditions of the living environment of our ancestors. However, sedaDNA recovery from tropical environments is challenging because high temperatures, UV irradiation, and desiccation result in highly degraded DNA. Consequently, most of the DNA fragments in tropical sediments are too short for PCR amplification. We analyzed sedaDNA in the upper 70 m of the composite sediment core of the HSPDP drill site at Chew Bahir for eukaryotic remnants. We first tested shotgun high throughput sequencing which leads to metagenomes dominated by bacterial DNA of the deep biosphere, while only a small fraction was derived from eukaryotic, and thus probably ancient, DNA. Subsequently, we performed cross-species hybridization capture of sedaDNA to enrich ancient DNA (aDNA) from eukaryotic remnants for paleoenvironmental analysis, using established barcoding genes (cox1 and rbcL for animals and plants, respectively) from 199 species that may have had relatives in the past biosphere at Chew Bahir. Metagenomes yielded after hybridization capture are richer in reads with similarity to cox1 and rbcL in comparison to metagenomes without prior hybridization capture. Taxonomic assignments of the reads from these hybridization capture metagenomes also yielded larger fractions of the eukaryotic domain. For reads assigned to cox1, inferred wet periods were associated with high inferred relative abundances of putative limnic organisms (gastropods, green algae), while inferred dry periods showed increased relative abundances for insects. These findings indicate that cross-species hybridization capture can be an effective approach to enhance the information content of sedaDNA in order to explore biosphere changes associated with past environmental conditions, enabling such analyses even under tropical conditions. KW - Chew Bahir KW - hybridization capture KW - ICDP KW - paleoclimate KW - past biosphere KW - sedaDNA KW - sediment core Y1 - 2021 U6 - https://doi.org/10.3389/feart.2021.683010 SN - 2296-6463 SP - 1 EP - 20 PB - Frontiers in Earth Science CY - Lausanne, Schweiz ER - TY - THES A1 - Lenz, Josefine T1 - Thermokarst dynamics in central-eastern Beringia T1 - Thermokarstdynamik im zentral-östlichen Beringia BT - insights from permafrost and lacustrine sediment cores BT - Einblicke durch Permafrost- und Seesedimentkerne N2 - Widespread landscape changes are presently observed in the Arctic and are most likely to accelerate in the future, in particular in permafrost regions which are sensitive to climate warming. To assess current and future developments, it is crucial to understand past environmental dynamics in these landscapes. Causes and interactions of environmental variability can hardly be resolved by instrumental records covering modern time scales. However, long-term environmental variability is recorded in paleoenvironmental archives. Lake sediments are important archives that allow reconstruction of local limnogeological processes as well as past environmental changes driven directly or indirectly by climate dynamics. This study aims at reconstructing Late Quaternary permafrost and thermokarst dynamics in central-eastern Beringia, the terrestrial land mass connecting Eurasia and North America during glacial sea-level low stands. In order to investigate development, processes and influence of thermokarst dynamics, several sediment cores from extant lakes and drained lake basins were analyzed to answer the following research questions: 1. When did permafrost degradation and thermokarst lake development take place and what were enhancing and inhibiting environmental factors? 2. What are the dominant processes during thermokarst lake development and how are they reflected in proxy records? 3. How did, and still do, thermokarst dynamics contribute to the inventory and properties of organic matter in sediments and the carbon cycle? Methods applied in this study are based upon a multi-proxy approach combining sedimentological, geochemical, geochronological, and micropaleontological analyses, as well as analyses of stable isotopes and hydrochemistry of pore-water and ice. Modern field observations of water quality and basin morphometrics complete the environmental investigations. The investigated sediment cores reveal permafrost degradation and thermokarst dynamics on different time scales. The analysis of a sediment core from GG basin on the northern Seward Peninsula (Alaska) shows prevalent terrestrial accumulation of yedoma throughout the Early to Mid Wisconsin with intermediate wet conditions at around 44.5 to 41.5 ka BP. This first wetland development was terminated by the accumulation of a 1-meter-thick airfall tephra most likely originating from the South Killeak Maar eruption at 42 ka BP. A depositional hiatus between 22.5 and 0.23 ka BP may indicate thermokarst lake formation in the surrounding of the site which forms a yedoma upland till today. The thermokarst lake forming GG basin initiated 230 ± 30 cal a BP and drained in Spring 2005 AD. Four years after drainage the lake talik was still unfrozen below 268 cm depth. A permafrost core from Mama Rhonda basin on the northern Seward Peninsula preserved a full lacustrine record including several lake phases. The first lake generation developed at 11.8 cal ka BP during the Lateglacial-Early Holocene transition; its old basin (Grandma Rhonda) is still partially preserved at the southern margin of the study basin. Around 9.0 cal ka BP a shallow and more dynamic thermokarst lake developed with actively eroding shorelines and potentially intermediate shallow water or wetland phases (Mama Rhonda). Mama Rhonda lake drainage at 1.1 cal ka BP was followed by gradual accumulation of terrestrial peat and top-down refreezing of the lake talik. A significant lower organic carbon content was measured in Grandma Rhonda deposits (mean TOC of 2.5 wt%) than in Mama Rhonda deposits (mean TOC of 7.9 wt%) highlighting the impact of thermokarst dynamics on biogeochemical cycling in different lake generations by thawing and mobilization of organic carbon into the lake system. Proximal and distal sediment cores from Peatball Lake on the Arctic Coastal Plain of Alaska revealed young thermokarst dynamics since about 1,400 years along a depositional gradient based on reconstructions from shoreline expansion rates and absolute dating results. After its initiation as a remnant pond of a previous drained lake basin, a rapidly deepening lake with increasing oxygenation of the water column is evident from laminated sediments, and higher Fe/Ti and Fe/S ratios in the sediment. The sediment record archived characterizing shifts in depositional regimes and sediment sources from upland deposits and re-deposited sediments from drained thaw lake basins depending on the gradually changing shoreline configuration. These changes are evident from alternating organic inputs into the lake system which highlights the potential for thermokarst lakes to recycle old carbon from degrading permafrost deposits of its catchment. The lake sediment record from Herschel Island in the Yukon (Canada) covers the full Holocene period. After its initiation as a thermokarst lake at 11.7 cal ka BP and intense thermokarst activity until 10.0 cal ka BP, the steady sedimentation was interrupted by a depositional hiatus at 1.6 cal ka BP which likely resulted from lake drainage or allochthonous slumping due to collapsing shore lines. The specific setting of the lake on a push moraine composed of marine deposits is reflected in the sedimentary record. Freshening of the maturing lake is indicated by decreasing electrical conductivity in pore-water. Alternation of marine to freshwater ostracods and foraminifera confirms decreasing salinity as well but also reflects episodical re-deposition of allochthonous marine sediments. Based on permafrost and lacustrine sediment records, this thesis shows examples of the Late Quaternary evolution of typical Arctic permafrost landscapes in central-eastern Beringia and the complex interaction of local disturbance processes, regional environmental dynamics and global climate patterns. This study confirms that thermokarst lakes are important agents of organic matter recycling in complex and continuously changing landscapes. N2 - Derzeit werden deutliche Landschaftsveränderungen in der Arktis beobachtet, welche sich höchstwahrscheinlich zukünftig v.a. in den Permafrostregionen verstärken, da diese besonders empfindlich auf Klimaveränderungen reagieren. Um derzeitige und zukünftige Entwicklungen einschätzen zu können, ist es wichtig vergangene Umweltprozesse zu verstehen. Ursachen und Wechselwirkungen von Umweltveränderungen können nur bedingt durch instrumentelle Aufzeichnungen erklärt werden, doch Paleo-Umweltarchive können weit in die Vergangenheit reichende Umweltdynamiken aufzeichnen. Seesedimente sind wichtige Archive, die lokale limnogeologische Prozesse, aber auch direkt oder indirekt klimatisch gesteuerte Umweltveränderungen der Vergangenheit aufzeichnen. Ziel der vorliegenden Arbeit ist es, spätquartäre Permafrost- und Thermokarstdynamik im zentral-östlichen Beringia zu rekonstruieren. Beringia umfasst jene terrestrische Landmasse, welche Eurasien und Nord-Amerika zu Zeiten von Meeresspiegeltiefständen verband. Um die Entwicklung, die Prozesse und den Einfluss von Thermokarstdynamik zu untersuchen, wurden mehrere Sedimentkerne von rezenten Seen und ausgelaufenen Seebecken analysiert, um folgende Forschungsfragen zu beantworten: 1. Zu welcher Zeit degradierte Permafrost und wann entwickelten sich Thermokarstseen? Was waren hemmende oder verstärkende Faktoren? 2. Was sind dominierende Prozesse während der Entwicklung von Thermokarstseen und wie spiegeln sich diese in Proxy-Aufzeichnungen wieder? 3. Wie hat Thermokarstdynamik damals und heute zur Bedeutung von organischer Substanz in Sedimenten und im Kohlenstoffkreislauf beigetragen? Die in dieser Arbeit angewandten Methoden basieren auf einem sogenannten „multi-proxy“ Ansatz, der sedimentologische, geochemische, geochronologische und mikropaläontologische Analysen, sowie die Untersuchung von stabilen Isotopen und die Hydrochemie von Porenwasser und -eis, verbindet. Feldmessungen der modernen Wasserqualität und Beckenmorphometrie komplettieren die Umweltuntersuchungen. Auf Grundlage der untersuchten Sedimentkerne lässt sich die Degradation von Permafrost und die Dynamik von Thermokarst auf zeitlich verschiedenen Skalen rekonstruieren. Die Analyse eines Sedimentkerns vom GG-Becken auf der nördlichen Seward-Halbinsel (Alaska) zeigt eine vorwiegend terrestrische Akkumulation von Yedoma während des Früh- und Mittel-Wisconsin mit zwischenzeitlich feuchteren Verhältnissen zwischen 44,5 und 41,5 ka BP. Diese frühe Feuchtgebietsphase wurde durch die Akkumulation einer 1 m dicken Tephra-Lage beendet, welche sehr wahrscheinlich von der Eruption des heutigen South Killeak Maar vor etwa 42.000 Jahren stammt. Eine Schichtlücke im Sedimentkern von etwa 22,5 und 0,23 ka BP gibt einen Hinweis auf Thermokarstentwicklung in der Umgebung der Kernlokation, welche bis heute ein Yedoma-Rudiment bildet. Der Thermokarstsee, der GG-Becken formte, entstand 230 ± 30 cal a BP und drainierte im Frühling 2005 AD. Vier Jahre nach der Drainage war der Talik des Sees in einer Tiefe von 268 cm noch ungefroren. Ein Permafrostkern vom Mama Rhonda-Becken auf der nördlichen Seward-Halbinsel archivierte eine vollständige limnische Fazies mit mehreren Seephasen. Die erste Seegeneration entstand am Übergang vom Spätglazial zum Frühholozän um etwa 11,8 cal ka BP; das alte Seebecken (Grandma Rhonda) ist bis heute südlich der Kernlokation erhalten. Etwa um 9,0 cal ka BP entwickelte sich ein eher flaches und dynamisches Seesystem mit aktiv erodierenden Ufern und potenziell zwischengeschalteten Flachwasser- oder Feuchtgebietsphasen (Mama Rhonda). Die Drainage vom Mama Rhonda-See etwa 1,1 cal ka BP wurde gefolgt von gradueller Torfakkumulation und einem von oben zurückfrierenden See-Talik Es wurde ein deutlich geringerer organischer Kohlenstoff-Gehalt in Grandma Rhonda-Ablagerungen (TOC im Mittel 2,5 Gew.-%) festgestellt, als in Mama Rhonda Ablagerungen (TOC im Mittel 7,9 Gew.-%). Dies zeigt den bedeutenden Einfluss von Thermokarst auf biogeochemische Kreisläufe, da in verschiedenen Seegenerationen organischen Kohlenstoff durch Permafrost-Tauen im Seesystem mobilisiert wird. Seesedimentkerne aus der Uferzone und dem zentralen Bereich von Peatball Lake auf der Arktischen Küstenebene von Alaska, ergaben eine junge Thermokarstdynamik von 1.400 Jahren, welche auf der Basis von absoluten Datierungen und Uferexpansionsraten rekonstruiert wurde. Nach der Seeinitiierung als Rest-See eines zuvor ausgelaufenen Seebeckens, vertiefte sich Peatball Lake verhältnismäßig schnell mit zunehmender Sauerstoffanreicherung der Wassersäule, wie aus laminierten Sedimenten und hohen Fe/Ti- und Fe/S-Verhältnissen im Sediment ersichtlich ist. Die Sedimente von Peatball Lake archivierten einen Wechsel des Ablagerungsregimes bei Ausdehnung der Seefläche und einen Wechsel der Sedimentquelle von ursprünglichen, rein terrestrischen Ablagerungen und bereits umgelagerten Sedimenten aus drainierten Seebecken. Angezeigt wird dieser Wechsel durch eine Veränderung im Eintrag organischen Materials in das Seesystem, was wiederum das Potential von Thermokarstseen bei der Aufarbeitung alten Kohlenstoffs aus degradierendem Permafrost im Einzugsgebiet verdeutlicht. Der Seesedimentkern von der Herschel Insel im Yukon (Kanada) deckt das gesamte Holozän ab. Nach der Seeentstehung um 11,7 cal ka BP und einer Zeit intensiver Thermokarstaktivität bis 11,0 cal ka BP, wird die Phase einer eher kontinuierlichen Sedimentation von einer Schichtlücke um 1,6 cal ka BP unterbrochen. Diese wurde entweder durch die Drainage des Sees oder einer allochthonen Rutschung instabiler Uferlinien verursacht. Die spezielle Situation des Sees auf einer Stauchendmoräne aus marinem Material spiegelt sich auch in dem Seesedimentarchiv wieder. Das Aussüßen des wachsenden Sees wird durch die abnehmende elektrische Leitfähigkeit im Porenwasser angezeigt. Der Wechsel von marinen und Süßwasserostrakoden- und Foraminiferengemeinschaften bestätigt zum einen die abnehmende Salinität des Sees, aber zeigt zum anderen auch episodische Umlagerung von allochthonem, marinem Sediment. Auf der Grundlange von Permafrost- und Seesedimentkernen zeigt diese Arbeit Beispiele spätquartärer Entwicklungsgeschichte typischer Arktischer Permafrostlandschaften im zentral-östlichen Beringia. Es werden komplexe Zusammenhänge zwischen lokalen Störungsprozessen, regionaler Umweltdynamik und globalen Klimaveränderungen aufgezeigt. Thermokarstseen spielen dabei eine wichtige Rolle im sich kontinuierlich verändernden Landschaftsbild der hohen Breiten und im Stoffkreislauf bei der Aufarbeitung organischer Substanz. KW - paleolimnology KW - permafrost degradation KW - periglacial landscape evolution KW - thermokarst processes KW - carbon cycling KW - central-eastern Beringia KW - Paläolimnologie KW - Permafrostdegradation KW - periglaziale Landschaftsentwicklung KW - Thermokarstprozesse KW - Kohlenstoffkreislauf KW - zentral-östliches Beringia Y1 - 2016 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-101364 ER - TY - BOOK A1 - Smirnov, Sergey A1 - Reijers, Hajo A. A1 - Nugteren, Thijs A1 - Weske, Mathias T1 - Business process model abstraction : theory and practice N2 - Business process management aims at capturing, understanding, and improving work in organizations. The central artifacts are process models, which serve different purposes. Detailed process models are used to analyze concrete working procedures, while high-level models show, for instance, handovers between departments. To provide different views on process models, business process model abstraction has emerged. While several approaches have been proposed, a number of abstraction use case that are both relevant for industry and scientifically challenging are yet to be addressed. In this paper we systematically develop, classify, and consolidate different use cases for business process model abstraction. The reported work is based on a study with BPM users in the health insurance sector and validated with a BPM consultancy company and a large BPM vendor. The identified fifteen abstraction use cases reflect the industry demand. The related work on business process model abstraction is evaluated against the use cases, which leads to a research agenda. T3 - Technische Berichte des Hasso-Plattner-Instituts für Digital Engineering an der Universität Potsdam - 35 Y1 - 2010 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-41782 SN - 978-3-86956-054-0 PB - Universitätsverlag Potsdam CY - Potsdam ER - TY - THES A1 - Löffler, Frank T1 - Numerical simulations of neutron star - black hole mergers T1 - Computersimulationen von Zusammenstößen eines schwarzen Lochs und eines Neutronensterns N2 - Collisions of black holes and neutron stars, named mixed binaries in the following, are interesting because of at least two reasons. Firstly, it is expected that they emit a large amount of energy as gravitational waves, which could be measured by new detectors. The form of those waves is expected to carry information about the internal structure of such systems. Secondly, collisions of such objects are the prime suspects of short gamma ray bursts. The exact mechanism for the energy emission is unknown so far. In the past, Newtonian theory of gravitation and modifications to it were often used for numerical simulations of collisions of mixed binary systems. However, near to such objects, the gravitational forces are so strong, that the use of General Relativity is necessary for accurate predictions. There are a lot of problems in general relativistic simulations. However, systems of two neutron stars and systems of two black holes have been studies extensively in the past and a lot of those problems have been solved. One of the remaining problems so far has been the use of hydrodynamic on excision boundaries. Inside excision regions, no evolution is carried out. Such regions are often used inside black holes to circumvent instabilities of the numerical methods near the singularity. Methods to handle hydrodynamics at such boundaries have been described and tests are shown in this work. One important test and the first application of those methods has been the simulation of a collapsing neutron star to a black hole. The success of these simulations and in particular the performance of the excision methods was an important step towards simulations of mixed binaries. Initial data are necessary for every numerical simulation. However, the creation of such initial data for general relativistic situations is in general very complicated. In this work it is shown how to obtain initial data for mixed binary systems using an already existing method for initial data of two black holes. These initial data have been used for evolutions of such systems and problems encountered are discussed in this work. One of the problems are instabilities due to different methods, which could be solved by dissipation of appropriate strength. Another problem is the expected drift of the black hole towards the neutron star. It is shown, that this can be solved by using special gauge conditions, which prevent the black hole from moving on the computational grid. The methods and simulations shown in this work are only the starting step for a much more detailed study of mixed binary system. Better methods, models and simulations with higher resolution and even better gauge conditions will be focus of future work. It is expected that such detailed studies can give information about the emitted gravitational waves, which is important in view of the newly built gravitational wave detectors. In addition, these simulations could give insight into the processes responsible for short gamma ray bursts. N2 - Zusammenstöße eines schwarzen Lochs und eines Neutronensterns, im Folgenden "gemischte Zusammenstöße" genannt, sind aus wenigstens zwei Gründen interessant. Erstens wird erwartet, dass dabei große Mengen Energie als Gravitationswellen freigesetzt werden und diese mit neuen Detektoren gemessen werden können. Die Form dieser Wellen verrät viel über die Beschaffenheit eines solchen Systems und stellt neben elektromagnetischen Wellen eine wichtige Informationsquelle dar. Zweitens sind Zusammenstöße von kompakten Objekten wie Neutronensternen und schwarze Löchern sehr wahrscheinlich die Ursache sogenannter kurzer Gammastrahlungsblitze. Deren genauer Mechanismus für die Umwandlung der gewaltigen Energiemengen, die bei diesen Blitzen ausgesandt werden, ist jedoch bisher unbekannt. Computersimulationen von Zusammenstößen eines gemischten Systems wurden bisher oft unter Benutzung der Newtonschen Gravitationstheorie, bzw. Korrekturen dazu, durchgeführt. In der Nähe so kompakte Objekte wie schwarzer Löcher oder Neutronensterne ist jedoch die Gravitationswirkung so stark, dass Näherungen wie die erwähnten Korrekturen der Newtonschen Gravitationstheorie zu ungenau sind. Eine Benutzung der allgemeinen Relativitätstheorie ist daher für dieses Problem unumgänglich. Die Probleme allgemein-relativistischer Simulationen sind vielfältig. Jedoch wurden Binärsysteme zweier schwarzer Löcher und zweier Neutronensterne schon eingehend untersucht, und so viele Probleme, die auch Simulationen gemischter Systeme betreffen, gelöst. Eins der bisher ausstehenden Probleme war die Behandlung der Hydrodynamik an Ausschneiderändern; Rändern zu Gebieten, die in der Zeitentwicklung der Simulation ignoriert werden. Solche Ränder werden zum Beispiel innerhalb eines schwarzen Lochs benutzt, um Instabilitäten des Programms in der Nähe der Singularität zu vermeiden. Methoden, solche Ränder zu behandeln wurden in der Arbeit entwickelt, getestet und gezeigt, dass sie verlässlich arbeiten. Ein wichtiger Test für diese Methoden, der gleichzeitig der Gewinnung neuer Erkenntnisse diente, war deren Anwendung auf Simulationen von zu schwarzen Löchern kollabierenden, rotierenden Sternen. Der Erfolg, diese Simulationen ohne Probleme mit den erwähnten Methoden durchzuführen, war ein wichtiger Schritt zu Simulationen gemischter Binärsysteme. Für Computersimulationen sind Anfangsdaten notwendig, die das gewünschte Problem beschreiben. Die Erstellung solcher Anfangsdaten ist jedoch unter Benutzung der allgemeinen Relativitätstheorie ausser in Spezialfällen sehr komplex. Wir zeigen, wie man einen schon vorhandenen Algorithmus für Anfangsdaten für zwei schwarze Löcher ändern kann, um Anfangsdaten für ein gemischtes Binärsystem zu erhalten. Diese Anfangsdaten wurden für Simulationen eines gemischten Binärsystems benutzt. Während dieser Simulationen traten mehrere Probleme auf. Zwei dieser Probleme waren numerische Instabilitäten unterschiedlicher Herkunft. Beide konnten jedoch mit angepasst starker Dissipation (der künstliche Entnahme von hochfrequenter Energie aus dem System) unterdrückt werden. Ein weiteres Problem war die erwartete Bewegung des schwarzen Lochs in Richtung des Neutronensterns. Da ein Teil des Simulationsgebietes innerhalb des schwarzen Lochs ausgeschnitten wird und das verwendete Programm bewegte Ausschneidegebiete nicht behandeln kann, darf sich das schwarze Loch jedoch auf dem Gitter kaum bewegen. Wir haben dieses Problem durch eine an das Problem angepasste Eichbedingung gelöst, die auf Bewegungen des scheinbaren Horizons reagiert und die Position des schwarzen Lochs auf diese Weise nahezu konstant hält. Die Methoden und Simulationen dieser Arbeit sind nur der Anfangspunkt einer ausführlichen Studie von Binärsystemen eines schwarzen Lochs und eines Neutronensterns. Bessere Methoden, Modelle und Simulationen mit höherer Auflösung und besser an das System angepassten Koordinaten werden Mittelpunkt zukünftiger Arbeit sein. Es wird erwartet, dass solche detailierten Studien Erkenntnisse über die abgestrahlten Gravitationswellen liefern, die gerade in Hinblick auf die neuen Gravitationswellendetektoren wichtig sind. Weiterhin könnten diese Simulationen dabei helfen, die Prozesse, die kurze Gammastrahlungsblitze hervorrufen, und über die im Moment kaum etwas bekannt ist, aufzuklären. KW - Relativistische Astrophysik KW - Neutronensterne KW - schwarze Löcher KW - neutron stars KW - black holes Y1 - 2005 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-7743 ER - TY - THES A1 - Schauer, Nicolas T1 - Quantitative trait loci (QTL) for metabolite accumulation and metabolic regulation : metabolite profiling of interspecific crosses of tomato T1 - Metabolomische Analyse von interspezifischen Tomaten N2 - The advent of large-scale and high-throughput technologies has recently caused a shift in focus in contemporary biology from decades of reductionism towards a more systemic view. Alongside the availability of genome sequences the exploration of organisms utilizing such approach should give rise to a more comprehensive understanding of complex systems. Domestication and intensive breeding of crop plants has led to a parallel narrowing of their genetic basis. The potential to improve crops by conventional breeding using elite cultivars is therefore rather limited and molecular technologies, such as marker assisted selection (MAS) are currently being exploited to re-introduce allelic variance from wild species. Molecular breeding strategies have mostly focused on the introduction of yield or resistance related traits to date. However given that medical research has highlighted the importance of crop compositional quality in the human diet this research field is rapidly becoming more important. Chemical composition of biological tissues can be efficiently assessed by metabolite profiling techniques, which allow the multivariate detection of metabolites of a given biological sample. Here, a GC/MS metabolite profiling approach has been applied to investigate natural variation of tomatoes with respect to the chemical composition of their fruits. The establishment of a mass spectral and retention index (MSRI) library was a prerequisite for this work in order to establish a framework for the identification of metabolites from a complex mixture. As mass spectral and retention index information is highly important for the metabolomics community this library was made publicly available. Metabolite profiling of tomato wild species revealed large differences in the chemical composition, especially of amino and organic acids, as well as on the sugar composition and secondary metabolites. Intriguingly, the analysis of a set of S. pennellii introgression lines (IL) identified 889 quantitative trait loci of compositional quality and 326 yield-associated traits. These traits are characterized by increases/decreases not only of single metabolites but also of entire metabolic pathways, thus highlighting the potential of this approach in uncovering novel aspects of metabolic regulation. Finally the biosynthetic pathway of the phenylalanine-derived fruit volatiles phenylethanol and phenylacetaldehyde was elucidated via a combination of metabolic profiling of natural variation, stable isotope tracer experiments and reverse genetic experimentation. N2 - Die Einführung von Hochdurchsatzmethoden zur Analyse von biologischen Systemen, sowie die umfangreiche Sequenzierung von Genomen haben zu einer Verlagerung der Forschung „im Detail“ zu einer ganzheitlicheren Betrachtungsweise auf Systemebene geführt. Aus einer jahrhundertlangen, intensiven Züchtung und Selektion von Nutzpflanzen resultierte gleichzeitig eine Abnahme der genetischen Varianz. Daraus resultierend sind Nutzpflanzen anfälliger gegenüber Stressfaktoren, wie Pathogenen, hohen Salzkonzentrationen oder Trockenheit, als ihre Wildarten. Das Potential konventioneller Züchtung scheint somit heute an seine Grenzen gekommen zu sein. Daher versucht man mittels moderner Molekulartechnik, wie zum Beispiel Marker-gestützte Selektion, Gene oder ganze Genombereiche von Wildarten mit hoher genetischer Variation in Nutzpflanzen einzukreuzen, vornehmlich mit dem Ziel einer Ertrags- bzw. Resistenzsteigerung. Neueste medizinische Studien belegen, dass die Ernährung eine wesentliche Rolle für die menschliche Gesundheit spielt. Besonders wichtig sind hierbei die gesundheitsfördernden Substanzen in pflanzlichen Nahrungsmitteln. Aus diesem Grund kommt der Erforschung der biochemischen Zusammensetzung von biologischen Proben eine immer größere Bedeutung zu. Diese Untersuchung kann elegant durch Metabolitenprofile, welche die multivariate Analyse komplexer biologischer Proben erlauben, durchgeführt werden. In dieser Arbeit wurde zur Untersuchung der biochemischen Zusammensetzung von Tomatenwildarten und interspezifischen S. pennellii Tomatenintrogressionslinien (IL) eine GC/MS basierte Metabolitenanalyseplattform verwendet. Hierzu war es zunächst notwendig eine Massenspektrenbibliothek, zur Annotierung von Massenspektren und Retentionsindices von, in pflanzlichen Proben vorkommenden, Metaboliten anzulegen. Die Analyse der Tomatenwildarten ergab große Unterschiede gegenüber der Kulturtomate im Hinblick auf den Gehalt an Amino- und organischen Säuren, sowie der Zuckerzusammensetzung und den Gehalt an Sekundärmetaboliten. Die darauf folgende Analyse der ILs, von den jede ein genau definiertes genomisches Segment von S. pennellii beinhaltet, bestätigte diese enorme Variation mit 889 metabolischen und 326 ertragsassozierten-Veränderungen in den ILs. Die metabolischen Veränderungen zeichneten sich durch abnehmende bzw. steigende Gehalte von einzelnen Metaboliten, aber auch durch eine koordinierte Änderung aus. In dieser Arbeit wurde weiterhin der Biosyntheseweg der Volatilenstoffe Phenylethanol und Phenylacetaldehyd mit Hilfe einer IL untersucht. Hierbei konnten durch stabile Isotopenmarkierung und eines „reverse genetics“-Ansatzes Gene bzw. Enzyme identifiziert werden, die für die Dekarboxylierung des Eduktes Phenylalanin verantwortlich sind. Diese Arbeit beschreibt erstmals die umfassende Analyse von biochemischen Komponenten auf Genombasis in Tomatenintrogressionslinien und zeigt damit ein Werkzeug auf zur Identifizierung von qualitativen biochemischen Merkmalen in der modernen molekularen Züchtung. KW - Tomate KW - Metabolit KW - GC-MS KW - Introgression KW - Frucht KW - Metabolome KW - Züchtung KW - metabolic genomics KW - Tomato KW - metabolite profiling KW - metabolome KW - breeding KW - crops KW - fruit KW - metabolite breeding KW - metabolic genomics Y1 - 2006 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-7643 ER - TY - INPR A1 - Roelly, Sylvie A1 - Fradon, Myriam T1 - Infinite system of Brownian balls : equilibrium measures are canonical Gibbs N2 - We consider a system of infinitely many hard balls in Rd undergoing Brownian motions and submitted to a smooth pair potential. It is modelized by an infinite-dimensional stochastic differential equation with a local time term. We prove that the set of all equilibrium measures, solution of a detailed balance equation, coincides with the set of canonical Gibbs measures associated to the hard core potential added to the smooth interaction potential. KW - Stochastic Differential Equation KW - hard core potential KW - Canonical Gibbs measure KW - detailed balance equation KW - reversible measure Y1 - 2006 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-6720 ER - TY - BOOK ED - Ishihara, Shinichiro ED - Schmitz, Michaela ED - Schwarz, Anne T1 - Interdisciplinary studies on information structure : ISIS ; working papers of the SFB 632. - Vol. 1 N2 - Contents: A1: Phonology and syntax of focussing and topicalisation: Gisbert Fanselow: Cyclic Phonology–Syntax-Interaction: Movement to First Position in German Caroline Féry and Laura Herbst: German Sentence Accent Revisited Shinichiro Ishihara: Prosody by Phase: Evidence from Focus Intonation–Wh-scope Correspondence in Japanese A2: Quantification and information structure: Cornelia Endriss and Stefan Hinterwimmer: The Influence of Tense in Adverbial Quantification A3: Rhetorical Structure in Spoken Language: Modeling of Global Prosodic Parameters: Ekaterina Jasinskaja, Jörg Mayer and David Schlangen: Discourse Structure and Information Structure: Interfaces and Prosodic Realization B2: Focussing in African Tchadic languages: Katharina Hartmann and Malte Zimmermann: Focus Strategies in Chadic: The Case of Tangale Revisited D1: Linguistic database for information structure: Annotation and retrieval: Stefanie Dipper, Michael Götze, Manfred Stede and Tillmann Wegst: ANNIS: A Linguistic Database for Exploring Information Structure T3 - Interdisciplinary studies on information structure : ISIS ; working papers of the SFB 632 - 1 Y1 - 2004 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-8237 SN - 1866-4725 ER - TY - BOOK ED - Dipper, Stefanie ED - Götze, Michael ED - Stede, Manfred T1 - Heterogeneity in focus : creating and using linguistic databases N2 - The papers in this volume were presented at the workshop Heterogeneity in Linguistic Databases', which took place on July 9, 2004 at the University of Potsdam. The workshop was organized by project D1: Linguistic Database for Information Structure: Annotation and Retrieval', a member project of the SFB 632, a collaborative research center entitled Information Structure: the Linguistic Means for Structuring Utterances, Sentences and Texts'. The workshop brought together both developers and users of linguistic databases from a number of research projects which work on an empirical basis, all of which have to cope with different sorts of heterogeneity: primary linguistic data and annotated information may be heterogeneous, as well as the data structures representing them. The first four papers (by Wagner, Schmidt, Lüdeling, and Witt) address aspects of heterogeneous data from the point of view of database developers; the remaining three papers (by Meyer, Smith, and Teich/Fankhauser) focus on data exploitation by the users. T3 - Interdisciplinary studies on information structure : ISIS ; working papers of the SFB 632 - 2 Y1 - 2005 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-8244 SN - 978-3-937786-48-3 PB - Universitätsverlag Potsdam CY - Potsdam ER - TY - THES A1 - Andersen, Audrée T1 - Surfactant dynamics at interfaces : a series of second harmonic generation experiments T1 - Surfactant Dynamik an Grenzflächen : eine Studie über SHG-Experimente N2 - Adsorption layers of soluble surfactants enable and govern a variety of phenomena in surface and colloidal sciences, such as foams. The ability of a surfactant solution to form wet foam lamellae is governed by the surface dilatational rheology. Only systems having a non-vanishing imaginary part in their surface dilatational modulus, E, are able to form wet foams. The aim of this thesis is to illuminate the dissipative processes that give rise to the imaginary part of the modulus. There are two controversial models discussed in the literature. The reorientation model assumes that the surfactants adsorb in two distinct states, differing in their orientation. This model is able to describe the frequency dependence of the modulus E. However, it assumes reorientation dynamics in the millisecond time regime. In order to assess this model, we designed a SHG pump-probe experiment that addresses the orientation dynamics. Results obtained reveal that the orientation dynamics occur in the picosecond time regime, being in strong contradiction with the two states model. The second model regards the interface as an interphase. The adsorption layer consists of a topmost monolayer and an adjacent sublayer. The dissipative process is due to the molecular exchange between both layers. The assessment of this model required the design of an experiment that discriminates between the surface compositional term and the sublayer contribution. Such an experiment has been successfully designed and results on elastic and viscoelastic surfactant provided evidence for the correctness of the model. Because of its inherent surface specificity, surface SHG is a powerful analytical tool that can be used to gain information on molecular dynamics and reorganization of soluble surfactants. They are central elements of both experiments. However, they impose several structural elements of the model system. During the course of this thesis, a proper model system has been identified and characterized. The combination of several linear and nonlinear optical techniques, allowed for a detailed picture of the interfacial architecture of these surfactants. N2 - Amphiphile vereinen zwei gegensätzliche Strukturelemente in einem Molekül, eine hydrophile Kopfgruppe und ein hydrophobe, meist aliphatische Kette. Aufgrund der molekularen Asymmetrie erfolgt eine spontane Adsorption an der Wasser-Luft Grenzfläche. Die Adsorptionsschicht verändert die makroskopischen Eigenschaften des Materials, z.B. die Grenzflächenspannung wird erniedrigt. Amphiphile sind zentrale Bauelemente der Kolloid- und Grenzflächenforschung, die Phänomene, wie Schäume ermöglichen. Eine Schaumlamelle besteht aus einem dünnen Wasserfilm, der durch zwei Adsorptionsschichten stabilisiert wird. Die Stabilität der Lamelle wird durch die Grenzflächenrheologie entscheidend geprägt. Die wesentliche makroskopische Größe in diesem Zusammenhang ist das so genannte Grenzflächendilatationsmodul E. Es beschreibt die Fähigkeit des Systems die Gleichgewichtsgrenzflächenspannung nach einer Expansion oder Dilatation der Adsorptionschicht wieder herzustellen. Das Modul E ist eine komplexe Größe, in dem der Imaginärteil direkt mit der Schaumstabilität korreliert. Diese Arbeit widmet sich der Grenzflächenrheologie. In der Literatur werden zwei kontroverse Modelle zur Interpretation dieser Größe diskutiert. Diese Modelle werden experimentell in dieser Arbeit überprüft. Dies erfordert die Entwicklung neuer experimenteller Aufbauten basierend auf nichtlinearen, optischen Techniken. Mit diesen Experimenten konnte eines der Modelle bestätigt werden. KW - Tensid KW - Grenzflächenchemie KW - Nichtlineare Spektroskopie KW - Oscillating Bubble KW - surfactants KW - nonlinear optics KW - surface rheology KW - air-water interface KW - oscillating bubble Y1 - 2005 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-6553 ER - TY - BOOK A1 - Gabbert, Silke A1 - Weikard, Hans-Peter T1 - Food deficits, food security and food aid : concepts and measurement N2 - The concepts of food deficit, hunger, undernourishment and food security are discussed. Axioms and indices for the assessment of nutrition of individuals and groups are suggested. Furthermore a measure for food aid donor performance is developed and applied to a sample of bilateral and multilateral donors providing food aid for African countries. T3 - Finanzwissenschaftliche Diskussionsbeiträge - Bd. 21 Y1 - 1998 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-8589 ER - TY - BOOK A1 - Hans, Silke T1 - Migrants in Germany, Sweden and the United Kingdom BT - patterns of assimilation and welfare N2 - Contents: 1. Introduction 2. Migration and Assimilation – Theoretical Approaches 2.1 Meaning and Definition of the Terms Migration and Migrant 2.2 Milton M. Gordon – Sub Processes of Assimilation 2.3 Hartmut Esser - Acculturation, Integration, and Assimilation 2.4 The Concept of Integration and Assimilation 2.5 Straight–line Assimilation and its Implications 2.6 Segmented Assimilation and its Implications 3. Social Inequality and Welfare – Theoretical Approaches 3.1 Dimensions of Inequality 3.2 Welfare Regimes and Social Inequality 3.3 Migration, Assimilation and Inequality 4. Research Design 4.1 Research Question and General Proceeding 4.2 Sample and Data Base 4.3 Operationalisation and Indicators 5. Migration, Welfare and Inequality in Three European Countries 6. Empirical Results 6.1 Performance of Migrants Compared With Natives 6.2 Different Trajectories of Assimilation 6.3 Trajectories of Segmented Assimilation and their Determinants 6.4 Policies, Attitudes and Assimilation – An Aggregate Analysis 6.5 Summary – What Determines the Performance of Migrants? 7. Discussion of Empirical Results in Terms of Theoretical Approaches 7.1 The Situation of Migrants in Three European Countries 7.2 Assessment of the Trajectories of Assimilation 8. Conclusion – Future Prospects of Migration in Europe T3 - Potsdamer Beiträge zur Sozialforschung - 21 Y1 - 2004 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-11248 ER - TY - THES A1 - Hoffmann, Toni T1 - Cloning and characterisation of the HMA3 gene and its promoter from Arabidopsis halleri (L.) O'Kane and Al'Shehbaz and Arabidopsis thaliana (L.) Heynhold T1 - Klonierung und Charakterisierung des HMA3 Genes und seines Promotors aus Arabidopsis halleri (L.) O'Kane und Al'Shehbaz und Arabidopsis thaliana (L.) Heynhold N2 - Being living systems unable to adjust their location to changing environmental conditions, plants display homeostatic networks that have evolved to maintain transition metal levels in a very narrow concentration range in order to avoid either deficiency or toxicity. Hence, plants possess a broad repertoire of mechanisms for the cellular uptake, compartmentation and efflux, as well as for the chelation of transition metal ions. A small number of plants are hypertolerant to one or a few specific transition metals. Some metal tolerant plants are also able to hyperaccumulate metal ions. The Brassicaceae family member Arabidopis halleri ssp. halleri (L.) O´KANE and AL´SHEHBAZ is a hyperaccumulator of zinc (Zn), and it is closely related to the non-hypertolerant and non-hyperaccumulating model plant Arabidopsis thaliana (L.) HEYNHOLD. The close relationship renders A. halleri a promising emerging model plant for the comparative investigation of the molecular mechanisms behind hypertolerance and hyperaccumulation. Among several potential candidate genes that are probably involved in mediating the zinc-hypertolerant and zinc-hyperaccumulating trait is AhHMA3. The AhHMA3 gene is highly similar to AtHMA3 (AGI number: At4g30120) in A. thaliana, and its encoded protein belongs to the P-type IB ATPase family of integral membrane transporter proteins that transport transition metals. In contrast to the low AtHMA3 transcript levels in A. thaliana, the gene was found to be constitutively highly expressed across different Zn treatments in A. halleri, especially in shoots. In this study, the cloning and characterisation of the HMA3 gene and its promoter from Arabidopsis halleri (L.) O´KANE and AL´SHEHBAZ and Arabidopsis thaliana (L.) HEYNHOLD is described. Heterologously expressed AhHMA3 mediated enhanced tolerance to Zn and to a much lesser degree to cadmium (Cd) but not to cobalt (Co) in metal-sensitive mutant strains of budding yeast. It is demonstrated that the genome of A. halleri contains at least four copies of AhHMA3, AhHMA3-1 to AhHMA3-4. A copy-specific real-time RT-PCR indicated that an AhHMA3-1 related gene copy is the source of the constitutively high transcript level in A. halleri and not a gene copy similar to AhHMA3-2 or AhHMA3-4. In accordance with the enhanced AtHMA3mRNA transcript level in A. thaliana roots, an AtHMA3 promoter-GUS gene construct mediated GUS activity predominantly in the vascular tissues of roots and not in shoots. However, the observed AhHMA3-1 and AhHMA3-2 promoter-mediated GUS activity in A. thaliana or A. halleri plants did not reflect the constitutively high expression of AhHMA3 in shoots of A. halleri. It is suggested that other factors e. g. characteristic sequence inserts within the first intron of AhHMA3-1 might enable a constitutively high expression. Moreover, the unknown promoter of the AhHMA3-3 gene copy could be the source of the constitutively high AhHMA3 transcript levels in A. halleri. In that case, the AhHMA3-3 sequence is predicted to be highly homologous to AhHMA3-1. The lack of solid localisation data for the AhHMA3 protein prevents a clear functional assignment. The provided data suggest several possible functions of the AhHMA3 protein: Like AtHMA2 and AtHMA4 it might be localised to the plasma membrane and could contribute to the efficient translocation of Zn from root to shoot and/or to the cell-to-cell distribution of Zn in the shoot. If localised to the vacuolar membrane, then a role in maintaining a low cytoplasmic zinc concentration by vacuolar zinc sequestration is possible. In addition, AhHMA3 might be involved in the delivery of zinc ions to trichomes and mesophyll leaf cells that are major zinc storage sites in A. halleri. N2 - Pflanzen sind lebende Systeme, die nicht in der Lage sind ihren Standort sich ändernden Umweltbedingungen anzupassen. Infolgedessen weisen Pflanzen homöostatischeNetzwerke auf, welche die Mengen an intrazellulären Übergangsmetallen in einem sehr engen Konzentrationsbereich kontrollieren um somit Vergiftungs- oder Mangelerscheinungen zu vermeiden. Eine kleine Anzahl von Pflanzen ist hypertolerant gegenüber einem oder mehreren Übergangsmetallen. Einige wenige dieser metalltoleranten Pflanzen sind fähig Übergangsmetalle in beträchtlichen Mengen zu speichern, sprich zu hyperakkumulieren, ohne Vergiftungserscheinungen zu zeigen. Die Haller’sche Schaumkresse (Arabidopis halleri ssp. halleri (L.) O´KANE und AL´SHEHBAZ) aus der Familie der Kreuzblütler (Brassicaceae) ist ein solcher Hyperakkumulator für Zink (Zn). Sie ist nah verwandt mit der Modellpflanze Ackerschmalwand (Arabidopsis thaliana (L.) HEYNHOLD), die jedoch nicht-hypertolerant und nicht-hyperakkumulierend für Übergangsmetalle ist. Diese nahe Verwandtschaft erlaubt vergleichende Studien der molekularen Mechanismen, die Hypertoleranz und Hyperakkumulation zu Grunde liegen. Zu der Gruppe von Kandidatengenen, die möglicherweise von Bedeutung für die Zink-hypertoleranten und -hyperakkumulierenden Eigenschaften von A. halleri sind, gehört AhHMA3, ein Gen mit großer Ähnlichkeit zu AtHMA3 (AGI Nummer: At4g30120) aus A. thaliana. Es kodiert ein Protein aus der Familie transmembraner Übergangsmetall-Transportproteine, den P-typ IB ATPasen. Im Gegensatz zu den niedrigen AtHMA3 Transkriptmengen in A. thaliana wird das AhHMA3 Gen in A. halleri in Gegenwart verschiedener Zn Konzentrationen konstitutiv hoch exprimiert, insbesondere im Spross der Pflanze. Diese Arbeit beschreibt die Klonierung und Charakterisierung des HMA3 Gens und seines Promoters aus A. halleri und A. thaliana. Es wurde gezeigt, dass heterolog exprimiertes AhHMA3 Protein in metallsensitiven Hefestämmen eine erhöhte Toleranz gegenüber Zink und zu einem geringen Grad gegenüber Kadmium (Cd) jedoch nicht gegenüber Kobalt (Co) vermittelt.Weiterhin wurden im Genom von A. halleri mindestens vier AhHMA3 Genkopien, AhHMA3-1 bis AhHMA3-4, nachgewiesen. Eine Genkopie-spezifische Echtzeit-RT-PCR (real-time RT-PCR) deutete darauf hin, dass eine zu AhHMA3-1 und nicht zu AhHMA3-2 oder AhHMA3-4 ähnliche Genkopie die Quelle der konstitutiv hohen Transkriptmengen in A. halleri ist. In Übereinstimmung mit erhöhten mRNS Transkriptmengen inWurzeln von A. thaliana, vermittelte ein AtHMA3 Promoter-GUS (ß-Glucuronidase) Genkonstrukt GUS-Aktivität hauptsächlich in den Leitgeweben der Wurzeln jedoch nicht des Sprosses. Die vermittelte GUS-Aktivität durch Promoterfragmente von AhHMA3-1 und AhHMA3-2 in A. thaliana oder A. halleri Pflanzen spiegelte jedoch nicht die konstitutiv hohe AhHMA3 Expression im Spross von A. halleri wieder. Es wird vermutet, dass andere Faktoren die konstitutiv hohe Expression ermöglichen wie zum Beispiel die gefundenen kopiespezifischen Sequenzinsertionen innerhalb des ersten AhHMA3-1 Introns. Weiterhin ist es denkbar, dass der unbekannte Promoter der AhHMA3-3 Genkopie die Quelle der konstitutiv hohen AhHMA3 Transkriptmengen ist. In diesem Fall wird eine sehr hohe Ähnlichkeit zwischen den Sequenzen von AhHMA3-3 und der AhHMA3-1 vorhergesagt. Es konnten keine deutlichen Ergebnisse zur intrazellulären Lokalisierung gemacht werden, die eine exakte Einordnung der Funktion des AhHMA3 Proteins erlauben würden. Die bisher ermittelten Ergebnisse schlagen jedoch mehrere mögliche Funktionen für AhHMA3 vor: Ähnlich den AhHMA3 homologen Proteinen, AtHMA2 und AtHMA4, könnte AhHMA3 in der Plasmamembran der Zelle sitzen und dort zur effizienten Translokation von Zink aus der Wurzel in den Spross und/oder zur Zell-zu-Zell Verteilung von Zn im Spross beitragen. Falls AhHMA3 in der Membran der Vakuole sitzt, könnte es eine Rolle bei der Aufrechterhaltung niedriger zytoplasmatischer Zinkkonzentrationen durch vakuoläre Zinksequestrierung spielen. Zusätzlich ist es denkbar, dass AhHMA3 an der Abgabe von Zinkionen an Trichome und Blattmesophyllzellen beteiligt ist, die die Haupteinlagerungsorte für Zink in A. halleri darstellen. KW - P-Typ ATPase KW - Übergangsmetalle KW - Hyperakkumulation KW - Zink KW - HMA KW - p-type ATPase KW - transition metals KW - hyperaccumulation KW - zinc KW - HMA Y1 - 2007 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-15259 ER - TY - THES A1 - Köchert, Karl T1 - Development of a method to assess EAAT1 transcription levels in Alzheimer's disease N2 - Zur Zeit leiden ca. 24 Millionen Menschen auf der ganzen Welt unter Demenz, Alzheimer macht dabei 50-60% aller Demenzfälle aus. Da der Anteil der Bevölkerung, der an Demenz leidet, proportional zum Alter zunimmt und der Anteil älterer Menschen in der Gesellschaft von Jahr zu Jahr steigt, wird Alzheimer immer mehr zu einem ernstzunehmenden, gesellschaftlichen Problem. Zum Stand der heutigen Forschung ist es etabliert, dass die Aminosäure Glutamat - quantitativ einer der wichtigsten Neurotransmitter im Zentralen Nervensystem (ZNS) - toxische Konzentrationen erreichen kann wenn sie - im Zuge der Übertragung von Aktionspotentialen - nach ihrer Freisetzung nicht aus dem Synaptischen Spalt entfernt wird. Viele Studien haben gezeigt, dass in der Alzheimerschen Krankheit die Glutamataufnahme beeinträchtigt ist, was zu toxischen Konzentrationen von Glutamat und dem daraus folgenden Absterben von Neuronen führt. Der exitatorische Aminosäuretransporter 1 (EAAT1) gehört zu der Familie der Na+-abhängigen Glutamattransporter und stellt nach EAAT2 den quantitativ wichtigsten Glutamattransporter im ZNS dar. In diesem Projekt wurde eine bis dahin für den Menschen nicht bekannte EAAT1 Spleißvariante, in der Exon 3 ausgeschnitten wird, nachgewiesen. Diese Variante wurde EAAT1Δ3 genannt und stellt damit mit EAAT1Δ9 die zweite für EAAT1 nachgewiesene Spleißvariante dar. Eine auf real-time RT-PCR basierende Methode wurde entwickelt, um die Transkripte von EAAT1 wildtyp (EAAT1 wt), EAAT1Δ3 und EAAT1Δ9 zu quantifizieren. Proben aus verschiedenen Hirnarealen wurden aus einem Set von Kontrollen und Alzheimerfällen bei der Quantifizierung verwendet. Die gewählten Areale sind von der Alzheimerschen Krankheit unterschiedlich stark betroffen. Dies diente als interne Kontrolle für die durchgeführten Experimente und ermöglichte so die Differenzierung zwischen beobachteten Effekten: Nur Effekte die alleinig in von Alzheimer betroffenen Gehirnarealen auftreten, können als spezifisch für die Krankheit angesehen werden. Die Resultate diese Projektes zeigen, dass EAAT1Δ3 in sehr geringer Anzahl transkribiert wird, die nur 0.15% der EAAT1 wt Transkription entspricht. Dahingegen entspricht das EAAT1 Δ9 Transkript im Durchschnitt 26.6% des EAAT1 wt Transkripts. Es wurde nachgewiesen, dass die Transkriptionsrate aller EAAT1 Varianten in Alzheimerfällen signifikant reduziert ist (P<0.0001). Dies unterstützt die Theorie, dass bei Alzheimerfällen die EAAT1 Proteinexpression stark reduziert und der Glutamattransport, der normalerweise durch diesen Transporter gewährleistet wird, stark eingeschränkt ist. Dies wiederum resultiert in toxisch hohen Glutamatkonzentrationen und damit dem Absterben von Neuronen. Die gefundene Reduktion der EAAT1Transkription ist nicht spezifisch für Gehirnareale die von Alzheimer betroffen sind, sondern tritt in selbem Maße in nicht von Alzheimer betroffenen Gehirnarealen auf. Daraus lässt sich schließen, dass die Reduktion der EAAT1 Transkription eher ein Resultat eines in der Alzheimerschen Krankheit präsenten, grundlegenden Krankheitsmechanismus ist als deren Ursache. N2 - Today about 24 Million people worldwide suffer from dementia, Alzheimer’s Disease accounts for approximately 50-60% of all dementia cases. As the prevalence of dementia grows with increasing age Alzheimer’s Disease becomes more and more of an issue for society as the proportion of elderly people increases from year to year. It is well established, that the amino acid glutamate - quantitatively being the most important neurotransmitter in the central nervous system (CNS) - may reach toxic concentrations if not cleared from the synaptic cleft into which it is released during transmittance of action potentials. In Alzheimer’s Disease there is strong evidence for a generally impaired glutamate uptake system which in turn is thought to result in toxic levels of the amino acid with the potential to kill off neurons. The excitatory amino acid transporter 1 (EAAT1) belongs to the family of Na+-dependent glutamate transporter and accounts together with EAAT2 for most of the glutamate uptake in the CNS. In this project a new splice variant of EAAT1, skipping exon 3 was detected in human brain samples and subsequently called EAAT1Δ3, this being the second splice variant found after the recent detection of EAAT1Δ9. A method was developed to quantify the transcript of EAAT1 wt, EAAT1Δ3 and EAAT1Δ9 by means of real-time PCR. Samples were taken from different brain areas of a set of control and AD cases. The areas chosen for examination are affected differently in Alzheimer’s Disease, this was used an internal control for the experiments done in this project as to determine whether any effect observed is specific for AD, i.e. AD affected areas or is generally seen in all areas examined. The results of this project show that EAAT1Δ3 is transcribed in very low copy numbers making up a proportion of 0.15% of EAAT1 wt whereas EAAT1Δ9 is transcribed in a considerably large proportion of EAAT1 wt of 26.6%. It was moreover found that all EAAT1 variants are transcribed at significantly lower rates (P<0.0001) in AD cases, supporting the theory that EAAT1 protein expression is reduced to a point where glutamate uptake normally mediated by this transporter is impaired. This in turn is thought to result in toxic levels glutamate accounting for neuronal loss in the disease. No area-dependent effects were found, suggesting that the reduction of EAAT1 transcription is rather a result of an underlying general mechanism present in AD. Further research will have to be done to assess the degree of EAAT1 expression in AD and whether those future findings match with the result of this project. KW - Morbus Alzheimer KW - Glutamat KW - EAAT1 KW - Spleißvariante KW - Alzheimer's Disease KW - Glutamate KW - EAAT1 KW - Splice Variant Y1 - 2007 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-15965 ER - TY - THES A1 - Imran ul-haq, Muhammad T1 - Synthesis of fluorinated polymers in supercritical carbon dioxide (scCO₂) T1 - Synthese von Fluorpolymeren in überkritischem Kohlendioxid (scCO₂) N2 - For the first time stabilizer-free vinylidene fluoride (VDF) polymerizations were carried out in homogeneous phase with supercritical CO₂. Polymerizations were carried out at 140°C, 1500 bar and were initiated with di-tert-butyl peroxide (DTBP). In-line FT-NIR (Fourier Transform- Near Infrared) spectroscopy showed that complete monomer conversion may be obtained. Molecular weights were determined via size-exclusion chromatography (SEC) and polymer end group analysis by 1H-NMR spectroscopy. The number average molecular weights were below 104 g∙mol−1 and polydispersities ranged from 3.1 to 5.7 depending on DTBP and VDF concentration. To allow for isothermal reactions high CO₂ contents ranging from 61 to 83 wt.% were used. The high-temperature, high-pressure conditions were required for homogeneous phase polymerization. These conditions did not alter the amount of defects in VDF chaining. Scanning electron microscopy (SEM) indicated that regular stack-type particles were obtained upon expansion of the homogeneous polymerization mixture. To reduce the required amount of initiator, further VDF polymerizations using chain transfer agents (CTAs) to control molecular weights were carried out in homogeneous phase with supercritical carbon dioxide (scCO₂) at 120 °C and 1500 bar. Using perfluorinated hexyl iodide as CTA, polymers of low polydispersity ranging from 1.5 to 1.2 at the highest iodide concentration of 0.25 mol·L-1 were obtained. Electrospray ionization- mass spectroscopy (ESI-MS) indicates the absence of initiator derived end groups, supporting livingness of the system. The “livingness” is based on the labile C-I bond. However, due to the weakness of the C-I bond perfluorinated hexyl iodide also contributes to initiation. To allow for kinetic analyses of VDF polymerizations the CTA should not contribute to initiation. Therefore, additional CTAs were applied: BrCCl3, C6F13Br and C6F13H. It was found that C6F13H does not contribute to initiation. At 120°C and 1500 bar kp/kt0.5~ 0.64 (L·mol−1·s−1)0.5 was derived. The chain transfer constant (CT) at 120°C has been determined to be 8·10−1, 9·10−2 and 2·10−4 for C6F13I, C6F13Br and C6F13H, respectively. These CT values are associated with the bond energy of the C-X bond. Moreover, the labile C-I bond allows for functionalization of the polymer to triazole end groups applying click reactions. After substitution of the iodide end group by an azide group 1,3 dipolar cycloadditions with alkynes yield polymers with 1,2,3 triazole end groups. Using symmetrical alkynes the reactions may be carried out in the absence of any catalyst. This end-functionalized poly (vinylidene fluoride) (PVDF) has higher thermal stability as compared to the normal PVDF. PVDF samples from homogeneous phase polymerizations in supercritical CO₂ and subsequent expansion to ambient conditions were analyzed with respect to polymer end groups, crystallinity, type of polymorphs and morphology. Upon expansion the polymer was obtained as white powder. Scanning electron microscopy (SEM) showed that DTBP derived polymer end groups led to stack-type particles whereas sponge- or rose-type particles were obtained in case of CTA fragments as end groups. Fourier-Transform Infrared spectroscopy and wide angle X-ray diffraction indicated that the type of polymorph, α or β crystal phase was significantly affected by the type of end group. The content of β-phase material, which is responsible for piezoelectricity of PVDF, is the highest for polymer with DTBP-derived end groups. In addition, the crystallinity of the material, as determined via differential scanning calorimetry is affected by the end groups and polymer molecular weights. For example, crystallinity ranges from around 26 % for DTBP-derived end groups to a maximum of 62 % for end groups originating from perfluorinated hexyl iodide for polymers with Mn ~2200 g·mol–1. Expansion of the homogeneous polymerization mixture results in particle formation by a non-optimized RESS (Rapid Expansion from Supercritical Solution) process. Thus, it was tested how polymer end groups affect the particles size distribution obtained from RESS process under controlled conditions (T = 50°C and P = 200 bar). In all RESS experiments, small primary PVDF with diameters less than 100 nm without the use of liquid solvents, surfactants, or other additives were produced. A strong correlation between particle size and particle size distribution with polymer end groups and molecular weight of the original material was observed. The smallest particles were found for RESS of PVDF with Mn~ 4000 g·mol–1 and PFHI (C6F13I) - derived end groups. N2 - Erstmalig gelang es, stabilisatorfreie Vinylidenfluorid (VDF)-Polymerisationen in homogener Phase mit überkritischem CO₂ (scCO₂) bis zu vollständigem Monomerumsatz durchzuführen. Die Homogenität während der Polymerisation wurde durch in-line Fourier-Transform Nahinfrarot Spektroskopie beobachtet. Für Polymerisationen bei 140 °C und 1500 bar wurde Di-tert-butylperoxid (DTBP) als Initiator verwendet. Es wurden Polymere mit einem Zahlenmittel der Molmasse kleiner 104 g·mol–1 und Polydispersitäten zwischen 3.1 und 5.7. erhalten. Um isotherme Reaktionen zu ermöglichen, wurden CO₂-Gehalte zwischen 61 und 83 wt.% verwendet. Die für die homogene Reaktionsführung erforderlichen hohen Drücke und Temperaturen haben keinen Einfluss auf die Mikrostruktur des Polymers. Zur Verringerung der Initiatorkonzentration wurden weitere Polymerisationen unter Verwendung von Kettentransferreagenzien (CTA) bei 120 °C und 1500 bar in homogener Phase mit scCO₂ durchgeführt. Perfluoriertes Hexyliodid als CTA ermöglicht kontrollierte radikalische Polymerisationen, wobei Polymere mit geringer Polydispersität zwischen 1.5 und 1.2 erhalten wurden. Endgruppenanalyse mit Elektronenspray-Ionisations-Massen¬spektro¬metrie (ESI-MS) zeigte, dass keine Initiatorendgruppen im Polymer enthalten sind. Diese Beobachtung unterstützt den lebenden Charakter der Polymerisationen und basiert auf einer labilen C-I-Bindung im Polymer. Aufgrund der schwachen C-I-Bindung trägt das perfluorierte Hexyliodid (C6F13I) auch zur Initiierung bei. Polymerisationen in Gegenwart von BrCCl3, C6F13Br und C6F13H zeigten, dass nur C6F13H keinen Beitrag zur Initiierung leistet. Bei 120 °C und 1500 bar wurde ein kp/kt0.5 von ~ 0.64 (L·mol−1·s−1)0.5 bestimmt, wobei kp der Wachstums- und kt der Terminierungsgeschwindigkeitskoeffizient sind. Die Kettentransfer¬konstanten (CT) bei 120°C betragen 8·10−1, 9·10−2 und 2·10−4 für C6F13I, C6F13Br und C6F13H. Die Änderung der CT-Werte lässt sich mit der zunehmenden Bindungsenergie in der Reihe C-I, C-Br und C-H erklären. Die labile C-I-Bindung ermöglicht eine Funktionalisierung des Polymers durch Click-Reaktionen. Nach Substitution der Iodid-Endgruppe durch eine Azidgruppe erfolgte eine katalysatorfreie 1,3-dipolare Cyclaoaddition mit Alkinen zu Polymeren mit 1,2,3-Triazol-Endgruppen. Dieses endfunktionalisierte PVDF besitzt im Vergleich zu konventionellem PVDF eine höhere thermische Stabilität. Nach der Expansion der Polymerisationsmischung mit scCO₂ auf Umgebungsbedingungen lag das Polymer als weißes Pulver vor, das im Hinblick auf z.B. Polymerendgruppen, Kristallinität, Gestalt und Größe der Partikel untersucht wurde. Rasterelektronenmikroskopie zeigte, dass Polymere mit DTBP-Endgruppen zu stapelförmigen Partikeln führen, während bei CTA-Fragmenten als Endgruppen schwamm- oder rosenartige Partikel erhalten wurden. Ergebnisse der FT-IR Spektroskopie und Weitwinkelröntgenbeugung zeigten, dass der höchste Gehalt an β-phasigem Material, der für die Piezoelektrizität des PVDF verantwortlich ist, für PVDF mit Initiatorendgruppen erhalten wurde. DSC (Differential Scanning Calorimetry) Messungen ergaben zudem, dass der Kristallinitätsgrad durch Endgruppen und Polymermasse beeinflusst wird. Die Expansion der homogenen Polymermischung kann als nicht-optimierter RESS-Prozess (Rapid Expanison from Supercritical Solution,) angesehen werden. Aus RESS Experimenten unter kontrollierten Bedingungen wurden jeweils nanoskalige primäre PVDF-Partikel ohne Verwendung von Lösungsmitteln, Tensiden oder anderen Additiven erhalten. Es besteht ein enger Zusammenhang zwischen einerseits der Partikelgröße und der Partikelgrößenverteilung und andererseits der Polymerkonzentration in scCO₂ vor der Expansion, bestimmt durch Polymerendgruppen und Molmassen der eingesetzten Materialien. KW - Synthese KW - Fluorpolymere KW - überkritisches Kohlendioxid (scCO₂) KW - Synthesis KW - fluorinated polymers KW - supercritical carbon dioxide (scCO₂) Y1 - 2008 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-19868 ER - TY - THES A1 - Miteva, Rositsa Stoycheva T1 - Electron acceleration at localized wave structures in the solar corona T1 - Elektronenbeschleunigung an lokalen Wellenstrukturen in der Sonnenkorona N2 - Our dynamic Sun manifests its activity by different phenomena: from the 11-year cyclic sunspot pattern to the unpredictable and violent explosions in the case of solar flares. During flares, a huge amount of the stored magnetic energy is suddenly released and a substantial part of this energy is carried by the energetic electrons, considered to be the source of the nonthermal radio and X-ray radiation. One of the most important and still open question in solar physics is how the electrons are accelerated up to high energies within (the observed in the radio emission) short time scales. Because the acceleration site is extremely small in spatial extent as well (compared to the solar radius), the electron acceleration is regarded as a local process. The search for localized wave structures in the solar corona that are able to accelerate electrons together with the theoretical and numerical description of the conditions and requirements for this process, is the aim of the dissertation. Two models of electron acceleration in the solar corona are proposed in the dissertation: I. Electron acceleration due to the solar jet interaction with the background coronal plasma (the jet--plasma interaction) A jet is formed when the newly reconnected and highly curved magnetic field lines are relaxed by shooting plasma away from the reconnection site. Such jets, as observed in soft X-rays with the Yohkoh satellite, are spatially and temporally associated with beams of nonthermal electrons (in terms of the so-called type III metric radio bursts) propagating through the corona. A model that attempts to give an explanation for such observational facts is developed here. Initially, the interaction of such jets with the background plasma leads to an (ion-acoustic) instability associated with growing of electrostatic fluctuations in time for certain range of the jet initial velocity. During this process, any test electron that happen to feel this electrostatic wave field is drawn to co-move with the wave, gaining energy from it. When the jet speed has a value greater or lower than the one, required by the instability range, such wave excitation cannot be sustained and the process of electron energization (acceleration and/or heating) ceases. Hence, the electrons can propagate further in the corona and be detected as type III radio burst, for example. II. Electron acceleration due to attached whistler waves in the upstream region of coronal shocks (the electron--whistler--shock interaction) Coronal shocks are also able to accelerate electrons, as observed by the so-called type II metric radio bursts (the radio signature of a shock wave in the corona). From in-situ observations in space, e.g., at shocks related to co-rotating interaction regions, it is known that nonthermal electrons are produced preferably at shocks with attached whistler wave packets in their upstream regions. Motivated by these observations and assuming that the physical processes at shocks are the same in the corona as in the interplanetary medium, a new model of electron acceleration at coronal shocks is presented in the dissertation, where the electrons are accelerated by their interaction with such whistlers. The protons inflowing toward the shock are reflected there by nearly conserving their magnetic moment, so that they get a substantial velocity gain in the case of a quasi-perpendicular shock geometry, i.e, the angle between the shock normal and the upstream magnetic field is in the range 50--80 degrees. The so-accelerated protons are able to excite whistler waves in a certain frequency range in the upstream region. When these whistlers (comprising the localized wave structure in this case) are formed, only the incoming electrons are now able to interact resonantly with them. But only a part of these electrons fulfill the the electron--whistler wave resonance condition. Due to such resonant interaction (i.e., of these electrons with the whistlers), the electrons are accelerated in the electric and magnetic wave field within just several whistler periods. While gaining energy from the whistler wave field, the electrons reach the shock front and, subsequently, a major part of them are reflected back into the upstream region, since the shock accompanied with a jump of the magnetic field acts as a magnetic mirror. Co-moving with the whistlers now, the reflected electrons are out of resonance and hence can propagate undisturbed into the far upstream region, where they are detected in terms of type II metric radio bursts. In summary, the kinetic energy of protons is transfered into electrons by the action of localized wave structures in both cases, i.e., at jets outflowing from the magnetic reconnection site and at shock waves in the corona. N2 - Die Sonne ist ein aktiver Stern, was sich nicht nur in den allseits bekannten Sonnenflecken, sondern auch in Flares manifestiert. Während Flares wird eine große Menge gespeicherter, magnetischer Energie in einer kurzen Zeit von einigen Sekunden bis zu wenigen Stunden in der Sonnenkorona freigesetzt. Dabei werden u.a. energiereiche Elektronen erzeugt, die ihrerseits nichtthermische Radio- und Röntgenstrahlung, wie sie z.B. am Observatorium für solare Radioastronomie des Astrophysikalischen Instituts Potsdam (AIP) in Tremsdorf und durch den NASA-Satelliten RHESSI beobachtet werden, erzeugen. Da diese Elektronen einen beträchtlichen Anteil der beim Flare freigesetzten Energie tragen, ist die Frage, wie Elektronen in kurzer Zeit auf hohe Energien in der Sonnenkorona beschleunigt werden, von generellem astrophysikalischen Interesse, da solche Prozesse auch in anderen Sternatmosphären und kosmischen Objekten, wie z.B. Supernova-Überresten, stattfinden. In der vorliegenden Dissertation wird die Elektronenbeschleunigung an lokalen Wellenstrukturen im Plasma der Sonnenkorona untersucht. Solche Wellen treten in der Umgebung der magnetischen Rekonnektion, die als ein wichtiger Auslöser von Flares angesehen wird, und in der Nähe von Stoßwellen, die infolge von Flares erzeugt werden, auf. Generell werden die Elektronen als Testteilchen behandelt. Sie werden durch ihre Wechselwirkung mit den elektrischen und magnetischen Feldern, die mit den Plasmawellen verbunden sind, beschleunigt. Infolge der magnetischen Rekonnektion als Grundlage des Flares werden starke Plasmaströmungen (sogenannte Jets) erzeugt. Solche Jets werden im Licht der weichen Röntgenstrahlung, wie z.B. durch den japanischen Satelliten YOHKOH, beobachtet. Mit solchen Jets sind solare Typ III Radiobursts als Signaturen von energiereichen Elektronenstrahlen in der Sonnenkorona verbunden. Durch die Wechselwirkung eines Jets mit dem umgebenden Plasma werden lokal elektrische Felder erzeugt, die ihrerseits Elektronen beschleunigen können. Dieses hier vorgestellte Szenarium kann sehr gut die Röntgen- und Radiobeobachtungen von Jets und den damit verbundenen Elektronenstrahlen erklären. An koronalen Stoßwellen, die infolge Flares entstehen, werden Elektronen beschleunigt, deren Signatur man in der solaren Radiostrahlung in Form von sogenannten Typ II Bursts beobachten kann. Stoßwellen in kosmischen Plasmen können mit Whistlerwellen (ein spezieller Typ von Plasmawellen) verbunden sein. In der vorliegenden Arbeit wird ein Szenarium vorgestellt, das aufzeigt, wie solche Whistlerwellen an koronalen Stoßwellen erzeugt werden und durch ihre resonante Wechselwirkung mit den Elektronen dieselben beschleunigen. Dieser Prozess ist effizienter als bisher vorgeschlagene Mechanismen und kann deshalb auch auf andere Stoßwellen im Kosmos, wie z.B. an Supernova-Überresten, zur Erklärung der dort erzeugten Radio- und Röntgenstrahlung dienen. KW - Elektronenbeschleunigung KW - Sonnenkorona KW - Jets KW - Stoßwellen KW - Nichtlineare Wellen KW - Electron acceleration KW - Solar corona KW - Jets KW - Shock waves KW - Nonlinear waves Y1 - 2007 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-14775 ER - TY - THES A1 - Kellermann, Thorsten T1 - Accurate numerical relativity simulations of non-vacuumspace-times in two dimensions and applications to critical collapse T1 - Exakte numerisch relativistische Simulationen der Nicht-Vakuum-Raum-Zeit in zwei Dimensionen und deren Anwendung zu Problemen des kritischen Kollaps N2 - This Thesis puts its focus on the physics of neutron stars and its description with methods of numerical relativity. In the first step, a new numerical framework the Whisky2D code will be developed, which solves the relativistic equations of hydrodynamics in axisymmetry. Therefore we consider an improved formulation of the conserved form of these equations. The second part will use the new code to investigate the critical behaviour of two colliding neutron stars. Considering the analogy to phase transitions in statistical physics, we will investigate the evolution of the entropy of the neutron stars during the whole process. A better understanding of the evolution of thermodynamical quantities, like the entropy in critical process, should provide deeper understanding of thermodynamics in relativity. More specifically, we have written the Whisky2D code, which solves the general-relativistic hydrodynamics equations in a flux-conservative form and in cylindrical coordinates. This of course brings in 1/r singular terms, where r is the radial cylindrical coordinate, which must be dealt with appropriately. In the above-referenced works, the flux operator is expanded and the 1/r terms, not containing derivatives, are moved to the right-hand-side of the equation (the source term), so that the left hand side assumes a form identical to the one of the three-dimensional (3D) Cartesian formulation. We call this the standard formulation. Another possibility is not to split the flux operator and to redefine the conserved variables, via a multiplication by r. We call this the new formulation. The new equations are solved with the same methods as in the Cartesian case. From a mathematical point of view, one would not expect differences between the two ways of writing the differential operator, but, of course, a difference is present at the numerical level. Our tests show that the new formulation yields results with a global truncation error which is one or more orders of magnitude smaller than those of alternative and commonly used formulations. The second part of the Thesis uses the new code for investigations of critical phenomena in general relativity. In particular, we consider the head-on-collision of two neutron stars in a region of the parameter space where two final states a new stable neutron star or a black hole, lay close to each other. In 1993, Choptuik considered one-parameter families of solutions, S[P], of the Einstein-Klein-Gordon equations for a massless scalar field in spherical symmetry, such that for every P > P⋆, S[P] contains a black hole and for every P < P⋆, S[P] is a solution not containing singularities. He studied numerically the behavior of S[P] as P → P⋆ and found that the critical solution, S[P⋆], is universal, in the sense that it is approached by all nearly-critical solutions regardless of the particular family of initial data considered. All these phenomena have the common property that, as P approaches P⋆, S[P] approaches a universal solution S[P⋆] and that all the physical quantities of S[P] depend only on |P − P⋆|. The first study of critical phenomena concerning the head-on collision of NSs was carried out by Jin and Suen in 2007. In particular, they considered a series of families of equal-mass NSs, modeled with an ideal-gas EOS, boosted towards each other and varied the mass of the stars, their separation, velocity and the polytropic index in the EOS. In this way they could observe a critical phenomenon of type I near the threshold of black-hole formation, with the putative solution being a nonlinearly oscillating star. In a successive work, they performed similar simulations but considering the head-on collision of Gaussian distributions of matter. Also in this case they found the appearance of type-I critical behaviour, but also performed a perturbative analysis of the initial distributions of matter and of the merged object. Because of the considerable difference found in the eigenfrequencies in the two cases, they concluded that the critical solution does not represent a system near equilibrium and in particular not a perturbed Tolmann-Oppenheimer-Volkoff (TOV) solution. In this Thesis we study the dynamics of the head-on collision of two equal-mass NSs using a setup which is as similar as possible to the one considered above. While we confirm that the merged object exhibits a type-I critical behaviour, we also argue against the conclusion that the critical solution cannot be described in terms of equilibrium solution. Indeed, we show that, in analogy with what is found in, the critical solution is effectively a perturbed unstable solution of the TOV equations. Our analysis also considers fine-structure of the scaling relation of type-I critical phenomena and we show that it exhibits oscillations in a similar way to the one studied in the context of scalar-field critical collapse. N2 - Diese Arbeit legt seinen Schwerpunkt auf die Physik von Neutronensternen und deren Beschreibung mit Methoden der numerischen Relativitätstheorie. Im ersten Schritt wird eine neue numerische Umgebung, der Whisky2D Code entwickelt, dieser löst die relativistischen Gleichungen der Hydrodynamik in Axialymmetrie. Hierzu betrachten wir eine verbesserte Formulierung der sog. "flux conserved formulation" der Gleichungen. Im zweiten Teil wird der neue Code verwendet , um das kritische Verhalten zweier kollidierenden Neutronensternen zu untersuchen. In Anbetracht der Analogie, um Übergänge in der statistischen Physik Phase werden wir die Entwicklung der Entropie der Neutronensterne während des gesamten Prozesses betrachten. Ein besseres Verständnis der Evolution von thermodynamischen Größen, wie der Entropie in kritischer Prozess, sollte zu einem tieferen Verständnis der relativistischen Thermodynamik führen. Der Whisky2D Code, zur Lösung Gleichungen relativistischer Hydrodynamik wurde in einer „flux conserved form“ und in zylindrischen Koordinaten geschrieben. Hierdurch entstehen 1 / r singuläre Terme, wobei r der ist, die entsprechend behandelt werden müssen. In früheren Arbeiten, wird der Operator expandiert und die 1 / r spezifisch Therme auf die rechte Seite geschrieben, so dass die linke Seite eine Form annimmt, die identisch ist mit der kartesischen Formulierung. Wir nennen dies die Standard-Formulierung. Eine andere Möglichkeit ist, die Terme nicht zu expandieren, den und den 1/r Term in die Gleichung hinein zu ziehen. Wir nennen dies die Neue-Formulierung. Die neuen Gleichungen werden mit den gleichen Verfahren wie im kartesischen Fall gelöst. Aus mathematischer Sicht ist keine Unterschiede zwischen den beiden Formulierungen zu erwarten, erst die numerische Sicht zeigt die Unterschiede auf. Versuche zeigen, dass die Neue-Formulierung numerische Fehler um mehrere Größenordnungen reduziert. Der zweite Teil der Dissertation verwendet den neuen Code für die Untersuchung kritischer Phänomene in der allgemeinen Relativitätstheorie. Insbesondere betrachten wir die Kopf-auf-Kollision zweier Neutronensterne in einem Bereich des Parameter Raums, deren zwei mögliche Endzustände entweder einen neuen stabilen Neutronenstern oder ein Schwarzes Loch darstellen. Im Jahr 1993, betrachtete Choptuik Ein-Parameter-Familien von Lösungen, S [P], der Einstein-Klein-Gordon-Gleichung für ein masseloses Skalarfeld in sphärischer Symmetrie, so dass für jedes P> P ⋆, S[P] ein Schwarzes Loch enthalten ist und jedes P

10000 years down to a seasonal resolution. Since lake basins additionally act as natural sediment traps, the riverine sediment supply, which is preserved as detrital event layers in the lake sediments, can be used as a proxy for extreme discharge events. Within my thesis I examined a ~ 8.50 m long sedimentary record from the pre-Alpine Lake Mondsee (Northeast European Alps), which covered the last 7000 years. This sediment record consists of calcite varves and intercalated detrital layers, which range in thickness from 0.05 to 32 mm. Detrital layer deposition was analysed by a combined method of microfacies analysis via thin sections, Scanning Electron Microscopy (SEM), μX-ray fluorescence (μXRF) scanning and magnetic susceptibility. This approach allows characterizing individual detrital event layers and assigning a corresponding input mechanism and catchment. Based on varve counting and controlled by 14C age dates, the main goals of this thesis are (i) to identify seasonal runoff processes, which lead to significant sediment supply from the catchment into the lake basin and (ii) to investigate flood frequency under changing climate boundary conditions. This thesis follows a line of different time slices, presenting an integrative approach linking instrumental and historical flood data from Lake Mondsee in order to evaluate the flood record inferred from Lake Mondsee sediments. The investigation of eleven short cores covering the last 100 years reveals the abundance of 12 detrital layers. Therein, two types of detrital layers are distinguished by grain size, geochemical composition and distribution pattern within the lake basin. Detrital layers, which are enriched in siliciclastic and dolomitic material, reveal sediment supply from the Flysch sediments and Northern Calcareous Alps into the lake basin. These layers are thicker in the northern lake basin (0.1-3.9 mm) and thinner in the southern lake basin (0.05-1.6 mm). Detrital layers, which are enriched in dolomitic components forming graded detrital layers (turbidites), indicate the provenance from the Northern Calcareous Alps. These layers are generally thicker (0.65-32 mm) and are solely recorded within the southern lake basin. In comparison with instrumental data, thicker graded layers result from local debris flow events in summer, whereas thin layers are deposited during regional flood events in spring/summer. Extreme summer floods as reported from flood layer deposition are principally caused by cyclonic activity from the Mediterranean Sea, e.g. July 1954, July 1997 and August 2002. During the last two millennia, Lake Mondsee sediments reveal two significant flood intervals with decadal-scale flood episodes, during the Dark Ages Cold Period (DACP) and the transition from the Medieval Climate Anomaly (MCA) into the Little Ice Age (LIA) suggesting a linkage of transition to climate cooling and summer flood recurrences in the Northeastern Alps. In contrast, intermediate or decreased flood episodes appeared during the MWP and the LIA. This indicates a non-straightforward relationship between temperature and flood recurrence, suggesting higher cyclonic activity during climate transition in the Northeast Alps. The 7000-year flood chronology reveals 47 debris flows and 269 floods, with increased flood activity shifting around 3500 and 1500 varve yr BP (varve yr BP = varve years before present, before present = AD 1950). This significant increase in flood activity shows a coincidence with millennial-scale climate cooling that is reported from main Alpine glacier advances and lower tree lines in the European Alps since about 3300 cal. yr BP (calibrated years before present). Despite relatively low flood occurrence prior to 1500 varve yr BP, floods at Lake Mondsee could have also influenced human life in early Neolithic lake dwellings (5750-4750 cal. yr BP). While the first lake dwellings were constructed on wetlands, the later lake dwellings were built on piles in the water suggesting an early flood risk adaptation of humans and/or a general change of the Late Neolithic Culture of lake-dwellers because of socio-economic reasons. However, a direct relationship between the final abandonment of the lake dwellings and higher flood frequencies is not evidenced. N2 - Ein verstärktes Auftreten von Hochwassern, sowohl in ihrer Häufigkeit als auch in ihrer Frequenz, wird im Zuge der Klimaerwärmung und einer möglichen Intensivierung des hydrologischen Kreislaufs diskutiert. Die Kenntnis über die natürliche Variabilität von Hochwasserereignissen ist dabei eine grundlegende Voraussetzung, um die Hochwassergefahr für die Zukunft abschätzen zu können. Da instrumentelle Hochwasserzeitreihen meist nur die letzten 150 Jahre abbilden sind andere Methoden erforderlich, um das Auftreten von historischen und prä-historischen Hochwassern festzustellen. Jährlich laminierte (warvierte) Seesedimente sind bedeutende natürliche Archive, denn sie liefern kontinuierliche Zeitreihen > 10000 Jahre mit einer bis zur saisonalen Auflösung. Seebecken stellen natürliche Sedimentfallen dar, wobei eingetragenes Flusssediment in den Seesedimenten als eine distinkte detritische Lage aufgezeichnet wird, und daher zur Rekonstruktion von extremen Abflussereignissen genutzt werden. Im Rahmen meiner Doktorarbeit habe ich einen 8.50 m langen Sedimentkern aus dem Mondsee (Nordostalpen) untersucht, welcher die letzten 7000 Jahre abdeckt. Dieser Sedimentkern besteht aus Kalzitwarven und eingeschalteten detritischen Lagen mit einer Mächtigkeit von 0.05-32 mm. Detritische Lagen wurden mit Hilfe einer kombinierten Methode untersucht: Mikrofaziesanalyse, Rasterelektronenmikroskopie, Röntgenfluoreszenzanalyse (µXRF) und magnetische Suszeptibilität. Dieser Ansatz ermöglicht die Charakterisierung der einzelnen detritischen Lagen bezüglich der Eintragsprozesse und die Lokalisierung des Einzugsgebietes. Auf Grundlage der Warvenzählung und 14C Datierungen sind die wichtigsten Ziele dieser Arbeit: (i) die Identifizierung der Eintragsprozesse, welche zu einem Sedimenteintrag vom Einzugsgebiet bis in den See führen und (ii) die Rekonstruktion der Hochwasserfrequenz unter veränderten Klimabedingungen. Diese Arbeit zeigt eine Untersuchung auf verschiedenen Zeitscheiben, wobei instrumentelle und historische Daten genutzt werden, um die Aufzeichnung von pre-historischen Hochwasser in den Mondseesedimenten besser zu verstehen. Innerhalb der letzten 100 Jahre wurden zwölf Abflussereignisse aufgezeichnet. Zwei Typen von detritschen Lagen können anhand von Korngröße, geochemischer Zusammensetzung und des Verteilungsmusters unterschieden werden. Detritische Lagen, welche aus siliziklastischen und dolomitischen Material bestehen, zeigen eine Sedimentherkunft vom Teileinzugsgebiet des Flysch (nördliches Einzugsgebiet) und der Nördlichen Kalkalpen (südliches Teileinzugsgebiet) auf. Diese Lagen sind im Nördlichen Becken mächtiger (0.1-3.9 mm) als im südlichen Seebecken (0.05-1.6 mm). Detritische Lagen, welche nur aus dolomitischem Material bestehen und Turbititlagen aufzeigen (0.65-32 mm), weisen auf eine Herkunft aus den Nördlichen Kalkalpen hin. Im Vergleich mit instrumentellen Zeitreihen, stammen die mächtigeren Lagen von lokalen Murereignissen im Sommer und feinere Eintragslagen von regionalen Frühjahrs- und Sommerhochwassern. Extreme Sommerhochwasser am Mondsee werden hauptsächlich durch Zyklonen vom Mittelmeer ausgelöst, z.B. Juli 1954, Juli 1997 und August 2002. Die Untersuchung des langen Sedimentkerns vom Mondsee zeigt während der letzten 2000 Jahre signifikante Hochwasserintervalle mit dekadischen Hochwasserepisoden während der Völkerwanderungszeit und im Übergang vom Mittelalter in die Kleine Eiszeit. Dies weist auf eine Verknüpfung von Abkühlungsphasen und Sommerhochwassern im Nordostalpenraum hin. Während der Mittelalterlichen Wärmephase und in der Kleinen Eiszeit kam es jedoch zu einer geringeren Hochwasseraktivität. Dies zeigt einen komplexen Zusammenhang von Temperaturentwicklung und Hochwasseraktivität in den Nordostalpen, mit einer erhöhten Zyklonenaktivät in den Übergängen von wärmeren zu kälteren Phasen. Während der letzten 7000 Jahre wurden 47 Muren und 269 Hochwasser aufgezeichnet, wobei es eine signifikante Änderung mit erhöhter Häufigkeit um 3500 und 1500 Warvenjahre v. h. gab (v.h. = vor heute = AD 1950). Diese signifikante Änderung stimmt mit einem langfristigem Abkühlungstrend überein, welcher durch alpine Gletschervorstöße und das Absinken von Baumgrenzen seit etwa 3300 Warvenjahre v.h. berichtet wird. Trotz relativ geringer Hochwasseraktivität um 1500 Warvenjahre v.h., könnte das Auftreten von Hochwasser auch das Leben Menschen in Neolithischen Pfahlbausiedlungen (5750-4750 cal. yr BP) beeinflusst haben. Während die ersten Pfahlbauten noch als Feuchtbodensiedlungen am Land entstanden, wurden spätere Siedlungen eventuell als Anpassung an stark schwankenden Seewasserspiegeln auf Pfählen im Wasser gebaut und/oder zeigen eine allgemeine Veränderung der Siedlungsaktivitäten der Neolithischen Pfahlbaukultur an, aufgrund sozio-ökonomischer Veränderungen. Ein direkter Zusammenhang zwischen dem Verlassen der Pfahlbausiedlungen und einer erhöhten Hochwasseraktivität konnte jedoch nicht festgestellt werden. KW - Mondsee KW - Paläohochwasser KW - Seesedimente KW - Warven KW - Klimarekonstruktion KW - Mondsee KW - Paleofloods KW - Lake sediments KW - Warves KW - Climate reconstruction Y1 - 2012 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-66702 ER - TY - THES A1 - Gassner, Alexandra Carina T1 - The character of the core-mantle boundary : a systematic study using PcP N2 - Assuming that liquid iron alloy from the outer core interacts with the solid silicate-rich lower mantle the influence on the core-mantle reflected phase PcP is studied. If the core-mantle boundary is not a sharp discontinuity, this becomes apparent in the waveform and amplitude of PcP. Iron-silicate mixing would lead to regions of partial melting with higher density which in turn reduces the velocity of seismic waves. On the basis of the calculation and interpretation of short-period synthetic seismograms, using the reflectivity and Gauss Beam method, a model space is evaluated for these ultra-low velocity zones (ULVZs). The aim of this thesis is to analyse the behaviour of PcP between 10° and 40° source distance for such models using different velocity and density configurations. Furthermore, the resolution limits of seismic data are discussed. The influence of the assumed layer thickness, dominant source frequency and ULVZ topography are analysed. The Gräfenberg and NORSAR arrays are then used to investigate PcP from deep earthquakes and nuclear explosions. The seismic resolution of an ULVZ is limited both for velocity and density contrasts and layer thicknesses. Even a very thin global core-mantle transition zone (CMTZ), rather than a discrete boundary and also with strong impedance contrasts, seems possible: If no precursor is observable but the PcP_model /PcP_smooth amplitude reduction amounts to more than 10%, a very thin ULVZ of 5 km with a first-order discontinuity may exist. Otherwise, if amplitude reductions of less than 10% are obtained, this could indicate either a moderate, thin ULVZ or a gradient mantle-side CMTZ. Synthetic computations reveal notable amplitude variations as function of the distance and the impedance contrasts. Thereby a primary density effect in the very steep-angle range and a pronounced velocity dependency in the wide-angle region can be predicted. In view of the modelled findings, there is evidence for a 10 to 13.5 km thick ULVZ 600 km south-eastern of Moscow with a NW-SE extension of about 450 km. Here a single specific assumption about the velocity and density anomaly is not possible. This is in agreement with the synthetic results in which several models create similar amplitude-waveform characteristics. For example, a ULVZ model with contrasts of -5% VP , -15% VS and +5% density explain the measured PcP amplitudes. Moreover, below SW Finland and NNW of the Caspian Sea a CMB topography can be assumed. The amplitude measurements indicate a wavelength of 200 km and a height of 1 km topography, previously also shown in the study by Kampfmann and Müller (1989). Better constraints might be provided by a joined analysis of seismological data, mineralogical experiments and geodynamic modelling. N2 - Unter der Annahme, dass flüssiges Eisen aus dem äußeren Erdkern mit dem festen, silikat-reichen Unteren Mantel reagiert, wird eine Einflussnahme auf die Kern-Mantel Reflexionsphase PcP erwartet. Ist die Kern-Mantel Grenze aufgeweicht, und nicht wie bislang angenommen ein diskreter Übergang, so zeichnet sich dies in der Wellenform und Amplitude von PcP ab. Die Interaktion mit Eisen führt zu teilweise aufgeschmolzenen Bereichen höherer Dichte, welche die seismischen Wellengeschwindigkeiten herabsetzen. Basierend auf den Berechnungen von kurzperiodischen synthetischen Seismogrammen, mittels der Reflektivitäts- und Gauss Beam Methode, soll ein möglicher Modellraum dieser Niedriggeschwindigkeitszonen ermittelt werden. Das Ziel dieser Arbeit ist es das Verhalten von PcP im Distanzbereich von 10° bis 40° unter dem Einfluss dieser Modelle mit diversen Geschwindigkeits- und Dichtekontrasten zu untersuchen. Ferner wird das Auflösungsvermögen hinsichtlich seismischer Daten diskutiert. Entscheidende Parameter wie Anomaliedicke, Quellfrequenz und Topographie werden hierbei analysiert. Tiefe Erdbeben und Kernexplosionen, die sich im entsprechenden Entfernungsbereich zum Gräfenberg und NORSAR Array befinden, werden anschließend im Hinblick auf PcP ausgewertet. Das seismische Auflösungsvermögen von Niedriggeschwindigkeitszonen ist stark begrenzt sowohl in Bezug auf Geschwindigkeits- und Dichtekontraste als auch hinsichtlich der Mächtigkeit. Es besteht sogar die Möglichkeit einer dünnen, globalen Kern-Mantel Übergangszone, selbst mit großen Impedanzkontrasten, ohne dass dies mit seismologischen Methoden detektiert werden könnte: Wird kein precursor zu PcP beobachtet aber das PcPmodel /PcPsmooth Amplitudenverhältnis zeigt gleichzeitig eine Reduktion von mehr als 10%, dann könnte eine sehr dünne Niedriggeschwindigkeitszone von ca. 5 km Mächtigkeit und einer Diskontinuität erster Ordnung vorliegen. Andererseits, ist PcP um weniger als 10% reduziert, könnte dies entweder auf eine dünne, moderate Niedriggeschwindigkeitszone oder einen graduellen Kern-Mantel Übergang hindeuten. Die synthetischen Berechnungen ergeben starke Amplitudenvariationen als Funktion der Distanz, welche auf den Impedanzkontrast zurückzuführen sind. Dabei ergibt sich ein primärer Dichteeffekt im extremen Steilwinkelbereich und ein maßgeblicher Geschwindigkeitseinfluss im Weitwinkelbereich. Im Hinblick auf die modellierten Resultate lässt sich eine 10 - 13.5 km mächtige Niedriggeschwindigkeitszone 600 km südöstlich von Moskau mit einer NW-SE Ausdehnung von mindestens 450 km folgern, wobei eine exakte Aussage über Geschwindigkeiten und Dichte nicht möglich ist. Dies ist im Konsens mit den synthetischen Berechnungen, wonach viele unterschiedliche Modelle ähnliche Amplituden- und Wellenformcharakteristiken erzeugen. Zum Beispiel erklärt ein Modell mit Kontrasten von -5% VP , -15% VS and +5% Dichte die gemessenen PcP Amplituden. Darüber hinaus können unterhalb des südwestlichen Finnlands und nord-nordwestlich des Kaspischen Meeres Undulationen an der Kern-Mantel Grenze selbst vermutet werden. Unter Berücksichtigung früherer Studien, z. B. von Kampfmann and Müller (1989), deuten die Messergebnisse auf eine laterale Topographie von 200 km und eine Höhe von 1 km hin. Eine Eingrenzung der potentiellen Anomaliemodelle kann nur durch eine gemeinsame Auswertung mit mineralogischen Experimenten und geodynamischen Modellierungen erfolgen. KW - Kern-Mantel Grenze KW - Seismologie KW - Ultra-Niedriggeschwindigkeitszonen KW - Steilwinkel-Analyse von PcP KW - Tiefbeben und Kernexplosionen KW - core-mantle boundary KW - seismology KW - ultra-low velocity zones KW - steep-angle analysis of PcP KW - deep earthquakes and nuclear explosions Y1 - 2012 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-63590 ER - TY - THES A1 - Oey, Melanie T1 - Chloroplasts as bioreactors : high-yield production of active bacteriolytic protein antibiotics T1 - Chloroplasten als Bioreaktoren : hocheffiziente Produktion von aktiven, bakteriolytischen Proteinantibiotika N2 - Plants, more precisely their chloroplasts with their bacterial-like expression machinery inherited from their cyanobacterial ancestors, can potentially offer a cheap expression system for proteinaceous pharmaceuticals. This system would be easily scalable and provides appropriate safety due to chloroplasts maternal inheritance. In this work, it was shown that three phage lytic enzymes (Pal, Cpl-1 and PlyGBS) could be successfully expressed at very high levels and with high stability in tobacco chloroplasts. PlyGBS expression reached an amount of foreign protein accumulation (> 70% TSP) that has never been obtained before. Although the high expression levels of PlyGBS caused a pale green phenotype with retarded growth, presumably due to exhaustion of plastid protein synthesis capacity, development and seed production were not impaired under greenhouse conditions. Since Pal and Cpl-1 showed toxic effects when expressed in E. coli, a special plastid transformation vector (pTox) was constructed to allow DNA amplification in bacteria. The construction of the pTox transformation vector allowing a recombinase-mediated deletion of an E. coli transcription block in the chloroplast, leading to an increase of foreign protein accumulation to up to 40% of TSP for Pal and 20% of TSP for Cpl-1. High dose-dependent bactericidal efficiency was shown for all three plant-derived lytic enzymes using their pathogenic target bacteria S. pyogenes and S. pneumoniae. Confirmation of specificity was obtained for the endotoxic proteins Pal and Cpl-1 by application to E. coli cultures. These results establish tobacco chloroplasts as a new cost-efficient and convenient production platform for phage lytic enzymes and address the greatest obstacle for clinical application. The present study is the first report of lysin production in a non-bacterial system. The properties of chloroplast-produced lysins described in this work, their stability, high accumulation rate and biological activity make them highly attractive candidates for future antibiotics. N2 - Lytische Enzyme aus Bakteriophagen bieten Eigenschaften, die sie zu vielversprechenden Medikamenten im Einsatz gegen bakterielle Krankheiten machen. Obwohl sie speziell beim Einsatz gegen bakterielle Infektionen, welche durch Antibiotika resistente Erreger hervorgerufen werden, eine maßgebende Rolle spielen könnten, waren bisher die hohen Produktionskosten ein Hindernis für die medizinische Anwendung. Ein kostengünstiges und einfach zu handhabendes System, wie beispielsweise Chloroplasten in Pflanzen, würde diese lytischen Enzyme zu einer effizienten Alternative zu herkömmlichen Antibiotika machen. In dieser Arbeit wird erstmals die erfolgreiche Produktion von lytischen Enzymen in Tabak-Chloroplasten vorgestellt, welche mit einem Fremdproteingehalt von mehr als 70% des gesamtlöslichen Proteins der Pflanze eine Menge beschreibt, die bisher mit diesem Verfahren noch nicht erreicht wurde. Alle in Chloroplasten hergestellten lytischen Enzyme zeigten hohe spezifische bakteriolytische Aktivität gegen die gewählten Humanpathogene und waren innerhalb von Minuten in der Lage diese Bakterien abzutöten. Zur Herstellung von zwei lytischen Enzymen wurde in dieser Arbeit ein spezieller Shuttle-Vektor entworfen, der die Expression von toxischen Genen innerhalb von E. coli Zellen im Zuge der DNA Replikation vermeidet, jedoch die Herstellung einer ungehinderten Expression der toxischen Gene in den Chloroplasten nach Beseitigung des Selektionsmarkers erlaubte. Ein Vergleich zwischen einem herkömmlich verwendeten Transformationsvektor und dem Shuttle-Vektor mittels eines Reportergens zeigte, dass das neu entwickelte System bis zu 4 mal mehr Protein produzierte. Diese Ergebnisse zeigen das Potential von Chloroplasten als kostengünstige und leicht zu handhabende Produktionsplattform für lytische Enzyme, welche als neue Generation von Antibiotika attraktive Alternativen zu herkömmlichen Therapien bieten. KW - Phagenlysine KW - Chloroplastentransformation KW - Antibiotikaersatz KW - Antibiotikaresistenz KW - Phage lysins KW - Chloroplast transformation KW - Antibiotic alternatives KW - Antibiotic resistance Y1 - 2008 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-28950 ER - TY - THES A1 - Regel, Stefanie T1 - The comprehension of figurative language : electrophysiological evidence on the processing of irony T1 - Zum Verstehen figurativer Sprache : elektrophysiologische Studien zur Verarbeitung von Ironie N2 - Diese Dissertation untersucht das Verstehen figurativer Sprache, im Besonderen die zeitliche Verarbeitung von verbaler Ironie. In sechs Experimenten wurde mittels ereignis-korrelierter Potentiale (EKP) die Gehirnaktivität beim Verstehen ironischer Äußerungen im Vergleich zu entsprechenden nicht-ironischen Äußerungen gemessen und analysiert. Darüberhinaus wurde der Einfluss verschiedener sprachbegleitender Hinweisreize, z.B. von Prosodie oder der Verwendung von Satzzeichen, sowie außersprachlicher Hinweisreize, wie bspw. pragmatischen Wissens, auf das Ironieverstehen untersucht. Auf Grundlage dieser Ergebnisse werden verschiedene psycholinguistische Modelle figurativer Sprachverarbeitung, d.h. 'standard pragmatic model', 'graded salience hypothesis', sowie 'direct access view', diskutiert. N2 - This dissertation investigates the comprehension of figurative language, in particular the temporal processing of verbal irony. In six experiments using event-related potentials(ERP) brain activity during the comprehension of ironic utterances in relation to equivalent non-ironic utterances was measured and analyzed. Moreover, the impact of various language-accompanying cues, e.g., prosody or the use of punctuation marks, as well as non-verbal cues such as pragmatic knowledge has been examined with respect to the processing of irony. On the basis of these findings different models on figurative language comprehension, i.e., the 'standard pragmatic model', the 'graded salience hypothesis', and the 'direct access view', are discussed. KW - Figurative Sprachverarbeitung KW - verbale Ironie KW - Pragmatik KW - Diskursverstehen KW - EKP KW - Figurative language processing KW - verbal irony KW - pragmatics KW - discourse comprehension KW - ERP Y1 - 2008 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-33376 ER - TY - THES A1 - Mörbt, Nora T1 - Differential proteome analysis of human lung epithelial cells following exposure to aromatic volatile organic compounds T1 - Differentielle Proteomeanalyse humaner Lungenepithelzellen nach Exposition mit aromatischen flüchtigen Substanzen N2 - The widespread usage of products containing volatile organic compounds (VOC) has lead to a general human exposure to these chemicals in work places or homes being suspected to contribute to the growing incidence of environmental diseases. Since the causal molecular mechanisms for the development of these disorders are not completely understood, the overall objective of this thesis was to investigate VOC-mediated molecular effects on human lung cells in vitro at VOC concentrations comparable to exposure scenarios below current occupational limits. Although differential expression of single proteins in response to VOCs has been reported, effects on complex protein networks (proteome) have not been investigated. However, this information is indispensable when trying to ascertain a mechanism for VOC action on the cellular level and establishing preventive strategies. For this study, the alveolar epithelial cell line A549 has been used. This cell line, cultured in a two-phase (air/liquid) model allows the most direct exposure and had been successfully applied for the analysis of inflammatory effects in response to VOCs. Mass spectrometric identification of 266 protein spots provided the first proteomic map of A549 cell line to this extent that may foster future work with this frequently used cellular model. The distribution of three typical air contaminants, monochlorobenzene (CB), styrene and 1,2 dichlorobenzene (1,2-DCB), between gas and liquid phase of the exposure model has been analyzed by gas chromatography. The obtained VOC partitioning was in agreement with available literature data. Subsequently the adapted in vitro system has been successfully employed to characterize the effects of the aromatic compound styrene on the proteome of A549 cells (Chapter 4). Initially, the cell toxicity has been assessed in order to ensure that most of the concentrations used in the following proteomic approach were not cytotoxic. Significant changes in abundance and phosphorylation in the total soluble protein fraction of A549 cells have been detected following styrene exposure. All proteins have been identified using mass spectrometry and the main cellular functions have been assigned. Validation experiments on protein and transcript level confirmed the results of the 2-DE experiments. From the results, two main cellular pathways have been identified that were induced by styrene: the cellular oxidative stress response combined with moderate pro-apoptotic signaling. Measurement of cellular reactive oxygen species (ROS) as well as the styrene-mediated induction of oxidative stress marker proteins confirmed the hypothesis of oxidative stress as the main molecular response mechanism. Finally, adducts of cellular proteins with the reactive styrene metabolite styrene 7,8 oxide (SO) have been identified. Especially the SO-adducts observed at both the reactive centers of thioredoxin reductase 1, which is a key element in the control of the cellular redox state, may be involved in styrene-induced ROS formation and apoptosis. A similar proteomic approach has been carried out with the halobenzenes CB and 1,2-DCB (Chapter 5). In accordance with previous findings, cell toxicity assessment showed enhanced toxicity compared to the one caused by styrene. Significant changes in abundance and phosphorylation of total soluble proteins of A549 cells have been detected following exposure to subtoxic concentrations of CB and 1,2-DCB. All proteins have been identified using mass spectrometry and the main cellular functions have been assigned. As for the styrene experiment, the results indicated two main pathways to be affected in the presence of chlorinated benzenes, cell death signaling and oxidative stress response. The strong induction of pro-apoptotic signaling has been confirmed for both treatments by detection of the cleavage of caspase 3. Likewise, the induction of redox-sensitive protein species could be correlated to an increased cellular level of ROS observed following CB treatment. Finally, common mechanisms in the cellular response to aromatic VOCs have been investigated (Chapter 6). A similar number (4.6-6.9%) of all quantified protein spots showed differential expression (p<0.05) following cell exposure to styrene, CB or 1,2-DCB. However, not more than three protein spots showed significant regulation in the same direction for all three volatile compounds: voltage-dependent anion-selective channel protein 2, peroxiredoxin 1 and elongation factor 2. However, all of these proteins are important molecular targets in stress- and cell death-related signaling pathways. N2 - Die vermehrte Verwendung von Produkten, welche flüchtige organische Substanzen (VOC - volatile organic compound) enthalten, hat eine generelle Exposition der Bevölkerung mit diesen Substanzen an Arbeitsplätzen aber auch in Wohnräumen bedingt. VOCs stehen im Verdacht, zur zunehmenden Inzidenz umweltbedingter Erkrankungen beizutragen. Da die molekularen Ursachen dieser Erkrankungen bisher noch unverstanden sind, war es ein übergeordnetes Ziel dieser Arbeit, VOC-vermittelte molekulare Effekte in menschlichen Lungenepithelzellen anhand eines in vitro Modells zu untersuchen. Dabei sollten vor allem Konzentrationen unterhalb der gültigen Arbeitsplatzgrenzwerte untersucht werden. Obwohl Effekte auf einzelne Proteine bekannt sind, wurden bisher keine Effekte der VOC-Exposition auf das komplexe Netzwerk der zellulären Proteine (Proteom) untersucht. Dieses Wissen ist essentiell, um induzierte zelluläre Mechanismen zu verstehen und Strategien zu deren Vermeidung zu entwickeln. Für die hier durchgeführten Untersuchungen wurde die Lungenepithelzelllinie A549 in einem Zweiphasenexpositionsmodell eingesetzt. Dieses ermöglichte eine möglichst direkte zelluläre Exposition und wurde bereits erfolgreich verwendet, um durch VOC hervorgerufene Entzündungseffekte zu identifizieren. Die massen-spektrometrische Identifikation von 266 Proteinflecken lieferte die erste umfassende Proteomkarte der A549 Zelllinie, welche nachfolgende Untersuchungen mit diesem häufig verwendeten Zelltyp erleichtern wird. Zusätzlich wurde die Verteilung der drei gängigen Luftkontaminanten Chlorbenzol (CB), Styrol and 1,2-Dichlorobenzol (1,2-DCB) zwischen den beiden Phasen (gas/flüssig) des Expositionsmodells gaschromatographisch bestimmt. Die Verteilung entsprach den verfügbaren Literaturdaten. Anschließend wurde das modifizierte Expositionsmodell erfolgreich eingesetzt, um styrol-vermittelte Effekte auf das Proteom der A549 Zellen zu charakterisieren (Kapitel 4). Zu Beginn erfolgte die Erfassung der Zelltoxizität der Substanz, um sicher zu stellen, daß der überwiegende Teil der späteren Expositionsexperimente mit subtoxischen Konzentrationen durchgeführt wird. Es konnte eine signifikant veränderte Expression und Phosphorylierung der löslichen Proteinfraktion der A549 Zellen als Reaktion auf die Styrolexposition festgestellt werden. Die regulierten Proteine wurden massenspektrometrisch identifiziert und ihre wichtigsten Funktionen wurden zugewiesen. Validierungsexperimente auf Protein- und auf Transkriptebene bestätigten die 2-DE Ergebnisse. Insgesamt konnte die zelluläre Reaktion durch die styrol-vermittelte Induktion zweier zentraler Mechanismen erklärt werden: oxidativer zellulärer Stress und beginnende Apoptose. Folgeexperimente wie die Messung der Menge der zellulären reaktiven Sauerstoffspezies (ROS) und die Induktion von redox-sensitiven Markerproteinen konnte die Hypothese eines styrol-induzierten oxidativen Milieus bestätigen. Schließlich wurden Proteinaddukte des reaktiven Styrolmetaboliten Styrol 7,8 epoxide (SO) identifiziert. Besonders die SO-Addukte, welche and den beiden aktiven Zentren der Thioredoxin Reduktase 1 gefunden wurden könnten eine wichtige Rolle bei der styrol-induzierten ROS-Bildung sowie der beginnenden Apoptose spielen. In Analogie zum Styrolexperiment wurden die Effekte der halogenierten Benzole CB und 1,2-DCB untersucht (Kapitel 5). Es konnten ebenfalls sämtliche Proteine identifiziert und die wichtigsten zellulären Funktionen zugewiesen werden. Diese Substanzen modulierten ebenfalls apoptotische Signalwege und die zelluläre Antwort auf oxidativen Streß. Der beobachtete starke pro-apoptotische Effekt konnte für beide Substanzen mit der Spaltung der Caspase 3 nachgewiesen werden. Weiterhin konnte für CB die Induktion redox-sensitiver Proteinspezies mit einem beobachteten höherem Gehalt an ROS erklärt werden. Schließlich wurden ähnliche Mechanismen der zellulären Antwort auf die Exposition mit den drei untersuchten aromatischen VOCs diskutiert (Kapitel 6). Alle getesteten VOCs verursachten eine vergleichbare differentielle Expression (p<0,05) von 4,6-6,9% aller quantifizierten Proteinspezies. Nur drei Proteinspots wurden dabei gemeinsam für alle VOCs reguliert: voltage-dependent anion-selective channel protein 2, peroxiredoxin 1 and elongation factor 2. Allerdings gehören diese drei Proteine zu wichtigen zellulären Zielstrukturen der Signalwege für Stressantwort und Zelltod. KW - VOC KW - Proteom KW - Styrol KW - chlorbenzol KW - dichlorbenzol KW - VOC KW - proteome KW - styrene KW - monochlorobenzene KW - dichlorobenzene Y1 - 2010 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-49257 ER - TY - BOOK A1 - Pfau, Roland A1 - Steinbach, Markus T1 - Modality-independent and modality-specific aspects of grammaticalization in sign languages N2 - One type of internal diachronic change that has been extensively studied for spoken languages is grammaticalization whereby lexical elements develop into free or bound grammatical elements. Based on a wealth of spoken languages, a large amount of prototypical grammaticalization pathways has been identified. Moreover, it has been shown that desemanticization, decategorialization, and phonetic erosion are typical characteristics of grammaticalization processes. Not surprisingly, grammaticalization is also responsible for diachronic change in sign languages. Drawing data from a fair number of sign languages, we show that grammaticalization in visual-gestural languages – as far as the development from lexical to grammatical element is concerned – follows the same developmental pathways as in spoken languages. That is, the proposed pathways are modalityindependent. Besides these intriguing parallels, however, sign languages have the possibility of developing grammatical markers from manual and non-manual co-speech gestures. We will discuss various instances of grammaticalized gestures and we will also briefly address the issue of the modality-specificity of this phenomenon. T3 - Linguistics in Potsdam - 24 KW - grammaticalization KW - sign languages KW - modality KW - gesture KW - non-manuals KW - typology Y1 - 2006 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-10886 SN - 978-3-939469-53-7 SN - 1864-1857 SN - 1616-7392 PB - Universitätsverlag Potsdam CY - Potsdam ER - TY - GEN A1 - Roelly, Sylvie A1 - Sortais, Michel T1 - Space-time asymptotics of an infinite-dimensional diffusion having a long- range memory N2 - We develop a cluster expansion in space-time for an infinite-dimensional system of interacting diffusions where the drift term of each diffusion depends on the whole past of the trajectory; these interacting diffusions arise when considering the Langevin dynamics of a ferromagnetic system submitted to a disordered external magnetic field. KW - Random Field Ising Model KW - Langevin Dynamics KW - Interacting Diffusion Processes KW - Space-Time Cluster Expansions Y1 - 2004 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-6700 ER - TY - GEN A1 - Roelly, Sylvie A1 - Thieullen, Michèle T1 - Duality formula for the bridges of a Brownian diffusion : application to gradient drifts N2 - In this paper, we consider families of time Markov fields (or reciprocal classes) which have the same bridges as a Brownian diffusion. We characterize each class as the set of solutions of an integration by parts formula on the space of continuous paths C[0; 1]; R-d) Our techniques provide a characterization of gradient diffusions by a duality formula and, in case of reversibility, a generalization of a result of Kolmogorov. KW - reciprocal processes KW - stochastic bridge KW - mixture of bridges KW - integration by parts formula KW - Malliavin calculus KW - entropy KW - time reversal Y1 - 2005 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-6710 ER - TY - GEN A1 - Roelly, Sylvie A1 - Dai Pra, Paolo T1 - An existence result for infinite-dimensional Brownian diffusions with non- regular and non Markovian drift N2 - We prove in this paper an existence result for infinite-dimensional stationary interactive Brownian diffusions. The interaction is supposed to be small in the norm ||.||∞ but otherwise is very general, being possibly non-regular and non-Markovian. Our method consists in using the characterization of such diffusions as space-time Gibbs fields so that we construct them by space-time cluster expansions in the small coupling parameter. KW - infinite-dimensional Brownian diffusion KW - space-time Gibbs field KW - cluster expansion Y1 - 2004 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-6684 ER - TY - RPRT A1 - Becker, Ralf E. T1 - Revisiting public investment BT - consumption equivalent public capital and the social discount rate N2 - The consumption equivalence method is the theoretical basis of public cost-benefit analysis. Consumption equivalence public capital prices are explicitly introduces in order to sufficiently care for the opportunity cost of public expenditure. This can solve the dispute about the social rate of discount within public cost-benefit analysis witch was generated on a criterion looking similar to the capital value formula, known as Lind’s approach. The social rate of discount is liberated from opportunity costs considerations and the discounting away of the effects for future welfare vanishes. The corresponding question whether one should accept a positive value of the pure rate of social time preference is an old issue. Its current state between the prescriptive and descriptive view can also be interpreted as a consequence of the oversimplification of standard cost– benefit analysis. But apart from an economic self-process the pure rate of social time preference is also defined as a business-as-usual value of social distance discounting. Hence, a political choice has to be made about this rate which is free in principal. T3 - Finanzwissenschaftliche Diskussionsbeiträge - 47 Y1 - 2004 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-9025 SN - 0948-7549 ER - TY - RPRT A1 - Drechsler, Denis T1 - Unemployment in Germany and the Eurosclerosis debate BT - Can the Hartz reforms induce higher employment? N2 - Many European countries have experienced a significant increase of unemployment in recent years. This paper reviews several theoretical models that try to explain this phenomenon. Predominantly, these models claim a link between the poor performance of European labor markets and the high level of market regulation. Commonly referred to as the Eurosclerosis debate, prominent approaches consider insider-outsider relationships, search-models, and the influence of hiring and firing costs on equilibrium employment. The paper presents empirical evidence of each model and studies the relevance of the identified rigidities as a determinant of high unemployment in Europe. Furthermore, a case study analyzes the unemployment problem in Germany and critically discusses new reform efforts. In particular this section analyzes whether the recently enacted Hartz reforms can induce higher employment. T3 - Finanzwissenschaftliche Diskussionsbeiträge - 48 Y1 - 2005 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-9036 ER - TY - RPRT A1 - Eberhardt, Björn T1 - Public pensions in the U.S. BT - fitting social security for the future N2 - Contents: The Public Old Age Insurance of the U.S. -Historical overview -Technical details -Individual equity and social adequacy The Economic Problem of Old Age -Risks and economic security -Old age, retirement, and idividual precaution -Insurance markets, market failures, and social insurance -Options for public pension systems The Problems of Social Security -The financial balance of OASDI -Causes of the long-run problems -Rates of return -Conclusion - The case for Social Security reform Proposed Remedies -Full, partial, or no privatization? -The President's Commission to Strengthen Social Security -Kotlikoff's Personal Security System -The Diamond-Orszag Three-Part plan T3 - Finanzwissenschaftliche Diskussionsbeiträge - 49 Y1 - 2005 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-9058 ER - TY - INPR A1 - Witt, Annette A1 - Kurths, Jürgen A1 - Krause, F. A1 - Fischer, K. T1 - On the validity of a model for the reversals of the Earth‘s magnetic field N2 - We have used techniques of nonlinear dynamics to compare a special model for the reversals of the Earth's magnetic field with the observational data. Although this model is rather simple, there is no essential difference to the data by means of well-known characteristics, such as correlation function and probability distribution. Applying methods of symbolic dynamics we have found that the considered model is not able to describe the dynamical properties of the observed process. These significant differences are expressed by algorithmic complexity and Renyi information. T3 - NLD Preprints - 4 Y1 - 1994 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-13460 ER - TY - INPR A1 - Kurths, Jürgen A1 - Voss, A. A1 - Witt, Annette A1 - Saparin, P. A1 - Kleiner, H. J. A1 - Wessel, Niels T1 - Quantitative analysis of heart rate variability N2 - In the modern industrialized countries every year several hundred thousands of people die due to the sudden cardiac death. The individual risk for this sudden cardiac death cannot be defined precisely by common available, non-invasive diagnostic tools like Holter-monitoring, highly amplified ECG and traditional linear analysis of heart rate variability (HRV). Therefore, we apply some rather unconventional methods of nonlinear dynamics to analyse the HRV. Especially, some complexity measures that are basing on symbolic dynamics as well as a new measure, the renormalized entropy, detect some abnormalities in the HRV of several patients who have been classified in the low risk group by traditional methods. A combination of these complexity measures with the parameters in the frequency domain seems to be a promising way to get a more precise definition of the individual risk. These findings have to be validated by a representative number of patients. T3 - NLD Preprints - 5 Y1 - 1994 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-13470 ER - TY - THES A1 - Rust, Henning T1 - Detection of long-range dependence : applications in climatology and hydrology T1 - Detektion langreichweitiger Korrelationen : Anwendungen in Klimatologie und Hydrologie N2 - It is desirable to reduce the potential threats that result from the variability of nature, such as droughts or heat waves that lead to food shortage, or the other extreme, floods that lead to severe damage. To prevent such catastrophic events, it is necessary to understand, and to be capable of characterising, nature's variability. Typically one aims to describe the underlying dynamics of geophysical records with differential equations. There are, however, situations where this does not support the objectives, or is not feasible, e.g., when little is known about the system, or it is too complex for the model parameters to be identified. In such situations it is beneficial to regard certain influences as random, and describe them with stochastic processes. In this thesis I focus on such a description with linear stochastic processes of the FARIMA type and concentrate on the detection of long-range dependence. Long-range dependent processes show an algebraic (i.e. slow) decay of the autocorrelation function. Detection of the latter is important with respect to, e.g. trend tests and uncertainty analysis. Aiming to provide a reliable and powerful strategy for the detection of long-range dependence, I suggest a way of addressing the problem which is somewhat different from standard approaches. Commonly used methods are based either on investigating the asymptotic behaviour (e.g., log-periodogram regression), or on finding a suitable potentially long-range dependent model (e.g., FARIMA[p,d,q]) and test the fractional difference parameter d for compatibility with zero. Here, I suggest to rephrase the problem as a model selection task, i.e.comparing the most suitable long-range dependent and the most suitable short-range dependent model. Approaching the task this way requires a) a suitable class of long-range and short-range dependent models along with suitable means for parameter estimation and b) a reliable model selection strategy, capable of discriminating also non-nested models. With the flexible FARIMA model class together with the Whittle estimator the first requirement is fulfilled. Standard model selection strategies, e.g., the likelihood-ratio test, is for a comparison of non-nested models frequently not powerful enough. Thus, I suggest to extend this strategy with a simulation based model selection approach suitable for such a direct comparison. The approach follows the procedure of a statistical test, with the likelihood-ratio as the test statistic. Its distribution is obtained via simulations using the two models under consideration. For two simple models and different parameter values, I investigate the reliability of p-value and power estimates obtained from the simulated distributions. The result turned out to be dependent on the model parameters. However, in many cases the estimates allow an adequate model selection to be established. An important feature of this approach is that it immediately reveals the ability or inability to discriminate between the two models under consideration. Two applications, a trend detection problem in temperature records and an uncertainty analysis for flood return level estimation, accentuate the importance of having reliable methods at hand for the detection of long-range dependence. In the case of trend detection, falsely concluding long-range dependence implies an underestimation of a trend and possibly leads to a delay of measures needed to take in order to counteract the trend. Ignoring long-range dependence, although present, leads to an underestimation of confidence intervals and thus to an unjustified belief in safety, as it is the case for the return level uncertainty analysis. A reliable detection of long-range dependence is thus highly relevant in practical applications. Examples related to extreme value analysis are not limited to hydrological applications. The increased uncertainty of return level estimates is a potentially problem for all records from autocorrelated processes, an interesting examples in this respect is the assessment of the maximum strength of wind gusts, which is important for designing wind turbines. The detection of long-range dependence is also a relevant problem in the exploration of financial market volatility. With rephrasing the detection problem as a model selection task and suggesting refined methods for model comparison, this thesis contributes to the discussion on and development of methods for the detection of long-range dependence. N2 - Die potentiellen Gefahren und Auswirkungen der natürlicher Klimavariabilitäten zu reduzieren ist ein wünschenswertes Ziel. Solche Gefahren sind etwa Dürren und Hitzewellen, die zu Wasserknappheit führen oder, das andere Extrem, Überflutungen, die einen erheblichen Schaden an der Infrastruktur nach sich ziehen können. Um solche katastrophalen Ereignisse zu vermeiden, ist es notwendig die Dynamik der Natur zu verstehen und beschreiben zu können. Typischerweise wird versucht die Dynamik geophysikalischer Datenreihen mit Differentialgleichungssystemen zu beschreiben. Es gibt allerdings Situationen in denen dieses Vorgehen nicht zielführend oder technisch nicht möglich ist. Dieses sind Situationen in denen wenig Wissen über das System vorliegt oder es zu komplex ist um die Modellparameter zu identifizieren. Hier ist es sinnvoll einige Einflüsse als zufällig zu betrachten und mit Hilfe stochastischer Prozesse zu modellieren. In dieser Arbeit wird eine solche Beschreibung mit linearen stochastischen Prozessen der FARIMA-Klasse angestrebt. Besonderer Fokus liegt auf der Detektion von langreichweitigen Korrelationen. Langreichweitig korrelierte Prozesse sind solche mit einer algebraisch, d.h. langsam, abfallenden Autokorrelationsfunktion. Eine verläßliche Erkennung dieser Prozesse ist relevant für Trenddetektion und Unsicherheitsanalysen. Um eine verläßliche Strategie für die Detektion langreichweitig korrelierter Prozesse zur Verfügung zu stellen, wird in der Arbeit ein anderer als der Standardweg vorgeschlagen. Gewöhnlich werden Methoden eingesetzt, die das asymptotische Verhalten untersuchen, z.B. Regression im Periodogramm. Oder aber es wird versucht ein passendes potentiell langreichweitig korreliertes Modell zu finden, z.B. aus der FARIMA Klasse, und den geschätzten fraktionalen Differenzierungsparameter d auf Verträglichkeit mit dem trivialen Wert Null zu testen. In der Arbeit wird vorgeschlagen das Problem der Detektion langreichweitiger Korrelationen als Modellselektionsproblem umzuformulieren, d.h. das beste kurzreichweitig und das beste langreichweitig korrelierte Modell zu vergleichen. Diese Herangehensweise erfordert a) eine geeignete Klasse von lang- und kurzreichweitig korrelierten Prozessen und b) eine verläßliche Modellselektionsstrategie, auch für nichtgenestete Modelle. Mit der flexiblen FARIMA-Klasse und dem Whittleschen Ansatz zur Parameterschätzung ist die erste Voraussetzung erfüllt. Hingegen sind standard Ansätze zur Modellselektion, wie z.B. der Likelihood-Ratio-Test, für nichtgenestete Modelle oft nicht trennscharf genug. Es wird daher vorgeschlagen diese Strategie mit einem simulationsbasierten Ansatz zu ergänzen, der insbesondere für die direkte Diskriminierung nichtgenesteter Modelle geeignet ist. Der Ansatz folgt einem statistischen Test mit dem Quotienten der Likelihood als Teststatistik. Ihre Verteilung wird über Simulationen mit den beiden zu unterscheidenden Modellen ermittelt. Für zwei einfache Modelle und verschiedene Parameterwerte wird die Verläßlichkeit der Schätzungen für p-Wert und Power untersucht. Das Ergebnis hängt von den Modellparametern ab. Es konnte jedoch in vielen Fällen eine adäquate Modellselektion etabliert werden. Ein wichtige Eigenschaft dieser Strategie ist, dass unmittelbar offengelegt wird, wie gut sich die betrachteten Modelle unterscheiden lassen. Zwei Anwendungen, die Trenddetektion in Temperaturzeitreihen und die Unsicherheitsanalyse für Bemessungshochwasser, betonen den Bedarf an verläßlichen Methoden für die Detektion langreichweitiger Korrelationen. Im Falle der Trenddetektion führt ein fälschlicherweise gezogener Schluß auf langreichweitige Korrelationen zu einer Unterschätzung eines Trends, was wiederum zu einer möglicherweise verzögerten Einleitung von Maßnahmen führt, die diesem entgegenwirken sollen. Im Fall von Abflußzeitreihen führt die Nichtbeachtung von vorliegenden langreichweitigen Korrelationen zu einer Unterschätzung der Unsicherheit von Bemessungsgrößen. Eine verläßliche Detektion von langreichweitig Korrelierten Prozesse ist somit von hoher Bedeutung in der praktischen Zeitreihenanalyse. Beispiele mit Bezug zu extremem Ereignissen beschränken sich nicht nur auf die Hochwasseranalyse. Eine erhöhte Unsicherheit in der Bestimmung von extremen Ereignissen ist ein potentielles Problem von allen autokorrelierten Prozessen. Ein weiteres interessantes Beispiel ist hier die Abschätzung von maximalen Windstärken in Böen, welche bei der Konstruktion von Windrädern eine Rolle spielt. Mit der Umformulierung des Detektionsproblems als Modellselektionsfrage und mit der Bereitstellung geeigneter Modellselektionsstrategie trägt diese Arbeit zur Diskussion und Entwicklung von Methoden im Bereich der Detektion von langreichweitigen Korrelationen bei. KW - langreichweitige Korrelationen KW - nichtgenestete Modellselektion KW - FARIMA KW - Unsicherheitsanalyse KW - Bemessungshochwasser KW - long-range dependence KW - long-memory KW - non-nested model selection KW - FARIMA KW - uncertainty analysis KW - return level estimation Y1 - 2007 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-13347 ER - TY - INPR A1 - Thiessenhusen, Kai-Uwe A1 - Esposito, Larry W. A1 - Kurths, Jürgen A1 - Spahn, Frank T1 - Detection of hidden resonances in Saturn's B-ring N2 - The Voyager 2 Photopolarimeter experiment has yielded the highest resolved data of Saturn's rings, exhibiting a wide variety of features. The B-ring region between 105000 km and 110000 km distance from Saturn has been investigated. It has a high matter density and contains no significance features visible by eye. Analysis with statistical methods has let us to the detection of two significant events. These features are correlated with the inner 3:2 resonances of the F-ring shepherd satellites Pandora and Prometheus, and may be evidence of large ring paricles caught in the corotation resonances. T3 - NLD Preprints - 13 KW - Planetary Rings Y1 - 1995 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-13618 ER - TY - GEN A1 - Dosche, Carsten A1 - Mickler, Wulfhard A1 - Löhmannsröben, Hans-Gerd A1 - Agenet, Nicolas A1 - Vollhardt, K. Peter C. T1 - Photoinduced electron transfer in [N]phenylenes N2 - First studies of electron transfer in [N]phenylenes were performed in bimolecular quenching reactions of angular [3]- and triangular [4]phenylene with various electron acceptors. The relation between the quenching rate constants kq and the free energy change of the electron transfer (ΔG0CS ) could be described by the Rehm-Weller equation. From the experimental results, a reorganization energy λ of 0.7 eV was derived. Intramolecular electron transfer reactions were studied in an [N]phenylene bichomophore and a corresponding reference compound. Fluorescence lifetime and quantum yield of the bichromophor display a characteristic dependence on the solvent polarity, whereas the corresponding values of the reference compound remain constant. From the results, a nearly isoenergonic ΔG0CS can be determined. As the triplet quantum yield is nearly independent of the polarity, charge recombination leads to the population of the triplet state. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 23 KW - [N]phenylenes KW - photoinduced electron transfer KW - [N]phenylene dyads Y1 - 2007 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-12463 ER - TY - THES A1 - Demircioglu, Aydin T1 - Reconstruction of deligne classes and cocycles T1 - Rekonstruktion von Deligne Klassen und Kozykeln N2 - In der vorliegenden Arbeit verallgemeinern wir im Wesentlichen zwei Theoreme von Mackaay-Picken und Picken (2002, 2004). Im ihrem Artikel zeigen Mackaay und Picken,dass es eine bijektive Korrespodenz zwischen Deligne 2-Klassen $\xi \in \check{H}^2(M, \mathcal{D}^2)$ und Holonomie Abbildungen von der zweiten dünnen Homotopiegruppe $\pi_2^2(M)$ in die abelsche Gruppe $U(1)$ gibt. Im zweiten Artikel wird eine Verallgemeinerung dieses Theorems bewiesen: Picken zeigt, dass es eine Bijektion gibt zwischen Deligne 2-Kozykeln und gewissen 2-dimensionalen topologischen Quantenfeldtheorien. In dieser Arbeit zeigen wir, dass diese beiden Theoreme in allen Dimensionen gelten.Wir betrachten zunächst den Holonomie Fall und können mittels simplizialen Methoden nachweisen, dass die Gruppe der glatten Deligne $d$-Klassen isomorph ist zu der Gruppe der glatten Holonomie Abbildungen von der $d$-ten dünnen Homotopiegruppe $\pi_d^d(M)$ nach $U(1)$, sofern $M$ eine $(d-1)$-zusammenhängende Mannigfaltigkeit ist. Wir vergleichen dieses Resultat mit einem Satz von Gajer (1999). Gajer zeigte, dass jede Deligne $d$-Klasse durch eine andere Klasse von Holonomie-Abbildungen rekonstruiert werden kann, die aber nicht nur Holonomien entlang von Sphären, sondern auch entlang von allgemeinen $d$-Mannigfaltigkeiten in $M$ enthält. Dieser Zugang benötigt dann aber nicht, dass $M$ hoch-zusammenhängend ist. Wir zeigen, dass im Falle von flachen Deligne $d$-Klassen unser Rekonstruktionstheorem sich von Gajers unterscheidet, sofern $M$ nicht als $(d-1)$, sondern nur als $(d-2)$-zusammenhängend angenommen wird. Stiefel Mannigfaltigkeiten besitzen genau diese Eigenschaft, und wendet man unser Theorem auf diese an und vergleicht das Resultat mit dem von Gajer, so zeigt sich, dass es zuviele Deligne Klassen rekonstruiert. Dies bedeutet, dass unser Rekonstruktionsthreorem ohne die Zusatzbedingungen an die Mannigfaltigkeit M nicht auskommt, d.h. unsere Rekonstruktion benötigt zwar weniger Informationen über die Holonomie entlang von d-dimensionalen Mannigfaltigkeiten, aber dafür muss M auch $(d-1)$-zusammenhängend angenommen werden. Wir zeigen dann, dass auch das zweite Theorem verallgemeinert werden kann: Indem wir das Konzept einer Picken topologischen Quantenfeldtheorie in beliebigen Dimensionen einführen, können wir nachweisen, dass jeder Deligne $d$-Kozykel eine solche $d$-dimensionale Feldtheorie mit zwei besonderen Eigenschaften, der dünnen Invarianz und der Glattheit, induziert. Wir beweisen, dass jede $d$-dimensionale topologische Quantenfeldtheorie nach Picken mit diesen zwei Eigenschaften auch eine Deligne $d$-Klasse definiert und prüfen nach, dass diese Konstruktion sowohl surjektiv als auch injektiv ist. Demzufolge sind beide Gruppen isomorph. N2 - In this thesis we mainly generalize two theorems from Mackaay-Picken and Picken (2002, 2004). In the first paper, Mackaay and Picken show that there is a bijective correspondence between Deligne 2-classes $\xi \in \check{H}^2(M,\mathcal{D}^2)$ and holonomy maps from the second thin-homotopy group $\pi_2^2(M)$ to $U(1)$. In the second one, a generalization of this theorem to manifolds with boundaries is given: Picken shows that there is a bijection between Deligne 2-cocycles and a certain variant of 2-dimensional topological quantum field theories. In this thesis we show that these two theorems hold in every dimension. We consider first the holonomy case, and by using simplicial methods we can prove that the group of smooth Deligne $d$-classes is isomorphic to the group of smooth holonomy maps from the $d^{th}$ thin-homotopy group $\pi_d^d(M)$ to $U(1)$, if $M$ is $(d-1)$-connected. We contrast this with a result of Gajer (1999). Gajer showed that Deligne $d$-classes can be reconstructed by a different class of holonomy maps, which not only include holonomies along spheres, but also along general $d$-manifolds in $M$. This approach does not require the manifold $M$ to be $(d-1)$-connected. We show that in the case of flat Deligne $d$-classes, our result differs from Gajers, if $M$ is not $(d-1)$-connected, but only $(d-2)$-connected. Stiefel manifolds do have this property, and if one applies our theorem to these and compare the result with that of Gajers theorem, it is revealed that our theorem reconstructs too many Deligne classes. This means, that our reconstruction theorem cannot live without the extra assumption on the manifold $M$, that is our reconstruction needs less informations about the holonomy of $d$-manifolds in $M$ at the price of assuming $M$ to be $(d-1)$-connected. We continue to show, that also the second theorem can be generalized: By introducing the concept of Picken-type topological quantum field theory in arbitrary dimensions, we can show that every Deligne $d$-cocycle induces such a $d$-dimensional field theory with two special properties, namely thin-invariance and smoothness. We show that any $d$-dimensional topological quantum field theory with these two properties gives rise to a Deligne $d$-cocycle and verify that this construction is surjective and injective, that is both groups are isomorphic. KW - Holonomie KW - Hauptfaserbündel KW - Gerben KW - Deligne Kohomologie KW - Globale Differentialgeometrie KW - Holonomy KW - Prinicipal Fibre Bundles KW - Gerbes KW - Deligne Cohomology KW - Global Differentialgeometry Y1 - 2007 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-13755 ER - TY - JOUR A1 - Block, Andrea A1 - Bonaventura, Klaus A1 - Grahn, Patricia A1 - Bestgen, Felix A1 - Wippert, Pia-Maria T1 - Stress management in pre-and postoperative care amongst practitioners and patients in cardiac catheterization laboratory: a study protocol JF - Frontiers in Cardiovascular Medicine N2 - Background: As the number of cardiac diseases continuously increases within the last years in modern society, so does cardiac treatment, especially cardiac catheterization. The procedure of a cardiac catheterization is challenging for both patients and practitioners. Several potential stressors of psychological or physical nature can occur during the procedure. The objective of the study is to develop and implement a stress management intervention for both practitioners and patients that aims to reduce the psychological and physical strain of a cardiac catheterization. Methods: The clinical study (DRKS00026624) includes two randomized controlled intervention trials with parallel groups, for patients with elective cardiac catheterization and practitioners at the catheterization lab, in two clinic sites of the Ernst-von-Bergmann clinic network in Brandenburg, Germany. Both groups received different interventions for stress management. The intervention for patients comprises a psychoeducational video with different stress management technics and additional a standardized medical information about the cardiac catheterization examination. The control condition includes the in hospitals practiced medical patient education before the examination (usual care). Primary and secondary outcomes are measured by physiological parameters and validated questionnaires, the day before (M1) and after (M2) the cardiac catheterization and at a postal follow-up 6 months later (M3). It is expected that people with standardized information and psychoeducation show reduced complications during cardiac catheterization procedures, better pre- and post-operative wellbeing, regeneration, mood and lower stress levels over time. The intervention for practitioners includes a Mindfulness-based stress reduction program (MBSR) over 8 weeks supervised by an experienced MBSR practitioner directly at the clinic site and an operative guideline. It is expected that practitioners with intervention show improved perceived and chronic stress, occupational health, physical and mental function, higher effort-reward balance, regeneration and quality of life. Primary and secondary outcomes are measured by physiological parameters (heart rate variability, saliva cortisol) and validated questionnaires and will be assessed before (M1) and after (M2) the MBSR intervention and at a postal follow-up 6 months later (M3). Physiological biomarkers in practitioners will be assessed before (M1) and after intervention (M2) on two work days and a two days off. Intervention effects in both groups (practitioners and patients) will be evaluated separately using multivariate variance analysis. Discussion: This study evaluates the effectiveness of two stress management intervention programs for patients and practitioners within cardiac catheter laboratory. Study will disclose strains during a cardiac catheterization affecting both patients and practitioners. For practitioners it may contribute to improved working conditions and occupational safety, preservation of earning capacity, avoidance of participation restrictions and loss of performance. In both groups less anxiety, stress and complications before and during the procedures can be expected. The study may add knowledge how to eliminate stressful exposures and to contribute to more (psychological) security, less output losses and exhaustion during work. The evolved stress management guidelines, training manuals and the standardized patient education should be transferred into clinical routines KW - stress management KW - mindfulness-based stress reduction KW - psychoeducation KW - standardized patient information KW - stress intervention KW - distress KW - study protocol KW - cardiac catheterization (CC) Y1 - 2022 U6 - https://doi.org/10.3389/fcvm.2022.830256 SN - 2297-055X VL - 9 SP - 1 EP - 10 PB - Frontiers CY - Lausanne, Schweiz ER - TY - JOUR A1 - Ellermann, Christin A1 - McDowell, Michelle A1 - Schirren, Clara O. A1 - Lindemann, Ann-Kathrin A1 - Koch, Severine A1 - Lohmann, Mark A1 - Jenny, Mirjam Annina T1 - Identifying content to improve risk assessment communications within the Risk Profile: Literature reviews and focus groups with expert and non-expert stakeholders JF - PLoS ONE N2 - Objective To improve consumer decision making, the results of risk assessments on food, feed, consumer products or chemicals need to be communicated not only to experts but also to non-expert audiences. The present study draws on evidence from literature reviews and focus groups with diverse stakeholders to identify content to integrate into an existing risk assessment communication (Risk Profile). Methods A combination of rapid literature reviews and focus groups with experts (risk assessors (n = 15), risk managers (n = 8)), and non-experts (general public (n = 18)) were used to identify content and strategies for including information about risk assessment results in the “Risk Profile” from the German Federal Institute for Risk Assessment. Feedback from initial focus groups was used to develop communication prototypes that informed subsequent feedback rounds in an iterative process. A final prototype was validated in usability tests with experts. Results Focus group feedback and suggestions from risk assessors were largely in line with findings from the literature. Risk managers and lay persons offered similar suggestions on how to improve the existing communication of risk assessment results (e.g., including more explanatory detail, reporting probabilities for individual health impairments, and specifying risks for subgroups in additional sections). Risk managers found information about quality of evidence important to communicate, whereas people from the general public found this information less relevant. Participants from lower educational backgrounds had difficulties understanding the purpose of risk assessments. User tests found that the final prototype was appropriate and feasible to implement by risk assessors. Conclusion An iterative and evidence-based process was used to develop content to improve the communication of risk assessments to the general public while being feasible to use by risk assessors. Remaining challenges include how to communicate dose-response relationships and standardise quality of evidence ratings across disciplines. Y1 - 2022 U6 - https://doi.org/10.1371/journal.pone.0266800 SN - 1553-7358 VL - 17 PB - Public Library of Science (PLOS) CY - San Francisco, California, USA ET - 4 ER - TY - JOUR A1 - Yang, Jingdan A1 - Kim, Jae-Hyun A1 - Tuomainen, Outi A1 - Rattanasone, Nan Xu T1 - Bilingual Mandarin-English preschoolers’ spoken narrative skills and contributing factors BT - A remote online story-retell study JF - Frontiers in Psyhology N2 - This study examined the spoken narrative skills of a group of bilingual Mandarin–English speaking 3–6-year-olds (N = 25) in Australia, using a remote online story-retell task. Bilingual preschoolers are an understudied population, especially those who are speaking typologically distinct languages such as Mandarin and English which have fewer structural overlaps compared to language pairs that are typologically closer, reducing cross-linguistic positive transfer. We examined these preschoolers’ spoken narrative skills as measured by macrostructures (the global organization of a story) and microstructures (linguistic structures, e.g., total number of utterances, nouns, verbs, phrases, and modifiers) across and within each language, and how various factors such as age and language experiences contribute to individual variability. The results indicate that our bilingual preschoolers acquired spoken narrative skills similarly across their two languages, i.e., showing similar patterns of productivity for macrostructure and microstructure elements in both of their two languages. While chronological age was positively correlated with macrostructures in both languages (showing developmental effects), there were no significant correlations between measures of language experiences and the measures of spoken narrative skills (no effects for language input/output). The findings suggest that although these preschoolers acquire two typologically diverse languages in different learning environments, Mandarin at home with highly educated parents, and English at preschool, they displayed similar levels of oral narrative skills as far as these macro−/micro-structure measures are concerned. This study provides further evidence for the feasibility of remote online assessment of preschoolers’ narrative skills. KW - narrative skills KW - Mandarin-English bilinguals KW - preschoolers KW - macrostructure KW - microstructure Y1 - 2022 U6 - https://doi.org/10.3389/fpsyg.2022.797602 SN - 1664-1078 VL - 13 PB - Frontiers Media SA CY - Lausanne, Schweiz ER - TY - JOUR A1 - Orland, Andreas A1 - Padubrin, Max T1 - Is there a gender hiring gap in academic economics? Evidence from a network analysis JF - Royal Society Open Science N2 - We collect a network dataset of tenured economics faculty in Austria, Germany and Switzerland. We rank the 100 institutions included with a minimum violation ranking. This ranking is positively and significantly correlated with the Times Higher Education ranking of economics institutions. According to the network ranking, individuals on average go down about 23 ranks from their doctoral institution to their employing institution. While the share of females in our dataset is only 15%, we do not observe a significant gender hiring gap (a difference in rank changes between male and female faculty). We conduct a robustness check with the Handelsblatt and the Times Higher Education ranking. According to these rankings, individuals on average go down only about two ranks. We do not observe a significant gender hiring gap using these two rankings (although the dataset underlying this analysis is small and these estimates are likely to be noisy). Finally, we discuss the limitations of the network ranking in our context. Y1 - 2022 U6 - https://doi.org/10.1098/rsos.210717 SN - 2054-5703 VL - 9 SP - 1 EP - 9 PB - Royal Society of London CY - London ET - 2 ER - TY - JOUR A1 - Herold, Fabian A1 - Labott, Berit K. A1 - Grässler, Bernhard A1 - Halfpaap, Nicole A1 - Langhans, Corinna A1 - Müller, Patrick A1 - Ammar, Achraf A1 - Dordevic, Milos A1 - Hökelmann, Anita A1 - Müller, Notger Germar T1 - A Link between Handgrip Strength and Executive Functioning: A Cross-Sectional Study in Older Adults with Mild Cognitive Impairment and Healthy Controls JF - Healthcare : open access journal N2 - Older adults with amnestic mild cognitive impairment (aMCI) who in addition to their memory deficits also suffer from frontal-executive dysfunctions have a higher risk of developing dementia later in their lives than older adults with aMCI without executive deficits and older adults with non-amnestic MCI (naMCI). Handgrip strength (HGS) is also correlated with the risk of cognitive decline in the elderly. Hence, the current study aimed to investigate the associations between HGS and executive functioning in individuals with aMCI, naMCI and healthy controls. Older, right-handed adults with amnestic MCI (aMCI), non-amnestic MCI (naMCI), and healthy controls (HC) conducted a handgrip strength measurement via a handheld dynamometer. Executive functions were assessed with the Trail Making Test (TMT A&B). Normalized handgrip strength (nHGS, normalized to Body Mass Index (BMI)) was calculated and its associations with executive functions (operationalized through z-scores of TMT B/A ratio) were investigated through partial correlation analyses (i.e., accounting for age, sex, and severity of depressive symptoms). A positive and low-to-moderate correlation between right nHGS (rp (22) = 0.364; p = 0.063) and left nHGS (rp (22) = 0.420; p = 0.037) and executive functioning in older adults with aMCI but not in naMCI or HC was observed. Our results suggest that higher levels of nHGS are linked to better executive functioning in aMCI but not naMCI and HC. This relationship is perhaps driven by alterations in the integrity of the hippocampal-prefrontal network occurring in older adults with aMCI. Further research is needed to provide empirical evidence for this assumption. KW - MCI KW - hippocampal-prefrontal network KW - handgrip strength KW - exercise cognition KW - aging KW - brain health Y1 - 2022 U6 - https://doi.org/10.3390/healthcare10020230 SN - 2227-9032 VL - 10 SP - 1 EP - 14 PB - MDPI CY - Basel, Schweiz ET - 2 ER - TY - JOUR A1 - Kaboth-Bahr, Stefanie A1 - Bahr, André A1 - Stepanek, Christian A1 - Catunda, Maria Carolina Amorim A1 - Karas, Cyrus A1 - Ziegler, Martin A1 - García-Gallardo, Ángela A1 - Grunert, Patrick T1 - Mediterranean heat injection to the North Atlantic delayed the intensification of Northern Hemisphere glaciations JF - Communications Earth & Environment N2 - The intensification of Northern Hemisphere glaciations at the end of the Pliocene epoch marks one of the most substantial climatic shifts of the Cenozoic. Despite global cooling, sea surface temperatures in the high latitude North Atlantic Ocean rose between 2.9–2.7 million years ago. Here we present sedimentary geochemical proxy data from the Gulf of Cadiz to reconstruct the variability of Mediterranean Outflow Water, an important heat source to the North Atlantic. We find evidence for enhanced production of Mediterranean Outflow from the mid-Pliocene to the late Pliocene which we infer could have driven a sub-surface heat channel into the high-latitude North Atlantic. We then use Earth System Models to constrain the impact of enhanced Mediterranean Outflow production on the northward heat transport in the North Atlantic. In accord with the proxy data, the numerical model results support the formation of a sub-surface channel that pumped heat from the subtropics into the high latitude North Atlantic. We further suggest that this mechanism could have delayed ice sheet growth at the end of the Pliocene. Y1 - 2021 U6 - https://doi.org/10.1038/s43247-021-00232-5 SN - 2662-4435 SP - 1 EP - 9 PB - Springer Nature CY - London ER - TY - JOUR A1 - de Pinho Tavares Leal, Pedro Ernesto A1 - da Silva, Alexandre Alves A1 - Rocha-Gomes, Arthur A1 - Riul, Tania Regina A1 - Cunha, Rennan Augusto A1 - Reichetzeder, Christoph A1 - Villela, Daniel Campos T1 - High-Salt Diet in the Pre- and Postweaning Periods Leads to Amygdala Oxidative Stress and Changes in Locomotion and Anxiety-Like Behaviors of Male Wistar Rats JF - Frontiers in Behavioral Neuroscience N2 - High-salt (HS) diets have recently been linked to oxidative stress in the brain, a fact that may be a precursor to behavioral changes, such as those involving anxiety-like behavior. However, to the best of our knowledge, no study has evaluated the amygdala redox status after consuming a HS diet in the pre- or postweaning periods. This study aimed to evaluate the amygdala redox status and anxiety-like behaviors in adulthood, after inclusion of HS diet in two periods: preconception, gestation, and lactation (preweaning); and only after weaning (postweaning). Initially, 18 females and 9 male Wistar rats received a standard (n = 9 females and 4 males) or a HS diet (n = 9 females and 5 males) for 120 days. After mating, females continued to receive the aforementioned diets during gestation and lactation. Weaning occurred at 21-day-old Wistar rats and the male offspring were subdivided: control-control (C-C)—offspring of standard diet fed dams who received a standard diet after weaning (n = 9–11), control-HS (C-HS)—offspring of standard diet fed dams who received a HS diet after weaning (n = 9–11), HS-C—offspring of HS diet fed dams who received a standard diet after weaning (n = 9–11), and HS-HS—offspring of HS diet fed dams who received a HS diet after weaning (n = 9–11). At adulthood, the male offspring performed the elevated plus maze and open field tests. At 152-day-old Wistar rats, the offspring were euthanized and the amygdala was removed for redox state analysis. The HS-HS group showed higher locomotion and rearing frequency in the open field test. These results indicate that this group developed hyperactivity. The C-HS group had a higher ratio of entries and time spent in the open arms of the elevated plus maze test in addition to a higher head-dipping frequency. These results suggest less anxiety-like behaviors. In the analysis of the redox state, less activity of antioxidant enzymes and higher levels of the thiobarbituric acid reactive substances (TBARS) in the amygdala were shown in the amygdala of animals that received a high-salt diet regardless of the period (pre- or postweaning). In conclusion, the high-salt diet promoted hyperactivity when administered in the pre- and postweaning periods. In animals that received only in the postweaning period, the addition of salt induced a reduction in anxiety-like behaviors. Also, regardless of the period, salt provided amygdala oxidative stress, which may be linked to the observed behaviors. KW - high-sodium KW - open-field KW - elevated plus-maze KW - pre-natal KW - post-natal KW - redox state Y1 - 2022 U6 - https://doi.org/10.3389/fnbeh.2021.779080 SN - 1662-5153 VL - 15 SP - 1 EP - 12 PB - Frontiers Research Foundation CY - Lausanne, Schweiz ER - TY - JOUR A1 - Vogel, Johannes A1 - Paton, Eva Nora A1 - Aich, Valentin T1 - Seasonal ecosystem vulnerability to climatic anomalies in the Mediterranean JF - Biogeosciences N2 - Mediterranean ecosystems are particularly vulnerable to climate change and the associated increase in climate anomalies. This study investigates extreme ecosystem responses evoked by climatic drivers in the Mediterranean Basin for the time span 1999–2019 with a specific focus on seasonal variations as the seasonal timing of climatic anomalies is considered essential for impact and vulnerability assessment. A bivariate vulnerability analysis is performed for each month of the year to quantify which combinations of the drivers temperature (obtained from ERA5-Land) and soil moisture (obtained from ESA CCI and ERA5-Land) lead to extreme reductions in ecosystem productivity using the fraction of absorbed photosynthetically active radiation (FAPAR; obtained from the Copernicus Global Land Service) as a proxy. The bivariate analysis clearly showed that, in many cases, it is not just one but a combination of both drivers that causes ecosystem vulnerability. The overall pattern shows that Mediterranean ecosystems are prone to three soil moisture regimes during the yearly cycle: they are vulnerable to hot and dry conditions from May to July, to cold and dry conditions from August to October, and to cold conditions from November to April, illustrating the shift from a soil-moisture-limited regime in summer to an energy-limited regime in winter. In late spring, a month with significant vulnerability to hot conditions only often precedes the next stage of vulnerability to both hot and dry conditions, suggesting that high temperatures lead to critically low soil moisture levels with a certain time lag. In the eastern Mediterranean, the period of vulnerability to hot and dry conditions within the year is much longer than in the western Mediterranean. Our results show that it is crucial to account for both spatial and temporal variability to adequately assess ecosystem vulnerability. The seasonal vulnerability approach presented in this study helps to provide detailed insights regarding the specific phenological stage of the year in which ecosystem vulnerability to a certain climatic condition occurs. How to cite. Vogel, J., Paton, E., and Aich, V.: Seasonal ecosystem vulnerability to climatic anomalies in the Mediterranean, Biogeosciences, 18, 5903–5927, https://doi.org/10.5194/bg-18-5903-2021, 2021. Y1 - 2021 U6 - https://doi.org/10.5194/bg-18-5903-2021 SN - 1726-4189 VL - 18 SP - 5903 EP - 5927 PB - Copernicus CY - Göttingen ET - 22 ER - TY - JOUR A1 - Baritello, Omar A1 - Salzwedel, Annett A1 - Sündermann, Simon A1 - Niebauer, Josef A1 - Völler, Heinz T1 - The Pandora's Box of frailty assessments: Which is the best for clinical purposes in TAVI patients? A critical review JF - Journal of Clinical Medicine N2 - Frailty assessment is recommended before elective transcatheter aortic valve implantation (TAVI) to determine post-interventional prognosis. Several studies have investigated frailty in TAVI-patients using numerous assessments; however, it remains unclear which is the most appropriate tool for clinical practice. Therefore, we evaluate which frailty assessment is mainly used and meaningful for ≤30-day and ≥1-year prognosis in TAVI patients. Randomized controlled or observational studies (prospective/retrospective) investigating all-cause mortality in older (≥70 years) TAVI patients were identified (PubMed; May 2020). In total, 79 studies investigating frailty with 49 different assessments were included. As single markers of frailty, mostly gait speed (23 studies) and serum albumin (16 studies) were used. Higher risk of 1-year mortality was predicted by slower gait speed (highest Hazard Ratios (HR): 14.71; 95% confidence interval (CI) 6.50–33.30) and lower serum albumin level (highest HR: 3.12; 95% CI 1.80–5.42). Composite indices (five items; seven studies) were associated with 30-day (highest Odds Ratio (OR): 15.30; 95% CI 2.71–86.10) and 1-year mortality (highest OR: 2.75; 95% CI 1.55–4.87). In conclusion, single markers of frailty, in particular gait speed, were widely used to predict 1-year mortality. Composite indices were appropriate, as well as a comprehensive assessment of frailty. View Full-Text KW - frailty tool KW - TAVI KW - older patients KW - elderly KW - cardiology KW - mortality Y1 - 2021 U6 - https://doi.org/10.3390/jcm10194506 SN - 2077-0383 VL - 10 SP - 1 EP - 17 PB - MDPI CY - Basel, Schweiz ET - 19 ER - TY - JOUR A1 - Wiepke, Axel P. A1 - Miklashevsky, Alex T1 - Imaginary Worlds and Their Borders: An Opinion Article JF - Frontiers Media SA KW - imaginary world KW - fiction KW - narrative KW - embodied cognition KW - virtual reality KW - feeling of presence KW - mental simulation Y1 - 2021 U6 - https://doi.org/10.3389/fpsyg.2021.793764 SN - 1664-1078 VL - 12 SP - 1 EP - 2 PB - Frontiers Research Foundation CY - Lausanne, Schweiz ER - TY - JOUR A1 - Teichmann, Erik A1 - Lewandowski, Heather J. A1 - Alemani, Micol T1 - Investigating students’ views of experimental physics in German laboratory classes JF - Physical Review Physics Education Research N2 - There is a large variety of goals instructors have for laboratory courses, with different courses focusing on different subsets of goals. An often implicit, but crucial, goal is to develop students’ attitudes, views, and expectations about experimental physics to align with practicing experimental physicists. The assessment of laboratory courses upon this one dimension of learning has been intensively studied in U.S. institutions using the Colorado Learning Attitudes about Science Survey for Experimental Physics (E-CLASS). However, there is no such an instrument available to use in Germany, and the influence of laboratory courses on students views about the nature of experimental physics is still unexplored at German-speaking institutions. Motivated by the lack of an assessment tool to investigate this goal in laboratory courses at German-speaking institutions, we present a translated version of the E-CLASS adapted to the context at German-speaking institutions. We call the German version of the E-CLASS, the GE-CLASS. We describe the translation process and the creation of an automated web-based system for instructors to assess their laboratory courses. We also present first results using GE-CLASS obtained at the University of Potsdam. A first comparison between E-CLASS and GE-CLASS results shows clear differences between University of Potsdam and U.S. students’ views and beliefs about experimental physics. Y1 - 2022 U6 - https://doi.org/10.1103/PhysRevPhysEducRes.18.010135 SN - 1554-9178 VL - 18 SP - 010135-1 EP - 010135-17 PB - APS CY - College Park, Maryland, United States ET - 1 ER - TY - JOUR A1 - Ehlert, Antje A1 - Poltz, Nadine A1 - Quandte, Sabine A1 - Kohn-Henkel, Juliane A1 - Kucian, Karin A1 - Aster, Michael von A1 - Esser, Günter T1 - Taking a closer look: The relationship between pre-school domain general cognition and school mathematics achievement when controlling for intelligence JF - Journal of Intelligence N2 - Intelligence, as well as working memory and attention, affect the acquisition of mathematical competencies. This paper aimed to examine the influence of working memory and attention when taking different mathematical skills into account as a function of children’s intellectual ability. Overall, intelligence, working memory, attention and numerical skills were assessed twice in 1868 German pre-school children (t1, t2) and again at 2nd grade (t3). We defined three intellectual ability groups based on the results of intellectual assessment at t1 and t2. Group comparisons revealed significant differences between the three intellectual ability groups. Over time, children with low intellectual ability showed the lowest achievement in domain-general and numerical and mathematical skills compared to children of average intellectual ability. The highest achievement on the aforementioned variables was found for children of high intellectual ability. Additionally, path modelling revealed that, depending on the intellectual ability, different models of varying complexity could be generated. These models differed with regard to the relevance of the predictors (t2) and the future mathematical skills (t3). Causes and conclusions of these findings are discussed. KW - intellectual ability KW - intelligence KW - pre-school KW - mathematical development KW - school mathematics KW - longitudinal KW - numerical skills KW - working memory KW - attention Y1 - 2022 U6 - https://doi.org/10.3390/jintelligence10030070 SN - 2079-3200 VL - 10 SP - 1 EP - 23 PB - MDPI CY - Basel, Schweiz ET - 3 ER - TY - JOUR A1 - Ladleif, Jan A1 - Weske, Mathias T1 - Which event happened first? BT - Deferred choice on blockchain using oracles JF - Frontiers in blockchain N2 - First come, first served: Critical choices between alternative actions are often made based on events external to an organization, and reacting promptly to their occurrence can be a major advantage over the competition. In Business Process Management (BPM), such deferred choices can be expressed in process models, and they are an important aspect of process engines. Blockchain-based process execution approaches are no exception to this, but are severely limited by the inherent properties of the platform: The isolated environment prevents direct access to external entities and data, and the non-continual runtime based entirely on atomic transactions impedes the monitoring and detection of events. In this paper we provide an in-depth examination of the semantics of deferred choice, and transfer them to environments such as the blockchain. We introduce and compare several oracle architectures able to satisfy certain requirements, and show that they can be implemented using state-of-the-art blockchain technology. KW - business processes KW - business process management KW - deferred choice KW - workflow patterns KW - blockchain KW - smart contracts KW - oracles KW - formal semantics Y1 - 2021 U6 - https://doi.org/10.3389/fbloc.2021.758169 SN - 2624-7852 VL - 4 SP - 1 EP - 16 PB - Frontiers in Blockchain CY - Lausanne, Schweiz ER - TY - JOUR A1 - Raatz, Larissa A1 - Pirhofer-Walzl, Karin A1 - Müller, Marina E.H. A1 - Scherber, Christoph A1 - Joshi, Jasmin Radha T1 - Who is the culprit: Is pest infestation responsible for crop yield losses close to semi-natural habitats? JF - Ecology and Evolution N2 - Semi-natural habitats (SNHs) are becoming increasingly scarce in modern agricultural landscapes. This may reduce natural ecosystem services such as pest control with its putatively positive effect on crop production. In agreement with other studies, we recently reported wheat yield reductions at field borders which were linked to the type of SNH and the distance to the border. In this experimental landscape-wide study, we asked whether these yield losses have a biotic origin while analyzing fungal seed and fungal leaf pathogens, herbivory of cereal leaf beetles, and weed cover as hypothesized mediators between SNHs and yield. We established experimental winter wheat plots of a single variety within conventionally managed wheat fields at fixed distances either to a hedgerow or to an in-field kettle hole. For each plot, we recorded the fungal infection rate on seeds, fungal infection and herbivory rates on leaves, and weed cover. Using several generalized linear mixed-effects models as well as a structural equation model, we tested the effects of SNHs at a field scale (SNH type and distance to SNH) and at a landscape scale (percentage and diversity of SNHs within a 1000-m radius). In the dry year of 2016, we detected one putative biotic culprit: Weed cover was negatively associated with yield values at a 1-m and 5-m distance from the field border with a SNH. None of the fungal and insect pests, however, significantly affected yield, neither solely nor depending on type of or distance to a SNH. However, the pest groups themselves responded differently to SNH at the field scale and at the landscape scale. Our findings highlight that crop losses at field borders may be caused by biotic culprits; however, their negative impact seems weak and is putatively reduced by conventional farming practices. KW - arable weeds KW - cereal leaf beetle KW - fungal pathogens KW - herbivory KW - structural equation model KW - wheat Y1 - 2021 U6 - https://doi.org/10.1002/ece3.8046 SN - 1467-6435 VL - 11 SP - 13232 EP - 13246 PB - Wiley-Blackwell CY - Oxford ET - 19 ER - TY - JOUR A1 - Sarabadani, Jalal A1 - Metzler, Ralf A1 - Ala-Nissila, Tapio T1 - Driven polymer translocation into a channel: Isoflux tension propagation theory and Langevin dynamics simulations JF - Physical Review Research N2 - Isoflux tension propagation (IFTP) theory and Langevin dynamics (LD) simulations are employed to study the dynamics of channel-driven polymer translocation in which a polymer translocates into a narrow channel and the monomers in the channel experience a driving force fc. In the high driving force limit, regardless of the channel width, IFTP theory predicts τ ∝ f βc for the translocation time, where β = −1 is the force scaling exponent. Moreover, LD data show that for a very narrow channel fitting only a single file of monomers, the entropic force due to the subchain inside the channel does not play a significant role in the translocation dynamics and the force exponent β = −1 regardless of the force magnitude. As the channel width increases the number of possible spatial configurations of the subchain inside the channel becomes significant and the resulting entropic force causes the force exponent to drop below unity. Y1 - 2022 U6 - https://doi.org/10.1103/PhysRevResearch.4.033003 SN - 2643-1564 VL - 4 SP - 033003-1 EP - 033003-14 PB - American Physical Society CY - College Park, Maryland, USA ET - 3 ER - TY - JOUR A1 - Sposini, Vittoria A1 - Krapf, Diego A1 - Marinari, Enzo A1 - Sunyer, Raimon A1 - Ritort, Felix A1 - Taheri, Fereydoon A1 - Selhuber-Unkel, Christine A1 - Benelli, Rebecca A1 - Weiss, Matthias A1 - Metzler, Ralf A1 - Oshanin, Gleb T1 - Towards a robust criterion of anomalous diffusion JF - Communications Physics N2 - Anomalous-diffusion, the departure of the spreading dynamics of diffusing particles from the traditional law of Brownian-motion, is a signature feature of a large number of complex soft-matter and biological systems. Anomalous-diffusion emerges due to a variety of physical mechanisms, e.g., trapping interactions or the viscoelasticity of the environment. However, sometimes systems dynamics are erroneously claimed to be anomalous, despite the fact that the true motion is Brownian—or vice versa. This ambiguity in establishing whether the dynamics as normal or anomalous can have far-reaching consequences, e.g., in predictions for reaction- or relaxation-laws. Demonstrating that a system exhibits normal- or anomalous-diffusion is highly desirable for a vast host of applications. Here, we present a criterion for anomalous-diffusion based on the method of power-spectral analysis of single trajectories. The robustness of this criterion is studied for trajectories of fractional-Brownian-motion, a ubiquitous stochastic process for the description of anomalous-diffusion, in the presence of two types of measurement errors. In particular, we find that our criterion is very robust for subdiffusion. Various tests on surrogate data in absence or presence of additional positional noise demonstrate the efficacy of this method in practical contexts. Finally, we provide a proof-of-concept based on diverse experiments exhibiting both normal and anomalous-diffusion. Y1 - 2022 U6 - https://doi.org/10.1038/s42005-022-01079-8 SN - 2399-3650 VL - 5 PB - Springer Nature CY - London ER - TY - JOUR A1 - Evans, Myfanwy E. A1 - Hyde, Stephen T. T1 - Symmetric Tangling of Honeycomb Networks JF - Symmetry N2 - Symmetric, elegantly entangled structures are a curious mathematical construction that has found their way into the heart of the chemistry lab and the toolbox of constructive geometry. Of particular interest are those structures—knots, links and weavings—which are composed locally of simple twisted strands and are globally symmetric. This paper considers the symmetric tangling of multiple 2-periodic honeycomb networks. We do this using a constructive methodology borrowing elements of graph theory, low-dimensional topology and geometry. The result is a wide-ranging enumeration of symmetric tangled honeycomb networks, providing a foundation for their exploration in both the chemistry lab and the geometers toolbox. KW - tangles KW - knots KW - networks KW - periodic entanglement KW - molecular weaving KW - graphs Y1 - 2022 U6 - https://doi.org/10.3390/sym14091805 SN - 2073-8994 VL - 14 SP - 1 EP - 13 PB - MDPI CY - Basel, Schweiz ET - 9 ER - TY - JOUR A1 - Puerto Valencia, Laura Maria A1 - Arampatzis, Adamantios A1 - Beck, Heidrun A1 - Dreinhöfer, Karsten E. A1 - Drießlein, Drießlein A1 - Mau, Wilfried A1 - Zimmer, Julia-Marie A1 - Schäfer, Michael A1 - Steinfeldt, Friedemann A1 - Wippert, Pia-Maria T1 - RENaBack: Low back pain patients in rehabilitation: Study Protocol for a Multicenter, Randomized Controlled Trial JF - Trials N2 - Background Millions of people in Germany suffer from chronic pain, in which course and intensity are multifactorial. Besides physical injuries, certain psychosocial risk factors are involved in the disease process. The national health care guidelines for the diagnosis and treatment of non-specific low back pain recommend the screening of psychosocial risk factors as early as possible, to be able to adapt the therapy to patient needs (e.g., unimodal or multimodal). However, such a procedure has been difficult to implement in practice and has not yet been integrated into the rehabilitation care structures across the country. Methods The aim of this study is to implement an individualized therapy and aftercare program within the rehabilitation offer of the German Pension Insurance in the area of orthopedics and to examine its success and sustainability in comparison to the previous standard aftercare program. The study is a multicenter randomized controlled trial including 1204 patients from six orthopedic rehabilitation clinics. A 2:1 allocation ratio to intervention (individualized and home-based rehabilitation aftercare) versus the control group (regular outpatient rehabilitation aftercare) is set. Upon admission to the rehabilitation clinic, participants in the intervention group will be screened according to their psychosocial risk profile. They could then receive either unimodal or multimodal, together with an individualized training program. The program is instructed in the clinic (approximately 3 weeks) and will continue independently at home afterwards for 3 months. The success of the program is examined by means of a total of four surveys. The co-primary outcomes are the Characteristic Pain Intensity and Disability Score assessed by the German version of the Chronic Pain Grade questionnaire (CPG). Discussion An improvement in terms of pain, work ability, patient compliance, and acceptance in our intervention program compared to the standard aftercare is expected. The study contributes to provide individualized care also to patients living far away from clinical centers. Trial registration DRKS, DRKS00020373. Registered on 15 April 2020 KW - Chronic low back pain KW - Aftercare KW - Individualized therapy KW - Randomized controlled trial KW - Rehabilitation Y1 - 2021 U6 - https://doi.org/10.1186/s13063-021-05823-3 SN - 1745-6215 SP - 1 EP - 18 PB - Springer Nature / BMC CY - Heidelberg ER - TY - JOUR A1 - Stuchtey, Fidelis Christin A1 - Block, Andrea A1 - Osei, Francis A1 - Wippert, Pia-Maria T1 - Lipid Biomarkers in Depression: Does Antidepressant Therapy Have an Impact? JF - Healthcare : open access journal N2 - Studies have revealed mixed results on how antidepressant drugs affect lipid profiles of patients with major depression disorder (MDD). Even less is known about how patients respond to a switch of antidepressant medication with respect to their metabolic profile. For this, effects of a switch in antidepressants medication on lipid markers were studied in MDD patients. 15 participants (females = 86.67%; males = 13.33%; age: 49.45 ± 7.45 years) with MDD and a prescribed switch in their antidepressant medication were recruited at a psychosomatic rehabilitation clinic. Participants were characterized (with questionnaires and blood samples) at admission to the rehabilitation clinic (baseline, T0) and followed up with a blood sample two weeks (T1) later. HDL, LDL, total cholesterol, and triglycerides were determined (T0), and their change analyzed (Wilcoxon test) at follow up (T1). Decrements in HDL (p = 0.041), LDL (p < 0.001), and total cholesterol (p < 0.001) were observed two weeks after a switch in antidepressant medication. Triglycerides showed no difference (p = 0.699). Overall, LDL, HDL, and total cholesterol are affected by a change in antidepressant drugs in patients with MDD. These observations are of clinical relevance for medical practitioners in the planning and management of treatment strategies for MDD patients. KW - major depressive disorder KW - antidepressants KW - high density lipoprotein cholesterol KW - HDL KW - low density lipoprotein cholesterol KW - LDL KW - cholesterol KW - triglycerides KW - lipids Y1 - 2022 U6 - https://doi.org/10.3390/healthcare10020333 SN - 2227-9032 VL - 10 SP - 1 EP - 11 PB - MDPI CY - Basel, Schweiz ET - 2 ER - TY - THES A1 - Radloff, Katrin T1 - The role of the fatty acid profile and its modulation by cytokines in the systemic inflammation in cancer cachexia T1 - O papel e a modulação do perfil de ácidos graxos por citocinas na inflamação da caquexia associada ao câncer T1 - Die Rolle des Fettsäure-Profils und dessen entzündungsbedingten Veränderungen in der Tumorkachexie N2 - Systemic inflammation is a hallmark of cancer cachexia. Among tumor-host interactions, the white adipose tissue (WAT) is an important contributor to inflammation as it suffers morphological reorganization and lipolysis, releasing free fatty acids (FA), bioactive lipid mediators (LM) and pro-inflammatory cytokines, which accentuate the activation of pro-inflammatory signaling pathways and the recruitment of immune cells to the tissue. This project aimed to investigate which inflammatory factors are involved in the local adipose tissue inflammation and what is the influence of such factors upon enzymes involved in FA or LM metabolism in healthy individuals (Control), weight stable gastro-intestinal cancer patients (WSC) and cachectic cancer patients (CC). The results demonstrated that the inflammatory signature of systemic inflammation is different from local adipose tissue inflammation. The systemic inflammation of the cachectic cancer patients was characterized by higher levels of circulating saturated fatty acids (SFA), tumor-necrosis-factor-α (TNF-α), interleukins IL-6, IL-8 and CRP while levels of polyunsaturated fatty acids (PUFAs), especially n3-PUFAs, were lower in CC than in the other groups. In vitro and in adipose tissue explants, pro-inflammatory cytokines and SFAs were shown to increase the chemokines IL-8 and CXCL10 that were found to be augmented in adipose tissue inflammation in CC which was more profound in the visceral adipose tissue (VAT) than in subcutaneous adipose tissue (SAT). Systemic inflammation was negatively associated with the expression of PUFA synthesizing enzymes, though gene and protein expression did hardly differ between groups. The effects of inflammatory factors on enzymes in the whole tissue could have been masked by differentiated modulation of the diverse cell types in the same tissue. In vitro experiments showed that the expression of FA-modifying enzymes such as desaturases and elongases in adipocytes and macrophages was regulated into opposing directions by TNF-α, IL-6, LPS or palmitate. The higher plasma concentration of the pro-resolving LM resolvin D1 in CC cannot compensate the overall inflammatory status and the results indicate that inflammatory cytokines interfere with synthesis pathways of pro-resolving LM. In summary, the data revealed a complex inter-tissue and inter-cellular crosstalk mediated by pro-inflammatory cytokines and lipid compounds enhancing inflammation in cancer cachexia by feed-forward mechanisms. N2 - Systemische Entzündung ist ein grundlegendes Merkmal der Tumorkachexie. Bei den entzündungstreibenden Wechselwirkungen zwischen Tumor und Wirt spielt das weiße Fettgewebe eine besondere Rolle, da es, bedingt durch morphologische Veränderungen und Lipolyse, freie Fettsäuren, bioaktive Lipidmediatoren (LM) und pro-inflammatorische Cytokine freisetzt. Diese verschiedenen Substanzen verstärken die Aktivierung entzündungsfördernder Signalwege und eine Rekrutierung von Immunzellen in das Gewebe. Das Ziel dieser Arbeit war es daher zu untersuchen, welche Faktoren an der Entwicklung der lokalen Fettgewebsentzündung beteiligt sind und wie diese Faktoren Syntheseenzyme von Fettsäuren und Lipidmediatoren beeinflussen könnten. Dazu wurden Plasma und Fettgewebeproben von gesunden Kontrollpersonen (Control) und normalgewichtigen (WSC) sowie kachektischen Magen-Darm-Krebs-Patienten (CC) untersucht. Die Ergebnisse zeigten, dass sich die inflammatorischen Charakteristiken der systemischen Entzündung von denen der lokalen Fettgewebsentzündung unterscheiden. Die systemische Entzündung war gekennzeichnet durch höhere Spiegel gesättigter Fettsäuren (SFA), Tumor-necrosis-factor alpha (TNF-α), Interleukin IL-6, IL-8 und C-reactive protein (CRP) während die Konzentrationen von mehrfachungesättigten Fettsäuren (PUFA) –besonders n3-Fettsäuren- geringer in CC waren als in den anderen Gruppen. In vitro und in ex vivo kultivierten Fettgewebssegmenten konnte gezeigt werden, dass die Inkubation mit pro-inflammatorischen Cytokinen und gesättigten Fettsäuren zu einem Anstieg der Chemokine IL-8 sowie CXCL10 führte. Erhöhte Spiegel dieser Moleküle wurden auch in der Fettgewebsentzündung bei kachektischen Patienten beobachtet, welche im viszeralen Fettgewebe ausgeprägter war als im subkutanen. Systemische Entzündungsmarker waren negativ mit der Expression PUFA-synthetisierender Enzyme assoziiert, obwohl sich Gesamt-mRNA-sowie Proteingehalt kaum zwischen den Studiengruppen unterschieden. Die Effekte von Entzündungsfaktoren auf diese Enzyme im Gesamtgewebe könnten durch eine differenzielle Modulierung in diversen Zelltypen des Gewebes maskiert sein. Denn in in vitro-Experimenten zeigte die Inkubation mit TNF-α, IL-6, LPS oder Palmitat, dass die GeneExpression von Fettsäure-modifizierenden Enzymen wie Desaturasen oder Elongasen in Adipozyten und Makrophagen in entgegengesetzte Richtungen reguliert wird. Die höhere Plasmakonzentration des entzündungslösenden LM Resolvin D1 in CC konnte dem inflammatorischen Zustand nicht entgegenwirken und die Ergebnisse deuten darauf hin, dass inflammatorische Cytokine in die Synthesewege von entzündungslösenden LM eingreifen. Zusammenfassend demonstrieren die Daten das komplexe Zusammenspiel zwischen verschiedenen Geweben und Zelltypen, in dem Cytokine und Lipidverbindungen aus dem Blutkreislauf die Entzündung der Tumorkachexie durch selbst-verstärkende Mechanismen vorantreiben. N2 - A inflamação sistêmica é uma das características que marcam o diagnóstico da caquexia associada ao câncer. Entre as interações tumor-hospedeiro, o tecido adiposo branco contribui à inflamação, uma vez que ele sofre uma reorganização morfológica e lipólise, liberando ácidos graxos livres (AGLs), mediadores lipídicos (LMs) e citocinas pró-inflamatórias, que acentuam a ativação de vias de sinalização pró-inflamatória e o recrutamento de células do sistema imunológico para o tecido. O objetivo deste projeto foi investigar quais fatores inflamatórios sistêmicos estão envolvidos na inflamação do tecido adiposo e qual é a influência desses fatores sobre as enzimas envolvidas no metabolismo dos AGs ou LMs em indivíduos saudáveis (Controle), pacientes com câncer gastrointestinal com peso estável (WSC) e pacientes com câncer e caquexia (CC). Os resultados demonstraram que a resposta inflamatória sistêmica é diferente da resposta encontrada no tecido adiposo. A inflamação sistêmica dos pacientes com câncer e caquexia (CC) foi caracterizada por níveis circulantes mais elevados de ácidos graxos saturados (SFAs), tumor-necrosis-factor-α (TNF-α), Interleukin IL-6, IL-8 e proteina C-reativa (PCR), enquanto os níveis de ácidos graxos poliinsaturados (PUFAs), especialmente n3-PUFAs, foram menores em CC que nos demais grupos. In vitro e em explantes de tecido adiposo, citocinas pró-inflamatórias e SFAs aumentaram a expressão das quimiocinas IL-8 e CXCL10. E tambêm observamos um aumento na expressão destas quimiocinas na inflamação do tecido adiposo no CC, que era mais profundo no tecido adiposo visceral (VAT) quando comparado ao tecido adiposo subcutâneo (SAT). A inflamação sistêmica foi negativamente associada com a expressão de enzimas sintetizadoras dos PUFAs, embora a expressão gênica e protéica mostraram somente pequenas diferencias entre os grupos. Os efeitos dos fatores inflamatórios sobre as enzimas no tecido adiposo podem ter sido mascarados pela modulação diferenciada dos diversos tipos celulares constituintes desse tecido. Experimentos in vitro mostraram que a expressão de enzimas que modificam os AGs, tais como as dessaturases e elongases em adipócitos e macrófagos, foram reguladas em direções opostas por TNF-α, IL-6, LPS e palmitato. Mesmo os pacientes CC demonstrando uma maior concentração plasmática da Resolvina D1, que é um mediador lipídico de resolução da inflamação, ainda assim, a inflamação sistêmica é maior nesses pacientes, e os resultados indicam que as citoquinas inflamatórias interferem com as vias de síntese das LMs da resolução. Concluímos que, os dados revelaram um crosstalk inter-tecidual e intercelular complexo mediado por citocinas pró-inflamatórias e compostos lipídicos que aumentam a inflamação na caquexia associada ao câncer por mecanismos autoregulação. KW - cancer cachexia KW - inflammation KW - adipose tissue KW - cytokines KW - chemokines KW - SFA KW - PUFA Y1 - 2018 ER - TY - BOOK A1 - Skopeteas, Stavros A1 - Fiedler, Ines A1 - Hellmuth, Sam A1 - Schwarz, Anne A1 - Stoel, Ruben A1 - Fanselow, Gisbert A1 - Féry, Caroline A1 - Krifka, Manfred T1 - Questionnaire on information structure (OUIS): reference manual N2 - Contents: Chapter 1. Introduction 1 Information Structure 2 Grammatical Correlates of Information Structure 3 Structure of the Questionnaire 4 Experimental Tasks 5 Technicalities 6 Archiving 7 Acknowledgments Chapter 2. General Questions 1 General Information 2 Phonology 3 Morphology and Syntax Chapter 3. Experimental tasks 1 Changes (Given/New in Intransitives and Transitives) 2 Giving (Given/New in Ditransitives) 3 Visibility (Given/New, Animacy and Type/Token Reference) 4 Locations (Given/New in Locative Expressions) 5 Sequences (Given/New/Contrast in Transitives) 6 Dynamic Localization (Given/New in Dynamic Loc. Descriptions) 7 Birthday Party (Weight and Discourse Status) 8 Static Localization (Macro-Planning and Given/New in Locatives) 9 Guiding (Presentational Utterances) 10 Event Cards (All New) 11 Anima (Focus types and Animacy) 12 Contrast (Contrast in pairing events) 13 Animal Game (Broad/Narrow Focus in NP) 14 Properties (Focus on Property and Possessor) 15 Eventives (Thetic and Categorical Utterances) 16 Tell a Story (Contrast in Text) 17 Focus Cards (Selective, Restrictive, Additive, Rejective Focus) 18 Who does What (Answers to Multiple Constituent Questions) 19 Fairy Tale (Topic and Focus in Coherent Discourse) 20 Map Task (Contrastive and Selective Focus in Spontaneous Dialogue) 21 Drama (Contrastive Focus in Argumentation) 22 Events in Places (Spatial, Temporal and Complex Topics) 23 Path Descriptions (Topic Change in Narrative) 24 Groups (Partial Topic) 25 Connections (Bridging Topic) 26 Indirect (Implicational Topic) 27 Surprises (Subject-Topic Interrelation) 28 Doing (Action Given, Action Topic) 29 Influences (Question Priming) Chapter 4. Translation tasks 1 Basic Intonational Properties 2 Focus Translation 3 Topic Translation 4 Quantifiers Chapter 5. Information structure summary survey 1 Preliminaries 2 Syntax 3 Morphology 4 Prosody 5 Summary: Information structure Chapter 6. Performance of Experimental Tasks in the Field 1 Field sessions 2 Field Session Metadata 3 Informants’ Agreement T3 - Interdisciplinary studies on information structure : ISIS ; working papers of the SFB 632 - 4 Y1 - 2006 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-12413 SN - 978-3-939469-14-8 PB - Universitätsverlag Potsdam CY - Potsdam ER - TY - THES A1 - Ruch, Joël T1 - Volcano deformation analysis in the Lazufre area (central Andes) using geodetic and geological observations T1 - Vulkan Deformationsanalyse im Bereich Lazufre (Zentral-Anden) mit geodätischen und geologischen Beobachtungen N2 - Large-scale volcanic deformation recently detected by radar interferometry (InSAR) provides new information and thus new scientific challenges for understanding volcano-tectonic activity and magmatic systems. The destabilization of such a system at depth noticeably affects the surrounding environment through magma injection, ground displacement and volcanic eruptions. To determine the spatiotemporal evolution of the Lazufre volcanic area located in the central Andes, we combined short-term ground displacement acquired by InSAR with long-term geological observations. Ground displacement was first detected using InSAR in 1997. By 2008, this displacement affected 1800 km2 of the surface, an area comparable in size to the deformation observed at caldera systems. The original displacement was followed in 2000 by a second, small-scale, neighbouring deformation located on the Lastarria volcano. We performed a detailed analysis of the volcanic structures at Lazufre and found relationships with the volcano deformations observed with InSAR. We infer that these observations are both likely to be the surface expression of a long-lived magmatic system evolving at depth. It is not yet clear whether Lazufre may trigger larger unrest or volcanic eruptions; however, the second deformation detected at Lastarria and the clear increase of the large-scale deformation rate make this an area of particular interest for closer continuous monitoring. N2 - Vulkanische Deformationen in großem Maßstab, die mittels InSAR gemessen wurden, liefern neue Informationen und dadurch einen neuen Blickwinkel auf vulkan-tektonische Aktivitäten und das Verständnis von langlebigen, magmatischen Systemen. Die Destabilisierung eines solchen Systems in der Tiefe beeinflusst dauerhaft die Oberfläche durch Versatz des Bodens, magmatische Einflüsse und vulkanische Unruhen. Mit der Kombination aus kleinräumigem Bodenversatz gemessen mittels InSAR, numerischer Modellierung und langfristigen geologischen Beobachtungen, analysieren wir die Gegend um den Vulkan Lazufre in den Zentralanden, um die raumzeitliche Entwicklung der Region zu bestimmen. Bodenversatz wurde hierbei im Jahr 1997 mittels Radar-Interferrometrie (InSAR) gemessen, was eine Fläche von 1800 km² ausmacht, vergleichbar mit der Größe der Deformation des Kraters. Im Jahr 2000 wurde zusätzlich eine kleinräumige Deformation am Nachbarvulkan Lastarria entdeckt. Wir sehen räumliche als auch zeitliche Verbindungen zwischen der Deformation des Vulkans und vulkanischen Strukturen innerhalb der betroffenen Gegend. Wir folgern daraus, dass diese Beobachtungen der Ausdruck eines langlebigen, magmatischen Systems in der Tiefe an der Oberfläche sind. Es ist noch nicht klar, ob Lazufre größere vulkanische Unruhen, wie zum Beispiel Eruptionen auslösen könnte, aber die Deformation am Vulkan Lastarria und ein Anstieg der großräumigen Deformationsrate, machen diese Region interessant für eine zukünftige, kontinuierliche Überwachung. KW - Vulkan Verformung KW - InSAR KW - zentralen Anden KW - Spannungsfeld KW - volcano deformation KW - InSAR KW - central Andes KW - stress field Y1 - 2010 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-47361 ER - TY - BOOK A1 - Wist, Dominic A1 - Schaefer, Mark A1 - Vogler, Walter A1 - Wollowski, Ralf T1 - STG decomposition : internal communication for SI implementability N2 - STG decomposition is a promising approach to tackle the complexity problems arising in logic synthesis of speed independent circuits, a robust asynchronous (i.e. clockless) circuit type. Unfortunately, STG decomposition can result in components that in isolation have irreducible CSC conflicts. Generalising earlier work, it is shown how to resolve such conflicts by introducing internal communication between the components via structural techniques only. N2 - STG-Dekomposition ist ein bewährter Ansatz zur Bewältigung der Komplexitätsprobleme bei der Logiksynthese von SI (speed independent) Schaltungen – ein robuster asynchroner (d.h. ohne Taktsignal arbeitender digitaler) Schaltungstyp. Allerdings können dabei Komponenten mit irreduziblen CSC-Konflikten entstehen. Durch Verallgemeinerung früherer Arbeiten wird gezeigt, wie solche Konflikte durch Einführung interner Kommunikation zwischen den Komponenten gelöst werden können, und zwar ausschließlich durch Verwendung an der Graphenstruktur ansetzender Verfahren. T3 - Technische Berichte des Hasso-Plattner-Instituts für Digital Engineering an der Universität Potsdam - 32 KW - Asynchrone Schaltung KW - Petrinetz KW - Signalflankengraph (SFG oder STG) KW - STG-Dekomposition KW - speed independent KW - CSC KW - Controller-Resynthese KW - Asynchronous circuit KW - petri net KW - signal transition graph KW - STG decomposition KW - speed independent KW - CSC KW - control resynthesis Y1 - 2010 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-40786 SN - 978-3-86956-037-3 PB - Universitätsverlag Potsdam CY - Potsdam ER - TY - BOOK A1 - Bauckmann, Jana A1 - Leser, Ulf A1 - Naumann, Felix T1 - Efficient and exact computation of inclusion dependencies for data integration N2 - Data obtained from foreign data sources often come with only superficial structural information, such as relation names and attribute names. Other types of metadata that are important for effective integration and meaningful querying of such data sets are missing. In particular, relationships among attributes, such as foreign keys, are crucial metadata for understanding the structure of an unknown database. The discovery of such relationships is difficult, because in principle for each pair of attributes in the database each pair of data values must be compared. A precondition for a foreign key is an inclusion dependency (IND) between the key and the foreign key attributes. We present with Spider an algorithm that efficiently finds all INDs in a given relational database. It leverages the sorting facilities of DBMS but performs the actual comparisons outside of the database to save computation. Spider analyzes very large databases up to an order of magnitude faster than previous approaches. We also evaluate in detail the effectiveness of several heuristics to reduce the number of necessary comparisons. Furthermore, we generalize Spider to find composite INDs covering multiple attributes, and partial INDs, which are true INDs for all but a certain number of values. This last type is particularly relevant when integrating dirty data as is often the case in the life sciences domain - our driving motivation. T3 - Technische Berichte des Hasso-Plattner-Instituts für Digital Engineering an der Universität Potsdam - 34 KW - Metadatenentdeckung KW - Metadatenqualität KW - Schemaentdeckung KW - Datenanalyse KW - Datenintegration KW - metadata discovery KW - metadata quality KW - schema discovery KW - data profiling KW - data integration Y1 - 2010 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-41396 SN - 978-3-86956-048-9 PB - Universitätsverlag Potsdam CY - Potsdam ER - TY - RPRT A1 - Becker, Ralf E. T1 - General classification of social choice situations T2 - Finanzwissenschaftliche Diskussionsbeiträge N2 - An exhaustive and disjoint decomposition of social choice situations is derived in a general set theoretical framework using the new tools of the Lifted Pareto relation on the power set of social states representing a pre-choice comparison of choice option sets. The main result is the classification of social choice situations which include three types of social choice problems. First, we usually observe the common incompleteness of the Pareto relation. Second, a kind of non-compactness problem of a choice set of social states can be generated. Finally, both can be combined. The first problem root can be regarded as natural everyday dilemma of social choice theory whereas the second may probably be much more due to modeling technique implications. The distinction is enabled at a very general set theoretical level. Hence, the derived classification of social choice situations is applicable on almost every relevant economic model. T3 - Finanzwissenschaftliche Diskussionsbeiträge - 46 Y1 - 2004 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-9012 SN - 0948-7549 SN - 1864-1431 IS - 46 ER - TY - THES A1 - Dubinovska, Daria T1 - Optical surveys of AGN and their host galaxies T1 - Optische Durchmusterungen von aktiven Galaxienkernen und ihren Muttergalaxien N2 - This thesis rests on two large Active Galactic Nuclei (AGNs) surveys. The first survey deals with galaxies that host low-level AGNs (LLAGN) and aims at identifying such galaxies by quantifying their variability. While numerous studies have shown that AGNs can be variable at all wavelengths, the nature of the variability is still not well understood. Studying the properties of LLAGNs may help to understand better galaxy evolution, and how AGNs transit between active and inactive states. In this thesis, we develop a method to extract variability properties of AGNs. Using multi-epoch deep photometric observations, we subtract the contribution of the host galaxy at each epoch to extract variability and estimate AGN accretion rates. This pipeline will be a powerful tool in connection with future deep surveys such as PANSTARS. The second study in this thesis describes a survey of X-ray selected AGN hosts at redshifts z>1.5 and compares them to quiescent galaxies. This survey aims at studying environments, sizes and morphologies of star-forming high-redshift AGN hosts in the COSMOS Survey at the epoch of peak AGN activity. Between redshifts 1.51.5 to date. We analyzed the evolution of structural parameters of AGN and non-AGN host galaxies with redshift, and compared their disturbance rates to identify the more probable AGN triggering mechanism in the 43.5 1.5, um sie mit inaktiven Galaxien zu vergleichen. Ziel ist, bei sternbildenden, hochrotverschobenen AGN-Muttergalaxien aus der COSMOS-Durchmusterung die Umgebung, Grösse und Morphologie zum Zeitpunkt der stärksten AGN Aktivität zu studieren. Die COSMOS-HST/ACS-Photometrie untersucht den ultravioletten Spektralbereich von Muttergalaxien bei einer Rotverschiebung von 1.5 < z < 3.8, wo es sehr schwierig ist, den Flussbeitrag des AGN von dem der Muttergalaxie zu trennen. Dennoch gelang es uns, mittels zweidimensionaler Modellierung der Flächenhelligkeitprofile Struktureigenschaften für 249 AGN-Muttergalaxien aus der COSMOS-Durchmusterung abzuleiten. Dies ist für AGN-Muttergalaxien mit einer Rotverschiebung z > 1.5 die bislang grösste Stichprobe. Wir haben die Entwicklung der Strukturparameter mit der Rotverschiebung von AGN-Muttergalaxien und Galaxien ohne aktiven Kern analysiert und die Häufigkeit morphologischer Besonderheiten bei diesen beiden Gruppen miteinander verglichen, um die wahrscheinlichste Ursache für AGN-Aktivität für Galaxien im Roentgen-Leuchtkraft-Bereich von 43.5 374◦C and P > 221 bar) geothermal reservoir. The results of the systematic and large-scale (25 x 200 m) CO2 flux scouting survey proved to be a fast and flexible way to identify areas of anomalous degassing. Subsequent sampling with high resolution surveys revealed the actual extent and heterogenous pattern of anomalous degassing areas. They have been related to the internal fault hydraulic architecture and allowed to assess favourable structural settings for fluid flow such as fault intersections. Finally, areas of unknown structurally controlled permeability with a connection to the superhot geothermal reservoir have been determined, which represent promising targets for future geothermal exploration and development. In the second study, I introduce a novel monitoring approach by examining the variation of CO2 flux to monitor changes in the reservoir induced by fluid reinjection. For that reason, an automated, multi-chamber CO2 flux system was deployed across the damage zone of a major normal fault crossing the Los Humeros geothermal field. Based on the results of the CO2 flux scouting survey, a suitable site was selected that had a connection to the geothermal reservoir, as identified by hydrothermal CO2 degassing and hot ground temperatures (> 50 °C). The results revealed a response of gas emissions to changes in reinjection rates within 24 h, proving an active hydraulic communication between the geothermal reservoir and the earth surface. This is a promising monitoring strategy that provides nearly real-time and in-situ data about changes in the reservoir and allows to timely react to unwanted changes (e.g., pressure decline, seismicity). The third study presents results from the Aluto geothermal field in Ethiopia where an area-wide and multi-parameter analysis, consisting of measurements of CO2 flux, 222Rn, and 220Rn activity concentrations and ground temperatures was conducted to detect hidden permeable structures. 222Rn and 220Rn activity concentrations are evaluated as a complementary soil gas parameter to CO2 flux, to investigate their potential to understand tectono-volcanic degassing. The combined measurement of all parameters enabled to develop soil gas fingerprints, a novel visualization approach. Depending on the magnitude of gas emissions and their migration velocities the study area was divided in volcanic (heat), tectonic (structures), and volcano-tectonic dominated areas. Based on these concepts, volcano-tectonic dominated areas, where hot hydrothermal fluids migrate along permeable faults, present the most promising targets for future geothermal exploration and development in this geothermal field. Two of these areas have been identified in the south and south-east which have not yet been targeted for geothermal exploitation. Furthermore, two unknown areas of structural related permeability could be identified by 222Rn and 220Rn activity concentrations. Eventually, the fourth study presents a novel measurement approach to detect structural controlled CO2 degassing, in Ngapouri geothermal area, New Zealand. For the first time, the tunable diode laser (TDL) method was applied in a low-degassing geothermal area, to evaluate its potential as a geothermal exploration method. Although the sampling approach is based on profile measurements, which leads to low spatial resolution, the results showed a link between known/inferred faults and increased CO2 concentrations. Thus, the TDL method proved to be a successful in the determination of structural related permeability, also in areas where no obvious geothermal activity is present. Once an area of anomalous CO2 concentrations has been identified, it can be easily complemented by CO2 flux grid measurements to determine the extent and orientation of the degassing segment. With the results of this work, I was able to demonstrate the applicability of systematic and area-wide soil gas measurements for geothermal exploration and monitoring purposes. In particular, the combination of different soil gases using different measurement networks enables the identification and characterization of fluid-bearing structures and has not yet been used and/or tested as standard practice. The different studies present efficient and cost-effective workflows and demonstrate a hands-on approach to a successful and sustainable exploration and monitoring of geothermal resources. This minimizes the resource risk during geothermal project development. Finally, to advance the understanding of the complex structure and dynamics of geothermal systems, a combination of comprehensive and cutting-edge geological, geochemical, and geophysical exploration methods is essential. N2 - Zu den großen Herausforderungen bei der Erkundung und Nutzung geothermischer Ressourcen, gehören die strukturgeologische Charakterisierung eines geothermischen Systems sowie die Anwendung nachhaltiger Überwachungskonzepte, um Veränderungen im geothermischen Reservoir während der Förderung und/oder Injektion von Fluiden zu verstehen. Bei unzureichender Permeabilität des Reservoirgesteins stellen Verwerfungen und Kluftnetzwerke bevorzugte Bohrziele dar, da sie potentielle Wegsamkeiten für heiße und/oder kalte Fluide sind. Entlang dieser fluidführenden Strukturen können in vulkanisch-geothermischen Systemen auch erhebliche Mengen an Gasemissionen an der Erdoberfläche freigesetzt werden. Im Rahmen dieser Arbeit wurden verschiedene methodische Ansätze und Messkonzepte entwickelt und getestet, um die räumliche und zeitliche Variation verschiedener Bodengasparameter zu bestimmen und diese im Kontext struktureller Permeabilitäten zu interpretieren. Um das Potential der Bodengasanalytik als innovative geothermische Explorations- und Überwachungsmethode zu validieren, wurden die methodischen Ansätze auf drei verschiedene vulkanisch-geothermische Systeme angewendet. Diesbezüglich wurde für jeden Standort ein individueller Messansatz hinsichtlich der bekannten strukturgeologischen Merkmale und standortspezifischen Fragestellung entwickelt. Die erste Studie präsentiert Ergebnisse aus der kombinierten Messung des CO2-Flusses, der Bodentemperatur und der Analyse von Isotopenverhältnissen (δ13CCO2, 3He/4He), welche systematisch und flächendeckend in der geothermischen Produktionszone des Geothermalfeldes Los Humeros, Mexiko, gemessen wurden. Ziel war es, Bereiche mit einer Verbindung zum überkritischen (T > 374◦C and P > 221 bar) und bisher noch ungenutzten geothermischen Reservoir zu identifizieren. Das mit großem Punktabstand und systematisch generierte Messnetz (25 x 200 m) für die Bestimmung des CO2-Flusses erwies sich als schnelle und flexible Anwendung zur Identifizierung von Gebieten mit anomaler CO2-Entgasung. Basierend auf diesen Ergebnissen wurde anschließend mit geringeren Messabständen die genaue Ausdehnung und das heterogene Muster der anomalen Entgasungsgebiete aufgelöst. Dadurch war es möglich, die Entgasungsmuster mit der internen strukturgeologischen Heterogenität einzelner Störungssegmente in Verbindung zu bringen, wodurch Bereiche, die den Gasfluss besonders begünstigen, wie z.B. Störungsschnittpunkte, ermittelt werden konnten. Schließlich wurden vorher unbekannte, geothermisch interessante Bereiche, die eine erhöhte strukturelle Permeabilität aufweisen und eine Verbindung zum überkritischen Reservoir darstellen, identifiziert. Diese Bereiche gelten als besonders vielversprechend für die zukünftige geothermische Exploration und Entwicklung des Geothermalfeldes. In der zweiten Studie wird ein neuartiger Überwachungsansatz vorgestellt, bei dem kontinuierlich der CO2-Fluss gemessen wurde, um Veränderungen im Reservoir zu überwachen, die durch die Reinjektion von kaltem Thermalwasser verursacht werden. Zu diesem Zweck wurde ein automatisiertes Mehrkammer-CO2-Flusssystem innerhalb der Bruchzone einer Hauptstörung aufgebaut. Die Grundlage eines geeigneten Standortes wurde durch die Ergebnisse der CO2-Explorationsuntersuchungen gegeben. Es war von großer Wichtigkeit, dass der Standort eine Verbindung zum geothermischen Reservoir aufweist, erkennbar an hydrothermaler CO2-Entgasung und heißen Bodentemperaturen (> 50 °C). Die Ergebnisse zeigten ein Sinken der Gasemissionen als Reaktion auf Änderungen der Reinjektionsraten innerhalb von 24 h, was auf eine aktive hydraulische Kommunikation zwischen dem geothermischen Reservoir und der Erdoberfläche hinweist. Dies ist ein vielversprechende Methode, da nahezu in Echtzeit und in situ Daten über Veränderungen im Reservoir angezeigt werden und eine rechtzeitige Reaktion auf unerwünschte Veränderungen (z.B. Druckabfall, Seismizität) möglich ist. Die dritte Studie präsentiert Ergebnisse aus dem Aluto-Geothermiefeld in Äthiopien, bei dem eine flächendeckende, Multiparameter-Analyse, bestehend aus CO2-Fluss, 222Rn- und 220Rn-Aktivitätskonzentrationen und Bodentemperaturen durchgeführt wurde, um verborgene fluidführende Strukturen zu erkennen. Die 222Rn- und 220Rn-Aktivitätskonzentrationen wurden als ergänzende Bodengasparameter zum CO2-Fluss verwendet, um ihr Potenzial als zusätzliche Explorationsparameter zu bewerten. Die kombinierte Messung aller Parameter ermöglichte die Entwicklung von Bodengas Fingerabdrücken – ein neuartiger Visualisierungsansatz. Dadurch lässt sich in Abhängigkeit von der Menge an Gasemissionen und deren Fließgeschwindigkeiten das Untersuchungsgebiet in vulkanisch (Wärme), tektonisch (Strukturen) und vulkanischtektonisch dominierte Gebiete unterteilen. Basierend auf diesem Konzept stellen vulkanischtektonisch dominierte Gebiete die vielversprechendsten Ziele für die zukünftige geothermische Exploration und Entwicklung an diesem Standort dar, da hier heiße hydrothermale Fluide entlang durchlässiger Strukturen migrieren. Zwei solche, bisher nicht berücksichtigte Gebiete wurden im Süden und Südosten identifiziert. Darüber hinaus konnten zwei bisher unbekannte Gebiete mit strukturell bedingter Durchlässigkeit anhand der Aktivitätskonzentrationen von 222Rn und 220Rn identifiziert werden. Schließlich wird in der vierten Studie ein neuartiger Messansatz zum Nachweis der strukturbedingten CO2-Entgasung im geothermischen Gebiet Ngapouri, Neuseeland, vorgestellt. Zum ersten Mal wurde die Tunable-Diode-Laser-Methode (TDL) in einem geothermischen Gebiet mit geringer Entgasung angewandt, um ihr Potenzial als geothermische Explorationsmethode zu bewerten. Obwohl der Messansatz auf Profilmessungen basiert, was zu einer geringen räumlichen Auflösung führt, zeigen die Ergebnisse einen Zusammenhang zwischen bekannten und unbekannten Störungen sowie erhöhten CO2-Konzentrationen. Somit erwies sich die TDL-Methode bei der Bestimmung der strukturbedingten Permeabilität auch in solchen Gebieten als erfolgreich, in denen keine offensichtliche geothermische Aktivität vorhanden ist. Mit systematischen und kleinskaligen CO2-Fluss-Messungen, kann anschließend die räumliche Auflösung der Abschnitte eines Profils mit erhöhten CO2-Konzentrationen, verfeinert werden. Mit den Ergebnissen dieser Arbeit konnte ich die Anwendbarkeit systematischer und flächendeckender Bodengasmessungen für geothermische Explorations- und Überwachungszwecke nachweisen. Die Kombination von verschiedenen Bodengasen und deren Messung anhand verschiedener Messnetze ermöglicht die genaue Identifizierung und Charakterisierung fluidführender Strukturen und wurde bisher noch nicht standardmäßig eingesetzt und/oder erprobt. Mit den Ergebnissen der jeweiligen Studien werden effiziente und kostengünstige Arbeitsabläufe dargelegt, die einen praxisorientierten Ansatz zeigen, der zu einer erfolgreichen und nachhaltigen Exploration und Überwachung geothermischer Ressourcen beitragen kann. Letztlich wird somit das Ressourcenrisiko bei der geothermischen Projektentwicklung minimiert. Um das Verständnis der komplexen Struktur und Dynamik geothermischer Systeme voranzutreiben, ist schließlich eine Kombination aus innovativen und flächendeckenden geologischen, geochemischen und geophysikalischen Methoden unerlässlich. KW - geothermal exploration KW - gas geochemistry KW - structural geology KW - geothermal monitoring KW - Gasgeochemie KW - geothermische Exploration KW - geothermische Überwachung KW - Strukturgeologie Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-544039 ER - TY - THES A1 - Neuharth, Derek T1 - Evolution of divergent and strike-slip boundaries in response to surface processes T1 - Die Entwicklung divergenter und transversaler Plattengrenzen unter dem Einfluss von Erdoberflächenprozessen N2 - Plate tectonics describes the movement of rigid plates at the surface of the Earth as well as their complex deformation at three types of plate boundaries: 1) divergent boundaries such as rift zones and mid-ocean ridges, 2) strike-slip boundaries where plates grind past each other, such as the San Andreas Fault, and 3) convergent boundaries that form large mountain ranges like the Andes. The generally narrow deformation zones that bound the plates exhibit complex strain patterns that evolve through time. During this evolution, plate boundary deformation is driven by tectonic forces arising from Earth’s deep interior and from within the lithosphere, but also by surface processes, which erode topographic highs and deposit the resulting sediment into regions of low elevation. Through the combination of these factors, the surface of the Earth evolves in a highly dynamic way with several feedback mechanisms. At divergent boundaries, for example, tensional stresses thin the lithosphere, forcing uplift and subsequent erosion of rift flanks, which creates a sediment source. Meanwhile, the rift center subsides and becomes a topographic low where sediments accumulate. This mass transfer from foot- to hanging wall plays an important role during rifting, as it prolongs the activity of individual normal faults. When rifting continues, continents are eventually split apart, exhuming Earth’s mantle and creating new oceanic crust. Because of the complex interplay between deep tectonic forces that shape plate boundaries and mass redistribution at the Earth’s surface, it is vital to understand feedbacks between the two domains and how they shape our planet. In this study I aim to provide insight on two primary questions: 1) How do divergent and strike-slip plate boundaries evolve? 2) How is this evolution, on a large temporal scale and a smaller structural scale, affected by the alteration of the surface through erosion and deposition? This is done in three chapters that examine the evolution of divergent and strike-slip plate boundaries using numerical models. Chapter 2 takes a detailed look at the evolution of rift systems using two-dimensional models. Specifically, I extract faults from a range of rift models and correlate them through time to examine how fault networks evolve in space and time. By implementing a two-way coupling between the geodynamic code ASPECT and landscape evolution code FastScape, I investigate how the fault network and rift evolution are influenced by the system’s erosional efficiency, which represents many factors like lithology or climate. In Chapter 3, I examine rift evolution from a three-dimensional perspective. In this chapter I study linkage modes for offset rifts to determine when fast-rotating plate-boundary structures known as continental microplates form. Chapter 4 uses the two-way numerical coupling between tectonics and landscape evolution to investigate how a strike-slip boundary responds to large sediment loads, and whether this is sufficient to form an entirely new type of flexural strike-slip basin. N2 - Plattentektonik beschreibt die Bewegung starrer tektonischer Platten an der Erdoberfläche sowie deren komplexe Deformation an drei Arten von Plattengrenzen: 1) divergenten Grenzen wie Grabenbrüchen und mittelozeanische Rücken, 2) transversalen Grenzen, an denen Platten gegeneinander verschoben werden, wie die San-Andreas-Verwerfung, und 3) konvergenten Grenzen, die große Gebirgszüge wie die Anden bilden. Diese schmalen Deformationszonen, die Platten begrenzen, weisen meist komplexe Dehnungsmuster auf, die sich im Laufe der Zeit entwickeln. Während dieser Entwicklung wird die Verformung der Plattengrenzen durch tektonische Kräfte aus dem tiefen Erdinneren und der Lithosphäre, aber auch durch Oberflächenprozesse, welche topografische Erhebungen erodieren und die daraus resultierenden Sedimente in tiefer gelegenen Gebieten ablagern, angetrieben. Durch das Zusammenwirken und die Rückkopplung dieser Faktoren entwickelt sich die Erdoberfläche in einer extrem dynamischen Art und Weise. An divergenten Grenzen beispielsweise dünnen Zugspannungen die Lithosphäre aus, was zu einer Hebung und anschließenden Erosion der Flanken eines Grabenbruchs führt, wobei wiederum Sedimente freigesetzt werden. Währenddessen sinkt das Zentrum des Grabens ab und wird zu einer topografischen Senke, in der sich Sedimente ablagern. Diese Massenumverteilung vom Fuß zum Hang einer Verwerfung spielt eine wichtige Rolle, da er die Aktivität einzelner Verwerfungen verlängert. Durch anhaltende Divergenz werden Kontinente schließlich auseinandergerissen, wodurch der Erdmantel an die Erdoberfläche gefördert und neue ozeanische Kruste gebildet wird. Aufgrund des komplexen Zusammenspiels zwischen tektonischen Kräften aus dem tiefen Erdinneren und der Massenumverteilung an der Erdoberfläche ist es von entscheidender Bedeutung, die Rückkopplungen zwischen diesen beiden Bereichen zu verstehen. In dieser Studie möchte ich Einblicke zu zwei Hauptfragen geben: 1) Wie entwickeln sich divergierende Plattengrenzen? 2) Wie wird diese Entwicklung auf einer großen zeitlichen und einer kleinen strukturellen Skala durch die Veränderung der Oberfläche durch Erosion und Sedimentation beeinflusst? In drei Kapiteln untersuche ich die Entwicklung von divergenten und streichenden Plattengrenzen anhand numerischer Modelle. In Kapitel 2 wird die Entwicklung von Grabenbrüchen anhand zweidimensionaler Modelle im Detail erforscht. Dabei extrahiere ich Verwerfungen aus einer Reihe von Modellen und korreliere sie über die Zeit, um zu untersuchen, wie sich Verwerfungsnetzwerke räumlich und zeitlich entwickeln. Durch die bidirektionale Kopplung des Geodynamik-Codes ASPECT und des Erdoberflächen-Codes FastScape untersuche ich, wie diese Verwerfungsnetzwerk und der Grabenbruch im Allgemeinen durch die Erosionseffizienz des Systems, welche viele Faktoren wie Lithologie oder Klima abbildet, beeinflusst werden. In Kapitel 3 untersuche ich die Entwicklung eines Grabenbruchs aus einer dreidimensionalen Perspektive. In diesem Kapitel analysiere ich wie sich gegeneinander versetzte Grabenbrüche verbinden und wann sich dabei schnell rotierende kontinentale Mikroplatten bilden. In Kapitel 4 nutze ich die entwickelte bidirektionale Kopplung zwischen Geodynamik und Erdoberflächenprozessen, um zu verstehen, wie transversale Plattengrenzen auf Sedimentlasten reagieren und ob die ausreicht, um einen völlig neue Art von Sedimentbecken in dieser Umgebung zu formen. KW - geodynamics KW - numerical modelling KW - rift KW - strike-slip KW - surface processes KW - microplate KW - FastScape KW - ASPECT KW - ASPECT KW - FastScape KW - Geodynamik KW - Mikroplatte KW - numerische Modellierung KW - Rift KW - Blattverschiebung KW - Oberflächenprozesse Y1 - 2022 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-549403 ER - TY - THES A1 - Werhahn, Maria T1 - Simulating galaxy evolution with cosmic rays: the multi-frequency view T1 - Galaxienentwicklung in Simulationen mit komischer Strahlung und deren Strahlungsprozessen N2 - Cosmic rays (CRs) constitute an important component of the interstellar medium (ISM) of galaxies and are thought to play an essential role in governing their evolution. In particular, they are able to impact the dynamics of a galaxy by driving galactic outflows or heating the ISM and thereby affecting the efficiency of star-formation. Hence, in order to understand galaxy formation and evolution, we need to accurately model this non-thermal constituent of the ISM. But except in our local environment within the Milky Way, we do not have the ability to measure CRs directly in other galaxies. However, there are many ways to indirectly observe CRs via the radiation they emit due to their interaction with magnetic and interstellar radiation fields as well as with the ISM. In this work, I develop a numerical framework to calculate the spectral distribution of CRs in simulations of isolated galaxies where a steady-state between injection and cooling is assumed. Furthermore, I calculate the non-thermal emission processes arising from the modelled CR proton and electron spectra ranging from radio wavelengths up to the very high-energy gamma-ray regime. I apply this code to a number of high-resolution magneto-hydrodynamical (MHD) simulations of isolated galaxies, where CRs are included. This allows me to study their CR spectra and compare them to observations of the CR proton and electron spectra by the Voyager-1 satellite and the AMS-02 instrument in order to reveal the origin of the measured spectral features. Furthermore, I provide detailed emission maps, luminosities and spectra of the non-thermal emission from our simulated galaxies that range from dwarfs to Milk-Way analogues to starburst galaxies at different evolutionary stages. I successfully reproduce the observed relations between the radio and gamma-ray luminosities with the far-infrared (FIR) emission of star-forming (SF) galaxies, respectively, where the latter is a good tracer of the star-formation rate. I find that highly SF galaxies are close to the limit where their CR population would lose all of their energy due to the emission of radiation, whereas CRs tend to escape low SF galaxies more quickly. On top of that, I investigate the properties of CR transport that are needed in order to match the observed gamma-ray spectra. Furthermore, I uncover the underlying processes that enable the FIR-radio correlation (FRC) to be maintained even in starburst galaxies and find that thermal free-free-emission naturally explains the observed radio spectra in SF galaxies like M82 and NGC 253 thus solving the riddle of flat radio spectra that have been proposed to contradict the observed tight FRC. Lastly, I scrutinise the steady-state modelling of the CR proton component by investigating for the first time the influence of spectrally resolved CR transport in MHD simulations on the hadronic gamma-ray emission of SF galaxies revealing new insights into the observational signatures of CR transport both spectrally and spatially. N2 - Kosmische Strahlung (CR) ist ein essentieller Bestandteil des interstellaren Mediums (ISM) von Galaxien und spielt eine wichtige Rolle in deren Entwicklung. Insbesondere ist sie in der Lage, die Dynamik einer Galaxie zu beeinflussen, indem sie galaktische Ausflüsse treibt oder das ISM aufheizt und sich dadurch auf die Effizienz der Sternentstehung auswirkt. Um Galaxienentstehung zu verstehen ist es daher notwendig, diesen nicht-thermischen Bestandteil des ISM genau zu modellieren. Aber außerhalb unserer lokalen Umgebung innerhalb der Milchstraße haben wir keine Möglichkeit, um CRs in anderen Galaxien direkt zu messen. Allerdings gibt es viele Möglichkeiten, CRs indirekt über die Strahlung zu beobachten, die sie auf Grund ihrer Interaktion mit Magnetfeldern und interstellarer Strahlung sowie mit dem ISM emittieren. In dieser Arbeit habe ich einen numerischen Code entwickelt, der die spektrale Verteilung der CRs in Simulationen von isolierten Galaxien berechnet, wobei ein stationäres Verhältnis zwischen Injektion und Kühlen angenommen wird. Des Weiteren berechnet er die nicht-thermischen Strahlungsprozesse, die aus den modellierten CR Protonen- und Elektronenspektren hervorgehen. Diese reichen von Radiowellenlängen bis hin zu hochenergetischer Gammastrahlung. Ich wende diesen Code auf eine Vielzahl von hoch aufgelösten, magneto-hydrodynamischen Simulationen von isolierten Galaxien an, die CRs beinhalten. Das ermöglicht es mir, ihre CR Spektren zu untersuchen und mit Beobachtungen des Voyager-1 Satelliten sowie des AMS-02 Instruments von CR Protonen- und Elektronenspektren zu vergleichen, um dem Ursprung von den gemessenen spektralen Besonderheiten nachzugehen. Außerdem lege ich detaillierte Emissionskarten, Leuchtkräfte und Spektren der nicht-thermischen Strahlung unserer simulierten Galaxien vor, die von Zwerggalaxien über Milchstraßen-ähnliche Galaxien bis hin zu Starburst-Galaxien bei verschiedensten Entwicklungsstadien reichen. Damit kann ich erfolgreich die beobachteten Zusammenhänge zwischen jeweils der Radio- und Gammastrahlungsleuchtkraft mit der Ferninfrarot (FIR) Strahlung der sternbildenden Galaxien reproduzieren, wobei die FIR Strahlung ein guter Indikator für die Rate der Sternentstehung ist. Dabei finde ich heraus, dass Galaxien mit einer hohen Rate an Sternentstehung sehr nah an dem Limit sind, in dem ihre CR Population all ihre Energie an die Produktion von Strahlung verlieren würde, während CRs dazu tendieren, Galaxien mit einer niedrigen Sternentstehungsrate schneller zu verlassen. Zusätzlich untersuche ich die Eigenschaften des Transports von CRs, die benötigt werden, um die beobachteten Spektren der Gammastrahlung zu reproduzieren. Außerdem decke ich die zugrundeliegenden physikalischen Prozesse auf, durch die die Korrelation zwischen der FIR- und Radioleuchtkraft auch in Starburst-Galaxien aufrecht erhalten werden kann und finde heraus, dass die thermische Emission natürlicherweise die beobachteten Radiospektren in Galaxien wie M82 und NGC 253 erklärt, wodurch sich das Rätsel der flachen Radiospektren löst, die scheinbar im Widerspruch zum beobachteten engen Zusammenhang zwischen der FIR- und Radioleuchtkraft standen. Zuletzt hinterfrage ich die Annahme eines stationären Zustandes bei der Modellierung der CR Protonenspektren, indem ich zum ersten Mal den Einfluss von spektral aufgelöstem Transport von CR Protonen in magneto-hydrodynamischen Simulationen auf die hadronische Gammastrahlung von sternbildenden Galaxien untersuche, was neue Einblicke in beobachtbare Signaturen, sowohl spektral als auch räumlich, von CR-Transport ermöglicht. KW - galaxies KW - cosmic rays KW - numerical astrophysics KW - kosmische Strahlung KW - Galaxien KW - numerische Astrophysik Y1 - 2023 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-572851 ER - TY - THES A1 - Michalik-Onichimowska, Aleksandra T1 - Real-time monitoring of (photo)chemical reactions in micro flow reactors and levitated droplets by IR-MALDI ion mobility and mass spectrometry N2 - Eine nachhaltigere chemische Industrie erfordert eine Minimierung der Lösungsmittel und Chemikalien. Daher werden Optimierung und Entwicklung chemischer Prozesse vor einer Produktion in großem Maßstab in kleinen Chargen durchgeführt. Der entscheidende Schritt bei diesem Ansatz ist die Skalierbarkeit von kleinen Reaktionssystemen auf große, kosteneffiziente Reaktoren. Die Vergrößerung des Volumens des Reaktionsmediums geht immer mit der Vergrößerung der Oberfläche einher, die mit dem begrenzenden Gefäß in Kontakt steht. Da das Volumen kubisch, während die Oberfläche quadratisch mit zunehmendem Radius skaliert, nimmt ihr Verhältnis nicht linear zu. Viele an der Grenzfläche zwischen Oberfläche und Flüssigkeit auftretende Phänomene können die Reaktionsgeschwindigkeiten und Ausbeuten beeinflussen, was zu falschen Prognosen aufgrund der kleinskaligen Optimierung führt. Die Anwendung von schwebenden Tropfen als behälterlose Reaktionsgefäße bietet eine vielversprechende Möglichkeit, die oben genannten Probleme zu vermeiden. In der vorgestellten Arbeit wurde eine effiziente Kopplung von akustisch schwebenden Tropfen und IM Spektrometer für die Echtzeitüberwachung chemischer Reaktionen entwickelt, bei denen akustisch schwebende Tropfen als Reaktionsgefäße fungieren. Das Design des Systems umfasst die berührungslose Probenahme und Ionisierung, die durch Laserdesorption und -ionisation bei 2,94 µm realisiert wird. Der Umfang der Arbeit umfasst grundlegende Studien zum Verständnis der Laserbestrahlung von Tropfen im akustischen Feld. Das Verständnis dieses Phänomens ist entscheidend, um den Effekt der zeitlichen und räumlichen Auflösung der erzeugten Ionenwolke zu verstehen, die die Auflösung des Systems beeinflusst. Der Aufbau umfasst eine akustische Falle, Laserbestrahlung und elektrostatische Linsen, die bei hoher Spannung unter Umgebungsdruck arbeiten. Ein effektiver Ionentransfer im Grenzflächenbereich zwischen dem schwebenden Tropfen und dem IMS muss daher elektrostatische und akustische Felder vollständig berücksichtigen. Für die Probenahme und Ionisation wurden zwei unterschiedliche Laserpulslängen untersucht, nämlich im ns- und µs-Bereich. Die Bestrahlung über µs-Laserpulse bietet gegenüber ns-Pulse mehrere Vorteile: i) das Tropfenvolumen wird nicht stark beeinflusst, was es ermöglichet, nur ein kleines Volumen des Tropfens abzutasten; ii) die geringere Fluenz führt zu weniger ausgeprägten Schwingungen des im akustischen Feld eingeschlossenen Tropfens und der Tropfen wird nicht aus dem akustischen Feld rückgeschlagen, was zum Verlust der Probe führen würde; iii) die milde Laserbestrahlung führt zu einer besseren räumlichen und zeitlichen Begrenzung der Ionenwolken, was zu einer besseren Auflösung der detektierten Ionenpakete führt. Schließlich ermöglicht dieses Wissen die Anwendung der Ionenoptik, die erforderlich ist, um den Ionenfluss zwischen dem im akustischen Feld suspendierten Tropfen und dem IM Spektrometer zu induzieren. Die Ionenoptik aus 2 elektrostatischen Linsen in der Nähe des Tropfens ermöglicht es, die Ionenwolke effektiv zu fokussieren und direkt zum IM Spektrometer-Eingang zu führen. Diese neuartige Kopplung hat sich beim Nachweis einiger basischer Moleküle als erfolgreich erwiesen. Um die Anwendbarkeit des Systems zu belegen, wurde die Reaktion zwischen N-Boc Cysteine Methylester und Allylalkohol in einem Chargenreaktor durchgeführt und online überwacht. Für eine Kalibrierung wurde der Reaktionsfortschritt parallel mittels 1H-NMR verfolgt. Der beobachtete Reaktionsumsatz von mehr als 50% innerhalb der ersten 20 Minuten demonstrierte die Eignung der Reaktion, um die Einsatzpotentiale des entwickelten Systems zu bewerten. N2 - One aspect of achieving a more sustainable chemical industry is the minimization of the usage of solvents and chemicals. Thus, optimization and development of chemical processes for large-scale production is favourably performed in small batches. The critical step in this approach is upscaling the batches from the small reaction systems to the large reactors mandatory for cost efficient production in an industrial environment. Scaling up the bulk volume always goes along with increasing the surface where the reaction medium is in contact with the confining vessel. Since volume scales proportional with the cubic dimension while the surface scales quadratic, their ratio is size-dependent. The influence of reaction vessel walls can change the reaction performance. A number of phenomena occurring at the surface-liquid interface can affect reaction rates and yields, resulting in possible difficulties in predicting and extrapolating from small size production scale to large industrial processes. The application of levitated droplets as a containerless reaction vessels provides a promising possibility to avoid the above-mentioned issues. In the presented work, an efficient coupling of acoustically levitated droplets to an ion mobility (IM) spectrometer, operating at ambient conditions, was designed for real-time monitoring of chemical reactions. The design of the system comprises noncontact sampling and ionization of the droplet realised by laser desorption/ionization at 2,94 µm. The scope of the work includes fundamental studies covering understanding of laser irradiation of droplets enclosed in an acoustical field. Understanding of this phenomenon is crucial to comprehending the effects of temporal and spatial resolution of the generated ion plume that influence the resolution of the system. The set-up includes an acoustic trap, laser irradiation and ion manipulation electrostatic lenses operating at high voltage at ambient pressure. The complexity of the design needs to fully be considered for an effective ion transfer at the interface region between the levitated droplet and IM spectrometer. For sampling and ionization, two distinct laser pulse lengths were evaluated, ns and µs. Irradiation via µs laser pulses provides several advantages: i) the droplet volume is not extensively impinged, as in case of ns laser pulses, allowing the sampling of only the small volume of the droplet; ii) the lower fluence results in less pronounced oscillations of the droplet confined in the acoustic field. The droplet will not be dissipated out of the acoustic field leading to loss of the sample; iii) the mild laser irradiation results in better spatial and temporal ion plume confinement, leading to better resolution of the detected ion packets. Finally, this knowledge allows the application of ion optics necessary to induce ion flow between the droplet suspended in the acoustic field and the IM spectrometer. The ion optics, composed of 2 electrostatic lenses placed in the near vicinity of the droplet, allow effective focusing of the ion plume and its redirection directly to the IM spectrometer entrance. This novel coupling has proved to be successful for detection of some simple molecules ionizable at the 2.94 µm wavelength. To further demonstrate the applicability of the system, a proof-of-principle reaction was selected, fulfilling the requirements of the system, and was subjected to comprehensive investigation of its performance. Herein, the reaction between N-Boc cysteine methyl ester and allyl alcohol has been performed in a batch reactor and on-line monitored via 1H NMR to establish reaction propagation. With the additional assessment, it was confirmed that the thiol-ene coupling can be performed within first 20 minutes of the irradiation with a reaction yield above 50%, proving that the reaction can be applied as a study case to assess the possibilities of the developed system. T2 - Echtzeit-Überwachung von (Photo)chemischen Reaktionen in Mikroströmungsreaktoren und schwebenden Tropfen durch IR-MALDI Ionenmoblität- und Massenspektrometrie KW - ion mobility spectrometry KW - mass spectrometry KW - acoustically levitated droplets KW - photochemical reactions KW - akustisch schwebende Tropfen KW - Ionenmobilitätspektrometrie KW - Massenspektrometrie KW - Photochemische Reaktionen Y1 - 2022 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-557298 ER -