@phdthesis{Schaefer2019, author = {Sch{\"a}fer, Merlin}, title = {Understanding and predicting global change impacts on migratory birds}, doi = {10.25932/publishup-43925}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-439256}, school = {Universit{\"a}t Potsdam}, pages = {XIV, 153}, year = {2019}, abstract = {This is a publication-based dissertation comprising three original research stud-ies (one published, one submitted and one ready for submission; status March 2019). The dissertation introduces a generic computer model as a tool to investigate the behaviour and population dynamics of animals in cyclic environments. The model is further employed for analysing how migratory birds respond to various scenarios of altered food supply under global change. Here, ecological and evolutionary time-scales are considered, as well as the biological constraints and trade-offs the individual faces, which ultimately shape response dynamics at the population level. Further, the effect of fine-scale temporal patterns in re-source supply are studied, which is challenging to achieve experimentally. My findings predict population declines, altered behavioural timing and negative carry-over effects arising in migratory birds under global change. They thus stress the need for intensified research on how ecological mechanisms are affected by global change and for effective conservation measures for migratory birds. The open-source modelling software created for this dissertation can now be used for other taxa and related research questions. Overall, this thesis improves our mechanistic understanding of the impacts of global change on migratory birds as one prerequisite to comprehend ongoing global biodiversity loss. The research results are discussed in a broader ecological and scientific context in a concluding synthesis chapter.}, language = {en} } @phdthesis{SchulteOsseili2019, author = {Schulte-Osseili, Christine}, title = {Vom Monomer zum Glykopolymer}, doi = {10.25932/publishup-43216}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-432169}, school = {Universit{\"a}t Potsdam}, pages = {xiii, 149}, year = {2019}, abstract = {Glykopolymere sind synthetische und nat{\"u}rlich vorkommende Polymere, die eine Glykaneinheit in der Seitenkette des Polymers tragen. Glykane sind durch die Glykan-Protein-Wechselwirkung verantwortlich f{\"u}r viele biologische Prozesse. Die Beteiligung der Glykanen in diesen biologischen Prozessen erm{\"o}glicht das Imitieren und Analysieren der Wechselwirkungen durch geeignete Modellverbindungen, z.B. der Glykopolymere. Dieses System der Glykan-Protein-Wechselwirkung soll durch die Glykopolymere untersucht und studiert werden, um die spezifische und selektive Bindung der Proteine an die Glykopolymere nachzuweisen. Die Proteine, die in der Lage sind, Kohlenhydratstrukturen selektiv zu binden, werden Lektine genannt. In dieser Dissertationsarbeit wurden verschiedene Glykopolymere synthetisiert. Dabei sollte auf einen effizienten und kosteng{\"u}nstigen Syntheseweg geachtet werden. Verschiedene Glykopolymere wurden durch funktionalisierte Monomere mit verschiedenen Zuckern, wie z.B. Mannose, Laktose, Galaktose oder N-Acetyl-Glukosamin als funktionelle Gruppe, hergestellt. Aus diesen funktionalisierten Glykomonomeren wurden {\"u}ber ATRP und RAFT-Polymerisation Glykopolymere synthetisiert. Die erhaltenen Glykopolymere wurden in Diblockcopolymeren als hydrophiler Block angewendet und die Selbstassemblierung in w{\"a}ssriger L{\"o}sung untersucht. Die Polymere formten in w{\"a}ssriger L{\"o}sung Mizellen, bei denen der Zuckerblock an der Oberfl{\"a}che der Mizellen sitzt. Die Mizellen wurden mit einem hydrophoben Fluoreszenzfarbstoff beladen, wodurch die CMC der Mizellenbildung bestimmt werden konnte. Außerdem wurden die Glykopolymere als Oberfl{\"a}chenbeschichtung {\"u}ber „Grafting from" mit SI-ATRP oder {\"u}ber „Grafting to" auf verschiedene Oberfl{\"a}chen gebunden. Durch die glykopolymerbschichteten Oberfl{\"a}chen konnte die Glykan Protein Wechselwirkung {\"u}ber spektroskopische Messmethoden, wie SPR- und Mikroring Resonatoren untersucht werden. Hierbei wurde die spezifische und selektive Bindung der Lektine an die Glykopolymere nachgewiesen und die Bindungsst{\"a}rke untersucht. Die synthetisierten Glykopolymere k{\"o}nnten durch Austausch der Glykaneinheit f{\"u}r andere Lektine adressierbar werden und damit ein weites Feld an anderen Proteinen erschließen. Die biovertr{\"a}glichen Glykopolymere w{\"a}ren alternativen f{\"u}r den Einsatz in biologischen Prozessen als Transporter von Medikamenten oder Farbstoffe in den K{\"o}rper. Außerdem k{\"o}nnten die funktionalisierten Oberfl{\"a}chen in der Diagnostik zum Erkennen von Lektinen eingesetzt werden. Die Glykane, die keine selektive und spezifische Bindung zu Proteinen eingehen, k{\"o}nnten als antiadsorptive Oberfl{\"a}chenbeschichtung z.B. in der Zellbiologie eingesetzt werden.}, language = {de} } @phdthesis{Schneider2019, author = {Schneider, Jan Niklas}, title = {Computational approaches for emotion research}, doi = {10.25932/publishup-45927}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-459275}, school = {Universit{\"a}t Potsdam}, pages = {xv, 145}, year = {2019}, abstract = {Emotionen sind ein zentrales Element menschlichen Erlebens und spielen eine wichtige Rolle bei der Entscheidungsfindung. Diese Dissertation identifiziert drei methodische Probleme der aktuellen Emotionsforschung und zeigt auf, wie diese mittels computergest{\"u}tzter Methoden gel{\"o}st werden k{\"o}nnen. Dieser Ansatz wird in drei Forschungsprojekten demonstriert, die die Entwicklung solcher Methoden sowie deren Anwendung auf konkrete Forschungsfragen beschreiben. Das erste Projekt beschreibt ein Paradigma welches es erm{\"o}glicht, die subjektive und objektive Schwierigkeit der Emotionswahrnehmung zu messen. Dar{\"u}ber hinaus erm{\"o}glicht es die Verwendung einer beliebigen Anzahl von Emotionskategorien im Vergleich zu den {\"u}blichen sechs Kategorien der Basisemotionen. Die Ergebnisse deuten auf eine Zunahme der Schwierigkeiten bei der Wahrnehmung von Emotionen mit zunehmendem Alter der Darsteller hin und liefern Hinweise darauf, dass junge Erwachsene, {\"a}ltere Menschen und M{\"a}nner ihre Schwierigkeit bei der Wahrnehmung von Emotionen untersch{\"a}tzen. Weitere Analysen zeigten eine geringe Relevanz personenbezogener Variablen und deuteten darauf hin, dass die Schwierigkeit der Emotionswahrnehmung vornehmlich durch die Auspr{\"a}gung der Wertigkeit des Ausdrucks bestimmt wird. Das zweite Projekt zeigt am Beispiel von Arousal, einem etablierten, aber vagen Konstrukt der Emotionsforschung, wie Face-Tracking-Daten dazu genutzt werden k{\"o}nnen solche Konstrukte zu sch{\"a}rfen. Es beschreibt, wie aus Face-Tracking-Daten Maße f{\"u}r die Entfernung, Geschwindigkeit und Beschleunigung von Gesichtsausdr{\"u}cken berechnet werden k{\"o}nnen. Das Projekt untersuchte wie diesen Maße mit der Arousal-Wahrnehmung in Menschen mit und ohne Autismus zusammenh{\"a}ngen. Der Abstand zum Neutralgesicht war pr{\"a}diktiv f{\"u}r die Arousal-Bewertungen in beiden Gruppen. Die Ergebnisse deuten auf eine qualitativ {\"a}hnliche Wahrnehmung von Arousal f{\"u}r Menschen mit und ohne Autismus hin. Im dritten Projekt stellen wir die Partial-Least-Squares-Analyse als allgemeine Methode vor, um eine optimale Repr{\"a}sentation zur Verkn{\"u}pfung zweier hochdimensionale Datens{\"a}tze zu finden. Das Projekt demonstriert die Anwendbarkeit dieser Methode in der Emotionsforschung anhand der Frage nach Unterschieden in der Emotionswahrnehmung zwischen M{\"a}nnern und Frauen. Wir konnten zeigen, dass die emotionale Wahrnehmung von Frauen systematisch mehr Varianz der Gesichtsausdr{\"u}cke erfasst und dass signifikante Unterschiede in der Art und Weise bestehen, wie Frauen und M{\"a}nner einige Gesichtsausdr{\"u}cke wahrnehmen. Diese konnten wir als dynamische Gesichtsausdr{\"u}cke visualisieren. Um die Anwendung der entwickelten Methode f{\"u}r die Forschungsgemeinschaft zu erleichtern, wurde ein Software-Paket f{\"u}r die Statistikumgebung R geschrieben. Zudem wurde eine Website entwickelt (thisemotiondoesnotexist.com), die es Besuchern erlaubt, ein Partial-Least-Squares-Modell von Emotionsbewertungen und Face-Tracking-Daten interaktiv zu erkunden, um die entwickelte Methode zu verbreiten und ihren Nutzen f{\"u}r die Emotionsforschung zu illustrieren.}, language = {en} } @phdthesis{Schmidt2019, author = {Schmidt, Martin}, title = {Fragmentation of landscapes: modelling ecosystem services of transition zones}, doi = {10.25932/publishup-44294}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-442942}, school = {Universit{\"a}t Potsdam}, pages = {XV, 103}, year = {2019}, abstract = {For millennia, humans have affected landscapes all over the world. Due to horizontal expansion, agriculture plays a major role in the process of fragmentation. This process is caused by a substitution of natural habitats by agricultural land leading to agricultural landscapes. These landscapes are characterized by an alternation of agriculture and other land use like forests. In addition, there are landscape elements of natural origin like small water bodies. Areas of different land use are beside each other like patches, or fragments. They are physically distinguishable which makes them look like a patchwork from an aerial perspective. These fragments are each an own ecosystem with conditions and properties that differ from their adjacent fragments. As open systems, they are in exchange of information, matter and energy across their boundaries. These boundary areas are called transition zones. Here, the habitat properties and environmental conditions are altered compared to the interior of the fragments. This changes the abundance and the composition of species in the transition zones, which in turn has a feedback effect on the environmental conditions. The literature mainly offers information and insights on species abundance and composition in forested transition zones. Abiotic effects, the gradual changes in energy and matter, received less attention. In addition, little is known about non-forested transition zones. For example, the effects on agricultural yield in transition zones of an altered microclimate, matter dynamics or different light regimes are hardly researched or understood. The processes in transition zones are closely connected with altered provisioning and regulating ecosystem services. To disentangle the mechanisms and to upscale the effects, models can be used. My thesis provides insights into these topics: literature was reviewed and a conceptual framework for the quantitative description of gradients of matter and energy in transition zones was introduced. The results of measurements of environmental gradients like microclimate, aboveground biomass and soil carbon and nitrogen content are presented that span from within the forest into arable land. Both the measurements and the literature review could not validate a transition zone of 100 m for abiotic effects. Although this value is often reported and used in the literature, it is likely to be smaller. Further, the measurements suggest that on the one hand trees in transition zones are smaller compared to those in the interior of the fragments, while on the other hand less biomass was measured in the arable lands' transition zone. These results support the hypothesis that less carbon is stored in the aboveground biomass in transition zones. The soil at the edge (zero line) between adjacent forest and arable land contains more nitrogen and carbon content compared to the interior of the fragments. One-year measurements in the transition zone also provided evidence that microclimate is different compared to the fragments' interior. To predict the possible yield decreases that transition zones might cause, a modelling approach was developed. Using a small virtual landscape, I modelled the effect of a forest fragment shading the adjacent arable land and the effects of this on yield using the MONICA crop growth model. In the transition zone yield was less compared to the interior due to shading. The results of the simulations were upscaled to the landscape level and exemplarily calculated for the arable land of a whole region in Brandenburg, Germany. The major findings of my thesis are: (1) Transition zones are likely to be much smaller than assumed in the scientific literature; (2) transition zones aren't solely a phenomenon of forested ecosystems, but significantly extend into arable land as well; (3) empirical and modelling results show that transition zones encompass biotic and abiotic changes that are likely to be important to a variety of agricultural landscape ecosystem services.}, language = {en} } @phdthesis{Schlenter2019, author = {Schlenter, Judith}, title = {Predictive language processing in late bilinguals}, doi = {10.25932/publishup-43249}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-432498}, school = {Universit{\"a}t Potsdam}, pages = {251}, year = {2019}, abstract = {The current thesis examined how second language (L2) speakers of German predict upcoming input during language processing. Early research has shown that the predictive abilities of L2 speakers relative to L1 speakers are limited, resulting in the proposal of the Reduced Ability to Generate Expectations (RAGE) hypothesis. Considering that prediction is assumed to facilitate language processing in L1 speakers and probably plays a role in language learning, the assumption that L1/L2 differences can be explained in terms of different processing mechanisms is a particularly interesting approach. However, results from more recent studies on the predictive processing abilities of L2 speakers have indicated that the claim of the RAGE hypothesis is too broad and that prediction in L2 speakers could be selectively limited. In the current thesis, the RAGE hypothesis was systematically put to the test. In this thesis, German L1 and highly proficient late L2 learners of German with Russian as L1 were tested on their predictive use of one or more information sources that exist as cues to sentence interpretation in both languages, to test for selective limits. The results showed that, in line with previous findings, L2 speakers can use the lexical-semantics of verbs to predict the upcoming noun. Here the level of prediction was more systematically controlled for than in previous studies by using verbs that restrict the selection of upcoming nouns to the semantic category animate or inanimate. Hence, prediction in L2 processing is possible. At the same time, this experiment showed that the L2 group was slower/less certain than the L1 group. Unlike previous studies, the experiment on case marking demonstrated that L2 speakers can use this morphosyntactic cue for prediction. Here, the use of case marking was tested by manipulating the word order (Dat > Acc vs. Acc > Dat) in double object constructions after a ditransitive verb. Both the L1 and the L2 group showed a difference between the two word order conditions that emerged within the critical time window for an anticipatory effect, indicating their sensitivity towards case. However, the results for the post-critical time window pointed to a higher uncertainty in the L2 group, who needed more time to integrate incoming information and were more affected by the word order variation than the L1 group, indicating that they relied more on surface-level information. A different cue weighting was also found in the experiment testing whether participants predict upcoming reference based on implicit causality information. Here, an additional child L1 group was tested, who had a lower memory capacity than the adult L2 group, as confirmed by a digit span task conducted with both learner groups. Whereas the children were only slightly delayed compared to the adult L1 group and showed the same effect of condition, the L2 speakers showed an over-reliance on surface-level information (first-mention/subjecthood). Hence, the pattern observed resulted more likely from L1/L2 differences than from resource deficits. The reviewed studies and the experiments conducted show that L2 prediction is affected by a range of factors. While some of the factors can be attributed to more individual differences (e.g., language similarity, slower processing) and can be interpreted by L2 processing accounts assuming that L1 and L2 processing are basically the same, certain limits are better explained by accounts that assume more substantial L1/L2 differences. Crucially, the experimental results demonstrate that the RAGE hypothesis should be refined: Although prediction as a fast-operating mechanism is likely to be affected in L2 speakers, there is no indication that prediction is the dominant source of L1/L2 differences. The results rather demonstrate that L2 speakers show a different weighting of cues and rely more on semantic and surface-level information to predict as well as to integrate incoming information.}, language = {en} } @phdthesis{Sarhan2019, author = {Sarhan, Radwan Mohamed}, title = {Plasmon-driven photocatalytic reactions monitored by surface-enhanced Raman spectroscopy}, doi = {10.25932/publishup-43330}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-433304}, school = {Universit{\"a}t Potsdam}, year = {2019}, abstract = {Plasmonic metal nanostructures can be tuned to efficiently interact with light, converting the photons into energetic charge carriers and heat. Therefore, the plasmonic nanoparticles such as gold and silver nanoparticles act as nano-reactors, where the molecules attached to their surfaces benefit from the enhanced electromagnetic field along with the generated energetic charge carriers and heat for possible chemical transformations. Hence, plasmonic chemistry presents metal nanoparticles as a unique playground for chemical reactions on the nanoscale remotely controlled by light. However, defining the elementary concepts behind these reactions represents the main challenge for understanding their mechanism in the context of the plasmonically assisted chemistry. Surface-enhanced Raman scattering (SERS) is a powerful technique employing the plasmon-enhanced electromagnetic field, which can be used for probing the vibrational modes of molecules adsorbed on plasmonic nanoparticles. In this cumulative dissertation, I use SERS to probe the dimerization reaction of 4-nitrothiophenol (4-NTP) as a model example of plasmonic chemistry. I first demonstrate that plasmonic nanostructures such as gold nanotriangles and nanoflowers have a high SERS efficiency, as evidenced by probing the vibrations of the rhodamine dye R6G and the 4-nitrothiophenol 4-NTP. The high signal enhancement enabled the measurements of SERS spectra with a short acquisition time, which allows monitoring the kinetics of chemical reactions in real time. To get insight into the reaction mechanism, several time-dependent SERS measurements of the 4-NTP have been performed under different laser and temperature conditions. Analysis of the results within a mechanistic framework has shown that the plasmonic heating significantly enhances the reaction rate, while the reaction is probably initiated by the energetic electrons. The reaction was shown to be intensity-dependent, where a certain light intensity is required to drive the reaction. Finally, first attempts to scale up the plasmonic catalysis have been performed showing the necessity to achieve the reaction threshold intensity. Meanwhile, the induced heat needs to quickly dissipate from the reaction substrate, since otherwise the reactants and the reaction platform melt. This study might open the way for further work seeking the possibilities to quickly dissipate the plasmonic heat generated during the reaction and therefore, scaling up the plasmonic catalysis.}, language = {en} } @phdthesis{Sablowski2019, author = {Sablowski, Daniel}, title = {Spectroscopic analysis of the benchmark system Alpha Aurigae}, doi = {10.25932/publishup-43239}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-432396}, school = {Universit{\"a}t Potsdam}, pages = {169}, year = {2019}, abstract = {Binaries play an important role in observational and theoretical astrophysics. Since the mass and the chemical composition are key ingredients for stellar evolution, high-resolution spectroscopy is an important and necessary tool to derive those parameters to high confidence in binaries. This involves carefully measured orbital motion by the determination of radial velocity (RV) shifts and sophisticated techniques to derive the abundances of elements within the stellar atmosphere. A technique superior to conventional cross-correlation methods to determine RV shifts in known as spectral disentangling. Hence, a major task of this thesis was the design of a sophisticated software package for this approach. In order to investigate secondary effects, such as flux and line-profile variations, imprinting changes on the spectrum the behavior of spectral disentangling on such variability is a key to understand the derived values, to improve them, and to get information about the variability itself. Therefore, the spectral disentangling code presented in this thesis and available to the community combines multiple advantages: separation of the spectra for detailed chemical analysis, derivation of orbital elements, derivation of individual RVs in order to investigate distorted systems (either by third body interaction or relativistic effects), the suppression of telluric contaminations, the derivation of variability, and the possibility to apply the technique to eclipsing binaries (important for orbital inclination) or in general to systems that undergo flux-variations. This code in combination with the spectral synthesis codes MOOG and SME was used in order to derive the carbon 12C/13C isotope ratio (CIR) of the benchmark binary Capella. The observational result will be set into context with theoretical evolution by the use of MESA models and resolves the discrepancy of theory and observations existing since the first measurement of Capella's CIR in 1976. The spectral disentangling code has been made available to the community and its applicability to completely different behaving systems, Wolf-Rayet stars, have also been investigated and resulted in a published article. Additionally, since this technique relies strongly on data quality, continues development of scientific instruments to achieve best observational data is of great importance in observational astrophysics. That is the reason why there has also been effort in astronomical instrumentation during the work on this thesis.}, language = {en} } @phdthesis{Ruschel2019, author = {Ruschel, Matthias}, title = {Das Preußische Erbrecht in der Judikatur des Berliner Obertribunals in den Jahren 1836 bis 1865}, doi = {10.25932/publishup-52779}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-527798}, school = {Universit{\"a}t Potsdam}, pages = {283}, year = {2019}, abstract = {Die Dissertation befasst sich mit dem Allgemeinen Preußischen Landrecht von 1794 und der hierzu ergangenen Rechtsprechung des Berliner Obertribunals. Im Fokus der Untersuchung stehen die erbrechtlichen Regelungen des Landrechts und deren Anwendung sowie Auslegung in der Judikatur des h{\"o}chsten preußischen Gerichts. Der Forschungsgegenstand ergibt sich aus dem im Landrecht kodifizierten speziellen Gesetzesverst{\"a}ndnisses. Nach diesem sollte die Gesetzesauslegung durch die Rechtsprechung auf ein Minimum, n{\"a}mlich die Auslegung allein anhand des Wortlauts der Regelung reduziert werden, um dem absolutistischen Regierungsanspruch der preußischen Monarchen, namentlich Friedrich des Großen, hinreichend Rechnung zu tragen. In diesem Kontext wird der Frage nachgegangen, inwieweit das preußische Obertribunal das im Landrecht statuierte „Auslegungsverbot" beachtet hat und in welchen F{\"a}llen sich das Gericht von der Vorgabe emanzipierte und weitere Auslegungsmethoden anwendete und sich so eine unabh{\"a}ngige Rechtsprechung entwickeln konnte. Die Arbeit gliedert sich in drei Hauptabschnitte. Im Anschluss an die Einleitung, in der zun{\"a}chst die rechtshistorische Bedeutung des Landrechts und des Erbrechts sowie der Untersuchungsgegenstand umrissen werden, folgt die Darstellung der Entstehungsgeschichte des Landrechts und des Berliner Obertribunals. Hieran schließt sich in einem dritten Abschnitt eine Analyse der erbrechtlichen Vorschriften des Landrechts an. In dieser wird auf die Entstehungsgeschichte der verschiedenen erbrechtlichen Institute wie beispielsweise der gesetzlichen und gewillk{\"u}rten Erbfolge, dem Pflichtteilsrecht etc., unter Ber{\"u}cksichtigung des zeitgen{\"o}ssischen wissenschaftlichen Diskurses eingegangen. Im vierten Abschnitt geht es um die Judikate des Berliner Obertribunals aus den Jahren 1836-1865 in denen die zuvor dargestellten erbrechtlichen Regelungen entscheidungserheblich waren. Dabei wird der Forschungsfrage, inwieweit das Obertribunal das im Landrecht statuierte Auslegungsverbot beachtet hat und in welchen F{\"a}llen es von diesem abwich bzw. weitere Auslegungsmethoden anwendete, konkret nachgegangen wird. Insgesamt werden 26 Entscheidungen des Obertribunals unter dem Aspekt der Auslegungspraxis, der Kontinuit{\"a}t und der Beschleunigung der Rechtsprechung analysiert und ausgewertet.}, language = {de} } @phdthesis{RomeroMujalli2019, author = {Romero Mujalli, Daniel}, title = {Ecological modeling of adaptive evolutionary responses to rapid climate change}, doi = {10.25932/publishup-43062}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-430627}, school = {Universit{\"a}t Potsdam}, pages = {167}, year = {2019}, abstract = {A contemporary challenge in Ecology and Evolutionary Biology is to anticipate the fate of populations of organisms in the context of a changing world. Climate change and landscape changes due to anthropic activities have been of major concern in the contemporary history. Organisms facing these threats are expected to respond by local adaptation (i.e., genetic changes or phenotypic plasticity) or by shifting their distributional range (migration). However, there are limits to their responses. For example, isolated populations will have more difficulties in developing adaptive innovations by means of genetic changes than interconnected metapopulations. Similarly, the topography of the environment can limit dispersal opportunities for crawling organisms as compared to those that rely on wind. Thus, populations of species with different life history strategy may differ in their ability to cope with changing environmental conditions. However, depending on the taxon, empirical studies investigating organisms' responses to environmental change may become too complex, long and expensive; plus, complications arising from dealing with endangered species. In consequence, eco-evolutionary modeling offers an opportunity to overcome these limitations and complement empirical studies, understand the action and limitations of underlying mechanisms, and project into possible future scenarios. In this work I take a modeling approach and investigate the effect and relative importance of evolutionary mechanisms (including phenotypic plasticity) on the ability for local adaptation of populations with different life strategy experiencing climate change scenarios. For this, I performed a review on the state of the art of eco-evolutionary Individual-Based Models (IBMs) and identify gaps for future research. Then, I used the results from the review to develop an eco-evolutionary individual-based modeling tool to study the role of genetic and plastic mechanisms in promoting local adaption of populations of organisms with different life strategies experiencing scenarios of climate change and environmental stochasticity. The environment was simulated through a climate variable (e.g., temperature) defining a phenotypic optimum moving at a given rate of change. The rate of change was changed to simulate different scenarios of climate change (no change, slow, medium, rapid climate change). Several scenarios of stochastic noise color resembling different climatic conditions were explored. Results show that populations of sexual species will rely mainly on standing genetic variation and phenotypic plasticity for local adaptation. Population of species with relatively slow growth rate (e.g., large mammals) - especially those of small size - are the most vulnerable, particularly if their plasticity is limited (i.e., specialist species). In addition, whenever organisms from these populations are capable of adaptive plasticity, they can buffer fitness losses in reddish climatic conditions. Likewise, whenever they can adjust their plastic response (e.g., bed-hedging strategy) they will cope with bluish environmental conditions as well. In contrast, life strategies of high fecundity can rely on non-adaptive plasticity for their local adaptation to novel environmental conditions, unless the rate of change is too rapid. A recommended management measure is to guarantee interconnection of isolated populations into metapopulations, such that the supply of useful genetic variation can be increased, and, at the same time, provide them with movement opportunities to follow their preferred niche, when local adaptation becomes problematic. This is particularly important for bluish and reddish climatic conditions, when the rate of change is slow, or for any climatic condition when the level of stress (rate of change) is relatively high.}, language = {en} } @phdthesis{Riemer2019, author = {Riemer, Janine}, title = {Synthese und Charakterisierung selektiver Fluoroionophore f{\"u}r intra- und extrazellul{\"a}re Bestimmungen von Kalium- und Natrium-Ionen}, doi = {10.25932/publishup-44193}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-441932}, school = {Universit{\"a}t Potsdam}, pages = {IV, 165}, year = {2019}, abstract = {Im Rahmen dieser Dissertation konnten neue Kalium- und Natrium-Ionen Fluoreszenzfarbstoffe von der Klasse der Fluoroionophore synthetisiert und charakterisiert werden. Sie bestehen aus einem N Phenylazakronenether als Ionophor und unterschiedlichen Fluorophoren und sind {\"u}ber einen π-konjugierten 1,2,3-Triazol-1,4-diyl Spacer verbunden. Dabei lag der Fokus w{\"a}hrend ihrer Entwicklung darauf, diese in ihrer Sensitivit{\"a}t, Selektivit{\"a}t und in ihren photophysikalischen Eigenschaften so zu funktionalisieren, dass sie f{\"u}r intra- bzw. extrazellul{\"a}re Konzentrationsbestimmungen geeignet sind. Durch Variation der in ortho Position der N-Phenylazakronenether befindlichen Alkoxy-Gruppen und der fluorophoren Gruppe der Fluoroionophore konnte festgestellt werden, dass die Sensitivit{\"a}t und Selektivit{\"a}t f{\"u}r Kalium- bzw. Natrium-Ionen jeweils durch eine bestimmte Isomerie der 1,2,3-Triazol-1,4-diyl-Einheit erh{\"o}ht wird. Des Weiteren wurde gezeigt, dass durch eine erh{\"o}hte Einschr{\"a}nkung der N,N-Diethylamino-Gruppe des Fluorophors eine Steigerung der Fluoreszenzquantenausbeute und eine Verschiebung des Emissionsmaximums auf {\"u}ber 500 nm erreicht werden konnte. Die Einf{\"u}hrung einer Isopropoxy-Gruppe an einem N-Phenylaza-[18]krone-6-ethers resultierte dabei in einem hoch selektiven Kalium-Ionen Fluoroionophor und erm{\"o}glichte eine in vitro {\"U}berwachung von 10 - 80 mM Kalium-Ionen. Die Substitution einer Methoxy-Gruppe an einem N-Phenylaza-[15]krone-5-ether kombiniert mit unterschiedlich N,N-Diethylamino-Coumarinen lieferte hingegen zwei Natrium-Ionen Fluoroionophore, die f{\"u}r die {\"U}berwachung von intra- bzw. extrazellul{\"a}ren Natrium-Ionen Konzentrationen geeignet sind. In einem weiteren Schritt wurden N-Phenylaza-[18]krone-6-ether mit einem Fluorophor, basierend auf einem [1,3]-Dioxolo[4,5-f][1,3]benzodioxol-(DBD)-Grundger{\"u}st, funktionalisiert. Die im Anschluss durchgef{\"u}hrten spektroskopischen Untersuchungen ergaben, dass die Isopropoxy-Gruppe in ortho Position des N-Phenylaza-[18]krone-6-ether in einen f{\"u}r extrazellul{\"a}re Kalium-Ionen Konzentrationen selektiven Fluoroionophor resultierte, der die Konzentrationsbestimmungen {\"u}ber die Fluoreszenzintensit{\"a}t und -lebensdauer erm{\"o}glicht. In einem abschließenden Schritt konnte unter Verwendung eines Pyrens als fluorophore Gruppe ein weiterer f{\"u}r extrazellul{\"a}re Kalium-Ionen Konzentrationen geeigneter Fluoroionophor entwickelt werden. Die Bestimmung der Kalium-Ionen Konzentration erfolgte hierbei anhand der Fluoreszenzintensit{\"a}tsverh{\"a}ltnisse bei zwei Emissionswellenl{\"a}ngen. Insgesamt konnten 17 verschiedene neue Fluoroionophore f{\"u}r die Bestimmung von Kalium- bzw. Natrium-Ionen synthetisiert und charakterisiert werden. Sechs dieser neuen Molek{\"u}le erm{\"o}glichen in vitro Messungen der intra- oder extrazellul{\"a}ren Kalium- und Natrium-Ionen Konzentrationen und k{\"o}nnten zuk{\"u}nftig f{\"u}r in vivo Konzentrationsmessungen verwendet werden.}, language = {de} } @phdthesis{Rezaei2019, author = {Rezaei, Mina}, title = {Deep representation learning from imbalanced medical imaging}, doi = {10.25932/publishup-44275}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-442759}, school = {Universit{\"a}t Potsdam}, pages = {xxviii, 160}, year = {2019}, abstract = {Medical imaging plays an important role in disease diagnosis, treatment planning, and clinical monitoring. One of the major challenges in medical image analysis is imbalanced training data, in which the class of interest is much rarer than the other classes. Canonical machine learning algorithms suppose that the number of samples from different classes in the training dataset is roughly similar or balance. Training a machine learning model on an imbalanced dataset can introduce unique challenges to the learning problem. A model learned from imbalanced training data is biased towards the high-frequency samples. The predicted results of such networks have low sensitivity and high precision. In medical applications, the cost of misclassification of the minority class could be more than the cost of misclassification of the majority class. For example, the risk of not detecting a tumor could be much higher than referring to a healthy subject to a doctor. The current Ph.D. thesis introduces several deep learning-based approaches for handling class imbalanced problems for learning multi-task such as disease classification and semantic segmentation. At the data-level, the objective is to balance the data distribution through re-sampling the data space: we propose novel approaches to correct internal bias towards fewer frequency samples. These approaches include patient-wise batch sampling, complimentary labels, supervised and unsupervised minority oversampling using generative adversarial networks for all. On the other hand, at algorithm-level, we modify the learning algorithm to alleviate the bias towards majority classes. In this regard, we propose different generative adversarial networks for cost-sensitive learning, ensemble learning, and mutual learning to deal with highly imbalanced imaging data. We show evidence that the proposed approaches are applicable to different types of medical images of varied sizes on different applications of routine clinical tasks, such as disease classification and semantic segmentation. Our various implemented algorithms have shown outstanding results on different medical imaging challenges.}, language = {en} } @phdthesis{Reeg2019, author = {Reeg, Jette}, title = {Simulating the impact of herbicide drift exposure on non-target terrestrial plant communities}, doi = {10.25932/publishup-42907}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-429073}, school = {Universit{\"a}t Potsdam}, pages = {178}, year = {2019}, abstract = {In Europe, almost half of the terrestrial landscape is used for agriculture. Thus, semi-natural habitats such as field margins are substantial for maintaining diversity in intensively managed farmlands. However, plants located at field margins are threatened by agricultural practices such as the application of pesticides within the fields. Pesticides are chemicals developed to control for undesired species within agricultural fields to enhance yields. The use of pesticides implies, however, effects on non-target organisms within and outside of the agricultural fields. Non-target organisms are organisms not intended to be sprayed or controlled for. For example, plants occurring in field margins are not intended to be sprayed, however, can be impaired due to herbicide drift exposure. The authorization of plant protection products such as herbicides requires risk assessments to ensure that the application of the product has no unacceptable effects on the environment. For non-target terrestrial plants (NTTPs), the risk assessment is based on standardized greenhouse studies on plant individual level. To account for the protection of plant populations and communities under realistic field conditions, i.e. extrapolating from greenhouse studies to field conditions and from individual-level to community-level, assessment factors are applied. However, recent studies question the current risk assessment scheme to meet the specific protection goals for non-target terrestrial plants as suggested by the European Food Safety Authority (EFSA). There is a need to clarify the gaps of the current risk assessment and to include suitable higher tier options in the upcoming guidance document for non-target terrestrial plants. In my thesis, I studied the impact of herbicide drift exposure on NTTP communities using a mechanistic modelling approach. I addressed main gaps and uncertainties of the current risk assessment and finally suggested this modelling approach as a novel higher tier option in future risk assessments. Specifically, I extended the plant community model IBC-grass (Individual-based community model for grasslands) to reflect herbicide impacts on plant individuals. In the first study, I compared model predictions of short-term herbicide impacts on artificial plant communities with empirical data. I demonstrated the capability of the model to realistically reflect herbicide impacts. In the second study, I addressed the research question whether or not reproductive endpoints need to be included in future risk assessments to protect plant populations and communities. I compared the consequences of theoretical herbicide impacts on different plant attributes for long-term plant population dynamics in the community context. I concluded that reproductive endpoints only need to be considered if the herbicide effect is assumed to be very high. The endpoints measured in the current vegetative vigour and seedling emergence studies had high impacts for the dynamic of plant populations and communities already at lower effect intensities. Finally, the third study analysed long-term impacts of herbicide application for three different plant communities. This study highlighted the suitability of the modelling approach to simulate different communities and thus detecting sensitive environmental conditions. Overall, my thesis demonstrates the suitability of mechanistic modelling approaches to be used as higher tier options for risk assessments. Specifically, IBC-grass can incorporate available individual-level effect data of standardized greenhouse experiments to extrapolate to community-level under various environmental conditions. Thus, future risk assessments can be improved by detecting sensitive scenarios and including worst-case impacts on non-target plant communities.}, language = {en} } @phdthesis{Rector2019, author = {Rector, Michael V.}, title = {The acute effect of exercise on flow-mediated dilation in young people with cystic fibrosis}, doi = {10.25932/publishup-43893}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-438938}, school = {Universit{\"a}t Potsdam}, pages = {121}, year = {2019}, abstract = {Introduction: Cystic fibrosis (CF) is a genetic disease which disrupts the function of an epithelial surface anion channel, CFTR (cystic fibrosis transmembrane conductance regulator). Impairment to this channel leads to inflammation and infection in the lung causing the majority of morbidity and mortality. However, CF is a multiorgan disease affecting many tissues, including vascular smooth muscle. Studies have revealed young people with cystic fibrosis lacking inflammation and infection still demonstrate vascular endothelial dysfunction, measured per flow-mediated dilation (FMD). In other disease cohorts, i.e. diabetic and obese, endurance exercise interventions have been shown improve or taper this impairment. However, long-term exercise interventions are risky, as well as costly in terms of time and resources. Nevertheless, emerging research has correlated the acute effects of exercise with its long-term benefits and advocates the study of acute exercise effects on FMD prior to longitudinal studies. The acute effects of exercise on FMD have previously not been examined in young people with CF, but could yield insights on the potential benefits of long-term exercise interventions. The aims of these studies were to 1) develop and test the reliability of the FMD method and its applicability to study acute exercise effects; 2) compare baseline FMD and the acute exercise effect on FMD between young people with and without CF; and 3) explore associations between the acute effects of exercise on FMD and demographic characteristics, physical activity levels, lung function, maximal exercise capacity or inflammatory hsCRP levels. Methods: Thirty young volunteers (10 people with CF, 10 non-CF and 10 non-CF active matched controls) between the ages of 10 and 30 years old completed blood draws, pulmonary function tests, maximal exercise capacity tests and baseline FMD measurements, before returning approximately 1 week later and performing a 30-min constant load training at 75\% HRmax. FMD measurements were taken prior, immediately after, 30 minutes after and 1 hour after constant load training. ANOVAs and repeated measures ANOVAs were employed to explore differences between groups and timepoints, respectively. Linear regression was implemented and evaluated to assess correlations between FMD and demographic characteristics, physical activity levels, lung function, maximal exercise capacity or inflammatory hsCRP levels. For all comparisons, statistical significance was set at a p-value of α < 0.05. Results: Young people with CF presented with decreased lung function and maximal exercise capacity compared to matched controls. Baseline FMD was also significantly decreased in the CF group (CF: 5.23\% v non-CF: 8.27\% v non-CF active: 9.12\%). Immediately post-training, FMD was significantly attenuated (approximately 40\%) in all groups with CF still demonstrating the most minimal FMD. Follow-up measurements of FMD revealed a slow recovery towards baseline values 30 min post-training and improvements in the CF and non-CF active groups 60 min post-training. Linear regression exposed significant correlations between maximal exercise capacity (VO2 peak), BMI and FMD immediately post-training. Conclusion: These new findings confirm that CF vascular endothelial dysfunction can be acutely modified by exercise and will aid in underlining the importance of exercise in CF populations. The potential benefits of long-term exercise interventions on vascular endothelial dysfunction in young people with CF warrants further investigation.}, language = {en} } @phdthesis{Ramachandran2019, author = {Ramachandran, Varsha}, title = {Massive star evolution, star formation, and feedback at low metallicity}, doi = {10.25932/publishup-43245}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-432455}, school = {Universit{\"a}t Potsdam}, pages = {291}, year = {2019}, abstract = {The goal of this thesis is to broaden the empirical basis for a better, comprehensive understanding of massive star evolution, star formation and feedback at low metallicity. Low metallicity massive stars are a key to understand the early universe. Quantitative information on metal-poor massive stars was sparse before. The quantitative spectroscopic studies of massive star populations associated with large-scale ISM structures were not performed at low metallicity before, but are important to investigate star-formation histories and feedback in detail. Much of this work relies on spectroscopic observations with VLT-FLAMES of ~500 OB stars in the Magellanic Clouds. When available, the optical spectroscopy was complemented by UV spectra from the HST, IUE, and FUSE archives. The two representative young stellar populations that have been studied are associated with the superbubble N 206 in the Large Magellanic Cloud (LMC) and with the supergiant shell SMC-SGS 1 in the Wing of the Small Magellanic Cloud (SMC), respectively. We performed spectroscopic analyses of the massive stars using the nonLTE Potsdam Wolf-Rayet (PoWR) model atmosphere code. We estimated the stellar, wind, and feedback parameters of the individual massive stars and established their statistical distributions. The mass-loss rates of N206 OB stars are consistent with theoretical expectations for LMC metallicity. The most massive and youngest stars show nitrogen enrichment at their surface and are found to be slower rotators than the rest of the sample. The N 206 complex has undergone star formation episodes since more than 30 Myr, with a current star formation rate higher than average in the LMC. The spatial age distribution of stars across the complex possibly indicates triggered star formation due to the expansion of the superbubble. Three very massive, young Of stars in the region dominate the ionizing and mechanical feedback among hundreds of other OB stars in the sample. The current stellar wind feedback rate from the two WR stars in the complex is comparable to that released by the whole OB sample. We see only a minor fraction of this stellar wind feedback converted into X-ray emission. In this LMC complex, stellar winds and supernovae equally contribute to the total energy feedback, which eventually powered the central superbubble. However, the total energy input accumulated over the time scale of the superbubble significantly exceeds the observed energy content of the complex. The lack of energy along with the morphology of the complex suggests a leakage of hot gas from the superbubble. With a detailed spectroscopic study of massive stars in SMC-SGS 1, we provide the stellar and wind parameters of a large sample of OB stars at low metallicity, including those in the lower mass-range. The stellar rotation velocities show a broad, tentatively bimodal distribution, with Be stars being among the fastest. A few very luminous O stars are found close to the main sequence, while all other, slightly evolved stars obey a strict luminosity limit. Considering additional massive stars in evolved stages, with published parameters and located all over the SMC, essentially confirms this picture. The comparison with single-star evolutionary tracks suggests a dichotomy in the fate of massive stars in the SMC. Only stars with an initial mass below 30 solar masses seem to evolve from the main sequence to the cool side of the HRD to become a red supergiant and to explode as type II-P supernova. In contrast, more massive stars appear to stay always hot and might evolve quasi chemically homogeneously, finally collapsing to relatively massive black holes. However, we find no indication that chemical mixing is correlated with rapid rotation. We measured the key parameters of stellar feedback and established the links between the rates of star formation and supernovae. Our study demonstrates that in metal-poor environments stellar feedback is dominated by core-collapse supernovae in combination with winds and ionizing radiation supplied by a few of the most massive stars. We found indications of the stochastic mode of star formation, where the resulting stellar population is fully capable of producing large-scale structures such as the supergiant shell SMC-SGS 1 in the Wing. The low level of feedback in metal-poor stellar populations allows star formation episodes to persist over long timescales. Our study showcases the importance of quantitative spectroscopy of massive stars with adequate stellar-atmosphere models in order to understand star-formation, evolution, and feedback. The stellar population analyses in the LMC and SMC make us understand that massive stars and their impact can be very different depending on their environment. Obviously, due to their different metallicity, the massive stars in the LMC and the SMC follow different evolutionary paths. Their winds differ significantly, and the key feedback agents are different. As a consequence, the star formation can proceed in different modes.}, language = {en} } @phdthesis{Rabe2019, author = {Rabe, Sophie}, title = {Wirksamkeit einer telemedizinisch assistierten Bewegungstherapie f{\"u}r die postrehabilitative Versorgung von Patienten mit Knie- oder H{\"u}ft-Totalendoprothese im berufsf{\"a}higen Alter}, doi = {10.25932/publishup-43055}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-430556}, school = {Universit{\"a}t Potsdam}, pages = {x, 78}, year = {2019}, abstract = {Einleitung Die Implantation einer Knie- oder H{\"u}ft-Totalendoprothese (TEP) ist eine der h{\"a}ufigsten operativen Eingriffe. Im Anschluss an die Operation und die postoperative Rehabilitation stellt die Bewegungstherapie einen wesentlichen Bestandteil der Behandlung zur Verbesserung der Gelenkfunktion und der Lebensqualit{\"a}t dar. In strukturschwachen Gebieten werden entsprechende Angebote nur in unzureichender Dichte vorgehalten. Zudem zeichnet sich ein fl{\"a}chendeckender Fachkr{\"a}ftemangel im Bereich der Physiotherapie ab. Die Tele-Nachsorge bietet daher einen innovativen Ansatz f{\"u}r die postrehabilitative Versorgung der Patienten. Das Ziel der vorliegenden Untersuchung war die {\"U}berpr{\"u}fung der Wirksamkeit einer interaktiven Tele-Nachsorgeintervention f{\"u}r Patienten mit Knie- oder H{\"u}ft-TEP im Vergleich zur herk{\"o}mmlichen Versorgung (usual care). Dazu wurden die Funktionalit{\"a}t und die berufliche Wiedereingliederung untersucht. Methode Zwischen August 2016 und August 2017 wurden 111 Patienten (54,9 ± 6,8 Jahre, 54,3 \% weiblich) zu Beginn ihrer station{\"a}ren Anschlussheilbehandlung nach Implantation einer Knie- oder H{\"u}ft-TEP in diese randomisiert, kontrolliert, multizentrische Studie eingeschlossen. Nach Entlassung aus der orthop{\"a}dischen Anschlussrehabilitation (Baseline) f{\"u}hrte die Interventionsgruppe (IG) ein dreimonatiges interaktives Training {\"u}ber ein Telerehabilitationssystem durch. Hierf{\"u}r erstellte ein betreuender Physiotherapeut einen individuellen Trainingsplan aus 38 {\"U}bungen zur Verbesserung der Kraft sowie der posturalen Kontrolle. Zur Anpassung des Trainingsplans {\"u}bermittelte das System dem Physiotherapeuten Daten zur Quantit{\"a}t sowie zur Qualit{\"a}t des Trainings. Die Kontrollgruppe (KG) konnte die herk{\"o}mmlichen Versorgungsangebote nutzen. Zur Beurteilung der Wirksamkeit der Intervention wurde die Differenz der Verbesserung im 6MWT zwischen der IG und der KG nach drei Monaten als prim{\"a}rer Endpunkt definiert. Als sekund{\"a}re Endpunkte wurden die Return-to-Work-Rate sowie die funktionelle Mobilit{\"a}t mittels des Stair Ascend Tests, des Five-Times-Sit-to-Stand Test und des Timed Up and Go Tests untersucht. Weiterhin wurden die gesundheitsbezogene Lebensqualit{\"a}t mit dem Short-Form 36 (SF-36) und die gelenkbezogenen Einschr{\"a}nkungen mit dem Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) evaluiert. Der prim{\"a}re und die sekund{\"a}ren Endpunkte wurden anhand von baseline-adjustierten Kovarianzanalysen im intention-to-treat-Ansatz ausgewertet. Zus{\"a}tzlich wurde die Teilnahme an Nachsorgeangeboten und die Adh{\"a}renz der Interventionsgruppe an der Tele-Nachsorge erfasst und evaluiert. Ergebnisse Zum Ende der Intervention wiesen beide Gruppen einen statistisch signifikanten Anstieg ihrer 6MWT Strecke auf (p < 0,001). Zu diesem Zeitpunkt legten die Teilnehmer der IG im Mittel 530,8 ± 79,7 m, die der KG 514,2 ± 71,2 m zur{\"u}ck. Dabei betrug die Differenz der Verbesserung der Gehstrecke in der IG 88,3 ± 57,7 m und in der KG 79,6 ± 48,7 m. Damit zeigt der prim{\"a}re Endpunkt keine signifikanten Gruppenunterschiede (p = 0,951). Bez{\"u}glich der beruflichen Wiedereingliederung konnte jedoch eine signifikant h{\"o}here Rate in der IG (64,6 \% versus 46,2 \%; p = 0,014) festgestellt werden. F{\"u}r die sekund{\"a}ren Endpunkte der funktionellen Mobilit{\"a}t, der Lebensqualit{\"a}t und der gelenkbezogenen Beschwerden belegen die Ergebnisse eine Gleichwertigkeit beider Gruppen zum Ende der Intervention. Schlussfolgerung Die telemedizinisch assistierte Bewegungstherapie f{\"u}r Knie- oder H{\"u}ft-TEP Patienten ist der herk{\"o}mmlichen Versorgung zur Nachsorge hinsichtlich der erzielten Verbesserungen der funktionellen Mobilit{\"a}t, der gesundheitsbezogenen Lebensqualit{\"a}t und der gelenkbezogenen Beschwerden gleichwertig. In dieser Patientenpopulation ließen sich klinisch relevante Verbesserungen unabh{\"a}ngig von der Form der Bewegungstherapie erzielen. Im Hinblick auf die berufliche Wiedereingliederung zeigte sich eine signifikant h{\"o}here Rate in der Interventionsgruppe. Die telemedizinisch assistierte Bewegungstherapie scheint eine geeignete Versorgungsform der Nachsorge zu sein, die orts- und zeitunabh{\"a}ngig durchgef{\"u}hrt werden kann und somit den Bed{\"u}rfnissen berufst{\"a}tiger Patienten entgegenkommt und in den Alltag der Patienten integriert werden kann. Die Tele-Nachsorge sollte daher als optionale und komplement{\"a}re Form der postrehabilitativen Nachsorge angeboten werden. Auch im Hinblick auf den zunehmenden Fachkr{\"a}ftemangel im Bereich der Physiotherapie und bestehende Versorgungsl{\"u}cken in strukturschwachen Gebieten kann der Einsatz der Tele-Nachsorge innovative und bedarfsgerechte L{\"o}sungsans{\"a}tze bieten.}, language = {de} } @phdthesis{Raatz2019, author = {Raatz, Michael}, title = {Strategies within predator-prey interactions - from individuals to ecosystems}, doi = {10.25932/publishup-42658}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-426587}, school = {Universit{\"a}t Potsdam}, pages = {175}, year = {2019}, abstract = {Predator-prey interactions provide central links in food webs. These interaction are directly or indirectly impacted by a number of factors. These factors range from physiological characteristics of individual organisms, over specifics of their interaction to impacts of the environment. They may generate the potential for the application of different strategies by predators and prey. Within this thesis, I modelled predator-prey interactions and investigated a broad range of different factors driving the application of certain strategies, that affect the individuals or their populations. In doing so, I focused on phytoplankton-zooplankton systems as established model systems of predator-prey interactions. At the level of predator physiology I proposed, and partly confirmed, adaptations to fluctuating availability of co-limiting nutrients as beneficial strategies. These may allow to store ingested nutrients or to regulate the effort put into nutrient assimilation. We found that these two strategies are beneficial at different fluctuation frequencies of the nutrients, but may positively interact at intermediate frequencies. The corresponding experiments supported our model results. We found that the temporal structure of nutrient fluctuations indeed has strong effects on the juvenile somatic growth rate of {\itshape Daphnia}. Predator colimitation by energy and essential biochemical nutrients gave rise to another physiological strategy. High-quality prey species may render themselves indispensable in a scenario of predator-mediated coexistence by being the only source of essential biochemical nutrients, such as cholesterol. Thereby, the high-quality prey may even compensate for a lacking defense and ensure its persistence in competition with other more defended prey species. We found a similar effect in a model where algae and bacteria compete for nutrients. Now, being the only source of a compound that is required by the competitor (bacteria) prevented the competitive exclusion of the algae. In this case, the essential compounds were the organic carbon provided by the algae. Here again, being indispensable served as a prey strategy that ensured its coexistence. The latter scenario also gave rise to the application of the two metabolic strategies of autotrophy and heterotrophy by algae and bacteria, respectively. We found that their coexistence allowed the recycling of resources in a microbial loop that would otherwise be lost. Instead, these resources were made available to higher trophic levels, increasing the trophic transfer efficiency in food webs. The predation process comprises the next higher level of factors shaping the predator-prey interaction, besides these factors that originated from the functioning or composition of individuals. Here, I focused on defensive mechanisms and investigated multiple scenarios of static or adaptive combinations of prey defense and predator offense. I confirmed and extended earlier reports on the coexistence-promoting effects of partially lower palatability of the prey community. When bacteria and algae are coexisting, a higher palatability of bacteria may increase the average predator biomass, with the side effect of making the population dynamics more regular. This may facilitate experimental investigations and interpretations. If defense and offense are adaptive, this allows organisms to maximize their growth rate. Besides this fitness-enhancing effect, I found that co-adaptation may provide the predator-prey system with the flexibility to buffer external perturbations. On top of these rather internal factors, environmental drivers also affect predator-prey interactions. I showed that environmental nutrient fluctuations may create a spatio-temporal resource heterogeneity that selects for different predator strategies. I hypothesized that this might favour either storage or acclimation specialists, depending on the frequency of the environmental fluctuations. We found that many of these factors promote the coexistence of different strategies and may therefore support and sustain biodiversity. Thus, they might be relevant for the maintenance of crucial ecosystem functions that also affect us humans. Besides this, the richness of factors that impact predator-prey interactions might explain why so many species, especially in the planktonic regime, are able to coexist.}, language = {en} } @phdthesis{Qin2019, author = {Qin, Qing}, title = {Chemical functionalization of porous carbon-based materials to enable novel modes for efficient electrochemical N2 fixation}, doi = {10.25932/publishup-44339}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-443397}, school = {Universit{\"a}t Potsdam}, pages = {146}, year = {2019}, abstract = {The central motivation of the thesis was to provide possible solutions and concepts to improve the performance (e.g. activity and selectivity) of electrochemical N2 reduction reaction (NRR). Given that porous carbon-based materials usually exhibit a broad range of structural properties, they could be promising NRR catalysts. Therefore, the advanced design of novel porous carbon-based materials and the investigation of their application in electrocatalytic NRR including the particular reaction mechanisms are the most crucial points to be addressed. In this regard, three main topics were investigated. All of them are related to the functionalization of porous carbon for electrochemical NRR or other electrocatalytic reactions. In chapter 3, a novel C-TixOy/C nanocomposite has been described that has been obtained via simple pyrolysis of MIL-125(Ti). A novel mode for N2 activation is achieved by doping carbon atoms from nearby porous carbon into the anion lattice of TixOy. By comparing the NRR performance of M-Ts and by carrying out DFT calculations, it is found that the existence of (O-)Ti-C bonds in C-doped TixOy can largely improve the ability to activate and reduce N2 as compared to unoccupied OVs in TiO2. The strategy of rationally doping heteroatoms into the anion lattice of transition metal oxides to create active centers may open many new opportunities beyond the use of noble metal-based catalysts also for other reactions that require the activation of small molecules as well. In chapter 4, a novel catalyst construction composed of Au single atoms decorated on the surface of NDPCs was reported. The introduction of Au single atoms leads to active reaction sites, which are stabilized by the N species present in NDPCs. Thus, the interaction within as-prepared AuSAs-NDPCs catalysts enabled promising performance for electrochemical NRR. For the reaction mechanism, Au single sites and N or C species can act as Frustrated Lewis pairs (FLPs) to enhance the electron donation and back-donation process to activate N2 molecules. This work provides new opportunities for catalyst design in order to achieve efficient N2 fixation at ambient conditions by utilizing recycled electric energy. The last topic described in chapter 5 mainly focused on the synthesis of dual heteroatom-doped porous carbon from simple precursors. The introduction of N and B heteroatoms leads to the construction of N-B motives and Frustrated Lewis pairs in a microporous architecture which is also rich in point defects. This can improve the strength of adsorption of different reactants (N2 and HMF) and thus their activation. As a result, BNC-2 exhibits a desirable electrochemical NRR and HMF oxidation performance. Gas adsorption experiments have been used as a simple tool to elucidate the relationship between the structure and catalytic activity. This work provides novel and deep insights into the rational design and the origin of activity in metal-free electrocatalysts and enables a physically viable discussion of the active motives, as well as the search for their further applications. Throughout this thesis, the ubiquitous problems of low selectivity and activity of electrochemical NRR are tackled by designing porous carbon-based catalysts with high efficiency and exploring their catalytic mechanisms. The structure-performance relationships and mechanisms of activation of the relatively inert N2 molecules are revealed by either experimental results or DFT calculations. These fundamental understandings pave way for a future optimal design and targeted promotion of NRR catalysts with porous carbon-based structure, as well as study of new N2 activation modes.}, language = {en} } @phdthesis{PerezMedrano2019, author = {P{\´e}rez Medrano, Cuauht{\´e}moc}, title = {Ficci{\´o}n her{\´e}tica}, publisher = {Universit{\"a}tsverlag Potsdam}, address = {Potsdam}, isbn = {978-3-86956-454-8}, issn = {2629-2548}, doi = {10.25932/publishup-42449}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-424490}, school = {Universit{\"a}t Potsdam}, pages = {226}, year = {2019}, abstract = {Mit der kubanischen Wirtschaftskrise entstanden neue literarische Gestaltungsprozesse nationaler Identit{\"a}tskonstruktionen. Die vorliegende Analyse geht der zeitgen{\"o}ssischen Literatur Kubas nach, in der soziale, kulturelle und politische Paradoxe der post-revolution{\"a}ren Weltanschauung zum Vorschein kommen und der Figur der „Insel" bzw. „Insularit{\"a}t" eine große Bedeutung f{\"u}r die Neukonfiguration der Nation zukommt. Die „Insularit{\"a}t" dr{\"u}ckt in literarischen Texten verschiedene Aneignungen des Raumes und somit auch eine Weltanschauungen aus. Die literarische Figur der „Insel" kann hypothetisch als „visuelles Ph{\"a}nomen" (Ette 2002) konzipiert werden, das durch soziokulturelle Umst{\"a}nde konfiguriert wird. Unterschiedliche postkommunistische Erfahrungen bilden sog. „erlebnisweltliche" Repr{\"a}sentationen und somit literarische und soziale Identit{\"a}tsbilder. Im Verlauf der Zeit werden die Metapher der „Insel" bzw. der „Insularit{\"a}t" anders beschrieben. Erste Untersuchungen der Metapher der „Insel" bzw. der „Insularit{\"a}t" finden sich in den Texten Noche insular (Lezama Lima 2000) und La isla en peso (Pi{\~n}era 1998). Die Metapher wird in den Begrifflichkeiten der „Simulation" und „Dissimulation" (Sarduy 1982) oder auch einer „visuellen Erscheinung" als „Grund-Ekphrasis" (Pimentel 2001) beschrieben. Demgegen{\"u}ber stellen sp{\"a}tere Arbeiten die literarische Figur der „Insel" als ein Instrument der Dekonstruktion der Nationalliteratur Kubas dar (Rojas 1998; Nuez 1998, Benitez Rojo 1998). In zeitgen{\"o}ssischen Analysen wird die Metapher in ihrer jeweiligen Beziehungen zur Repr{\"a}sentation und zum „Lebenswissen" (Ette 2010) herausgearbeitet. Die Repr{\"a}sentation der "Insel" bzw. der "Insularit{\"a}t" wird in der vorliegenden Arbeit anhand des soziokulturellen Kontextes in den letzten dreißig Jahren u.a. in den Romanen von Abilio Estevez Tuyo es el reino (1998), Atilio Caballero La {\´u}ltima playa (1999), Daniel D{\´i}az Mantilla Regreso a Utop{\´i}a (2007) sowie den Erz{\"a}hlungen von Ena Lucia Portela Huracan (2000), Antonio Jos{\´e} Ponte Un nuevo arte de hacer ruinas (2005), Emerio Medina Isla (2005), Orlando Lu{\´i}s Pardo Tokionama (2009), Ahmel Echeverria Isla (2014) und Anesly Negr{\´i}n Isla a mediod{\´i}a (2014) untersucht.}, language = {es} } @phdthesis{Pohlenz2019, author = {Pohlenz, Julia}, title = {Structural insights into sodium-rich silicate - carbonate glasses and melts}, doi = {10.25932/publishup-42382}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-423826}, school = {Universit{\"a}t Potsdam}, pages = {XXII, 117}, year = {2019}, abstract = {Carbonate-rich silicate and carbonate melts play a crucial role in deep Earth magmatic processes and their melt structure is a key parameter, as it controls physical and chemical properties. Carbonate-rich melts can be strongly enriched in geochemically important trace elements. The structural incorporation mechanisms of these elements are difficult to study because such melts generally cannot be quenched to glasses, which are usually employed for structural investigations. This thesis investigates the influence of CO2 on the local environments of trace elements contained in silicate glasses with variable CO2 concentrations as well as in silicate and carbonate melts. The compositions studied include sodium-rich peralkaline silicate melts and glasses and carbonate melts similar to those occurring naturally at Oldoinyo Lengai volcano, Tanzania. The local environments of the three elements yttrium (Y), lanthanum (La) and strontium (Sr) were investigated in synthesized glasses and melts using X-ray absorption fine structure (XAFS) spectroscopy. Especially extended X-ray absorption fine structure spectroscopy (EXAFS) provides element specific information on local structure, such as bond lengths, coordination numbers and the degree of disorder. To cope with the enhanced structural disorder present in glasses and melts, EXAFS analysis was based on fitting approaches using an asymmetric distribution function as well as a correlation model according to bond valence theory. Firstly, silicate glasses quenched from high pressure/temperature melts with up to 7.6 wt \% CO2 were investigated. In strongly and extremely peralkaline glasses the local structure of Y is unaffected by the CO2 content (with oxygen bond lengths of ~ 2.29 {\AA}). Contrary, the bond lengths for Sr-O and La-O increase with increasing CO2 content in the strongly peralkaline glasses from ~ 2.53 to ~ 2.57 {\AA} and from ~ 2.52 to ~ 2.54 {\AA}, respectively, while they remain constant in extremely peralkaline glasses (at ~ 2.55 {\AA} and 2.54 {\AA}, respectively). Furthermore, silicate and unquenchable carbonate melts were investigated in-situ at high pressure/temperature conditions (2.2 to 2.6 GPa, 1200 to 1500 °C) using a Paris-Edinburgh press. A novel design of the pressure medium assembly for this press was developed, which features increased mechanical stability as well as enhanced transmittance at relevant energies to allow for low content element EXAFS in transmission. Compared to glasses the bond lengths of Y-O, La-O and Sr-O are elongated by up to + 3 \% in the melt and exhibit higher asymmetric pair distributions. For all investigated silicate melt compositions Y-O bond lengths were found constant at ~ 2.37 {\AA}, while in the carbonate melt the Y-O length increases slightly to 2.41 {\AA}. The La-O bond lengths in turn, increase systematically over the whole silicate - carbonate melt joint from 2.55 to 2.60 {\AA}. Sr-O bond lengths in melts increase from ~ 2.60 to 2.64 {\AA} from pure silicate to silicate-bearing carbonate composition with constant elevated bond length within the carbonate region. For comparison and deeper insight, glass and melt structures of Y and Sr bearing sodium-rich silicate to carbonate compositions were simulated in an explorative ab initio molecular dynamics (MD) study. The simulations confirm observed patterns of CO2-dependent local changes around Y and Sr and additionally provide further insights into detailed incorporation mechanisms of the trace elements and CO2. Principle findings include that in sodium-rich silicate compositions carbon either is mainly incorporated as a free carbonate-group or shares one oxygen with a network former (Si or [4]Al) to form a non-bridging carbonate. Of minor importance are bridging carbonates between two network formers. Here, a clear preference for two [4]Al as adjacent network formers occurs, compared to what a statistical distribution would suggest. In C-bearing silicate melts minor amounts of molecular CO2 are present, which is almost totally dissolved as carbonate in the quenched glasses. The combination of experiment and simulation provides extraordinary insights into glass and melt structures. The new data is interpreted on the basis of bond valence theory and is used to deduce potential mechanisms for structural incorporation of investigated elements, which allow for prediction on their partitioning behavior in natural melts. Furthermore, it provides unique insights into the dissolution mechanisms of CO2 in silicate melts and into the carbonate melt structure. For the latter, a structural model is suggested, which is based on planar CO3-groups linking 7- to 9-fold cation polyhedra, in accordance to structural units as found in the Na-Ca carbonate nyerereite. Ultimately, the outcome of this study contributes to rationalize the unique physical properties and geological phenomena related to carbonated silicate-carbonate melts.}, language = {en} } @phdthesis{Peter2019, author = {Peter, Franziska}, title = {Transition to synchrony in finite Kuramoto ensembles}, doi = {10.25932/publishup-42916}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-429168}, school = {Universit{\"a}t Potsdam}, pages = {vi, 93}, year = {2019}, abstract = {Synchronisation - die Ann{\"a}herung der Rhythmen gekoppelter selbst oszillierender Systeme - ist ein faszinierendes dynamisches Ph{\"a}nomen, das in vielen biologischen, sozialen und technischen Systemen auftritt. Die vorliegende Arbeit befasst sich mit Synchronisation in endlichen Ensembles schwach gekoppelter selbst-erhaltender Oszillatoren mit unterschiedlichen nat{\"u}rlichen Frequenzen. Das Standardmodell f{\"u}r dieses kollektive Ph{\"a}nomen ist das Kuramoto-Modell - unter anderem aufgrund seiner L{\"o}sbarkeit im thermodynamischen Limes unendlich vieler Oszillatoren. {\"A}hnlich einem thermodynamischen Phasen{\"u}bergang zeigt im Fall unendlich vieler Oszillatoren ein Ordnungsparameter den {\"U}bergang von Inkoh{\"a}renz zu einem partiell synchronen Zustand an, in dem ein Teil der Oszillatoren mit einer gemeinsamen Frequenz rotiert. Im endlichen Fall treten Fluktuationen auf. In dieser Arbeit betrachten wir den bisher wenig beachteten Fall von bis zu wenigen hundert Oszillatoren, unter denen vergleichbar starke Fluktuationen auftreten, bei denen aber ein Vergleich zu Frequenzverteilungen im unendlichen Fall m{\"o}glich ist. Zun{\"a}chst definieren wir einen alternativen Ordnungsparameter zur Feststellung einer kollektiven Mode im endlichen Kuramoto-Modell. Dann pr{\"u}fen wir die Abh{\"a}ngigkeit des Synchronisationsgrades und der mittleren Rotationsfrequenz der kollektiven Mode von Eigenschaften der nat{\"u}rlichen Frequenzverteilung f{\"u}r verschiedene Kopplungsst{\"a}rken. Wir stellen dabei zun{\"a}chst numerisch fest, dass der Synchronisationsgrad stark von der Form der Verteilung (gemessen durch die Kurtosis) und die Rotationsfrequenz der kollektiven Mode stark von der Asymmetrie der Verteilung (gemessen durch die Schiefe) der nat{\"u}rlichen Frequenzen abh{\"a}ngt. Beides k{\"o}nnen wir im thermodynamischen Limes analytisch verifizieren. Mit diesen Ergebnissen k{\"o}nnen wir Erkenntnisse anderer Autoren besser verstehen und verallgemeinern. Etwas abseits des roten Fadens dieser Arbeit finden wir außerdem einen analytischen Ausdruck f{\"u}r die Volumenkontraktion im Phasenraum. Der zweite Teil der Arbeit konzentriert sich auf den ordnenden Effekt von Fluktuationen, die durch die Endlichkeit des Systems zustande kommen. Im unendlichen Modell sind die Oszillatoren eindeutig in koh{\"a}rent und inkoh{\"a}rent und damit in geordnet und ungeordnet getrennt. Im endlichen Fall k{\"o}nnen die auftretenden Fluktuationen zus{\"a}tzliche Ordnung unter den asynchronen Oszillatoren erzeugen. Das grundlegende Prinzip, die rauschinduzierte Synchronisation, ist aus einer Reihe von Publikationen bekannt. Unter den gekoppelten Oszillatoren n{\"a}hern sich die Phasen aufgrund der Fluktuationen des Ordnungsparameters an, wie wir einerseits direkt numerisch zeigen und andererseits mit einem Synchronisationsmaß aus der gerichteten Statistik zwischen Paaren passiver Oszillatoren nachweisen. Wir bestimmen die Abh{\"a}ngigkeit dieses Synchronisationsmaßes vom Verh{\"a}ltnis von paarweiser nat{\"u}rlicher Frequenzdifferenz zur Varianz der Fluktuationen. Dabei finden wir eine gute {\"U}bereinstimmung mit einem einfachen analytischen Modell, in welchem wir die deterministischen Fluktuationen des Ordnungsparameters durch weißes Rauschen ersetzen.}, language = {en} }