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This dissertation investigates work ability as a concept that supports workers, employers, and societies in the extension of working lives, and how work ability is related to the level of self-determination in the transition to retirement, and ultimately life satisfaction. In the first study of this dissertation, the Work Ability Survey-R (WAS-R) was translated from English into German and then evaluated regarding its psychometric properties and construct validity. The WAS-R operationalizes work ability as the interplay of personal and organizational resources and thus allows companies to derive targeted interventions to maintain work ability. In the second study, the WAS-R was examined together with the questionnaire Work-Related Behavior and Experience Pattern (Arbeitsbezogenes Verhaltens- und Erlebensmuster, AVEM) regarding its construct validity. A striking feature of this study was the high number of participants with the answering pattern indicating low work-related ambitions and protection. Persons with this pattern are in danger of entering the risk pattern for burnout in the future. The findings support the validity of the WAS-R. In the third contribution, two studies examined the experience of control (i.e., autonomy) in the transition to retirement as a mediator between previous work ability, health, and financial well-being, and later life satisfaction in retirement. Control was found to partially mediate the relationship between work ability and later life satisfaction. Different mechanisms on later life satisfaction of work ability and health, and the subjective and objective financial situation were found. This dissertation contributes to research on and practice with aging workers in two ways: (1) The German translation of the WAS-R is presented as a useful instrument for measuring work ability, assessing individual and organizational aspects and therefore enabling employers to make targeted interventions to maintain and improve work ability, and eventually enable control during later work life, the retirement transition and even old age. (2) This dissertation corroborates the importance of good work ability and health, even in old age, as well as control in these phases of life. Work ability is indirectly related to life satisfaction in the long period of retirement, mediated by a sense of control in the transition to retirement. This emphasizes the importance of the need for control as postulated by the SDT also in the transition to retirement.
Viable communication systems
(2020)
Society has come to the point that it requires a "Great Transformation" towards sustainability to ensure the viability of the planet for a vital society. The energy transition plays a central role for this transformation. For transforming the patterns of energy production and use in an energy transition as part of the "Great Transformation", this process of change now needs to strengthen its focus on information, communication, and knowledge systems. Human society needs to establish a knowledge system that has the potential to create usable knowledge for sustainability solutions. This requires organizing a communication system that is sufficiently complex, interconnected, and, at the same time, efficient for integrating reflexive, open-ended, inter- and transdisciplinary learning, evaluation, and knowledge co-production processes across multiple levels. This cumulative dissertation contributes to research in this direction by applying a systemic sustainability perspective on the content and organization of communication in the field of research on sustainable energy and the operational level of municipal climate action as part of the energy transition. Regarding sustainability, this thesis uses strong sustainability and its principles as a frame for evaluating the content of communication. Regarding the systemic perspective, the thesis particularly relies on the following theories: (i) the human-environment system model by R. Scholz as an overarching framework regarding interactions between humans and nature, (ii) social systems theory by N. Luhmann to reflect the complexity of society, (iii) knowledge management to consider the human character of knowledge and a practice-oriented perspective, and (iv) management cybernetics, in particular, the Viable System Model by S. Beer as a framework to analyze and assess organizational structures. Furthermore, the thesis leverages the potential of text mining as a method to identify and visualize patterns in texts that reflect prevalent paradigms in communication. The thesis applies the above conceptual and methodological basis in three case studies. Case Study 1 investigates the measures proposed in 16 municipal climate action plans of regional centers in Lower Saxony, Germany. It uses a text mining approach in the form of an Summary interpretation network analysis. It analyzes how different societal subsystems are connected at the semantic level and to what extent sustainability principles can be recognized. Case Study 2 analyzes and reflects paradigms and discursive network structures in international scientific publications on sustainable energy. The study investigates 26533 abstracts published from 1990 to 2016 using a text mining approach, in particular topic modeling via latent Dirichlet allocation. Case Study 3 turns again to the cases of municipal climate action in Lower Saxony examined in Case Study 1. It examines the involvement of climate action managers of these cities in multilevel knowledge processes. Using design principles for knowledge systems, it evaluates to what extent knowledge is managed in this field across levels for supporting the energy transition and to what extent local innovation potential is leveraged or supported. The three case studies show that international research on sustainable energy and municipal climate action in Germany provide promising contributions to achieve a transformation towards sustainability but do not fully reflect the complexity of society and still support a growth paradigm, in contrast to a holistic sustainability paradigm. Further, the case studies show that research and local action are actively engaging with the diversity of energy technologies but are lagging in dealing with the socio-epistemic (communication) system, especially with regard to achieving cohesion. Using the example of German municipalities, Case Studies 1 and 3 highlight the challenges of achieving coherent local action for sustainability and bottom-up organizational learning due to incomplete or uncoordinated multilevel knowledge exchange.
Sustainable landscape development is the main goal of decision makers worldwide. Achieving this goal in the long term leads to achieving social, economic and environmental sustainability. Remote sensing has been playing an essential role in monitoring remote areas. This study has employed part of the role of remote sensing in supporting the direction of decision makers towards sustainable landscape development. The study has focused on some of the main elements affecting sustainable environment: land uses, specifically agricultural land uses, water quality, forests, and water hazards such as floods. Three research programs were undertaken to investigate the role of Terrasar-x imagery, as a source of remote sensing data, in monitoring the environment and achieving the previous stated elements. The investigation was intended to investigate the effectiveness of TSX imagery in identifying the cropping pattern of selected study areas by employing a pixel-based supervised maximum likelihood classifier, as published in Paper I, assessment of the efficiency of using TSX imagery in determining land use and the flood risk maps by applying an object-based decision tree classifier as published in Paper II, and determination of the potential of inferential statistics tests such as the two samples Z-test and multivariate analysis, for example Factor Analysis, for identifying the kind of forest canopy, based on the backscattering coefficient of TSX imagery of forest plots, as presented in Paper III. Papers I and II covered two pilot areas in the Lower Saxonian Elbe Valley Biosphere Reserve “das Biosphärenreservat "Niedersächsische Elbtalaue" around Walmsburger Werder and Wehninger Werder. Paper III focused on the Fuhrberger Feld water protection area near Hanover in Germany. The inputs for this research were mainly SAR Imagery and the ground truth data collected from field surveys, in addition to databases, geo-databases and maps. The study presented in Paper I used two filters to decrease speckle noise namely De-Grandi as multi-temporal speckle filter, and Lee as an adaptive filter. A multi-temporal classification method was used to identify the different crops using a pixel-based maximum likelihood classifier. The classification accuracy was assessed based on the external user accuracy for each crop, the external producer accuracy for each crop, the Kappa index and the external total accuracy for the entire classification. Three cropping pattern maps were produced namely the cropping pattern map of Wehninger Werder in 2011 and the cropping pattern maps of Walmsburger Werder in 2010 and in 2011. The study showed that image filtering was essential for enhancing the accuracy of crop classification. The multi-temporal filter De-Grandi enhanced the producer accuracy by about 10% compared to the Lee filter. Furthermore, gathering and utilizing large ground truth data greatly enhanced the accuracy of the classification. The research verified that using sequence images covering the growing season usually improved the classification results. The results exposed the effect of the polarization and demonstrate that the majority of the classifications produced according to the crop calendar had higher total producer accuracy than using all acquisitions. The study demonstrated undertaken in Paper II applied the decision tree object-based classifier in determining the major land uses and the inundation extent areas in 2011 and 2013 using the Lee-filtered imagery. Based on the maps produced for the land uses and inundation areas, the hazard areas due to the floods in 2011 and 2013 were identified. The study illustrated that 95% of the inundated area was classified correctly, that 90% of vegetated lands were accurately determined, and around 80% of the forest and the residential areas were correctly recognized. The research undertaken in Paper III statistically analyzed the backscattering coefficient of the Lee-filtered TSX in some forest plots by the Factor Analysis and two sample Z-test. The study showed that Factor analysis tools succeeded in differentiating between the coniferous forest and the deciduous forest and mixed forest, but failed to discriminate between the deciduous and the mixed forest. On one hand, only one factor was extracted for each sample plot of the coniferous forest with approximately equal loadings during the whole acquisition period from March 2008 to January 2009. On the other hand, two factors were extracted for each deciduous or mixed forest sample plot, where one factor had high loadings during the leaf-on period from May to October, and the other one had high loadings during the leaf-off period from November to April. Furthermore, the research revealed that the two sample Z-test enabled not only differentiation between the deciduous and the mixed forest against the coniferous forest, but also discrimination between deciduous forest and the mixed forest. Statistically significant differences were observed between the mean backscatter values of the HH-polarized acquisitions for the deciduous forest and the mixed forest during the leaf-off period, but no statistically significant difference was found during the leaf-on period. Moreover, plot samples for the deciduous forest had slightly higher mean backscattering coefficients than those for the mixed forest during the leaf-off period.
To improve the properties of thermochemical heat storage materials, salt mixtures were evaluated for their heat storage capacity and cycle stability as part of the innovation incubator project "Thermochemical battery" of the Leuphana university Lüneburg. Based on naturally occurring compound minerals, 16 sulfates, 18 chlorides and 5 chloride multi-mixtures, 18 bromides and 5 intermixtures between sulfates, chlorides and bromides were synthesized either from liquid solution or by dry mixing for TGA/DSC screening before continuing the heat storage evaluation with five different measurement setups at a laboratory scale. The TGA/DSC analysis served as a screening process to reduce the number of testing materials for the upscaled experiments. The evaluation process consisted of a three-cycle dehydration/hydration measurement at Tmax=100°C and Tmax=200°C. In case of the bromide samples a measurement of hydration conditions with Tmax=110°C and a water flow at e=18.68mbar, were added to the procedure to detect the maximum water uptake temperature. Also, a single dehydration to a temperature of Tmax=500°C was implemented to observe melting behavior and to easier calculate the samples’ stages of hydration from the remaining anhydrous mass. Materials which showed high energy storage density and improved cycle stability during this first evaluation were cleared for multi-cycle measurements of 10 to 25 dehydration and hydration cycles at Tmax = 100 to 120°C and the evaluations at m=20 to 100g scale. An estimate for the specific heat capacities at different temperatures of the materials which passed the initial stage was calculated from the TGA/DSC results as well. The laboratory scale measurement setup went through five stages of refining, which led to reducing the intended maximum sample mass from m=100g to m=20g. A switch from supplied liquid water to water vapor as the used reactant was also implemented in exchange for improved dehydration conditions. Introducing a vacuum pump for evaporating the water limited the influence of outside heat sources during hydration and in-situ dehydration was enabled as to not disturb the state the samples were settling in between measurements. Baseline calculation from blanc measurements with glass powder and attempts to calculate the specific heat capacity cp of the tested materials by 6 applying the Joule-Lenz-law to the measurement apparatus was another step of method development. The evaluation process of the laboratory scale tests at the final setting consisted of 1 to 5 cycle measurements of in-situ dehydration and hydrations with applied vacuum for t=30 minutes at p~30mbar. Upscaling the sample mass to m=20g allowed for a close observation of different material behaviors. Agglomeration, melting and dissolving of the m=10mg samples during the TGA/DSC analysis can be deducted from the recorded measurement curves and the state of the sample after measurement. However, at laboratory scale the visible volume changes, observed sample consistency after agglomeration and an automatic removal of molten and dissolved sample mass during the measurement allowed for a better characterization and understanding of the magnitude of the actual changes. This was done for the first time, particularly for mixed salts. Of the original number of 62 samples, 4 mixtures which passed the initial TGA/DSC screening namely {2MgCl2+ KCl}, {2MgCl2+CaCl2}, {5SrBr2+8CaCl2} and {2ZnCl2 + CaCl2} were chosen for further evaluation. The multi-cycle TGA/DSC measurements of {2MgCl2+ KCl}, {2MgCl2+CaCl2} and {5SrBr2+8CaCl2} showed an improved cycle stability for all three materials over the untreated educts. Of the four materials {2ZnCl2 + CaCl2} displayed the strongest deliquescence during hydration in the upscaled experimental setup. {2MgCl2+CaCl2} proved to be the most stable material regarding the heat storage density. The {MgCl2} content of the mixture is likely to partially or completely react to {Mg(OH)Cl} at temperatures of T>110°C, which however does not impede the heat storage density. {5SrBr2+8CaCl2} displayed a low melting point in hydrated state, causing a fast material loss. This makes it an undesirable storage material. A lower heating rate may still help to avoid an early melting. The {2MgCl2+KCl} mixture was the most temperature stable of the mixtures showing no melting or dissolving behavior. A reaction of the {MgCl2} component of the mixture to {Mg(OH)Cl} was not observed within the applied temperature range of T=25 to 200°C.
Personally meaningful tourist experiences foster subjective mental wellbeing. Modern, human-centred technologies such as gamified technology have been recognised as a promising means to support tourists in their co-creation of meaningful tourist experiences. However, a deeper understanding and conceptualisation of tourists' engagement with gamified technologies in the tourist experience has remained absent so far. This study draws on positive psychology as the guiding theoretical lens to conceptualise and explore tourists' underlying motives for engaging with gamified technology, as well as the gratifications thereof for the tourist experience. In doing so, this thesis identifies how tourists generate meaning through interacting with gamified technology in the tourist experience, thereby fostering the co-creation of meaningful tourist experiences and contributing to subjective mental wellbeing. Being among the first studies to link the concepts of positive psychology, gamified technology, and tourist experiences, the results of this thesis provide rich findings on the underlying motives for tourists to engage with gamified technology during vacation, as well as the gratifications of gamified technology for the creation of meaning in the tourist experience. Using the theoretical lens of positive psychology and achievement motivation theory as the main theoretical underpinning, this study is positioned at the intersection of social psychology, human-computer interaction, and tourism as the field of application. Conceptually, this thesis provides an in-depth understanding of tourists’ engagement with gamified technology, including the socio-psychological motivators for engagement and the outcomes thereof for the tourist experience.
The literature on term bids by presidents tends to focus on the institutional arrangements to hinder such term bids in the first place, on presidential strategies to circumvent the constitutional law, or on counteractions of political elites. Mobilizations against such attempts by presidents to run for office again, after reaching the end of their last allowed term, are often solely included as "pressures from below". To address these shortcomings, this dissertation explores the issue of term amendment struggles through the lenses of contentious politics systematically combined with insights of revolution theories and democratization studies. Its conceptual perspective therefore lies on the interactions of actors and their constellations to each other as well as to institutions. The author deduces three diverse pathways to promote institutional change and prevent democratic backslidings – through political elites, (political) allies, and security forces. By selecting two cases that are most similar in terms of institutions and youth movements at the forefront, Senegal (2011-12) and Burkina Faso (2013-14), this analysis offers insight in the divergence of the struggles and their outcome. Because in both cases, the announcement of the presidents to run for another term in office led to broad mobilization led by youth movements against such tenure amendments, the political system in general and socioeconomic inequalities - but with diverging results. In Burkina Faso, Blaise Compaoré eventually resigned while Abdoulaye Wade in Senegal candidated again, legitimized by the Constitutional Court. Based on extensive fieldwork, including interviews with movement leaders and their allies, as well as a comprehensive media analysis and the SCAD databank for the analysis of protest events, the author differentiates and reconstructs the various phases of the conflict. The results of the dissertation point at two dimensions most relevant to comprehend the dissimilar pathways the struggles took – the reach of mobilization and, closely interlinked to the first, the refusal of soldiers to obey orders. It shows further that these differences go back to the respective history of each country, its former protest waves, and political culture. Although both presidents faced mass mobilization against their unconstitutional candidature, only in Burkina Faso it eventually led to an ungovernable situation. The dissertation concludes by reflecting on lessons learned for future democratic backslidings by presidents to come and avenues for future research – and thus offers fruitful insights.
Technological development made it possible to store and process data on a scale not imaginable decades ago — a development that also includes network data. A particular characteristic of network data is that, unlike standard data, the objects of interest, called nodes, have relationships to (possibly all) other objects in the network. Collecting empirical data is often complicated and cumbersome, hence, the observed data are typically incomplete and might also contain other types of errors. Because of the interdependent structure of network data, these errors have a severe impact on network analysis methods. This cumulative dissertation is about the impact of erroneous network data on centrality measures, which are methods to assess the position of an object, for example a person, with respect to all other objects in a network. Existing studies have shown that even small errors can substantially alter these positions. The impact of errors on centrality measures is typically quantified using a concept called robustness. The articles included in this dissertation contribute to a better understanding of the robustness of centrality measures in several aspects. It is argued why the robustness needs to be estimated and a new method is proposed. This method allows researchers to estimate the robustness of a centrality measure in a specific network and can be used as a basis for decision making. The relationship between network properties and the robustness of centrality measures is analyzed. Experimental and analytical approaches show that centrality measures are often more robust in networks with a larger average degree. The study of the impact of non-random errors on the robustness suggests that centrality measures are often more robust if missing nodes are more likely to belong to the same community compared to missingness completely at random. For the development of imputation procedures based on machine learning techniques, a process for the evaluation of node embedding methods is proposed.
Tropical forests worldwide support high biodiversity and contribute to the sustenance of local people’s livelihoods. However, the conservation and sustainability of these forests are threatened by land-use changes and a rapidly increasing human population. This dissertation, therefore, aimed to characterize biodiversity patterns in the moist Afromontane forests of southwestern Ethiopia and to examine how biodiversity patterns are affected by land-use and land-use changes (mediated by coffee management intensity, landscape attributes and housing development) in a context of a rapidly growing rural population. To achieve this goal, the author takes an interdisciplinary approach where, first, she examined the effects of coffee management intensity on diversity patterns of woody plants and birds, spanning a gradient of site-level disturbance from nearly undisturbed forest interior to highly managed shade coffee forests. Results showed that specialized species of woody plants (forest specialists) and birds (forest specialists, insectivores and frugivores) were affected by coffee management intensity. The richness of forest specialist trees and the richness and/or abundance of insectivores, frugivores and forest specialist birds decrease with increasing levels of disturbance. Second, the author investigated the effects of landscape context on woody plants, birds and mammals. Community composition and specialist species of woody plants and birds were sensitive to landscape context, where woody plants responded positively to gradients of edge-interior and birds to gradients of edge-interior and forest cover. Further results showed that a diverse mammal community, with 26 species, occurs at the forest edge of shade coffee forests and that the leopard, an apex predator in the region depended on large areas of natural forest. A closer examination of leopard activity patterns revealed a shift in the diel activity as a response to human disturbance inside the forest, further highlighting the importance of natural undisturbed forests for leopards in the region. Together, these findings demonstrate the value of low managed shade coffee forests for biodiversity, and importantly, emphasize the irreplaceable value of undisturbed natural forests for biodiversity. Third, the researcher investigated the effects of prospective rural population growth (mediated by housing development) on the forest mammal community. Here, population growth was projected to negatively influence several mammal species, including the leopard. Housing development that encroached the forest entailed worse outcomes for biodiversity than a combination of prioritized development in already developed areas and coffee forest protection. Fourth, to understand the motivations behind high human fertility rates in the region, she examined the determinants of women fertility preferences, including their perceptions on social and biophysical stressors affecting local livelihoods such as food insecurity and environmental degradation. Fertility preferences were influenced by underlying social norms and mindsets, a perceived utilitarian value of children and male dominance within the household, and were only marginally affected by perceptions of social and biophysical stressors. The findings suggest the need for new deliberative and culturally sensitive approaches that engage with pervasive social norms to slow down population growth. Overall, this dissertation demonstrates the key value of moist Afromontane forests in southwestern Ethiopia for biodiversity conservation. It indicates the need to promote coffee management practices that reduce forest degradation and highlights that high priority should be given to the conservation of undisturbed natural forests. It also suggests the need to integrate conservation goals with housing development in landscape planning. A promising approach to achieve the above conservation priorities would be the creation of a Biosphere Reserve and to promote the ecological connectivity between the larger forest remnants in the region. Finally, this dissertation demonstrates the importance of placed-based holistic approaches in conservation that consider both proximate and distal drivers of forest biodiversity decline.
This doctoral thesis contains four empirical studies analysing the personal accountability of prime ministers and the electoral presidentialisation of parliamentary elections in European democracies. It develops the concept of presidentialised prime ministerial accountability as a behavioural element in the chain of accountability in parliamentary systems. The ongoing presidentialisation of parliamentary elections, driven by changes in mass communication and erosion of societal cleavages, that fosters an increasing influence of prime ministers' and other leading candidates' personalities on vote choices, has called performance voting – and the resulting accountability mechanism of electoral punishment and reward of governing parties – into question. This thesis analyses whether performance voting can be extended to the personal level of parliamentary governments and asks whether voters hold prime ministers personally accountable for the performance of their government. Furthermore, it explores how voters change their opinion of prime ministers and how differences in party system stability and media freedom between Western and Central Eastern Europe contribute to higher electoral presidentialization in Central Eastern European parliamentary elections. This thesis relies on several national data sources: the "British Election Study", the "German Longitudinal Election Study" and other German election surveys, the "Danish Election Study", as well as, data from the "Forschungsgruppe Wahlen". In addition, it utilises cross-national data from the "Comparative Study of Electoral Systems".
Contemporary liberal-democracies are under stress and traditional political parties have become detached from their electorates. Since the 1980s, parties have been experiencing a crisis of legitimation, whose effects have become intensive especially in the early twenty-first century. New populist challengers have tried to fill the representative void left by mainstream parties; at the same time, technocracy has become one of the most prominent form of representation. Political responsibility and responsiveness appear often incompatible in the eyes of voters. Moreover, political personalization and processes of presidentialization have led to a situation where single political leaders have become the crucial political actors, to the detriment of party organizations. This Habilitation thesis investigates the linkage between representative democratic institutions in parliamentary and semi-presidential systems and political elites, trying to understand how this linkage has been affected by the change of party democracy. In particular, the thesis analyzes political institutions’ functioning in democratic contexts as well as parties’ responses and elites’ paths to power as indicators of a process of adaptation. Four main research questions inform the analysis: what structural opportunities and constraints do political elites meet when it comes to exercising political power?; how have the decline of party government and political personalization modified opportunity structures?; how do parties and elites cope with democratic change?; has democratic change produced new criteria for successful political careers? The institutional focus is on political executives and representative assemblies at different levels of government. Findings highlight that political elites adopts strategies of resistance and respond to democratic change through incremental steps. In other words, rather than anticipatory, political elites appear reactive, when they are confronted with substantial modifications of the political opportunity structure. Overall, the study contributes to the debate about the changing role of parties and political elites as connectors between the state and the society and provides insights about future developments.
The present doctoral dissertations seeks to shed theoretical and empirical light on how complexity and different approaches to manage it affect perceptions, behaviors, and outcomes in integrative negotiations. Chapter 1 summarizes the following chapters, describes their individual contribution to the present thesis, and outlines avenues for future research. In Chapter 2, a theoretical model comprising of task- and context-based determinants of complexity in negotiations is developed. In Chapter 3, the effects of the number of issues (high vs. low) as one essential determinant of complexity on parties' trade-off behavior and joint outcomes are investigated in a series of four experiments. Furthermore, negotiators' cognitive categorizing of issues (i.e., their mental-accounting approach) is examined as the underlying psychological mechanism. Results reveal that more issues lead to a higher risk of scattering the integrative potential between cognitive categories (i.e., mental accounts), reducing trade-off quality and joint outcomes. In Chapter 4, the generalizability of the detrimental effect of the number of issues on joint outcomes is tested across varying numbers of issues in a meta-analysis. Moreover, boundary conditions for the effect are investigated. Results confirm the generalizability of the number-of-issues effect, but no relevant boundary conditions are identified. In Chapter 5, the effects of different mental-accounting approaches on negotiators' judgment accuracy, trade-off behaviors, and negotiation outcomes are examined in a series of five experiments. Results demonstrate that categorizing a moderate number of issues into each mental account leads to a higher judgment accuracy, trade-off quality, and joint outcomes, but only if negotiators manage to pool the integrative potential within these accounts. Finally, Chapter 6 takes a broader perspective on different integrative strategies in negotiations (i.e., expanding the pie, logrolling, solving underlying interests), thereby laying the groundwork for future research.
As modern society progresses, waste treatment becomes a pressing issue. Not only are global waste amounts increasing, but there is also an unmet demand for sustainable materials (e.g. bioplastics). By identifying and developing processes, which efficiently treat waste while simultaneously generating sustainable materials, potentially both these issues might be alleviated. Following this line of thought, this dissertation focuses on procedures for treatment of the organic fraction of waste. Organic waste is a suitable starting material for microbial fermentation, where carbohydrates are converted to smaller molecules, such as ethanol, acetic acid, and lactic acid. Being the monomer of the thermoplastic poly-lactic acid, lactic acid is of particular interest with regard to bioplastics production and was selected as target compound for this dissertation. Organic waste acted as substrate for non-sterile batch and continuous fermentations. Fermentations were initiated with inoculum of Streptococcus sp. or with indigenous consortium alone. During batch mode, concentration, yield, and productivity reached maximum values of 50 g L−1, 63%, and 2.93 g L−1 h −1. During continuous operation at a dilution rate of 0.44 d−1, concentration and yield were increased to 69 g L−1 and 86%, respectively, while productivity was lowered to 1.27 g L−1 h −1 . To fully exploit the nutrients present in organic waste, phosphate recovery was analyzed using seashells as adsorbent. Furthermore, the pattern of the indigenous consortium was monitored. Evidently, a very efficient Enterococcus strain tended to dominate the indigenous consortium during fermentation. The isolation and cultivation of this consortium gave a very potent inoculum. In comparison to the non-inoculated fermentation of a different organic waste batch, addition of this inoculum lead to an improved fermentation performance. Lactic acid yield, concentration, and molar selectivity could be increased from 38% to 51%, 49 g L−1 to 65 g L−1, and 46% to 86%, respectively. Eventually, fermentation process data was used to perform techno-economic analysis proposing a waste treatment plant with different catchment area sizes ranging from 50,000 to 1,000,000 people. Economically profitable scenarios for both batch and continuous operation could be identified for a community with as few as 100,000 inhabitants. With the experimental data, as well as techno-economic calculations presented in this dissertation, a profound contribution to sustainable waste treatment and material production was made.
Existing institutions no longer appear to be sufficiently capable to deal with the complexity and uncertainty associated with the wicked problem of sustainability. Achieving the required sustainability transformation will thus require purposeful reform of existing institutional frameworks. However, existing research on the governance of sustainability of sustainability transformations has strongly focused on innovation and the more "creative" aspects of these processes, blinding our view to the fact that they go hand with the failure, decline or dismantling of institutions that are no longer considered functional or desirable. This doctoral dissertation thus seeks to better understand how institutional failure and decline can contribute productively to sustainability transformations and how such dynamics in institutional arrangements can serve to restructure existing institutional systems. A systematic review of the conceptual literature served to provide a concise synthesis of the research on "failure" and "decline" in the institutional literature, providing important first insights into their potentially productive functions. This was followed up by an archetype analysis of the productive functions of failure and decline, drawing on a wide range of literatures. This research identified five archetypical pathways: (1) crises triggering institutional adaptations toward sustainability, (2) systematic learning from failure and breakdown, (3) the purposeful destabilisation of unsustainable institutions, (4) making a virtue of inevitable decline, and (5) active and reflective decision making in the face of decline instead of leaving it to chance. Empirical case studies looking at the German energy transition and efforts to phase out coal in the Powering Past Coal Alliance served to provide more insights on (a) how to effectively harness "windows of opportunity" for change, and (b) the governance mechanisms used by governments to actively remove institutions. Results indicate that the lock-in of existing technologies, regulations and practices can throw up important obstacles for sustainability transformations. The intentional or unintentional destabilisation of the status quo may thus be required to enable healthy renewal within a system. This process required active and reflective management to avoid the irreversible loss of desirable institutional elements. Instruments such as "sunset clauses" and "experimental legislation" may serve as important tools to learn through "trial and error", whilst limiting the possible damage done by failure. Focusing on the subject of scale, this analysis finds that the level at which failure occurs is likely to determine the degree of change that can be achieved. Failures at the policy-level are most likely to merely lead to changes to the tools and instruments used by policy makers. This research thus suggests that failures on the polity- and political level may be required to achieve transformative changes to existing power structures, belief-systems and paradigms. Finally, this research briefly touches on the role of actor and agency in the governance of sustainabilitytransformations through failure and decline. It finds that actors may play an important role in causing a system or one of its elements to fail and in shaping the way events are come to be perceived.
Both sustainability and transdisciplinary research can change academic research, especially with regard to its relevance for, and relationship with, its environments. Transdisciplinary sustainability research (TSR), thus, offers the opportunity to change non-sustainable development paths of sciences themselves. In order to fully exploit this possibility, this PhD project addresses the question of how TSR, in the first place, does conceptualize and, in the second place, could conceptualize knowledge, research, and science. Firstly, this PhD project analyzes, from a discourse studies perspective, the term problem in TSR, against the background of discourses on sustainable development. Secondly, it explores the historical-analytical and transformative concept of the problematic. The results, firstly, show the consequences of a problem-solving focus for TSR, and secondly, differentiate it from a transformative direction of problematic designing, as a more appropriate view on the dimensions of transformation and their qualities of change that matter for TSR. This PhD project aims to contribute to a self-understanding of, and a philosophical communication about, TSR, as a research form in the sustainability sciences.
Educational research has shown that reflection and feedback are crucial for substantial development of pre-service teachers' professional competence. However, reflection and feedback sessions are not a standard element of teaching practicums due to time- and location-constraints. Digital practicum environments can lift these constraints. Digital reflection and feedback environments have typically applied either textual accounts or video sequences of classroom practice, with varying effects. Consequently, the studies presented in this cumulative dissertation are focused on how the use of text- or video-based digital reflection and feedback environments during a practicum influence specific components of pre-service teachers' professional competence (i.e., beliefs about teaching and learning, self-efficacy, professional vision of classroom management, feedback competence). All studies followed a quasi-experimental, pre-test-post-test design. Pre-service teachers at the fourth-semester bachelor level in a German university took part in the studies. Pre-service teachers participated in a four-week teaching practicum at local schools. During the teaching practicum, pre-service teachers were divided into five different groups. The control group (CG) took part in a traditional practicum with live observations and face-to-face reflection and feedback with peers and experts. Pre-service teachers of the intervention groups (IG 1, IG 2, IG 3, IG 4) reflected and received feedback in highly structured text- or video-based digital environments. Intervention groups 1 (IG 1) and 2 (IG 2) participated in a text-based digital reflection and feedback environment. While IG 1 participants only received feedback from peers, IG 2 pre-service teachers also received expert feedback. Intervention groups 3 (IG 3) and 4 (IG 4) took part in a video-based digital reflection and feedback environment. IG 3 pre-service teachers only received peer feedback, whereas IG 4 participants also received expert feedback. Mixed methods were applied by generating quantitative and quantitative-qualitative data was with questionnaires, a standardized video-based test and content analysis. The studies demonstrated that classroom videos and video-based digital reflection and feedback environments can effectively enhance pre-service teachers' professional competence. This finding can be predominantly attributed to two characteristics of the application in the digital reflection and feedback environments: (a) being able to revisit a multitude of authentic teaching situations without time pressure and (b) the degree of decomposition by deliberate, focused practice and scaffolding elements. Furthermore, expert feedback seemed to be of better quality and entailed more substantial effects than peer feedback. The results of the conducted studies on professional vision of classroom management, beliefs about teaching and learning and feedback competence showed that expert feedback can be seen as a lens reducing and focusing classroom complexity, enabling pre-service teachers to perceive crucial teaching situations that would have otherwise gone unnoticed and to benefit from expert modelling of high-quality feedback. Consequently, video-based digital reflection and feedback environments with expert feedback can significantly improve pre-service teachers' professional competence during teaching practicums and, thus, better prepare pre-service teachers for future classroom challenges, leading to better learning environments for school students.
Global environmental changes and the subsequent biodiversity loss has raised concerns over the consequences for the functioning of ecosystems and human well-being. This thesis provides new mechanistic insights into the role of tree diversity in regulating forest productivity and forests’ responses to climate change. The thesis also addresses the overlooked functional role of ecological continuity in mediating ecosystem processes in the context of multiple global environmental changes. The findings of the thesis emphasize the need to retain the functional integrity of forest ecosystem by preserving biodiversity and acknowledging the ecological memory forests.
This cumulative dissertation embraces four empirical papers addressing socio-economic issues relevant to policy-makers and society as a whole. These papers cover important aspects of human life including health at birth, life satisfaction, unemployment periods and retirement decisions. The analyses are carried out applying advanced econometric methods and are based on data sets consisting of survey data as well as administrative records. The first joint paper investigates the causal impact of prenatal exposure to air pollution on neonatal health in Italy in the 2000s combining detailed information on mother's residential location from birth certificates with PM10 concentrations from air pollution monitors. Variation in local weekly rainfall is exploited as an instrumental variable for non-random air pollution exposure. Using quasi-experimental variation in rainfall shocks allows to identify the effect of PM10, ruling out potential bias due to confounder pollutants. The paper estimates the effect of exposure for both the entire pregnancy period and separately for each trimester to test whether the neonatal health effects are driven by pollution exposure during a particular gestation period. This information enhances our understanding of the mechanisms at work and help prevent pregnant mothers from most dangerous exposure periods. Additionally, the effects of prenatal exposure to PM10 are estimated by maternal labor market status and maternal education level to understand how the pollution burden is shared across different population groups. This decomposition allows to identify possible mechanisms through which environmental inequality reinforces the negative impact of early-life exposure to air pollution. This study finds that average PM10 and days with PM10 level above the hazard limit reduce birth weight, gestational age, and measures of overall newborn health. Effects are largest for third trimester exposure and for low-income and less educated mothers. The second joint paper updates previous findings on the total East-West gap in overall life satisfaction and its trend by using data from the German Socio-Economic Panel for the years 1992 to 2013. Additionally, the effects are separately analyzed for men and women as well as for four birth cohorts. The results indicate that reported life satisfaction is, on average, significantly lower in East than in West German federal states and that part of the raw East-West gap is due to differences in household income and unemployment status. The conditional East-West gap decreased in the first years after the German reunification and remained quite stable and sizable since the mid-nineties. The results further indicate that gender differences are small. Finally, the East-West gap is significantly smaller and shows a trend towards convergence for younger birth cohorts. The third joint paper explores the effects of a major reform of unemployment benefits in Germany on the labor market outcomes of individuals with some health impairment. The reform induced a substantial reduction in the potential duration of regular unemployment benefits for older workers. This work analyzes the reform in a wider framework of institutional interactions, which allows to distinguish between its intended and unintended effects. The results based on routine data collected by the German Statutory Pension Insurance and a Difference-in-Differences design provide causal evidence for a significant decrease in the number of days in unemployment benefits and increase in the number of days in employment. However, they also suggest a significant increase in the number of days in unemployment assistance, granted upon exhaustion of unemployment benefits. Transitions to unemployment assistance represent an unintended effect, limiting the success of a policy change that aims to increase labor supply via reductions in the generosity of the unemployment insurance system. The fourth, single-authored paper explores how an increase in the early retirement age affects labor force participation of older workers. The analysis is based on a social security reform in Germany, which raised the early retirement age over several birth cohorts to boost employment of older people and ultimately alleviate the burden on the public pension system. Detailed administrative data from the Federal Employment Agency allow to distinguish between employment and unemployment as well as disability pensions and retirement benefits claims. Using a Regression Kink design in a quasi-experimental framework, the author shows that the raised early retirement age had positive employment effects and negative effects on retirement benefits claims. The results also show that some population groups are more sensitive to a reduction in retirement options and more likely to seek benefits from other government programs. In this respect, the author finds that workers in manufacturing sector respond to the raised early retirement age by claiming benefits from the disability insurance program designed to compensate for reduced earnings capacity due to severe health problems. The treatment heterogeneity analysis further suggests that high-wage workers are more likely to delay exits from employment, which is in line with incentives but might also indicate an increased inequality within the affected birth cohorts induced by the reform. Finally, women seem to rely on alternative sources of income such as retirement benefits for women, or spouse's or partner's income not observed in the data. All things considered, workers did not adjust to the increased early retirement age by substituting early retirement with other government programs but rather responded to the reform in line with the policy intent. At the same time, the findings point to heterogeneous behavioral responses across different population groups. This implies that raising the early retirement age is an effective policy tool to increase employment only among older people who have the real choice to delay employment exits. Therefore, reforms that raise statutory ages should ensure social support for workers only marginally attached to the labor market or not able to work longer due to potential health problems or other circumstances.
Establishing the identity of asylum seekers in the absence of credible documents represents a significant challenge for governments. To support decision-making processes in identity determination and verification procedures, Germany’s Federal Office for Migration and Refugees introduced three digital identification systems under the “Integrated Identity Management - plausibility, data quality and security aspects (IDMS)” programme. Because these algorithmic systems are deployed in highly political settings affecting vulnerable populations on the move, this research investigates how the Federal Office legitimises the policy and use of IDM-S that indicate a new direction of governance driven by so-called “innovative technologies”. In this context, legitimacy - considered a core virtue of just, democratic institutions - is understood as a justificatory concept seen in conjunction with (good) governance and the right to privacy as guaranteed under Article 17 of the International Covenant on Civil and Political Rights. The data justice framework is applied to structure the evaluation of state practices. In addition, the qualitative content analysis is used to find patterns in publicly available documents. Expert interviews were carried out to include experiences of affected individuals and to verify identified information provided by the government. The analysis revealed that efforts to legitimise IDM-S included four patterns: referring to the rule of law and national security concerns, non-disclosing delegitimising information and limiting accountability, emphasising performance efficiency and the systems’ high level of innovation, implying objective operations by means of a mathematical-technical approach. The results underscore profound discrepancies between justifications and state practices, outlining severe privacy violations as well as the lack of compliance to qualitative values in governance that pertain to participation, transparency, accountability, impartiality and scientific soundness of state operations.
Panic disorder is a common anxiety disorder, which is associated with high subjective burden as well as a high cost for the health economy. According to the National Treatment Guideline S3, cognitive behavior therapy is recommended as the most effective psychological treatment. However, many people in need do not have access to cognitive behavior therapy. Internet-based interventions have proven to be an effective way to provide access to evidence-based treatment to those affected. For anxiety disorders, such as panic disorder and agoraphobia, a good effectiveness of internet-based interventions has been proven in numerous international studies. However, the internet has changed over the last few years: mobile technologies have considerable potential to further improve the adherence and effectiveness of internet-based interventions. Against this background, the authors developed the hybrid online training "GET.ON Panic". In this training, an app has been integrated into a browser-based online training. The app consists of a mobile diary for self-monitoring as well as a mobile exposure-guide that supports participants in self-exposure exercises in their everyday lives.In an initial exploratory feasibility study, qualitative interview data and quantitative measurements were collected in a pre-post design of 10 participants. Usage, user friendliness, user satisfaction and acceptance of the app were generally considered high. The use of interoceptive exposure exercises and daily summaries of anxiety and mood were the most widely performed and rated the best, while in vivo exposure exercises and the monitoring of acute panic symptoms were found to be difficult.In the efficacy study, 92 participants with mild to moderate panic symptoms were randomized into two parallel groups. After eight weeks, the intervention group showed a significant improvement in the severity of panic symptoms compared to the waiting control group. Using the intention-to-treat approach, a covariance analysis with baseline values as a covariate yielded a mean effect of Cohen's d=0.66 in reducing the panic symptoms in favor of the intervention group. This effect increased to d=0.89 after three months and stayed at d=0.81 at the 6-month measurement point. Response and remission rates were also significantly higher in the intervention group. This positive effect was also shown for secondary outcomes such as depressive symptoms and quality of life. A correlation between app usage and clinical outcomes could not be found. This work was the first to demonstrate that a hybrid online training based on cognitive behavior therapy is effective in reducing panic symptoms as well as panic disorder. In addition, this work contributes to a deeper understanding of the potential of mobile technologies in the field of e-mental health.
Thermal energy storage systems have a high potential for a sustainable energy management. Low temperature thermochemical energy stores based on gas-solid reactions represent appealing alternative options to sensible and latent storage technologies, in particular for heating and cooling purposes. They convert heat energy provided from renewable energy and waste heat sources into chemical energy and can effectively contribute to load balancing and CO2 mitigation. At present, several obstacles are associated with the implementation in full-scale reactors. Notably, the mass and heat transfer must be optimized. Limitations in the heat transport and diffusions resistances are mainly related to physical stability issues, adsorption/desorption hysteresis and volume expansion and can impact the reversibility of gas-solid reactions. The aim of this thesis was to examine the energy storage and cooling efficiency of CaCl2, MgCl2, and their physical salt mixtures as adsorbents paired with water, ethanol and methanol as adsorbates for utilization in a closed, low level energy store. Two-component composite adsorbents were engineered using a representative set of different host matrices (activated carbon, binderless zeolite NaX, expanded natural graphite, expanded vermiculite, natural clinoptiolite, and silica gel). The energetic characteristics and sorption behavior of the parent salts and modified thermochemical materials were analyzed employing TGA/DSC, TG-MS, Raman spectroscopy, and XRD. Successive discharging/charging cycles were conducted to determine the cycle stability of the storage materials. The overall performance was strongly dependent on the material combination. Increase in the partial pressure of the adsorbate accelerated the overall adsorbate uptake. From energetic perspectives the CaCl2-H2O system exhibited higher energy storage densities than the CaCl2 and MgCl2 alcoholates studied. The latter were prone to irreversible decomposition. Ethyl chloride formation was observed for MgCl2 at room and elevated temperatures. TG-MS measurements confirmed the evolution of alkyl chloride from MgCl2 ethanolates and methanolates upon heating. However, CaCl2 and its ethanolates and methanolates proved reversible and cyclable in the temperature range between 25°C and 500°C. All composite adsorbents achieved intermediate energy storage densities between the salt and the matrix. The use of carbonaceous matrices had a heat and mass transfer promoting effect on the reaction system CaCl2-H2O. Expanded graphite affected only moderately the adsorption/desorption of methanol onto CaCl2. CaCl2 dispersed inside zeolite 13X showed excellent adsorption kinetics towards ethanol. However, main drawback of the molecular sieve used as supporting structure was the apparent high charging temperature. Despite variations in the reactivity over thermal cycling caused by structural deterioration, composite adsorbents based on CaCl2 have a good potential as thermochemical energy storage materials for heating and cooling applications. Further research is required so that the storage media tested can meet all necessary technical requirements.