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Genome-scale metabolic models are mathematical representations of all known reactions occurring in a cell. Combined with constraints based on physiological measurements, these models have been used to accurately predict metabolic fluxes and effects of perturbations (e.g. knock-outs) and to inform metabolic engineering strategies. Recently, protein-constrained models have been shown to increase predictive potential (especially in overflow metabolism), while alleviating the need for measurement of nutrient uptake rates. The resulting modelling frameworks quantify the upkeep cost of a certain metabolic flux as the minimum amount of enzyme required for catalysis. These improvements are based on the use of in vitro turnover numbers or in vivo apparent catalytic rates of enzymes for model parameterization. In this thesis several tools for the estimation and refinement of these parameters based on in vivo proteomics data of Escherichia coli, Saccharomyces cerevisiae, and Chlamydomonas reinhardtii have been developed and applied. The difference between in vitro and in vivo catalytic rate measures for the three microorganisms was systematically analyzed. The results for the facultatively heterotrophic microalga C. reinhardtii considerably expanded the apparent catalytic rate estimates for photosynthetic organisms. Our general finding pointed at a global reduction of enzyme efficiency in heterotrophy compared to other growth scenarios. Independent of the modelled organism, in vivo estimates were shown to improve accuracy of predictions of protein abundances compared to in vitro values for turnover numbers. To further improve the protein abundance predictions, machine learning models were trained that integrate features derived from protein-constrained modelling and codon usage. Combining the two types of features outperformed single feature models and yielded good prediction results without relying on experimental transcriptomic data. The presented work reports valuable advances in the prediction of enzyme allocation in unseen scenarios using protein constrained metabolic models. It marks the first successful application of this modelling framework in the biotechnological important taxon of green microalgae, substantially increasing our knowledge of the enzyme catalytic landscape of phototrophic microorganisms.
Traditionally, business models and software designs used to model the usage of artificial intelligence (AI) at a very specific point in the process or rather fix implemented application. Since applications can be based on AI, such as networked artificial neural networks (ANN) on top of which applications are installed, these on-top applications can be instructed directly from their underlying ANN compartments [1]. However, with the integration of several AI-based systems, their coordination is a highly relevant target factor for the operation and improvement of networked processes, such as they can be found in cross-organizational production contexts spanning multiple distributed locations. This work aims to extend prior research on managing artificial knowledge transfers among interlinked AIs as coordination instrument by examining effects of different activation types (respective activation rates and cycles) on by ANN-instructed production machines. In a design-science-oriented way, this paper conceptualizes rhythmic state descriptions for dynamic systems and associated 14 experiment designs. Two experiments have been realized, analyzed and evaluated thereafter in regard with their activities and processes induced. Findings show that the simulator [2] used and experiments designed and realized, here, (I) enable research on ANN activation types, (II) illustrate ANN-based production networks disrupted by activation types and clarify the need for harmonizing them. Further, (III) management interventions are derived for harmonizing interlinked ANNs. This study establishes the importance of site-specific coordination mechanisms and novel forms of management interventions as drivers of efficient artificial knowledge transfer.
With the further development of more and more production machines into cyber-physical systems, and their greater integration with artificial intelligence (AI) techniques, the coordination of intelligent systems is a highly relevant target factor for the operation and improvement of networked processes, such as they can be found in cross-organizational production contexts spanning multiple distributed locations. This work aims to extend prior research on managing their artificial knowledge transfers as coordination instrument by examining effects of different activation types (respective activation rates and cycles) on by Artificial Neural Network (ANN)-instructed production machines. For this, it provides a new integration type of ANN-based cyber-physical production system as a tool to research artificial knowledge transfers: In a design-science-oriented way, a prototype of a simulation system is constructed as Open Source information system which will be used in on-building research to (I) enable research on ANN activation types in production networks, (II) illustrate ANN-based production networks disrupted by activation types and clarify the need for harmonizing them, and (III) demonstrate conceptual management interventions. This simulator shall establish the importance of site-specific coordination mechanisms and novel forms of management interventions as drivers of efficient artificial knowledge transfer.
Online-Nutzer begegnen regelmäßig unterschwelligen manipulativen Designstrategien von Anbietern digitaler Produkte, welche sie zu rechtsgeschäftlich relevanten Entscheidungen bewegen sollen, die sie womöglich nicht - oder zumindest nicht so - beabsichtigt haben. Man spricht in diesem Zusammenhang von (vielgestaltig denkbaren) „Dark Patterns“ (dt. „dunkle Muster“). Der Beitrag geht der Frage nach, inwiefern diese insbesondere lauterkeitsrechtlich zulässig sind.
A remarkable peculiarity of videoconferencing (VC) applications – the self-view – a.k.a. digital mirror, is examined as a potential reason behind the voiced exhaustion among users. This work draws on technostress research and objective self-awareness theory and proposes the communication role (sender vs. receiver) as an interaction variable. We report the results of two studies among European employees (n1 = 176, n2 = 253) with a one-year time lag. A higher frequency of self-view in a VC when receiving a message, i.e., listening to others, indirectly increases negative affect (study 1 & 2) and exhaustion (study 2) via the increased state of public self-awareness. Self-viewing in the role of message sender, e.g., as an online presenter, also increases public self-awareness, but its overall effects are less harmful. As for individual differences, users predisposed to public self-consciousness were more concerned with how other VC participants perceived them. Gender effects were insignificant.
Using novel longitudinal data, this paper studies the short- and medium-term effects of Russia's invasion of Ukraine on February 24, 2022 on social trust of adolescents in Germany. Comparing adolescents who responded to our survey shortly before the start of the war with those who responded shortly after the conflict began and applying difference-in-differences (DiD) models over time, we find a significant decline in the outcome after the war started. These findings provide new evidence on how armed conflicts influence social trust and well-being among young people in a country not directly involved in the war.
Wie ist der „gute Ruf“ von Unternehmen und Einzelpersonen im Umfeld von Online-Bewertungsplattformen geschützt? Das Werk erforscht, ob und inwieweit das geltende Recht einen adäquaten und lückenlosen Schutz für die unternehmerische und personelle Reputation gewährleitstet. Die Systematisierung und Untersuchung des bestehenden Regelungsgefüges konzentriert sich auf das Lauterkeitsrecht und das allgemeine Deliktsrecht unter besonderer Berücksichtigung der rechtlichen Innovationen auf nationaler (UWG-Reform 2022) und europäischer (New Deal for Consumers, Digital Services Act) Ebene.
Die Dissertation wurde für den ›Justizpreis Berlin-Brandenburg – Carl Gottlieb Svarez 2024‹ vorgeschlagen.
Der Ruf nach gesetzgeberischen Reparaturmaßnahmen am unbestrittenermaßen missglückten § STGB § 142 StGB ist ein kriminalpolitischer Dauerbrenner. Neu sind recht konkrete Vorschläge aus dem Bundesministerium der Justiz zu einer Reduktion des objektiven Tatbestandes, durch die ein beträchtlicher Anteil der Anwendungsfälle künftig in das Ordnungswidrigkeitenrecht verlagert werden soll. Unfälle, die „reine Sachschäden“ verursachen, sollen eine nur noch bußgeldbewehrte Warte- und Feststellungsermöglichungspflicht auslösen. Die im Vorstadium eines Gesetzesentwurfs publizierten ministeriellen Ideen haben ein geteiltes Echo – Zustimmung und Ablehnung – ausgelöst. Der Beitrag befasst sich nicht mit der umstrittenen kriminalpolitischen Vernünftigkeit der Pläne, zeigt aber einige strafrechtsdogmatische Aspekte auf, die bei der Neufassung des Gesetzeswortlauts zu beachten sein werden.
Der untenstehende Text ist eine recht spontane Reaktion auf Bemerkungen, die jüngst von den Kollegen Armin Engländer und Christian Rückert zu einem Kodifizierungsvorschlag für die Regelungsthemen Notwehr, Notwehrexzess und subjektives Rechtfertigungselement in der Zeitschrift „Goltdammer’s Archiv für Strafrecht“ präsentiert wurden. Den Entwurfstext hat eine – kleine – Gruppe von Strafrechtslehrern erarbeitet. Er wurde letztes Jahr mittels eines Aufsatzes von Elisa Hoven und Wolfgang Mitsch – ebenfalls im „Goltdammer’s Archiv“ − vorgestellt und erläutert. Engländer und Rückert äußern stellenweise Zustimmung, üben aber auch zu vielen Punkten des Entwurfs und seiner Begründung Kritik. Da der hiesige Verfasser sowohl an der Entwicklung des Entwurfstextes als auch an dem genannten GA-Aufsatz als Ko-Autor beteiligt war, möchte er − im Folgenden: ich − zu einigen der Kritiken Stellung nehmen.
Organizations are investing billions on innovation and agility initiatives to stay competitive in their increasingly uncertain business environments. Design Thinking, an innovation approach based on human-centered exploration, ideation and experimentation, has gained increasing popularity. The market for Design Thinking, including software products and general services, is projected to reach 2.500 million $ (US-Dollar) by 2028. A dispersed set of positive outcomes have been attributed to Design Thinking. However, there is no clear understanding of what exactly comprises the impact of Design Thinking and how it is created. To support a billion-dollar market, it is essential to understand the value Design Thinking is bringing to organizations not only to justify large investments, but to continuously improve the approach and its application.
Following a qualitative research approach combined with results from a systematic literature review, the results presented in this dissertation offer a structured understanding of Design Thinking impact. The results are structured along two main perspectives of impact: the individual and the organizational perspective. First, insights from qualitative data analysis demonstrate that measuring and assessing the impact of Design Thinking is currently one central challenge for Design Thinking practitioners in organizations. Second, the interview data revealed several effects Design Thinking has on individuals, demonstrating how Design Thinking can impact boundary management behaviors and enable employees to craft their jobs more actively.
Contributing to innovation management research, the work presented in this dissertation systematically explains the Design Thinking impact, allowing other researchers to both locate and integrate their work better. The results of this research advance the theoretical rigor of Design Thinking impact research, offering multiple theoretical underpinnings explaining the variety of Design Thinking impact. Furthermore, this dissertation contains three specific propositions on how Design Thinking creates an impact: Design Thinking creates an impact through integration, enablement, and engagement. Integration refers to how Design Thinking enables organizations through effectively combining things, such as for example fostering balance between exploitation and exploration activities. Through Engagement, Design Thinking impacts organizations involving users and other relevant stakeholders in their work. Moreover, Design Thinking creates impact through Enablement, making it possible for individuals to enact a specific behavior or experience certain states.
By synthesizing multiple theoretical streams into these three overarching themes, the results of this research can help bridge disciplinary boundaries, for example between business, psychology and design, and enhance future collaborative research. Practitioners benefit from the results as multiple desirable outcomes are detailed in this thesis, such as successful individual job crafting behaviors, which can be expected from practicing Design Thinking. This allows practitioners to enact more evidence-based decision-making concerning Design Thinking implementation. Overall, considering multiple levels of impact as well as a broad range of theoretical underpinnings are paramount to understanding and fostering Design Thinking impact.
Illegales Wettrasen auf öffentlichen Straßen beschäftigt Staatsanwaltschaften und Strafgerichte, wenn dieses Ereignis stattgefunden und oftmals auch schwere Schäden verursacht hat. Jeder hat noch das Verfahren um das tödliche Geschehen auf der Berliner Tauentzienstrasse im Gedächtnis und vor Augen. Naturgemäß geht einer solchen Aktion stets eine – wenn auch nur kurze und evtl. nonverbale (z. B. Kopfnicken, Handzeichen) – Verständigung der Teilnehmer voraus. Praktisch mag die Frage keine Bedeutung haben, theoretisch interessant ist sie aber schon: Ist bereits diese Kommunikation in der Anbahnungsphase möglicherweise strafbares Verhalten? Praktisch würde sich die Möglichkeit der Strafverfolgung darauf beschränken, wenn aus irgendeinem Grund das Rennen dann doch nicht stattgefunden hat. Daher sollen hier – weil das nach meiner Beobachtung noch nirgends geschehen ist – zu diesem Thema ein paar klärende Ausführungen gemacht werden.
Fälle zum Strafprozessrecht
(2024)
Plate tectonic boundaries constitute the suture zones between tectonic plates. They are shaped by a variety of distinct and interrelated processes and play a key role in geohazards and georesource formation. Many of these processes have been previously studied, while many others remain unaddressed or undiscovered. In this work, the geodynamic numerical modeling software ASPECT is applied to shed light on further process interactions at continental plate boundaries. In contrast to natural data, geodynamic modeling has the advantage that processes can be directly quantified and that all parameters can be analyzed over the entire evolution of a structure. Furthermore, processes and interactions can be singled out from complex settings because the modeler has full control over all of the parameters involved. To account for the simplifying character of models in general, I have chosen to study generic geological settings with a focus on the processes and interactions rather than precisely reconstructing a specific region of the Earth.
In Chapter 2, 2D models of continental rifts with different crustal thicknesses between 20 and 50 km and extension velocities in the range of 0.5-10 mm/yr are used to obtain a speed limit for the thermal steady-state assumption, commonly employed to address the temperature fields of continental rifts worldwide. Because the tectonic deformation from ongoing rifting outpaces heat conduction, the temperature field is not in equilibrium, but is characterized by a transient, tectonically-induced heat flow signal. As a result, I find that isotherm depths of the geodynamic evolution models are shallower than a temperature distribution in equilibrium would suggest. This is particularly important for deep isotherms and narrow rifts. In narrow rifts, the magnitude of the transient temperature signal limits a well-founded applicability of the thermal steady-state assumption to extension velocities of 0.5-2 mm/yr. Estimation of the crustal temperature field affects conclusions on all temperature-dependent processes ranging from mineral assemblages to the feasible exploitation of a geothermal reservoir.
In Chapter 3, I model the interactions of different rheologies with the kinematics of folding and faulting using the example of fault-propagation folds in the Andean fold-and-thrust belt. The evolution of the velocity fields from geodynamic models are compared with those from trishear models of the same structure. While the latter use only geometric and kinematic constraints of the main fault, the geodynamic models capture viscous, plastic, and elastic deformation in the entire model domain. I find that both models work equally well for early, and thus relatively simple stages of folding and faulting, while results differ for more complex situations where off-fault deformation and secondary faulting are present. As fault-propagation folds can play an important role in the formation of reservoirs, knowledge of fluid pathways, for example via fractures and faults, is crucial for their characterization.
Chapter 4 deals with a bending transform fault and the interconnections between tectonics and surface processes. In particular, the tectonic evolution of the Dead Sea Fault is addressed where a releasing bend forms the Dead Sea pull-apart basin, while a restraining bend further to the North resulted in the formation of the Lebanese mountains. I ran 3D coupled geodynamic and surface evolution models that included both types of bends in a single setup. I tested various randomized initial strain distributions, showing that basin asymmetry is a consequence of strain localization. Furthermore, by varying the surface process efficiency, I find that the deposition of sediment in the pull-apart basin not only controls basin depth, but also results in a crustal flow component that increases uplift at the restraining bend.
Finally, in Chapter 5, I present the computational basis for adding further complexity to plate boundary models in ASPECT with the implementation of earthquake-like behavior using the rate-and-state friction framework. Despite earthquakes happening on a relatively small time scale, there are many interactions between the seismic cycle and the long time spans of other geodynamic processes. Amongst others, the crustal state of stress as well as the presence of fluids or changes in temperature may alter the frictional behavior of a fault segment. My work provides the basis for a realistic setup of involved structures and processes, which is therefore important to obtain a meaningful estimate for earthquake hazards.
While these findings improve our understanding of continental plate boundaries, further development of geodynamic software may help to reveal even more processes and interactions in the future.
Fischer Strafgesetzbuch
(2024)
Mantodea, commonly known as mantids, have captivated researchers owing to their enigmatic behavior and ecological significance. This order comprises a diverse array of predatory insects, boasting over 2,400 species globally and inhabiting a wide spectrum of ecosystems. In Iran, the mantid fauna displays remarkable diversity, yet numerous facets of this fauna remain poorly understood, with a significant dearth of systematic and ecological research. This substantial knowledge gap underscores the pressing need for a comprehensive study to advance our understanding of Mantodea in Iran and its neighboring regions.
The principal objective of this investigation was to delve into the ecology and phylogeny of Mantodea within these areas. To accomplish this, our research efforts concentrated on three distinct genera within Iranian Mantodea. These genera were selected due to their limited existing knowledge base and feasibility for in-depth study. Our comprehensive methodology encompassed a multifaceted approach, integrating morphological analysis, molecular techniques, and ecological observations.
Our research encompassed a comprehensive revision of the genus Holaptilon, resulting in the description of four previously unknown species. This extensive effort substantially advanced our understanding of the ecological roles played by Holaptilon and refined its systematic classification. Furthermore, our investigation into Nilomantis floweri expanded its known distribution range to include Iran. By conducting thorough biological assessments, genetic analyses, and ecological niche modeling, we obtained invaluable insights into distribution patterns and genetic diversity within this species. Additionally, our research provided a thorough comprehension of the life cycle, behaviors, and ecological niche modeling of Blepharopsis mendica, shedding new light on the distinctive characteristics of this mantid species. Moreover, we contributed essential knowledge about parasitoids that infect mantid ootheca, laying the foundation for future studies aimed at uncovering the intricate mechanisms governing ecological and evolutionary interactions between parasitoids and Mantodea.
Die Arbeit ist der Versuch einer zusammenhängenden historisierenden Lektüre der wichtigsten Essays und fiktionalen Prosatexte des Schriftstellers Ronald M. Schernikau (1960-1991). Der schwule Kommunist erklärte das Lob zur künstlerischen Strategie, formulierte gleichzeitig eine avancierte Gesellschaftskritik und verteidigte den realen Sozialismus auch gegen die Realität. Im Verlauf mehrerer Einzelstudien werden Themen, Schreibweisen und schließlich auch die Widersprüche, in die sich ein solches Projekt verstricken muss, analysiert. Vor dem Hintergrund zentraler politischer und ästhetischer Debatten der 1970er und -80er Jahre werden so die Umrisse einer politischen Poetik nachgezeichnet, die der Schönheit verpflichtet ist. Ein weiteres Augenmerk liegt dabei auf theorie- und bewegungsgeschichtlichen Aspekten.
Gibt es ein schwules Schreiben jenseits einer auktorialen Selbstpositionierung? Was würde eine kommunistische Literatur auszeichnen? Schernikau verhandelt poetologische Fragen um die Konzepte Autorschaft, Realismus und Werk, die nicht nur an gegenwärtige Diskurse anschlussfähig sind, sondern auf die Kernprobleme der politischen Literatur des Zwanzigsten Jahrhunderts verweisen.
Virtual Reality (VR) leads to the highest level of immersion if presented using a 1:1 mapping of virtual space to physical space—also known as real walking. The advent of inexpensive consumer virtual reality (VR) headsets, all capable of running inside-out position tracking, has brought VR to the home. However, many VR applications do not feature full real walking, but instead, feature a less immersive space-saving technique known as instant teleportation. Given that only 0.3% of home users run their VR experiences in spaces more than 4m2, the most likely explanation is the lack of the physical space required for meaningful use of real walking. In this thesis, we investigate how to overcome this hurdle. We demonstrate how to run 1:1-mapped VR experiences in small physical spaces and we explore the trade-off between space and immersion. (1) We start with a space limit of 15cm. We present DualPanto, a device that allows (blind) VR users to experience the virtual world from a 1:1 mapped bird’s eye perspective—by leveraging haptics. (2) We then relax our space constraints to 50cm, which is what seated users (e.g., on an airplane or train ride) have at their disposal. We leverage the space to represent a standing user in 1:1 mapping, while only compressing the user’s arm movement. We demonstrate our 4 prototype VirtualArms at the example of VR experiences limited to arm movement, such as boxing. (3) Finally, we relax our space constraints further to 3m2 of walkable space, which is what 75% of home users have access to. As well- established in the literature, we implement real walking with the help of portals, also known as “impossible spaces”. While impossible spaces on such dramatic space constraints tend to degenerate into incomprehensible mazes (as demonstrated, for example, by “TraVRsal”), we propose plausibleSpaces: presenting meaningful virtual worlds by adapting various visual elements to impossible spaces. Our techniques push the boundary of spatially meaningful VR interaction in various small spaces. We see further future challenges for new design approaches to immersive VR experiences for the smallest physical spaces in our daily life.
Phobic cosmopolitanism
(2024)
Begrenztes Cottbus?
(2024)
In diesem Band ermöglicht Mario Kaun ausgewählte Einblicke in die Lebenswelt der Cottbuser Exklavengesellschaft des 18. Jahrhunderts. Erstmalig erscheint hiermit für diesen Untersuchungsraum eine grundlegende Studie, die in umfassender Weise die Exklave und das Verhältnis von Militär und Gesellschaft näher erforscht sowie die wirtschaftliche Funktion der Garnison in einer aufstrebenden Stadt kritisch hinterfragt. Der Autor lenkt hierbei das Augenmerk auf etliche, bisher völlig unbekannte Perspektiven, die darüber hinaus einen wichtigen Beitrag zur Stadt- und Regionalgeschichtsforschung von Cottbus und der Niederlausitz leisten. Insbesondere die Befassung mit der brandenburgisch-preußischen Exklave stellt eine wertvolle Ergänzung zur bislang rudimentären Forschungslage dar.
The inclusion of exotic germplasm serves as a crucial means to enhance allelic and
consequently phenotypic diversity in inbred crop species. Such species have experienced a reduction in diversity due to artificial selection focused on a limited set of traits. The natural biodiversity within ecosystems presents an opportunity to explore various traits influencing plant survival, reproductive fitness and yield potential. In agricultural research, the study of wild species closely related to cultivated plants serves as a means to comprehend the genetic foundations of past domestication events and the polymorphisms essential for future breeding efforts to develop superior varieties. In order to examine the metabolic composition, pinpoint quantitative trait loci (QTL) and facilitate their resolution an extensive large-scale analysis of metabolic QTL (mQTL) was conducted on tomato backcross inbred lines (BILs) derived from a cross between the wild species S. pennellii (5240) incorporated into the background of S. lycopersicum cv. LEA determinate inbred which can be grown in open fields and cv. TOP indeterminate which can be grown in greenhouse conditions. A large number of mQTL associated with primary secondary and lipid metabolism in fruit were identified across the two BIL populations. Epistasis, the interactions between genes at different loci, has been an interest in molecular and quantitative genetics for many decades. The study of epistasis requires the analysis of very large populations with multiple independent genotypes that carry specific genomic regions. In order to understand the genetic basis of tomato fruit metabolism, I extended the work to investigate epistatic interactions of the genomic regions. In addition, two candidate genes were identified through quantitative trait loci underlying fruit-specific sucrose and jasmonic acid derivatives. Finally, in this study, I assessed the genetic framework of fruit metabolic traits with a high level of detail, utilizing the newly created Solanum pennellii (5240) backcrossed introgression lines (n=3000). This investigation resulted in the discovery of promising candidate loci associated with significant fruit quality traits, including those to the abundance of glutamic acid and aspartic acid crucial elements contributing to the development of acidity and flavors.
Klausur im Medienrecht
(2024)
Die Privatsphäre prominenter Personen wird häufig durch eine auf Sensationsgier ausgerichtete Presseberichterstattung gefährdet. Während sich die Presse dabei vordergründig auf ein öffentliches Interesse an solchen Berichten beruft, kann die Reputation der Betroffenen in der Öffentlichkeit stark und dauerhaft beeinträchtigt werden. Jedoch folgen aus dem Allgemeinen Persönlichkeitsrecht mehrere Ansprüche, mit denen diese Rechtsverletzungen abgewehrt und mögliche Schäden kompensiert werden können.
Cities and other human settlements are major contributors to climate change and are highly vulnerable to its impacts. They are also uniquely positioned to reduce greenhouse gas emissions and lead adaptation efforts. These compound challenges and opportunities require a comprehensive perspective on the public policy of human settlements. Drawing on core literature that has driven debate around cities and climate over recent decades, we put forward a set of boundary objects that can be applied to connect the knowledge of epistemic communities and support an integrated urbanism. We then use these boundary objects to develop the Goals-Intervention-Stakeholder-Enablers (GISE) framework for a public policy of human settlements that is both place-specific and provides insights and tools useful for climate action in cities and other human settlements worldwide. Using examples from Berlin, we apply this framework to show that climate mitigation and adaptation, public health, and well-being goals are closely linked and mutually supportive when a comprehensive approach to urban public policy is applied.
HPI Future SOC Lab
(2024)
The “HPI Future SOC Lab” is a cooperation of the Hasso Plattner Institute (HPI) and industry partners. Its mission is to enable and promote exchange and interaction between the research community and the industry partners.
The HPI Future SOC Lab provides researchers with free of charge access to a complete infrastructure of state of the art hard and software. This infrastructure includes components, which might be too expensive for an ordinary research environment, such as servers with up to 64 cores and 2 TB main memory. The offerings address researchers particularly from but not limited to the areas of computer science and business information systems. Main areas of research include cloud computing, parallelization, and In-Memory technologies.
This technical report presents results of research projects executed in 2020. Selected projects have presented their results on April 21st and November 10th 2020 at the Future SOC Lab Day events.
Floods continue to be the leading cause of economic damages and fatalities among natural disasters worldwide. As future climate and exposure changes are projected to intensify these damages, the need for more accurate and scalable flood risk models is rising. Over the past decade, macro-scale flood risk models have evolved from initial proof-of-concepts to indispensable tools for decision-making at global-, nationaland, increasingly, the local-level. This progress has been propelled by the advent of high-performance computing and the availability of global, space-based datasets. However, despite such advancements, these models are rarely validated and consistently fall short of the accuracy achieved by high-resolution local models. While capabilities have improved, significant gaps persist in understanding the behaviours of such macro-scale models, particularly their tendency to overestimate risk. This dissertation aims to address such gaps by examining the scale transfers inherent in the construction and application of coarse macroscale models. To achieve this, four studies are presented that, collectively, address exposure, hazard, and vulnerability components of risk affected by upscaling or downscaling.
The first study focuses on a type of downscaling where coarse flood hazard inundation grids are enhanced to a finer resolution. While such inundation downscaling has been employed in numerous global model chains, ours is the first study to focus specifically on this component, providing an evaluation of the state of the art and a novel algorithm. Findings demonstrate that our novel algorithm is eight times faster than existing methods, offers a slight improvement in accuracy, and generates more physically coherent flood maps in hydraulically challenging regions. When applied to a case study, the algorithm generated a 4m resolution inundation map from 30m hydrodynamic model outputs in 33 s, a 60-fold improvement in runtime with a 25% increase in RMSE compared with direct hydrodynamic modelling. All evaluated downscaling algorithms yielded better accuracy than the coarse hydrodynamic model when compared to observations, demonstrating similar limits of coarse hydrodynamic models reported by others. The substitution of downscaling into flood risk model chains, in place of high-resolution modelling, can drastically improve the lead time of impactbased forecasts and the efficiency of hazard map production. With downscaling, local regions could obtain high resolution local inundation maps by post-processing a global model without the need for expensive modelling or expertise.
The second study focuses on hazard aggregation and its implications for exposure, investigating implicit aggregations commonly used to intersect hazard grids with coarse exposure models. This research introduces a novel spatial classification framework to understand the effects of rescaling flood hazard grids to a coarser resolution. The study derives closed-form analytical solutions for the location and direction of bias from flood grid aggregation, showing that bias will always be present in regions near the edge of inundation. For example, inundation area will be positively biased when water depth grids are aggregated, while volume will be negatively biased when water elevation grids are aggregated. Extending the analysis to effects of hazard aggregation on building exposure, this study shows that exposure in regions at the edge of inundation are an order of magnitude more sensitive to aggregation errors than hazard alone. Among the two aggregation routines considered, averaging water surface elevation grids better preserved flood depths at buildings than averaging of water depth grids. The study provides the first mathematical proof and generalizeable treatment of flood hazard grid aggregation, demonstrating important mechanisms to help flood risk modellers understand and control model behaviour.
The final two studies focus on the aggregation of vulnerability models or flood damage functions, investigating the practice of applying per-asset functions to aggregate exposure models. Both studies extend Jensen’s inequality, a well-known 1906 mathematical proof, to demonstrate how the aggregation of flood damage functions leads to bias. Applying Jensen’s proof in this new context, results show that typically concave flood damage functions will introduce a positive bias (overestimation) when aggregated. This behaviour was further investigated with a simulation experiment including 2 million buildings in Germany, four global flood hazard simulations and three aggregation scenarios. The results show that positive aggregation bias is not distributed evenly in space, meaning some regions identified as “hot spots of risk” in assessments may in fact just be hot spots of aggregation bias. This study provides the first application of Jensen’s inequality to explain the overestimates reported elsewhere and advice for modellers to minimize such artifacts.
In total, this dissertation investigates the complex ways aggregation and disaggregation influence the behaviour of risk models, focusing on the scale-transfers underpinning macro-scale flood risk assessments. Extending a key finding of the flood hazard literature to the broader context of flood risk, this dissertation concludes that all else equal, coarse models overestimate risk. This dissertation goes beyond previous studies by providing mathematical proofs for how and where such bias emerges in aggregation routines, offering a mechanistic explanation for coarse model overestimates. It shows that this bias is spatially heterogeneous, necessitating a deep understanding of how rescaling may bias models to effectively reduce or communicate uncertainties. Further, the dissertation offers specific recommendations to help modellers minimize scale transfers in problematic regions. In conclusion, I argue that such aggregation errors are epistemic, stemming from choices in model structure, and therefore hold greater potential and impetus for study and mitigation. This deeper understanding of uncertainties is essential for improving macro-scale flood risk models and their effectiveness in equitable, holistic, and sustainable flood management.
High-growth firms (HGFs) are important for job creation and productivity growth. We investigate the relationship between product and labour market regulations, as well as the quality of regional governments that implement these regulations, and the development of HGFs across European regions. Using data from Eurostat, the Organisation for Economic Co-operation and Development (OECD), World Economic Forum (WEF), and Gothenburg University, we show that both regulatory stringency and the quality of the regional government relate to the regional shares of HGFs. In particular, we find that the effect of labour and product market regulations is moderated by the quality of regional government. Depending on the quality of regional governments, regulations may have a ‘good, bad or ugly’ influence on the development of HGFs. Our findings contribute to the debate on the effects of regulations and offer important building blocks to develop tailored policy measures that may influence the development of HGFs in a region.
State space models enjoy wide popularity in mathematical and statistical modelling across disciplines and research fields. Frequent solutions to problems of estimation and forecasting of a latent signal such as the celebrated Kalman filter hereby rely on a set of strong assumptions such as linearity of system dynamics and Gaussianity of noise terms.
We investigate fallacy in mis-specification of the noise terms, that is signal noise
and observation noise, regarding heavy tailedness in that the true dynamic frequently produces observation outliers or abrupt jumps of the signal state due to realizations of these heavy tails not considered by the model. We propose a formalisation of observation noise mis-specification in terms of Huber’s ε-contamination as well as a computationally cheap solution via generalised Bayesian posteriors with a diffusion Stein divergence loss resulting in the diffusion score matching Kalman filter - a modified algorithm akin in complexity to the regular Kalman filter. For this new filter interpretations of novel terms, stability and an ensemble variant are discussed. Regarding signal noise mis-specification, we propose a formalisation in the frame work of change point detection and join ideas from the popular CUSUM algo-
rithm with ideas from Bayesian online change point detection to combine frequent reliability constraints and online inference resulting in a Gaussian mixture model variant of multiple Kalman filters. We hereby exploit open-end sequential probability ratio tests on the evidence of Kalman filters on observation sub-sequences for aggregated inference under notions of plausibility.
Both proposed methods are combined to investigate the double mis-specification problem and discussed regarding their capabilities in reliable and well-tuned uncertainty quantification. Each section provides an introduction to required terminology and tools as well as simulation experiments on the popular target tracking task and the non-linear, chaotic Lorenz-63 system to showcase practical performance of theoretical considerations.
Learning in virtual, immersive environments must be well-designed to foster learning instead of overwhelming and distracting the learner. So far, learning instructions based on cognitive load theory recommend keeping the learning instructions clean and simple to reduce the extraneous cognitive load of the learner to foster learning performance. The advantages of immersive learning, such as multiple options for realistic simulation, movement and feedback, raise questions about the tension between an increase of excitement and flow with highly realistic environments on the one hand and a reduction of cognitive load by developing clean and simple surroundings on the other hand. This study aims to gain insights into learners' cognitive responses during the learning process by continuously assessing cognitive load through eye-tracking. The experiment compares two distinct immersive learning environments and varying methods of content presentation.
We study the effect of energy and transport policies on pollution in two developing country cities. We use a quantitative equilibrium model with choice of housing, energy use, residential location, transport mode, and energy technology. Pollution comes from commuting and residential energy use. The model parameters are calibrated to replicate key variables for two developing country cities, Maputo, Mozambique, and Yogyakarta, Indonesia. In the counterfactual simulations, we study how various transport and energy policies affect equilibrium pollution. Policies may induce rebound effects from increasing residential energy use or switching to high emission modes or locations. In general, these rebound effects tend to be largest for subsidies to public transport or modern residential energy technology.
This systematic literature review highlights the gap in demand forecasting in the manufacturing sector, which is challenged by complex supply chains and rapid market change. Traditional methods fall short in this dynamic environment, highlighting the need for an approach that combines advanced forecasting techniques, high-quality data, and industry-specific insights. Our research contributes by evaluating advanced forecasting methods, the effectiveness of AI and data strategies to improve accuracy. Our analysis reveals a shift towards machine learning and deep learning to improve accuracy and highlights the untapped potential of external data sources. Key findings provide both researchers and practitioners with guidance on effective forecasting strategies and key data types and offer an integrated framework for improving forecasting accuracy and strategic decision-making in manufacturing. This work fills a critical research gap and provides stakeholders with actionable insights to manage the complexity of modern manufacturing, representing a significant advance in forecasting practice.
The field of healthcare is characterized by constant innovation, with gender-specific medicine emerging as a new subfield that addresses sex and gender disparities in clinical manifestations, outcomes, treatment, and prevention of disease. Despite its importance, the adoption of gender-specific medicine remains understudied, posing potential risks to patient outcomes due to a lack of awareness of the topic. Building on the Innovation Decision Process Theory, this study examines the spread of information about gender-specific medicine in online networks. The study applies social network analysis to a Twitter dataset reflecting online discussions about the topic to gain insights into its adoption by health professionals and patients online. Results show that the network has a community structure with limited information exchange between sub-communities and that mainly medical experts dominate the discussion. The findings suggest that the adoption of gender-specific medicine might be in its early stages, focused on knowledge exchange. Understanding the diffusion of gender-specific medicine among medical professionals and patients may facilitate its adoption and ultimately improve health outcomes.
In dieser Arbeit wurde eine reaktive Wand in einem kleinskaligen Laborma\ss stab (Länge~=~40\,cm) entwickelt, die Eisen- und Sulfatbelastungen aus sauren Minenabwässern (engl. \textit{acid mine drainage} (AMD)) mit einer Effizienz von bis zu 30.2 bzw. 24.2\,\% über einen Zeitraum von 146~Tagen (50\,pv) abreinigen können sollte. Als reaktives Material wurde eine Mischung aus Gartenkompost, Buchenholz, Kokosnussschale und Calciumcarbonat verwendet. Die Zugabebedingungen waren eine Eisenkonzentration von 1000\,mg/L, eine Sulfatkonzentration von 3000\,mg/L und ein pH-Wert von 6.2.
Unterschiede in der Materialzusammensetzung ergaben keine grö\ss eren Änderungen in der Sanierungseffizienz von Eisen- und Sulfatbelastungen (12.0 -- 15.4\,\% bzw. 7.0 -- 10.1\,\%) über einen Untersuchungszeitraum von 108~Tagen (41 -- 57\,pv). Der wichtigste Einflussfaktor auf die Abreinigungsleistung von Sulfat- und Eisenbelastungen war die Verweilzeit der AMD-Lösung im reaktiven Material. Diese kann durch eine Verringerung des Durchflusses oder eine Erhöhung der Länge der reaktiven Wand (engl. \textit{Permeable Reactive Barrier} (PRB)) erhöht werden. Ein halbierter Durchfluss erhöhte die Sanierungseffizienzen von Eisen und Sulfat auf 23.4 bzw. 32.7\,\%. Weiterhin stieg die Sanierungseffizienz der Eisenbelastungen auf 24.2\,\% bei einer Erhöhung der Sulfatzugabekonzentration auf 6000\,mg/L. Saure Startbedingungen (pH~=~2.2) konnten, durch das Calciumcarbonat im reaktiven Material, über einen Zeitraum von 47~Tagen (24\,pv) neutralisiert werden. Durch die Neutralisierung der sauren Startbedingungen wurde Calciumcarbonat in der \gls{prb} verbraucht und Calcium-Ionen freigesetzt, die die Sulfatsanierungseffizienz erhöht haben (24.9\,\%). Aufgrund einer Vergrö\ss erung der \gls{prb} in Breite und Tiefe und einer 2D-Parameterbestimmung konnten Randläufigkeiten beobachtet werden, ohne deren Einfluss sich die Sanierungseffizienz für Eisen- und Sulfatbelastungen erhöht (30.2 bzw. 24.2\,\%). \par
Zur \textit{in-situ} Überwachung der \gls{prb} wurden optische Sensoren verwendet, um den pH-Wert, die Sauerstoffkonzentration und die Temperatur zu ermitteln. Es wurden, nach dem Ort und der Zeit aufgelöst, stabile Sauerstoffkonzentrationen und pH-Verläufe detektiert. Auch die Temperatur konnte nach dem Ort aufgelöst ermittelt werden. Damit zeigte diese Arbeit, dass optische Sensoren zur Überwachung der Stabilität einer \gls{prb} für die Reinigung von \gls{amd} verwendet werden können. \par
Mit dem Simulationsprogramm MIN3P wurde eine Simulation erstellt, die die entwickelte PRB darstellt. Die Simulation kann die erhaltenen Laborergebnisse gut wiedergeben. Anschlie\ss end wurde eine simulierte \gls{prb} bei unterschiedlichen Filtergeschwindigkeiten ((4.0 -- 23.5)~$\cdot~\mathrm{10^{-7}}$\,m/s) und Längen der PRB (25 -- 400\,cm) untersucht. Es wurden Zusammenhänge der untersuchten Parameter mit der Sanierungseffizienz von Eisen- und Sulfatbelastungen ermittelt. Diese Zusammenhänge können verwendet werden, um die benötigte Verweilzeit der AMD-Lösung in einem zukünftigen PRB-System, die für die maximal mögliche Sanierungsleistung notwendig ist, zu berechnen.
Proceedings of TripleA 10
(2024)
The TripleA workshop series was founded in 2014 by linguists from Potsdam and Tübingen with the aim of providing a platform for researchers that conduct theoretically-informed linguistic fieldwork on meaning. Its focus is particularly on languages that are under-represented in the current research landscape, including but not limited to languages of Africa, Asia, and Australia, hence TripleA.
For its 10th anniversary, TripleA returned to the University of Potsdam on the 7-9th of June 2023.
The programme included 21 talks dealing with no less than 22 different languages, including three invited talks given by Sihwei Chen (Academia Sinica), Jérémy Pasquereau (Laboratoire de Linguistique de Nantes, CNRS) and Agata Renans (Ruhr-Universität Bochum). Nine of these (invited or peer-reviewed) talks are featured in this volume.
Despite the high hopes associated with public sector digitalization, especially in times of crisis, it does not yet hold up to its potential. Both the negotiation and implementation of digitalization policy presents a challenge for all levels of government, requiring extensive coordination efforts. In general, there are conflicting views if more centralized or decentralized policy processes are more effective for coordination—a tension further exacerbated in the context of digitalization policy within multilevel systems, where the imperative of standardization collides with decentralization forces inherent in federalism.
Based on the analysis of expert interviews (n = 29), this chapter examines how digitalization policy in the context of the German federal intergovernmental relations context is located and negotiated, and how this relates to local policy implementation. Focusing on the decentralized German tax administration as a case study, the analysis reveals a shift from a conflicted to a multi-layered policy process, underpinned by a mechanism of “concentration without centralization.” Strategic and operational competencies are bundled in an institutionalized and legally regulated network for digitalization to achieve necessary standardization of digital infrastructure. Furthermore, the research emphasizes the influence of intergovernmental relations on local implementation and the associated challenges and opportunities.
Urban climate strategies have become central tools for steering climate policy in cities. Local policymakers must coordinate a wide range of actors, among them sub-municipal administrative units and neighbouring administrations, in order to ensure legitimate, socially accepted and effective policy. The study examines, from a comparative perspective, how intergovernmental relations (IGR) play out in the formulation and implementation of climate strategies in the metropolitan areas of Berlin and Paris. Embedded in different institutional contexts, both cities followed a trajectory initiated by relatively centralized strategy formulation with an ongoing shift towards more decentralized and coordinated intergovernmental approaches with their respective district administrations. In terms of horizontal IGR, Berlin took a decoupled approach with limited coordination with the state of Brandenburg, whereas Paris was much more closely integrated with its surrounding areas through the inter-municipal metropolis of Greater Paris. Institutional capacity, multilevel coordination and participation demands are identified as three challenges for the existing IGR structures. Addressing these challenges places significant strains on local administrative capacity. The findings highlight the limitations of centralized approaches to IGR at the local level and the importance of aligning the distribution of functional responsibilities with the rights of consultation and participation in climate policy formulation processes.
Migrant integration is a prime example of intergovernmental coordination and multilevel governance; first because no level of government can carry out this task alone, and second because its cross-cutting nature often leads to fragmented institutional structures that must be overcome. Within the research strand of intergovernmental relations (IGR), the focus has been on executive actors and governmental decision-makers, resulting in an underexposure of the role of public administration, known as inter-administrative relations (IAR). Against this backdrop, we aim to remedy some of the deficits in IGR research by (1) adopting an explicit IAR perspective which systematically addresses the role of local governments; (2) including a comparative dimension in IAR research that accounts for different administrative ‘starting conditions’ in European countries; and (3) using the policy area of migrant integration as a case in point to empirically investigate developments of institutional convergence and divergence in IAR patterns. It is argued that the coordination of migrant integration in the three countries examined has moved towards more intergovernmental coordination, on the one hand, and that the role of municipalities in this context has been enhanced—varying degrees of (de-)centralization notwithstanding. While certain convergent patterns of inter-governmental coordination have become apparent during the migration crisis, historical path dependencies and administrative cultures still appear to be factors that influence institutional development.
This open access book assesses the consequences of contemporary economic and political crises for intergovernmental relations in Europe. Focusing on the crises arising from the Covid-19 pandemic, climate change, surges in migration, and the resurgence of regional nationalist movements, it explores the shifting power balances within intergovernmental relations’ systems. The book takes a comparative analytical perspective on how intergovernmental relations are changing across Europe, and how central governments have responded to coordination challenges as recent crises have disrupted established service delivery chains and their underpinning political and bureaucratic arrangements. It also examines the relationship between recent crises and the sub-national resurgence of territorial politics in many European countries. The book will appeal to those with interests in public administration, sub-national governance and European politics.
Consumer behaviour changes and strategic management decisions are driving adaptations in manufacturing routines. Based on the theory of situational strength, we investigated how contextual and person-related factors influence workers’ adaptation in a two-worker position routine. Contextual factors, like retrieval cues (Study 1), time pressure (Study 2), and convenience (Study 3), were varied. Person-related factors included retentivity, general and routine-specific self-efficacy, and perceived adaptation costs. Dependent variables included various error types and production time before and after adaptation. In each study, 148 participants were trained in a production routine at t1 and executed an adapted routine at t2, one week later. Repeated measures ANOVA for performance at t1 and t2, and MANOVA for performance at t2, revealed that time increased for all groups at t2. For participants in Studies 1 & 2, error rates remained consistent. Retentivity significantly impacted errors at both t1 and t2, emphasising that routine changes in a ‘running business’ take time, regardless of contextual factors. Workers with lower retentivity may require additional support.
Um in der Schule bereits frühzeitig ein Verständnis für informatische Prozesse zu vermitteln wurde das neue Informatikfach Digitale Welt für die Klassenstufe 5 konzipiert mit der bundesweit einmaligen Verbindung von Informatik mit anwendungsbezogenen und gesellschaftlich relevanten Bezügen zur Ökologie und Ökonomie. Der Technische Report gibt eine Handreichung zur Einführung des neuen Faches.
Am Beispiel von Flüchtlingsintegration werden institutionelle Entwicklungen im Mehrebenensystem aus einer länderübergreifenden Perspektive analysiert. Insgesamt hat der Grad der Verwaltungsverflechtung und vertikalen Koordination in diesem Bereich zugenommen und die Rolle der Kommunen wurde – ungeachtet unterschiedlicher Ausprägungen der (De-)Zentralisierung – gestärkt. Während die starke fluchtbedingte Zuwanderung als äußerer Faktor dieser Entwicklung Vorschub geleistet hat, nehmen historische Pfadabhängigkeiten und die jeweiligen Verwaltungskulturen nach wie vor erheblichen Einfluss auf die genannten Entwicklungen.
Back to bureaucracy?
(2024)
In this contribution, the emergence of the neo-Weberian state (NWS) is analyzed with regard to German public administration. Drawing on the concept of a governance space, which consists of a hierarchy, markets, and networks, we distinguish between four empirical manifestations of the NWS, namely, the NWS as (1) come back of the public/ re-municipalization; (2) re-hierarchization; (3) de-agencification; (4) de-escalation in performance management. These movements can, on the one hand, be interpreted as a (partial) reversal of New Public Management (NPM) approaches and a “swinging back of the pendulum” (see Kuhlmann & Wollmann, 2019) toward public and classical Weberian principles (e.g., hierarchy, regulation, institutional re-aggregation). This reversal re-strengthened the hierarchy within the overall governance space to the detriment of, but without completely replacing, market mechanisms and networks. NPM’s failure to deliver what it promised and its inappropriateness as a response to more recent challenges connected to crises and wicked problems have engendered a partial return of the public and a move away from the economization logic of NPM. On the other hand, post-NPM reversals and managerial de-escalation gave rise to hybrid models that merge NPM and classic Weberian administration. While some well-functioning combinations of NPM and Weberianism exist, the hybridization of “old” and “neo” elements has also provoked ambivalent and negative assessments regarding the actual functioning of the NWS in Germany. Our analysis suggests that the NWS is only partially suitable as a model for reform and future administrative modernization, largely depending on the context surrounding reform and implementation practices.
The global drylands cover nearly half of the terrestrial surface and are home to more than two billion people. In many drylands, ongoing land-use change transforms near-natural savanna vegetation to agricultural land to increase food production. In Southern Africa, these heterogenous savanna ecosystems are also recognized as habitats of many protected animal species, such as elephant, lion and large herds of diverse herbivores, which are of great value for the tourism industry. Here, subsistence farmers and livestock herder communities often live in close proximity to nature conservation areas. Although these land-use transformations are different regarding the future they aspire to, both processes, nature conservation with large herbivores and agricultural intensification, have in common, that they change the vegetation structure of savanna ecosystems, usually leading to destruction of trees, shrubs and the woody biomass they consist of.
Such changes in woody vegetation cover and biomass are often regarded as forms of land degradation and forest loss. Global forest conservation approaches and international programs aim to stop degradation processes, also to conserve the carbon bound within wood from volatilization into earth’s atmosphere. In search for mitigation options against global climate change savannas are increasingly discussed as potential carbon sinks. Savannas, however, are not forests, in that they are naturally shaped by and adapted to disturbances, such as wildfires and herbivory. Unlike in forests, disturbances are necessary for stable, functioning savanna ecosystems and prevent these ecosystems from forming closed forest stands. Their consequently lower levels of carbon storage in woody vegetation have long been the reason for savannas to be overlooked as a potential carbon sink but recently the question was raised if carbon sequestration programs (such as REDD+) could also be applied to savanna ecosystems. However, heterogenous vegetation structure and chronic disturbances hamper the quantification of carbon stocks in savannas, and current procedures of carbon storage estimation entail high uncertainties due to methodological obstacles. It is therefore challenging to assess how future land-use changes such as agricultural intensification or increasing wildlife densities will impact the carbon storage balance of African drylands.
In this thesis, I address the research gap of accurately quantifying carbon storage in vegetation and soils of disturbance-prone savanna ecosystems. I further analyse relevant drivers for both ecosystem compartments and their implications for future carbon storage under land-use change. Moreover, I show that in savannas different carbon storage pools vary in their persistence to disturbance, causing carbon bound in shrub vegetation to be most likely to experience severe losses under land-use change while soil organic carbon stored in subsoils is least likely to be impacted by land-use change in the future.
I start with summarizing conventional approaches to carbon storage assessment and where and for which reasons they fail to accurately estimated savanna ecosystem carbon storage. Furthermore, I outline which future-making processes drive land-use change in Southern Africa along two pathways of land-use transformation and how these are likely to influence carbon storage. In the following chapters, I propose a new method of carbon storage estimation which is adapted to the specific conditions of disturbance-prone ecosystems and demonstrate the advantages of this approach in relation to existing forestry methods. Specifically, I highlight sources for previous over- and underestimation of savanna carbon stocks which the proposed methodology resolves. In the following chapters, I apply the new method to analyse impacts of land-use change on carbon storage in woody vegetation in conjunction with the soil compartment. With this interdisciplinary approach, I can demonstrate that indeed both, agricultural intensification and nature conservation with large herbivores, reduce woody carbon storage above- and belowground, but partly sequesters this carbon into the soil organic carbon stock. I then quantify whole-ecosystem carbon storage in different ecosystem compartments (above- and belowground woody carbon in shrubs and trees, respectively, as well as topsoil and subsoil organic carbon) of two savanna vegetation types (scrub savanna and savanna woodland). Moreover, in a space-for-time substitution I analyse how land-use changes impact carbon storage in each compartment and in the whole ecosystem. Carbon storage compartments are found to differ in their persistence to land-use change with carbon bound in shrub biomass being least persistent to future changes and subsoil organic carbon being most stable under changing land-use. I then explore which individual land-use change effects act as drivers of carbon storage through Generalized Additive Models (GAMs) and uncover non-linear effects, especially of elephant browsing, with implications for future carbon storage. In the last chapter, I discuss my findings in the larger context of this thesis and discuss relevant implications for land-use change and future-making decisions in rural Africa.
Laser induced switching offers an attractive possibility to manipulate small magnetic domains for prospective memory and logic devices on ultrashort time scales. Moreover, optical control of magnetization without high applied magnetic fields allows manipulation of magnetic domains individually and locally, without expensive heat dissipation. One of the major challenges for developing novel optically controlled magnetic memory and logic devices is reliable formation and annihilation of non-volatile magnetic domains that can serve as memory bits in ambient conditions. Magnetic skyrmions, topologically nontrivial spin textures, have been studied intensively since their discovery due to their stability and scalability in potential spintronic devices. However, skyrmion formation and, especially, annihilation processes are still not completely understood and further investigation on such mechanisms are needed. The aim of this thesis is to contribute to better understanding of the physical processes behind the optical control of magnetism in thin films, with the goal of optimizing material parameters and methods for their potential use in next generation memory and logic devices.
First part of the thesis is dedicated to investigation of all-optical helicity-dependent switching (AO-HDS) as a method for magnetization manipulation. AO-HDS in Co/Pt multilayer and CoFeB alloys with and without the presence of Dzyaloshinskii-Moriya interaction (DMI), which is a type of exchange interaction, have been investigated by magnetic imaging using photo-emission electron microscopy (PEEM) in combination with X-ray magnetic circular dichroism (XMCD). The results show that in a narrow range of the laser fluence, circularly polarized laser light induces a drag on domain walls. This enables a local deterministic transformation of the magnetic domain pattern from stripes to bubbles in out-of-plane magnetized Co/Pt multilayers, only controlled by the helicity of ultrashort laser pulses. The temperature and characteristic fields at which the stripe-bubble transformation occurs has been calculated using theory for isolated magnetic bubbles, using as parameters experimentally determined average size of stripe domains and the magnetic layer thickness.
The second part of the work aims at purely optical formation and annihilation of magnetic skyrmions by a single laser pulse. The presence of a skyrmion phase in the investigated CoFeB alloys was first confirmed using a Kerr microscope. Then the helicity-dependent skyrmion manipulation was studied using AO-HDS at different laser fluences. It was found that formation or annihilation individual skyrmions using AO-HDS is possible, but not always reliable, as fluctuations in the laser fluence or position can easily overwrite the helicity-dependent effect of AO-HDS. However, the experimental results and magnetic simulations showed that the threshold values for the laser fluence for the formation and annihilation of skyrmions are different. A higher fluence is required for skyrmion formation, and existing skyrmions can be annihilated by pulses with a slightly lower fluence. This provides a further option for controlling formation and annihilation of skyrmions using the laser fluence. Micromagnetic simulations provide additional insights into the formation and annihilation mechanism.
The ability to manipulate the magnetic state of individual skyrmions is of fundamental importance for magnetic data storage technologies. Our results show for the first time that the optical formation and annihilation of skyrmions is possible without changing the external field. These results enable further investigations to optimise the magnetic layer to maximise the energy gap between the formation and annihilation barrier. As a result, unwanted switching due to small laser fluctuations can be avoided and fully deterministic optical switching can be achieved.
Wars and the world
(2024)
This book offers a descriptive analysis of the Soviet/Russian wars in Afghanistan, Chechnya, and Georgia, as well as an in-depth exploration of the ways in which these wars are framed in the collective consciousness created by global popular culture. Russian and Western modalities of remembrance have been, and remain, engaged in a world war that takes place (not exclusively, but intensively) on the level of popular culture. The action/reaction dynamic, confrontational narratives and othering between the two "camps" never ceased. The Cold War, in many ways and contrary to the views of many others who hoped for the end of history, never really ended.
The trace elements copper, iron, manganese, selenium and zinc are essential micronutrients involved in various cellular processes, all with different responsibilities. Based on that importance, their concentrations are tightly regulated in mammalian organisms. The maintenance of those levels is termed trace element homeostasis and mediated by a combination of processes regulating absorption, cellular and systemic transport mechanisms, storage and effector proteins as well as excretion. Due to their chemical properties, some functions of trace elements overlap, as seen in antioxidative defence, for example, comprising an expansive spectrum of antioxidative proteins and molecules. Simultaneously, the same is true for regulatory mechanisms, causing trace elements to influence each other’s homeostases. To mimic physiological conditions, trace elements should therefore not be evaluated separately but considered in parallel. While many of these homeostatic mechanisms are well-studied, for some elements new pathways are still discovered. Additionally, the connections between dietary trace element intake, trace element status and health are not fully unraveled, yet. With current demographic developments, also the influence of ageing as well as of certain pathological conditions is of increasing interest. Here, the TraceAge research unit was initiated, aiming to elucidate the homeostases of and interactions between essential trace elements in healthy and diseased elderly. While human cohort studies can offer insights into trace element profiles, also in vivo model organisms are used to identify underlying molecular mechanisms. This is achieved by a set of feeding studies including mice of various age groups receiving diets of reduced trace element content. To account for cognitive deterioration observed with ageing, neurodegenerative diseases, as well as genetic mutations triggering imbalances in cerebral trace element concentrations, one TraceAge work package focuses on trace elements in the murine brain, specifically the cerebellum. In that context, concentrations of the five essential trace elements of interest, copper, iron, manganese, selenium and zinc, were quantified via inductively coupled plasma-tandem mass spectrometry, revealing differences in priority of trace element homeostases between brain and liver. Upon moderate reduction of dietary trace element supply, cerebellar concentrations of copper and manganese deviated from those in adequately supplied animals. By further reduction of dietary trace element contents, also concentrations of cerebellar iron and selenium were affected, but not as strong as observed in liver tissue. In contrast, zinc concentrations remained stable. Investigation of aged mice revealed cerebellar accumulation of copper and iron, possibly contributing to oxidative stress on account of their redox properties. Oxidative stress affects a multitude of cellular components and processes, among them, next to proteins and lipids, also the DNA. Direct insults impairing its integrity are of relevance here, but also indirect effects, mediated by the machinery ensuring genomic stability and its functionality. The system includes the DNA damage response, comprising detection of endogenous and exogenous DNA lesions, decision on subsequent cell fate and enabling DNA repair, which presents another pillar of genomic stability maintenance. Also in proteins of this machinery, trace elements act as cofactors, shaping the hypothesis of impaired genomic stability maintenance under conditions of disturbed trace element homeostasis. To investigate this hypothesis, a variety of approaches was used, applying OECD guidelines Organisation for Economic Co-operation and Development, adapting existing protocols for use in cerebellum tissue and establishing new methods. In order to assess the impact of age and dietary trace element depletion on selected endpoints estimating genomic instability, DNA damage and DNA repair were investigated. DNA damage analysis, in particular of DNA strand breaks and oxidatively modified DNA bases, revealed stable physiological levels which were neither affected by age nor trace element supply. To examine whether this is a result of increased repair rates, two steps characteristic for base excision repair, namely DNA incision and ligation activity, were studied. DNA glycosylases and DNA ligases were not reduced in their activity by age or trace element depletion, either. Also on the level of gene expression, major proteins involved in genomic stability maintenance were analysed, mirroring results obtained from protein studies. To conclude, the present work describes homeostatic regulation of trace elements in the brain, which, in absence of genetic mutations, is able to retain physiological levels even under conditions of reduced trace element supply to a certain extent. This is reflected by functionality of genomic stability maintenance mechanisms, illuminating the prioritization of the brain as vital organ.
A new challenger seeks to enter the German party system: Bündnis Sahra Wagenknecht (BSW). With her new party, former Die Linke politician Sahra Wagenknecht combines a left-authoritarian profile (economically left-leaning, but culturally conservative) with anti-US, pro-Russia and anti-elitist stances. This article provides the first large-n academic study of the voter potential of this new party by using a quasi-representative sample (n = 6,000) drawn from a Voting Advice Application-like dataset that comes from a website designed to explore the Bündnis Sahra Wagenknecht’s positions. The results show that congruence with foreign policy positions and anti-elitism are strong predictors of the propensity to vote for the Bündnis Sahra Wagenknecht. In contrast, social/welfare and immigration policies are less predictive for assessing the party’s potential. Among the different socio-demographic groups, the Bündnis Sahra Wagenknecht has a strong potential among baby boomers, the less educated and East Germans. Regarding party voters, the Bündnis Sahra Wagenknecht is favoured by supporters of some minor parties like dieBasis, Freie Wähler and Die PARTEI, but also non-voters. Among the established parties, the party’s potential is high among Die Linke voters and, to a lesser extent, voters of the Social democrats (SPD) and Alternative for Germany (AfD). A potential below the average is reported for the supporters of the Liberals (FDP) and Christian Democrats (CDU/CSU) and most clearly for Green and Volt voters.
Hardy inequalities on graphs
(2024)
The dissertation deals with a central inequality of non-linear potential theory, the Hardy inequality. It states that the non-linear energy functional can be estimated from below by a pth power of a weighted p-norm, p>1. The energy functional consists of a divergence part and an arbitrary potential part. Locally summable infinite graphs were chosen as the underlying space. Previous publications on Hardy inequalities on graphs have mainly considered the special case p=2, or locally finite graphs without a potential part.
Two fundamental questions now arise quite naturally: For which graphs is there a Hardy inequality at all? And, if it exists, is there a way to obtain an optimal weight? Answers to these questions are given in Theorem 10.1 and Theorem 12.1. Theorem 10.1 gives a number of characterizations; among others, there is a Hardy inequality on a graph if and only if there is a Green's function. Theorem 12.1 gives an explicit formula to compute optimal Hardy weights for locally finite graphs under some additional technical assumptions. Examples show that Green's functions are good candidates to be used in the formula.
Emphasis is also placed on illustrating the theory with examples. The focus is on natural numbers, Euclidean lattices, trees and star graphs. Finally, a non-linear version of the Heisenberg uncertainty principle and a Rellich inequality are derived from the Hardy inequality.
Resolving the evolutionary history of two hippotragin antelopes using archival and ancient DNA
(2024)
African antelopes are iconic but surprisingly understudied in terms of their genetics, especially when it comes to their evolutionary history and genetic diversity. The age of genomics provides an opportunity to investigate evolution using whole nuclear genomes. Decreasing sequencing costs enable the recovery of multiple loci per genome, giving more power to single specimen analyses and providing higher resolution insights into species and populations that can help guide conservation efforts. This age of genomics has only recently begun for African antelopes. Many African bovids have a declining population trend and hence, are often endangered. Consequently, contemporary samples from the wild are often hard to collect. In these cases, ex situ samples from contemporary captive populations or in the form of archival or ancient DNA (aDNA) from historical museum or archaeological/paleontological specimens present a great research opportunity with the latter two even offering a window to information about the past. However, the recovery of aDNA is still considered challenging from regions with prevailing climatic conditions that are deemed adverse for DNA preservation like the African continent. This raises the question if DNA recovery from fossils as old as the early Holocene from these regions is possible.
This thesis focuses on investigating the evolutionary history and genetic diversity of two species: the addax (Addax nasomaculatus) and the blue antelope (Hippotragus leucophaeus). The addax is critically endangered and might even already be extinct in the wild, while the blue antelope became extinct ~1800 AD, becoming the first extinct large African mammal species in historical times. Together, the addax and the blue antelope can inform us about current and past extinction events and the knowledge gained can help guide conservation efforts of threatened species. The three studies used ex situ samples and present the first nuclear whole genome data for both species. The addax study used historical museum specimens and a contemporary sample from a captive population. The two studies on the blue antelope used mainly historical museum specimens but also fossils, and resulted in the recovery of the oldest paleogenome from Africa at that time.
The aim of the first study was to assess the genetic diversity and the evolutionary history of the addax. It found that the historical wild addax population showed only limited phylogeographic structuring, indicating that the addax was a highly mobile and panmictic population and suggesting that the current European captive population might be missing the majority of the historical mitochondrial diversity. It also found the nuclear and mitochondrial diversity in the addax to be rather low compared to other wild ungulate species. Suggestions on how to best save the remaining genetic diversity are presented. The European zoo population was shown to exhibit no or only minor levels of inbreeding, indicating good prospects for the restoration of the species in the wild. The trajectory of the addax’s effective population size indicated a major bottleneck in the late Pleistocene and a low effective population size well before recent human impact led to the species being critically endangered today.
The second study set out to investigate the identities of historical blue antelope specimens using aDNA techniques. Results showed that six out of ten investigated specimens were misidentified, demonstrating the blue antelope to be one of the scarcest mammal species in historical natural history collections, with almost no bone reference material. The preliminary analysis of the mitochondrial genomes suggested a low diversity and hence low population size at the time of the European colonization of southern Africa.
Study three presents the results of the analyses of two blue antelope nuclear genomes, one ~200 years old and another dating to the early Holocene, 9,800–9,300 cal years BP. A fossil-calibrated phylogeny dated the divergence time of the three historically extant Hippotragus species to ~2.86 Ma and demonstrated the blue and the sable antelope (H. niger) to be sister species. In addition, ancient gene flow from the roan (H. equinus) into the blue antelope was detected. A comparison with the roan and the sable antelope indicated that the blue antelope had a much lower nuclear diversity, suggesting a low population size since at least the early Holocene. This concurs with findings from the fossil record that show a considerable decline in abundance after the Pleistocene–Holocene transition. Moreover, it suggests that the blue antelope persisted throughout the Holocene regardless of a low population size, indicating that human impact in the colonial era was a major factor in the blue antelope’s extinction.
This thesis uses aDNA analyses to provide deeper insights into the evolutionary history and genetic diversity of the addax and the blue antelope. Human impact likely was the main driver of extinction in the blue antelope, and is likely the main factor threatening the addax today. This thesis demonstrates the value of ex situ samples for science and conservation, and suggests to include genetic data for conservation assessments of species. It further demonstrates the beneficial use of aDNA for the taxonomic identification of historically important specimens in natural history collections. Finally, the successful retrieval of a paleogenome from the early Holocene of Africa using shotgun sequencing shows that DNA retrieval from samples of that age is possible from regions generally deemed unfavorable for DNA preservation, opening up new research opportunities. All three studies enhance our knowledge of African antelopes, contributing to the general understanding of African large mammal evolution and to the conservation of these and similarly threatened species.
Background: Societies worldwide have become more diverse yet continue to be inequitable. Understanding how youth growing up in these societies are socialized and consequently develop racial knowledge has important implications not only for their well-being but also for building more just societies. Importantly, there is a lack of research on these topics in Germany and Europe in general.
Aim and Method: The overarching aim of the dissertation is to investigate 1) where and how ethnic-racial socialization (ERS) happens in inequitable societies and 2) how it relates to youth’s development of racial knowledge, which comprises racial beliefs (e.g., prejudice, attitudes), behaviors (e.g., actions preserving or disrupting inequities), and identities (e.g., inclusive, cultural). Guided by developmental, cultural, and ecological theories of socialization and development, I first explored how family, as a crucial socialization context, contributes to the preservation or disruption of racism and xenophobia in inequitable societies through its influence on children’s racial beliefs and behaviors. I conducted a literature review and developed a conceptual model bridging research on ethnic-racial socialization and intergroup relations (Study 1). After documenting the lack of research on socialization and development of racial knowledge within and beyond family contexts outside of the U.S., I conducted a qualitative study to explore ERS in Germany through the lens of racially marginalized youth (Study 2). Then, I conducted two quantitative studies to explore the separate and interacting relations of multiple (i.e., family, school) socialization contexts for the development of racial beliefs and behaviors (Study 3), and identities (Studies 3, 4) in Germany. Participants of Study 2 were 26 young adults (aged between 19 and 32) of Turkish, Kurdish, East, and Southeast Asian heritage living across different cities in Germany. Study 3 was conducted with 503 eighth graders of immigrant and non-immigrant descent (Mage = 13.67) in Berlin, Study 4 included 311 early to mid-adolescents of immigrant descent (Mage= 13.85) in North Rhine-Westphalia with diverse cultural backgrounds.
Results and Conclusion: The findings revealed that privileged or marginalized positions of families in relation to their ethnic-racial and religious background in society entail differential experiences and thus are an important determining factor for the content/process of socialization and development of youth’s racial knowledge. Until recently, ERS research mostly focused on investigating how racially marginalized families have been the sources of support for their children in resisting racism and how racially privileged families contribute to transmission of information upholding racism (Study 1). ERS for racially marginalized youth in Germany centered heritage culture, discrimination, and resistance strategies to racism, yet resistance strategies transmitted to youth mostly help to survive racism (e.g., working hard) by upholding it instead of liberating themselves from racism by disrupting it (e.g., self-advocacy, Study 2). Furthermore, when families and schools foster heritage and intercultural learning, both contexts may separately promote stronger identification with heritage culture and German identities, and more prosocial intentions towards disadvantaged groups (i.e., refugees) among youth (Studies 3, 4). However, equal treatment in the school context led to mixed results: equal treatment was either unrelated to inclusive identity, or positively related to German and negatively related to heritage culture identities (Studies 3, 4). Additionally, youth receiving messages highlighting strained and preferential intergroup relations at home while attending schools promoting assimilation may develop a stronger heritage culture identity (Study 4). In conclusion, ERS happened across various social contexts (i.e., family, community centers, school, neighborhood, peer). ERS promoting heritage and intercultural learning, at least in one social context (family or school), might foster youth’s racial knowledge manifesting in stronger belonging to multiple cultures and in prosocial intentions toward disadvantaged groups. However, there is a need for ERS targeting increasing awareness of discrimination across social contexts of youth and teaching youth resistance strategies for liberation from racism.