@phdthesis{Adelt2024, author = {Adelt, Anne}, title = {The Relativized Minimality approach to comprehension of German relative clauses in aphasia}, doi = {10.25932/publishup-62331}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-623312}, school = {Universit{\"a}t Potsdam}, pages = {xiii, 166}, year = {2024}, abstract = {It is a well-attested finding in head-initial languages that individuals with aphasia (IWA) have greater difficulties in comprehending object-extracted relative clauses (ORCs) as compared to subject-extracted relative clauses (SRCs). Adopting the linguistically based approach of Relativized Minimality (RM; Rizzi, 1990, 2004), the subject-object asymmetry is attributed to the occurrence of a Minimality effect in ORCs due to reduced processing capacities in IWA (Garraffa \& Grillo, 2008; Grillo, 2008, 2009). For ORCs, it is claimed that the embedded subject intervenes in the syntactic dependency between the moved object and its trace, resulting in greater processing demands. In contrast, no such intervener is present in SRCs. Based on the theoretical framework of RM and findings from language acquisition (Belletti et al., 2012; Friedmann et al., 2009), it is assumed that Minimality effects are alleviated when the moved object and the intervening subject differ in terms of relevant syntactic features. For German, the language under investigation, the RM approach predicts that number (i.e., singular vs. plural) and the lexical restriction [+NP] feature (i.e., lexically restricted determiner phrases vs. lexically unrestricted pronouns) are considered relevant in the computation of Minimality. Greater degrees of featural distinctiveness are predicted to result in more facilitated processing of ORCs, because IWA can more easily distinguish between the moved object and the intervener. This cumulative dissertation aims to provide empirical evidence on the validity of the RM approach in accounting for comprehension patterns during relative clause (RC) processing in German-speaking IWA. For that purpose, I conducted two studies including visual-world eye-tracking experiments embedded within an auditory referent-identification task to study the offline and online processing of German RCs. More specifically, target sentences were created to evaluate (a) whether IWA demonstrate a subject-object asymmetry, (b) whether dissimilarity in the number and/or the [+NP] features facilitates ORC processing, and (c) whether sentence processing in IWA benefits from greater degrees of featural distinctiveness. Furthermore, by comparing RCs disambiguated through case marking (at the relative pronoun or the following noun phrase) and number marking (inflection of the sentence-final verb), it was possible to consider the role of the relative position of the disambiguation point. The RM approach predicts that dissimilarity in case should not affect the occurrence of Minimality effects. However, the case cue to sentence interpretation appears earlier within RCs than the number cue, which may result in lower processing costs in case-disambiguated RCs compared to number-disambiguated RCs. In study I, target sentences varied with respect to word order (SRC vs. ORC) and dissimilarity in the [+NP] feature (lexically restricted determiner phrase vs. pronouns as embedded element). Moreover, by comparing the impact of these manipulations in case- and number-disambiguated RCs, the effect of dissimilarity in the number feature was explored. IWA demonstrated a subject-object asymmetry, indicating the occurrence of a Minimality effect in ORCs. However, dissimilarity neither in the number feature nor in the [+NP] feature alone facilitated ORC processing. Instead, only ORCs involving distinct specifications of both the number and the [+NP] features were well comprehended by IWA. In study II, only temporarily ambiguous ORCs disambiguated through case or number marking were investigated, while controlling for varying points of disambiguation. There was a slight processing advantage of case marking as cue to sentence interpretation as compared to number marking. Taken together, these findings suggest that the RM approach can only partially capture empirical data from German IWA. In processing complex syntactic structures, IWA are susceptible to the occurrence of the intervening subject in ORCs. The new findings reported in the thesis show that structural dissimilarity can modulate sentence comprehension in aphasia. Interestingly, IWA can override Minimality effects in ORCs and derive correct sentence meaning if the featural specifications of the constituents are maximally different, because they can more easily distinguish the moved object and the intervening subject given their reduced processing capacities. This dissertation presents new scientific knowledge that highlights how the syntactic theory of RM helps to uncover selective effects of morpho-syntactic features on sentence comprehension in aphasia, emphasizing the close link between assumptions from theoretical syntax and empirical research.}, language = {en} } @phdthesis{Alawashra2024, author = {Alawashra, Mahmoud}, title = {Plasma instabilities of TeV pair beams induced by blazars}, doi = {10.25932/publishup-63013}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-630131}, school = {Universit{\"a}t Potsdam}, pages = {xxi, 130}, year = {2024}, abstract = {Relativistic pair beams produced in the cosmic voids by TeV gamma rays from blazars are expected to produce a detectable GeV-scale cascade emission missing in the observations. The suppression of this secondary cascade implies either the deflection of the pair beam by intergalactic magnetic fields (IGMFs) or an energy loss of the beam due to the electrostatic beam-plasma instability. IGMF of femto-Gauss strength is sufficient to significantly deflect the pair beams reducing the flux of secondary cascade below the observational limits. A similar flux reduction may result in the absence of the IGMF from the beam energy loss by the instability before the inverse Compton cooling. This dissertation consists of two studies about the instability role in the evolution of blazar-induced beams. Firstly, we investigated the effect of sub-fG level IGMF on the beam energy loss by the instability. Considering IGMF with correlation lengths smaller than a few kpc, we found that such fields increase the transverse momentum of the pair beam particles, dramatically reducing the linear growth rate of the electrostatic instability and hence the energy-loss rate of the pair beam. Our results show that the IGMF eliminates beam plasma instability as an effective energy-loss agent at a field strength three orders of magnitude below that needed to suppress the secondary cascade emission by magnetic deflection. For intermediate-strength IGMF, we do not know a viable process to explain the observed absence of GeV-scale cascade emission and hence can be excluded. Secondly, we probed how the beam-plasma instability feeds back on the beam, using a realistic two-dimensional beam distribution. We found that the instability broadens the beam opening angles significantly without any significant energy loss, thus confirming a recent feedback study on a simplified one-dimensional beam distribution. However, narrowing diffusion feedback of the beam particles with Lorentz factors less than 1e6 might become relevant even though initially it is negligible. Finally, when considering the continuous creation of TeV pairs, we found that the beam distribution and the wave spectrum reach a new quasi-steady state, in which the scattering of beam particles persists and the beam opening angle may increase by a factor of hundreds. This new intrinsic scattering of the cascade can result in time delays of around ten years, thus potentially mimicking the IGMF deflection. Understanding the implications on the GeV cascade emission requires accounting for inverse Compton cooling and simulating the beam-plasma system at different points in the IGM.}, language = {en} } @phdthesis{AlhosseiniAlmodarresiYasin2024, author = {Alhosseini Almodarresi Yasin, Seyed Ali}, title = {Classification, prediction and evaluation of graph neural networks on online social media platforms}, doi = {10.25932/publishup-62642}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-626421}, school = {Universit{\"a}t Potsdam}, pages = {xviii, 78}, year = {2024}, abstract = {The vast amount of data generated on social media platforms have made them a valuable source of information for businesses, governments and researchers. Social media data can provide insights into user behavior, preferences, and opinions. In this work, we address two important challenges in social media analytics. Predicting user engagement with online content has become a critical task for content creators to increase user engagement and reach larger audiences. Traditional user engagement prediction approaches rely solely on features derived from the user and content. However, a new class of deep learning methods based on graphs captures not only the content features but also the graph structure of social media networks. This thesis proposes a novel Graph Neural Network (GNN) approach to predict user interaction with tweets. The proposed approach combines the features of users, tweets and their engagement graphs. The tweet text features are extracted using pre-trained embeddings from language models, and a GNN layer is used to embed the user in a vector space. The GNN model then combines the features and graph structure to predict user engagement. The proposed approach achieves an accuracy value of 94.22\% in classifying user interactions, including likes, retweets, replies, and quotes. Another major challenge in social media analysis is detecting and classifying social bot accounts. Social bots are automated accounts used to manipulate public opinion by spreading misinformation or generating fake interactions. Detecting social bots is critical to prevent their negative impact on public opinion and trust in social media. In this thesis, we classify social bots on Twitter by applying Graph Neural Networks. The proposed approach uses a combination of both the features of a node and an aggregation of the features of a node's neighborhood to classify social bot accounts. Our final results indicate a 6\% improvement in the area under the curve score in the final predictions through the utilization of GNN. Overall, our work highlights the importance of social media data and the potential of new methods such as GNNs to predict user engagement and detect social bots. These methods have important implications for improving the quality and reliability of information on social media platforms and mitigating the negative impact of social bots on public opinion and discourse.}, language = {en} } @phdthesis{Antonoglou2024, author = {Antonoglou, Nikolaos}, title = {GNSS-based remote sensing: Innovative observation of key hydrological parameters in the Central Andes}, doi = {10.25932/publishup-62825}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-628256}, school = {Universit{\"a}t Potsdam}, pages = {xxii, 116}, year = {2024}, abstract = {The Central Andean region is characterized by diverse climate zones with sharp transitions between them. In this work, the area of interest is the South-Central Andes in northwestern Argentina that borders with Bolivia and Chile. The focus is the observation of soil moisture and water vapour with Global Navigation Satellite System (GNSS) remote-sensing methodologies. Because of the rapid temporal and spatial variations of water vapour and moisture circulations, monitoring this part of the hydrological cycle is crucial for understanding the mechanisms that control the local climate. Moreover, GNSS-based techniques have previously shown high potential and are appropriate for further investigation. This study includes both logistic-organization effort and data analysis. As for the prior, three GNSS ground stations were installed in remote locations in northwestern Argentina to acquire observations, where there was no availability of third-party data. The methodological development for the observation of the climate variables of soil moisture and water vapour is independent and relies on different approaches. The soil-moisture estimation with GNSS reflectometry is an approximation that has demonstrated promising results, but it has yet to be operationally employed. Thus, a more advanced algorithm that exploits more observations from multiple satellite constellations was developed using data from two pilot stations in Germany. Additionally, this algorithm was slightly modified and used in a sea-level measurement campaign. Although the objective of this application is not related to monitoring hydrological parameters, its methodology is based on the same principles and helps to evaluate the core algorithm. On the other hand, water-vapour monitoring with GNSS observations is a well-established technique that is utilized operationally. Hence, the scope of this study is conducting a meteorological analysis by examining the along-the-zenith air-moisture levels and introducing indices related to the azimuthal gradient. The results of the experiments indicate higher-quality soil moisture observations with the new algorithm. Furthermore, the analysis using the stations in northwestern Argentina illustrates the limits of this technology because of varying soil conditions and shows future research directions. The water-vapour analysis points out the strong influence of the topography on atmospheric moisture circulation and rainfall generation. Moreover, the GNSS time series allows for the identification of seasonal signatures, and the azimuthal-gradient indices permit the detection of main circulation pathways.}, language = {en} } @phdthesis{Aue2024, author = {Aue, Lars}, title = {Cyclone impacts on sea ice in the Atlantic Arctic Ocean}, doi = {10.25932/publishup-63445}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-634458}, school = {Universit{\"a}t Potsdam}, pages = {VIII, 131}, year = {2024}, abstract = {The Arctic is the hot spot of the ongoing, global climate change. Over the last decades, near-surface temperatures in the Arctic have been rising almost four times faster than on global average. This amplified warming of the Arctic and the associated rapid changes of its environment are largely influenced by interactions between individual components of the Arctic climate system. On daily to weekly time scales, storms can have major impacts on the Arctic sea-ice cover and are thus an important part of these interactions within the Arctic climate. The sea-ice impacts of storms are related to high wind speeds, which enhance the drift and deformation of sea ice, as well as to changes in the surface energy budget in association with air mass advection, which impact the seasonal sea-ice growth and melt. The occurrence of storms in the Arctic is typically associated with the passage of transient cyclones. Even though the above described mechanisms how storms/cyclones impact the Arctic sea ice are in principal known, there is a lack of statistical quantification of these effects. In accordance with that, the overarching objective of this thesis is to statistically quantify cyclone impacts on sea-ice concentration (SIC) in the Atlantic Arctic Ocean over the last four decades. In order to further advance the understanding of the related mechanisms, an additional objective is to separate dynamic and thermodynamic cyclone impacts on sea ice and assess their relative importance. Finally, this thesis aims to quantify recent changes in cyclone impacts on SIC. These research objectives are tackled utilizing various data sets, including atmospheric and oceanic reanalysis data as well as a coupled model simulation and a cyclone tracking algorithm. Results from this thesis demonstrate that cyclones are significantly impacting SIC in the Atlantic Arctic Ocean from autumn to spring, while there are mostly no significant impacts in summer. The strength and the sign (SIC decreasing or SIC increasing) of the cyclone impacts strongly depends on the considered daily time scale and the region of the Atlantic Arctic Ocean. Specifically, an initial decrease in SIC (day -3 to day 0 relative to the cyclone) is found in the Greenland, Barents and Kara Seas, while SIC increases following cyclones (day 0 to day 5 relative to the cyclone) are mostly limited to the Barents and Kara Seas. For the cold season, this results in a pronounced regional difference between overall (day -3 to day 5 relative to the cyclone) SIC-decreasing cyclone impacts in the Greenland Sea and overall SIC-increasing cyclone impacts in the Barents and Kara Seas. A cyclone case study based on a coupled model simulation indicates that both dynamic and thermodynamic mechanisms contribute to cyclone impacts on sea ice in winter. A typical pattern consisting of an initial dominance of dynamic sea-ice changes followed by enhanced thermodynamic ice growth after the cyclone passage was found. This enhanced ice growth after the cyclone passage most likely also explains the (statistical) overall SIC-increasing effects of cyclones in the Barents and Kara Seas in the cold season. Significant changes in cyclone impacts on SIC over the last four decades have emerged throughout the year. These recent changes are strongly varying from region to region and month to month. The strongest trends in cyclone impacts on SIC are found in autumn in the Barents and Kara Seas. Here, the magnitude of destructive cyclone impacts on SIC has approximately doubled over the last four decades. The SIC-increasing effects following the cyclone passage have particularly weakened in the Barents Sea in autumn. As a consequence, previously existing overall SIC-increasing cyclone impacts in this region in autumn have recently disappeared. Generally, results from this thesis show that changes in the state of the sea-ice cover (decrease in mean sea-ice concentration and thickness) and near-surface air temperature are most important for changed cyclone impacts on SIC, while changes in cyclone properties (i.e. intensity) do not play a significant role.}, language = {en} } @phdthesis{Baumgart2024, author = {Baumgart, Lene}, title = {Die Ambivalenz der Digitalisierung}, doi = {10.25932/publishup-63040}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-630401}, school = {Universit{\"a}t Potsdam}, pages = {137}, year = {2024}, abstract = {Ausgehend von der Beobachtung, dass die aktuelle Digitalisierungsforschung die Ambivalenz der Digitalisierung zwar erkennt, aber nicht zum Gegenstand ihrer Analysen macht, fokussiert die vorliegende kumulative Dissertation auf die ambivalente Dichotomie aus Potenzialen und Problemen, die mit digitalen Transformationen von Organisationen einhergeht. Entlang von sechs Publikationen wird mit einem systemtheoretischen Blick auf Organisationen die spannungsvolle Dichotomie hinsichtlich dreier ambivalenter Verh{\"a}ltnisse aufgezeigt: Erstens wird in Bezug auf das Verh{\"a}ltnis von Digitalisierung und Postb{\"u}rokratie deutlich, dass digitale Transformationen das Potenzial aufweisen, postb{\"u}rokratische Arbeitsweisen zu erleichtern. Parallel ergibt sich das Problem, dass auf Konsens basierende postb{\"u}rokratische Strukturen Digitalisierungsinitiativen erschweren, da diese auf eine Vielzahl von Entscheidungen angewiesen sind. Zweitens zeigt sich mit Blick auf das ambivalente Verh{\"a}ltnis von Digitalisierung und Vernetzung, dass einerseits organisationsweite Kooperation erm{\"o}glicht wird, w{\"a}hrend sich andererseits die Gefahr digitaler Widerspruchskommunikation auftut. Beim dritten Verh{\"a}ltnis zwischen Digitalisierung und Gender deutet sich das mit neuen digitalen Technologien einhergehende Potenzial f{\"u}r Gender Inklusion an, w{\"a}hrend zugleich das Problem einprogrammierter Gender Biases auftritt, die Diskriminierungen oftmals versch{\"a}rfen. Durch die Gegen{\"u}berstellung der Potenziale und Probleme wird nicht nur die Ambivalenz organisationaler Digitalisierung analysierbar und verst{\"a}ndlich, es stellt sich auch heraus, dass mit digitalen Transformationen einen doppelte Formalisierung einhergeht: Organisationen werden nicht nur mit den f{\"u}r Reformen {\"u}blichen Anpassungen der formalen Strukturen konfrontiert, sondern m{\"u}ssen zus{\"a}tzlich formale Entscheidungen zu Technikeinf{\"u}hrung und -beibehaltung treffen sowie formale L{\"o}sungen etablieren, um auf unvorhergesehene Potenziale und Probleme reagieren. Das Ziel der Dissertation ist es, eine analytisch generalisierte Heuristik an die Hand zu geben, mit deren Hilfe die Errungenschaften und Chancen digitaler Transformationen identifiziert werden k{\"o}nnen, w{\"a}hrend sich parallel ihr Verh{\"a}ltnis zu den gleichzeitig entstehenden Herausforderungen und Folgeproblemen erkl{\"a}ren l{\"a}sst.}, language = {de} } @phdthesis{Behrmann2024, author = {Behrmann, Helga}, title = {Digital Fashion}, doi = {10.25932/publishup-62026}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-620269}, school = {Universit{\"a}t Potsdam}, pages = {309}, year = {2024}, abstract = {Das virtuelle Kleid als mediale und soziokulturelle Alltagserscheinung der Gegenwart bildet den Gegenstand der vorliegenden interdisziplin{\"a}ren Unter-suchung. An der Schnittstelle zwischen Menschen, Medien und Mode ist das virtuelle Kleid an unrealen Orten und in synthetischen Situationen ausschließlich auf einem Screen erfahrbar. In diesem Dispositiv lassen sich K{\"o}rperkonzepte, Darstellungskonventionen, soziale Handlungsmuster und Kommunikations-strategien ausmachen, die zwar auf einer radikalen Abl{\"o}sung vom textilen Material beruhen, aber dennoch nicht ohne sehr konkrete Verweise auf das textile Material auskommen. Dies f{\"u}hrt zu neuen Ans{\"a}tzen der Auseinandersetzung mit Kleidern, die nun als Visualisierung geb{\"u}ndelter Datenpakete zu betrachten sind. Die dynamische Entwicklung neuer Erscheinungsformen und deren nahtlose Einbindung in traditionelle Gesch{\"a}ftsmodelle und bestehende Modekonzepte macht eine Positionsbestimmung notwendig, insbesondere im Hinblick auf gegenw{\"a}rtige Nachhaltigkeitsdiskurse um immaterielle Produkte. F{\"u}r diese Studie liefern die hinter den Bildern liegenden Prozesse der {\"o}konomischen Ausrichtung, der Herstellung, der Verwendung und der Rezeption den methodologischen Zugang f{\"u}r die Analyse. Mithilfe eines typologisierenden Instrumentariums wird aus der Vielzahl und Vielfalt der Darstellungen ein Set an forschungsleitenden Beispielen zusammengestellt, welche dann in einer mehrstufigen Kontextanalyse zu einer begrifflichen Fassung des virtuellen Kleides sowie zu f{\"u}nf Kontexteinheiten f{\"u}hren. Am Beispiel des virtuellen Kleides zeichnet diese Untersuchung den technischen, gesellschaftlichen und sozialen Wandel nach und arbeitet seine Bedeutung f{\"u}r zuk{\"u}nftige Modeentwicklungen heraus. Damit leistet die Untersuchung einen Beitrag zur medien- und sozialwissenschaftlichen Modeforschung der Gegenwart.}, language = {de} } @phdthesis{Benson2024, author = {Benson, Lawrence}, title = {Efficient state management with persistent memory}, doi = {10.25932/publishup-62563}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-625637}, school = {Universit{\"a}t Potsdam}, pages = {xiii, 124}, year = {2024}, abstract = {Efficiently managing large state is a key challenge for data management systems. Traditionally, state is split into fast but volatile state in memory for processing and persistent but slow state on secondary storage for durability. Persistent memory (PMem), as a new technology in the storage hierarchy, blurs the lines between these states by offering both byte-addressability and low latency like DRAM as well persistence like secondary storage. These characteristics have the potential to cause a major performance shift in database systems. Driven by the potential impact that PMem has on data management systems, in this thesis we explore their use of PMem. We first evaluate the performance of real PMem hardware in the form of Intel Optane in a wide range of setups. To this end, we propose PerMA-Bench, a configurable benchmark framework that allows users to evaluate the performance of customizable database-related PMem access. Based on experimental results obtained with PerMA-Bench, we discuss findings and identify general and implementation-specific aspects that influence PMem performance and should be considered in future work to improve PMem-aware designs. We then propose Viper, a hybrid PMem-DRAM key-value store. Based on PMem-aware access patterns, we show how to leverage PMem and DRAM efficiently to design a key database component. Our evaluation shows that Viper outperforms existing key-value stores by 4-18x for inserts while offering full data persistence and achieving similar or better lookup performance. Next, we show which changes must be made to integrate PMem components into larger systems. By the example of stream processing engines, we highlight limitations of current designs and propose a prototype engine that overcomes these limitations. This allows our prototype to fully leverage PMem's performance for its internal state management. Finally, in light of Optane's discontinuation, we discuss how insights from PMem research can be transferred to future multi-tier memory setups by the example of Compute Express Link (CXL). Overall, we show that PMem offers high performance for state management, bridging the gap between fast but volatile DRAM and persistent but slow secondary storage. Although Optane was discontinued, new memory technologies are continuously emerging in various forms and we outline how novel designs for them can build on insights from existing PMem research.}, language = {en} } @phdthesis{Boila2024, author = {Boila, Chiara}, title = {The processing of OVS and passive sentences in German monolingual and German-Italian simultaneous bilingual children}, doi = {10.25932/publishup-62972}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-629723}, school = {Universit{\"a}t Potsdam}, pages = {xv, 223}, year = {2024}, abstract = {It is a common finding that preschoolers have difficulties in identifying who is doing what to whom in non-canonical sentences, such as (object-verb-subject) OVS and passive sentences in German. This dissertation investigates how German monolingual and German-Italian simultaneous bilingual children process German OVS sentences in Study 1 and German passives in Study 2. Offline data (i.e., accuracy data) and online data (i.e., eye-gaze and pupillometry data) were analyzed to explore whether children can assign thematic roles during sentence comprehension and processing. Executive functions, language-internal and -external factors were investigated as potential predictors for children's sentence comprehension and processing. Throughout the literature, there are contradicting findings on the relation between language and executive functions. While some results show a bilingual cognitive advantage over monolingual speakers, others suggest there is no relationship between bilingualism and executive functions. If bilingual children possess more advanced executive function abilities than monolingual children, then this might also be reflected in a better performance on linguistic tasks. In the current studies monolingual and bilingual children were tested by means of two executive function tasks: the Flanker task and the task-switching paradigm. However, these findings showed no bilingual cognitive advantages and no better performance by bilingual children in the linguistic tasks. The performance was rather comparable between bilingual and monolingual children, or even better for the monolingual group. This may be due to cross-linguistic influences and language experience (i.e., language input and output). Italian was used because it does not syntactically overlap with the structure of German OVS sentences, and it only overlapped with one of the two types of sentence condition used for the passive study - considering the subject-(finite)verb alignment. The findings showed a better performance of bilingual children in the passive sentence structure that syntactically overlapped in the two languages, providing evidence for cross-linguistic influences. Further factors for children's sentence comprehension were considered. The parents' education, the number of older siblings and language experience variables were derived from a language background questionnaire completed by parents. Scores of receptive vocabulary and grammar, visual and short-term memory and reasoning ability were measured by means of standardized tests. It was shown that higher German language experience by bilinguals correlates with better accuracy in German OVS sentences but not in passive sentences. Memory capacity had a positive effect on the comprehension of OVS and passive sentences in the bilingual group. Additionally, a role was played by executive function abilities in the comprehension of OVS sentences and not of passive sentences. It is suggested that executive function abilities might help children in the sentence comprehension task when the linguistic structures are not yet fully mastered. Altogether, these findings show that bilinguals' poorer performance in the comprehension and processing of German OVS is mainly due to reduced language experience in German, and that the different performance of bilingual children with the two types of passives is mainly due to cross-linguistic influences.}, language = {en} } @phdthesis{Cheng2024, author = {Cheng, Feng}, title = {Evolution and ontogeny of electric organ discharge in African weakly electric fish genus Campylomormyrus: a genomic and transcriptomic perspective}, doi = {10.25932/publishup-63017}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-630172}, school = {Universit{\"a}t Potsdam}, pages = {176}, year = {2024}, abstract = {The African weakly electric fishes (Mormyridae) exhibit a remarkable adaptive radiation possibly due to their species-specific electric organ discharges (EODs). It is produced by a muscle-derived electric organ that is located in the caudal peduncle. Divergence in EODs acts as a pre-zygotic isolation mechanism to drive species radiations. However, the mechanism behind the EOD diversification are only partially understood. The aim of this study is to explore the genetic basis of EOD diversification from the gene expression level across Campylomormyrus species/hybrids and ontogeny. I firstly produced a high quality genome of the species C. compressirostris as a valuable resource to understand the electric fish evolution. The next study compared the gene expression pattern between electric organs and skeletal muscles in Campylomormyrus species/hybrids with different types of EOD duration. I identified several candidate genes with an electric organ-specific expression, e.g. KCNA7a, KLF5, KCNJ2, SCN4aa, NDRG3, MEF2. The overall genes expression pattern exhibited a significant association with EOD duration in all analyzed species/hybrids. The expression of several candidate genes, e.g. KCNJ2, KLF5, KCNK6 and KCNQ5, possibly contribute to the regulation of EOD duration in Campylomormyrus due to their increasing or decreasing expression. Several potassium channel genes showed differential expression during ontogeny in species and hybrid with EOD alteration, e.g. KCNJ2. I next explored allele specific expression of intragenus hybrids by crossing the duration EOD species C. compressirostris with the medium duration EOD species C. tshokwe and the elongated duration EOD species C. rhynchophorus. The hybrids exhibited global expression dominance of the C. compressirostris allele in the adult skeletal muscle and electric organ, as well as in the juvenile electric organ. Only the gene KCNJ2 showed dominant expression of the allele from C. rhynchophorus, and this was increasingly dominant during ontogeny. It hence supported our hypothesis that KCNJ2 is a key gene of regulating EOD duration. Our results help us to understand, from a genetic perspective, how gene expression effect the EOD diversification in the African weakly electric fish.}, language = {en} } @phdthesis{Damseaux2024, author = {Damseaux, Adrien}, title = {Improving permafrost dynamics in land surface models: insights from dual sensitivity experiments}, doi = {10.25932/publishup-63945}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-639450}, school = {Universit{\"a}t Potsdam}, pages = {xiii, 143}, year = {2024}, abstract = {The thawing of permafrost and the subsequent release of greenhouse gases constitute one of the most significant and uncertain positive feedback loops in the context of climate change, making predictions regarding changes in permafrost coverage of paramount importance. To address these critical questions, climate scientists have developed Land Surface Models (LSMs) that encompass a multitude of physical soil processes. This thesis is committed to advancing our understanding and refining precise representations of permafrost dynamics within LSMs, with a specific focus on the accurate modeling of heat fluxes, an essential component for simulating permafrost physics. The first research question overviews fundamental model prerequisites for the representation of permafrost soils within land surface modeling. It includes a first-of-its-kind comparison between LSMs in CMIP6 to reveal their differences and shortcomings in key permafrost physics parameters. Overall, each of these LSMs represents a unique approach to simulating soil processes and their interactions with the climate system. Choosing the most appropriate model for a particular application depends on factors such as the spatial and temporal scale of the simulation, the specific research question, and available computational resources. The second research question evaluates the performance of the state-of-the-art Community Land Model (CLM5) in simulating Arctic permafrost regions. Our approach overcomes traditional evaluation limitations by individually addressing depth, seasonality, and regional variations, providing a comprehensive assessment of permafrost and soil temperature dynamics. I compare CLM5's results with three extensive datasets: (1) soil temperatures from 295 borehole stations, (2) active layer thickness (ALT) data from the Circumpolar Active Layer Monitoring Network (CALM), and (3) soil temperatures, ALT, and permafrost extent from the ESA Climate Change Initiative (ESA-CCI). The results show that CLM5 aligns well with ESA-CCI and CALM for permafrost extent and ALT but reveals a significant global cold temperature bias, notably over Siberia. These results echo a persistent challenge identified in numerous studies: the existence of a systematic 'cold bias' in soil temperature over permafrost regions. To address this challenge, the following research questions propose dual sensitivity experiments. The third research question represents the first study to apply a Plant Functional Type (PFT)-based approach to derive soil texture and soil organic matter (SOM), departing from the conventional use of coarse-resolution global data in LSMs. This novel method results in a more uniform distribution of soil organic matter density (OMD) across the domain, characterized by reduced OMD values in most regions. However, changes in soil texture exhibit a more intricate spatial pattern. Comparing the results to observations reveals a significant reduction in the cold bias observed in the control run. This method shows noticeable improvements in permafrost extent, but at the cost of an overestimation in ALT. These findings emphasize the model's high sensitivity to variations in soil texture and SOM content, highlighting the crucial role of soil composition in governing heat transfer processes and shaping the seasonal variation of soil temperatures in permafrost regions. Expanding upon a site experiment conducted in Trail Valley Creek by \citet{dutch_impact_2022}, the fourth research question extends the application of the snow scheme proposed by \citet{sturm_thermal_1997} to cover the entire Arctic domain. By employing a snow scheme better suited to the snow density profile observed over permafrost regions, this thesis seeks to assess its influence on simulated soil temperatures. Comparing this method to observational datasets reveals a significant reduction in the cold bias that was present in the control run. In most regions, the Sturm run exhibits a substantial decrease in the cold bias. However, there is a distinctive overshoot with a warm bias observed in mountainous areas. The Sturm experiment effectively addressed the overestimation of permafrost extent in the control run, albeit resulting in a substantial reduction in permafrost extent over mountainous areas. ALT results remain relatively consistent compared to the control run. These outcomes align with our initial hypothesis, which anticipated that the reduced snow insulation in the Sturm run would lead to higher winter soil temperatures and a more accurate representation of permafrost physics. In summary, this thesis demonstrates significant advancements in understanding permafrost dynamics and its integration into LSMs. It has meticulously unraveled the intricacies involved in the interplay between heat transfer, soil properties, and snow dynamics in permafrost regions. These insights offer novel perspectives on model representation and performance.}, language = {en} } @phdthesis{Drescher2024, author = {Drescher, Cedric}, title = {Die Bek{\"a}mpfung transnationaler Kriminalit{\"a}t im Kontext fragiler Staatlichkeit}, doi = {10.25932/publishup-62854}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-628542}, school = {Universit{\"a}t Potsdam}, pages = {XIII, 541, LVIII}, year = {2024}, abstract = {Die Arbeit „Die Bek{\"a}mpfung transnationaler Kriminalit{\"a}t im Kontext fragiler Staatlichkeit" widmet sich dem Ph{\"a}nomen grenz{\"u}berschreitend t{\"a}tiger Akteure der organisierten Kriminalit{\"a}t die den Umstand ausnutzen, dass einige international anerkannte Regierungen nur eine unzureichende Kontrolle {\"u}ber Teile ihres Staatsgebietes aus{\"u}ben. Es wird untersucht, weshalb der durch die internationale Staatengemeinschaft geschaffene Rechtsrahmen, zur Bek{\"a}mpfung transnationaler Kriminalit{\"a}tsph{\"a}nomene im Kontext dieser fragilen Staaten, nicht oder nur defizit{\"a}r dazu beitr{\"a}gt die Kriminalit{\"a}tsph{\"a}nomene zu bek{\"a}mpfen. Nachdem zun{\"a}chst er{\"o}rtert wird, was im Rahmen der Untersuchung unter dem Begriff der transnationalen Kriminalit{\"a}t verstanden wird, wird der internationale Rechtsrahmen zur Bek{\"a}mpfung anhand von f{\"u}nf beispielhaft ausgew{\"a}hlten transnationalen Kriminalit{\"a}tsph{\"a}nomenen beschrieben. Im darauffolgenden Hauptteil der Untersuchung wird der Frage nachgegangen, weshalb dieser durch die internationale Staatengemeinschaft geschaffene Rechtsrahmen, gerade in fragilen Staaten, kaum einen Beitrag dazu leistet solchen Kriminalit{\"a}tsph{\"a}nomenen effektiv zu begegnen. Dabei wird festgestellt, dass die Genese des internationalen Rechtsrahmens zu einem Legitimit{\"a}tsdefizit desselbigen f{\"u}hrt. Auch die mangelhafte Ber{\"u}cksichtigung der speziellen Lebensrealit{\"a}ten, die in vielen fragilen Staaten vorzufinden sind, wirkt sich negativ auf die Durchsetzbarkeit des internationalen Rechtsrahmens aus. Es wird dargelegt, dass unterschiedlich hohe menschenrechtliche Schutzstandards zu Normenkollisionen bei der internationalen Zusammenarbeit der Staaten f{\"u}hren, insbesondere im Rahmen der internationalen Rechtshilfe. Da gerade fragile Staaten h{\"a}ufig durch eine defizit{\"a}re menschenrechtliche Situation gekennzeichnet sind, stellt dies konsolidierte Staaten im Rahmen der Zusammenarbeit mit fragilen Staaten {\"o}fters vor Herausforderungen. Schließlich wird aufgezeigt, dass auch die extraterritoriale Jurisdiktion und somit die strafrechtliche Verfolgung transnationaler Straftaten durch Drittstaaten mit rechtlichen und praktischen Problemen einhergeht. In einem letzten Kapitel der Arbeit wird der Frage nachgegangen, ob nicht ein alternativer Strafverfolgungsmechanismus geschaffen werden sollte, um transnationale Kriminalit{\"a}tsph{\"a}nomene zu verfolgen, die aus fragilen Staaten heraus begangen werden und wie ein solch alternativer Strafverfolgungsmechanismus konkret ausgestaltet sein sollte.}, language = {de} } @phdthesis{Doerries2024, author = {D{\"o}rries, Timo Julian}, title = {Anomalous transport and non-Gaussian dynamics in mobile-immobile models}, doi = {10.25932/publishup-63495}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-634959}, school = {Universit{\"a}t Potsdam}, pages = {ii, 177}, year = {2024}, abstract = {The mobile-immobile model (MIM) has been established in geoscience in the context of contaminant transport in groundwater. Here the tracer particles effectively immobilise, e.g., due to diffusion into dead-end pores or sorption. The main idea of the MIM is to split the total particle density into a mobile and an immobile density. Individual tracers switch between the mobile and immobile state following a two-state telegraph process, i.e., the residence times in each state are distributed exponentially. In geoscience the focus lies on the breakthrough curve (BTC), which is the concentration at a fixed location over time. We apply the MIM to biological experiments with a special focus on anomalous scaling regimes of the mean squared displacement (MSD) and non-Gaussian displacement distributions. As an exemplary system, we have analysed the motion of tau proteins, that diffuse freely inside axons of neurons. Their free diffusion thereby corresponds to the mobile state of the MIM. Tau proteins stochastically bind to microtubules, which effectively immobilises the tau proteins until they unbind and continue diffusing. Long immobilisation durations compared to the mobile durations give rise to distinct non-Gaussian Laplace shaped distributions. It is accompanied by a plateau in the MSD for initially mobile tracer particles at relevant intermediate timescales. An equilibrium fraction of initially mobile tracers gives rise to non-Gaussian displacements at intermediate timescales, while the MSD remains linear at all times. In another setting bio molecules diffuse in a biosensor and transiently bind to specific receptors, where advection becomes relevant in the mobile state. The plateau in the MSD observed for the advection-free setting and long immobilisation durations persists also for the case with advection. We find a new clear regime of anomalous diffusion with non-Gaussian distributions and a cubic scaling of the MSD. This regime emerges for initially mobile and for initially immobile tracers. For an equilibrium fraction of initially mobile tracers we observe an intermittent ballistic scaling of the MSD. The long-time effective diffusion coefficient is enhanced by advection, which we physically explain with the variance of mobile durations. Finally, we generalize the MIM to incorporate arbitrary immobilisation time distributions and focus on a Mittag-Leffler immobilisation time distribution with power-law tail ~ t^(-1-mu) with 0