Open Access

Over the last two decades, online advertising has become one of the most important dimension of corporate communications. Nowadays, companies promote their products and services through multiple online marketing channels, for example newsletters, display and video advertising, and most notably, search engine advertising. In this context, statistical models developed in research and practice can be used to measure the effectiveness of advertising activities. The results from these kinds of analyses can, for instance, be used to attribute marketing success (sales, registration, etc.) to individual advertising activities and, thus, to support budget planning for future advertising campaigns. In recent years, a new form of advertising on the Internet has emerged: real-time advertising. Among others, it allows companies to identify potential customers and target them with respect to their interests. In this way, real-time advertising can increase advertising effectiveness and it could, at the same time, improve user experience. With the emerge of this new form of advertising, statistical models have become even more important because they are now being increasingly used to predict online user behavior. The articles included in this dissertation analyze user-level clickstream data generated during multi-channel advertising campaigns (including TV advertising) and during real-time auctions. The goal of the analyses conducted here is to better understand advertising effects and to support decision-making in this context. Most of the analyses are based on Bayesian models. These models allow for a very flexible structure, which enables researchers to model, for instance, heterogeneity across different types of users or non-linear parameters such as users´ reaction times and exponential decay of advertising effects. In addition, these models allow for the inclusion of prior knowledge of parameter distributions, and, therefore, they are well suited for iterative analyses based on clickstream data. Bayesian models can be evaluated in different ways. Instead of only relying on statistical metrics, the articles included in this dissertation aim to estimate the economic value of these models based on their predictive performance. Although this measure can only approximate their true economic value, this approach can be used to compare and evaluate different models and to illustrate the impact of predictive analyses for companies in the context of big data. This dissertation contributes to both information systems research and marketing research and has many managerial implications. First, a process is developed to determine optimal sample sizes representing the best balance between computational costs and predictive accuracy in e-commerce in particular and big data contexts in general. In practice, this process can be used to reduce infrastructure and computational costs. Second, the articles included here describe models that can be used to measure the impact of television ads on users´ online shopping behavior. The models can provide insights concerning the effectiveness of individual television ads, the interactions between different advertising channels and the difference in user behavior of TV-induced customers and their non-TV-induced counterparts. Thereby, the models could support decision-making with respect to future advertising campaigns and targeting. Third, the articles describe several possibilities to extend and improve decision support systems currently used in e-commerce and marketing. These improvements enable practitioners to predict users´ interests for arbitrary products and services by using corresponding websites as dependent variables. This approach can be used to improve the effectiveness of real-time advertising campaigns, especially those intended to raise brand awareness among customers. In addition to these contributions, the articles describe possibilities for future research projects at the intersection of information systems and marketing. These kinds of projects could aim to develop methods to take advantage of new possibilities resulting from technological progress, to increase profits from advertising campaigns and selling ad inventories, to provide deeper insights concerning the effectiveness of multi-channel advertising campaigns, and to improve targeting of individual consumers by considering their interests and privacy concerns.

Among all attenuation processes, biodegradation plays one of the most important role and is one of the most desirable processes in the environment especially since products released during this bio-reactions, can be once again reintroduced into the natural element cycles. To assess biodegradation, a variety of biodegradation test procedures have been developed by several international organizations. OECD guidelines for ready biodegradability testing represent one of the most prominent group of internationally used screening biodegradation tests (series 301A-F). These tests are usually very simple in their designs and allow for the fast and cheap screening of biodegradability. However, because of their stringency, the test conditions are not close to simulating environmental conditions and may lead to unrealistic results. To overcome these limitations, OECD introduced simulation tests which are designed to investigate the behavior of chemicals in specified environmentally relevant compartments. Despite the fact that simulation tests give more insight into the fate of chemicals in the environment, they are not applied frequently as they are often tedious, time consuming and expensive. Consequently, there is a need to provide a new biodegradation testing method that would combine complex testing environment as in simulation tests, easiness in handling and good data repeatability as in screening biodegradation tests. Another challenge is an adaption of the existing biodegradation testing methods to new types of samples, i.e. mixtures of transformation products (TPs). The research on the presence of pharmaceuticals in the environment gained momentum in the 1990s; since then, it has been growing. Their presence in the environment is a wellestablished fact. A wide range of pharmaceuticals is continuously detected in many environmental compartments such as surface waters, soils, sediments, or ground waters. After pharmaceuticals reach the natural aquatic environment they may undergo a number of processes such as: photolysis (under direct sunlight), hydrolysis, oxidation and reduction reactions, sorption, biodegradation (by bacteria of fungi), and bioaccumulation. These processes, may cause their elimination from aquatic environment, if reaction is complete, or creation of new compounds i.e., transformation products (TPs). What is more, processes, like chlorination and advanced oxidation processes (AOPs), such as H2O2/UV, O3/UV, TiO2/UV, Fenton, and photo-Fenton, or UV treatment which might be applied in water or wastewater treatment, may also lead to the TPs introduction into aquatic environment. The research on the TPs brings many new challenges. From one side, there is a constant need for the the development of a sensitive and reliable analytical separation, detection, and structure elucidation methods. Additionally, there is a need for the preparation of appropriate assays for the investigation of properties of new compounds, especially those answering the question if TPs pose a higher risk to the aquatic ecosystems than their parent compounds. Among numerous groups of pharmaceuticals, two are of great importance: antibiotics since they might promote emergence and maintenance of antimicrobial resistance in the aquatic environment; and cytostatic drugs. Cytostatic drugs can exert carcinogenic, mutagenic and/or teratogenic effects in animals and humans. The challenges of biodegradation testing presented in this thesis, encompasses these different areas of interest and was divided into three objectives: 1) Identification of the knowledge gaps and data distribution of the two groups of pharmaceuticals antibiotics and cytostatic drugs (article I); 2) Increasing the knowledge on biodegradation of cytostatic drugs and their TPs (articles II, III, and IV) and 3) Establishment of a biodegradation test with closer to simulation tests conditions, that could be affordable and to support better understanding on processes in water sediment interface construction - screening water-sediment test. Further validation of the test with an insight into sorption and desorption processes (articles V and VI).

Habitat fragmentation and changes in land use are currently two major drivers of biodiversity loss around the world by causing habitat loss and reducing connectivity across landscapes. These processes affect not only species diversity, but genetic structure as well. The loss of habitat and the increased isolation prevent gene flow and accelerate genetic drift, causing loss of genetic diversity and facilitating development of genetic differentiation. The effects of habitat fragmentation and land use changes are usually studied by relating patterns of genetic diversity and differentiation to environmental factors, habitat history, landscape structure, or to a combination thereof. However, these three drivers are rarely addressed simultaneously. In addition, these studies are usually carried out in conservation-driven contexts, and therefore tend to concentrate on hyper-fragmented landscapes and on rare or endangered species. However, how habitat fragmentation and land use affect widespread species in more typical landscapes has not been fully investigated. In this thesis I address these two gaps, and do so in three study regions, allowing for generalization of the results. I used Abax parallelepipedus, a flightless ground beetle with low dispersal power as a model species to test how environmental factors, habitat history, and landscape structure affect genetic diversity and genetic differentiation in three study regions located across Germany. This species seldom leaves wooded habitats, and rarely crosses linear barriers such as roads and railways. It is also known to be susceptible to rapid changes in genetic structure after habitat fragmentation. Nevertheless, A. parallelepipedus is widely distributed as it can inhabit a variety of woodland types in which it maintains high population densities. Although all of my study regions represent fairly typical rural landscapes for central Europe, each consisting of a complex matrix of land uses, they differ from one another in terms of environmental factors, habitat history, and landscape structure, and thus can serve as three test cases. In the first stage of my work, I identified polymorphic microsatellite loci which could potentially be used to study genetic diversity and differentiation in A. parallelepipedus. I then developed PCR and genotyping protocols for two suites of loci, in the end selecting to use the set of 14 fully multiplexed loci for my study. After I had developed the needed study system, I genotyped over 3300 beetles from 142 study sites. In my investigation of how environmental factors and habitat history affect genetic diversity and genetic differentiation, I found that genetic diversity was being driven by variables that could be related to population sizes rather than by habitat history. I also did not find evidence of an influence of habitat history on the genetic differentiation patterns. Although populations of A. parallelepipedus in the past were probably smaller due to deforestation, they apparently remained large enough to prevent rapid genetic drift. Thus, recolonization processes of woodlands planted after the peak of deforestation either occurred without incurring founder effects or bottlenecks, or the effects of thereof have since been erased by gene flow. As the genetic structure found in my landscapes is driven current processes, rather than historical ones, I carried out a landscape genetics analysis of the genetic differentiation patterns found in each of my study regions, in which I examined the relationship between genetic differentiation and landscape structure. I tested whether I could find patterns of isolation by distance, isolation by resistance, or isolation by barriers in my study regions. Surprisingly, I found no effects of land use or of fragmentation. Based on the importance of population sizes found in my previous study, combined with the beetle´s known avoidance of non-wooded areas and its inability to cross roads, I conclude that although there is probably little gene flow across my study regions, large population sizes are preventing the rapid development of genetic differentiation. Models simulating the development of genetic differentiation over time in populations of different starting sizes support this conclusion. My work highlights the importance of population sizes in determining how patterns of genetic diversity and differentiation will develop across landscapes. While emphasis has been placed in conservation contexts on the deleterious effects of fragmentation on genetic structure, this may be overstated for widespread species in typical landscapes. In such cases, large population sizes may mitigate the development of genetic differentiation and prevent loss of alleles, despite existing barriers and lack of gene flow.

Economic globalization has not only reinforced the power of global firms, but also the sustainability challenges we are facing today on global and regional levels. Against this background, an increasingly broad range of governance efforts has aimed at fostering more sustainable business practices. At the national level, in addition to regulatory policy instruments, market-based and network instruments as well as self-regulatory Corporate Social Responsibility (CSR) initiatives have emerged. These instruments differ not only in their degree of bindingness between compulsory and voluntary, but also involve a greater diversity of actor groups like government, business, and civil society organizations. In addition, international instruments like the UN Global Compact principles, the GRI Reporting Guidelines or the

I aim to assess the sustainability of rural electrification efforts based on off-grid photovoltaic (PV) systems in three Andean countries: Chile, Ecuador, and Peru. Although deployment of off-grid PV solutions for rural electrification began in the early 1990s in the Andean region, most of the projects turned out to be unsustainable and did not last. Prior efforts have addressed the different issues and barriers that plagued these projects and inhibited their sustainability. However, these prior analyses were mostly quantitative; systematic qualitative evaluations have been scarce. In this thesis, I address the following research question: ´Are the rural electrification programs (based on off-grid PV Systems) in the Andean countries sustainable?´ In order to answer this research question, I conducted an exhaustive qualitative document analysis complemented by semi-structured expert interviews. The interviewees included experts from different ministries, project managers from leading Non-Governmental Organizations (NGOs), public and private companies´ representatives, supervisors, and researchers. Although I also describe several relevant PV-based electrification efforts in the Andean countries, my research was aimed at providing an overall picture of the rural electrification efforts in these countries, rather than measuring the success or failure of specific projects. The gathered information allowed me to assess the sustainability of rural electrification efforts in the Andean countries. This assessment was based on a set of indicators corresponding to the four dimensions of sustainability considered in this thesis: institutional, economical, environmental, and socio-cultural. I found that Ecuador and Chile have consistently failed to ensure mechanisms for the operation and maintenance of the deployed off-grid systems, which has made these solutions in poor Chilean and Ecuadorian communities inevitably unsustainable. Although Peru has adopted a cross-tariff scheme, the Peruvian case shows that ensuring the funding of off-grid PV solutions is not enough. Peruvian officials appear to be unaware of the importance of local participation (local values and lifestyles are constantly disregarded) and most of the projects have been designed without the participation and engagement of the communities, which has often led to project failures and payment defaults. Although each country has its particular challenges, I found that the three Andean countries have consistently neglected the importance of strong formal institutions with a flexible and decentralized structure, which in turn significantly compromised the rural electrification effort in these countries.

In an increasingly urbanized world, consequences for humans, animals, plants are often unknown. Fundamental changes in landscapes due to landscape fragmentation, intensified agriculture or biodiversity loss dramatically impact ecosystems and their functions. Humans increasingly shifted their lifestyle from outdoor activities towards indoors, which are facilitated and depend on mostly digital technologies that are discussed to increase the risk of nature alienation. On the other hand, these readily available digital technologies offer chances to connect with people worldwide. This connectivity offers manifold opportunities to share data and to recruit people looking for new entertaining and interesting experiences as cooperation partners for the scientific community in so-called citizen science approaches. In citizen science, non-scientists are integrated in the data gathering of scientists. Being part of scholarly research, the citizen scientists receive up-to-date information on the research topic, which fosters the learning of the scientific background and thereby ideally supports the general scientific literacy that might be little developed due to a lack of interaction with nature. Especially for children in an urban societal background, there are concerns of alienation from nature due a significant shift away from nature-based activity and recreation, when compared to past generations. However, even though direct contact with nature is nowadays often infrequent, a solid knowledge about nature is essential to understand the consequences of biodiversity loss, the limitation of natural resources and the need for a sustainable development. Theoretically, citizen science cooperation offers a unique opportunity to integrate the public in the scientific gain of knowledge, further explaining the nature of science and fostering an increased awareness for biodiversity conservation and sustainable development. Inspired by these challenges, I investigated in my dissertation seed predation, an important ecosystem function that has hardly been part of citizen science project. As seed predation has only rarely been investigated along urban-rural gradients and to integrate the question if the background (urban vs. rural) of primary school children affects their environmental knowledge, I selected study sites in and around Lüneburg and Hamburg, in Northern Germany. In my ecological experiments, I found that slugs are important seed predators that independently of urbanization predated about 30% of all seeds in the anthropogenically used landscapes investigated. Also, I could for the first time integrate primary school children in a citizen science approach into this research and show that even seven year old children can record data as reliable as a scientist. Finally, I investigated the native species knowledge from the children taking part as citizen scientists in my research, considering possible differences due to their urban or rural background. Contrary to my expectation, the urban or rural background had no significant effect on the species knowledge. However, my work provides a good foundation to transfer the approach of introducing a basic foundation of a taxonomical species concept in primary school to foster further understanding on biodiversity and ecosystem functions. In summary, my dissertation combined different disciplinary approaches showing synergies between the single disciplines to support strategies for a successful sustainable development in the spirit of an education for sustainability. I could highlight the great potential of inter- and transdisciplinary approaches combining natural research with scientific literacy in a citizen science project on a local scale, which may serve as a model for implementing citizen science projects in schools elsewhere. I highly recommend this successful approach for similar cooperation on larger scales to counter challenges of pressing societal problems. Even though each cooperation will has its own unique challenges, the synergetic advantages will likely outweigh the disadvantages. In this context, there should be more emphasis on the education for sustainable development, not only in schools but other educational institutions like universities, to face the global urbanization with its manifold challenges and opportunities.

Western organizations increasingly organize work in team-based structures. Members of these teams often differ in various diversity attributes (e. g., gender, age, cultural background). In response, research aims to provide evidence-based recommendations on how to effectively manage diversity in teams. Within diversity research, the diversity faultlines approach has been particularly fruitful. It considers the impact of the alignment of multiple diversity attributes in teams. Strong diversity faultlines are associated with the emergence of relatively homogeneous subgroups in teams and have an overall negative impact on team processes and outcomes. This dissertation investigates factors that mitigate the detrimental consequences of strong diversity faultlines in teams, namely pro-diversity beliefs. It extends faultline literature beyond the conventional focus on processes and outcomes related to team members by emphasizing the leaders´ perspective. The three empirical papers included in this dissertation systematically examine how strong pro-diversity beliefs can help unleashing the positive effects of team diversity despite strong faultlines. The first paper highlights the role of leaders´ pro-diversity beliefs in mitigating the negative impact of diversity faultlines on two team processes: perceived cohesion and social loafing. Moreover, it compares the impact of socio-demographic faultlines (based on gender and age) and experience-based faultlines (based on team tenure and education level). Data was collected in a multisource field sample with 217 team members nested in 44 teams and the corresponding leaders. We found that socio-demographic, but not experience-based faultlines were negatively related to perceived cohesion and positively to perceived loafing. Path analysis further revealed that these relationships were mitigated when leaders held strong pro-diversity beliefs. The second paper extends these findings by additionally taking the impact of members´ pro-diversity beliefs into account. It examines whether the impact of sociodemographic faultlines on performance is contingent on leaders´ and members´ pro-diversity beliefs. Moreover, we assumed that aggregate LMX would mediate this relationship. In a multisource data set obtained from 41 teams with 219 members and the corresponding leaders working for the German Ministry of Foreign Affairs, we found partial support for our hypotheses. As expected, the impact of strong socio-demographic faultlines on diplomats´ performance was least negative when both leaders and members held strong pro-diversity beliefs. However, neither the two-way interactions of faultlines and leaders´ or members´ prodiversity beliefs nor aggregate LMX had a significant impact in our research model. The third paper zooms into processes and outcomes related to team leaders. It investigates how leaders´ pro-diversity beliefs and their perceptions of members´ prodiversity beliefs in teams with strong socio-demographic faultlines impact leaders´ task role assignment, performance expectation, and motivation. To test our hypotheses, we conducted two experimental studies with students, one in Germany (N = 55) and one in the US (N = 134). Findings showed that strong pro-diversity beliefs held and perceived by leaders made them assign task roles that cross-cut rather than aligned with the subgroup structure created by faultlines. Moreover, leaders´ perceptions of members´ pro-diversity beliefs, but not their own beliefs, had a positive impact on their motivation, mediated by their performance expectation. In sum, findings of these three papers extend the literature on diversity faultlines and leadership by systematically demonstrating the mitigating impact of pro-diversity beliefs on faultlines´ detrimental consequences on processes and outcomes related to team leaders and members. Based on various samples, we showed that it is worthwhile to distinguish between pro-diversity beliefs held by leaders, pro-diversity beliefs held by members, and leaders´ perceptions of members´ pro-diversity beliefs. Fostering strong pro-diversity beliefs among leaders and members should thus be a crucial element of effective diversity faultline management in organizations.

Research on motivational and cognitive processes in entrepreneurship has commonly relied on a static approach, investigating entrepreneurs´ motivation and cognition at only one point in time. However, entrepreneurs´ motivation and cognition are dynamic processes that considerably change over time. The goal of this dissertation is thus to adopt a dynamic perspective on motivational and cognitive processes in entrepreneurship. In three different chapters, I examine dynamic changes in the level and impact of three different processes, i.e., creativity, entrepreneurial passion, and opportunity identification. In Chapter 2, I develop a theoretical model on the alternating role of creativity in the course of the entrepreneurial process. The model emphasizes that the effects of two components underlying creativity, i.e., divergent and convergent thinking, considerably change both in magnitude and in direction throughout the entrepreneurial process. In Chapter 3, I establish and empirically test a theoretical model on entrepreneurial passion. The theoretical analysis and empirical results show that the relationships between feelings of entrepreneurial passion, entrepreneurial self-efficacy, and entrepreneurial success are dynamic and reciprocal rather than static and unidirectional. In Chapter 4, I develop and test a theoretical model on the effect of entrepreneurship training on opportunity identification over time. The theoretical and empirical investigation indicates that entrepreneurship training effects systematically decay over time and that action planning and entrepreneurial action sustain the effects in the long term. Altogether, the research reported in this dissertation provides novel insights into entrepreneurs´ motivation and cognition which more static approaches would have obscured. Moreover, the theoretical and empirical results of each chapter resolve apparent contradictions in past research and integrate hitherto fragmented theoretical perspectives into more inclusive theoretical frameworks. Thereby, this dissertation represents an important step toward a more integrated understanding of motivational and cognitive mechanisms underlying successful entrepreneurship.

European species-rich grasslands, which provide many ecosystem functions and services, are threatened both by land use intensification as well as land abandonment. The studies shown in this thesis tested the possible use of ecological knowledge to ensure hay productivity whilst maintaining diversity of grasslands, with a view to informing ecological restoration. The overall approach was to understand interactions between plants, to study diversity effects on productivity, and mainly investigate how plant functional groups that arrive first in the system can create priority effects that influence community productivity both above- and belowground. A grassland field experiment was established and monitored for four years, in order to verify the effects of manipulating the order of arrival of different plant functional groups, as well as the sown diversity level on productivity and methane yield. The overall findings were: a) sowing legumes first created priority effects aboveground (higher biomass) and belowground (lower root length), plants invested less in roots and more in shoots, b) priority effects were more consistent below than aboveground, c) sown diversity did not affect aboveground biomass, d) the order of arrival treatments indirectly affected methane yield by affecting the relative dominance of plant functional groups. Since we lack information on how legumes and non-legumes interact spatially belowground, (particularly related to root foraging) a controlled experiment was performed, using two grass species and one legume. The identity and location of the neighbours played a role in interactions, and the order plants arrived modulated it. When the focal species (grass) was growing with a legume it generally equated to the same outcome as not having a neighbour. Roots from the focal species grew more toward the legume than the grass neighbour, indicating a spatial component of facilitation. Since these studies involved root measurements, a method study was also conducted to verify how comparable and accurate are root length estimates obtained from different techniques. Results showed that the use of different methods can lead to different results, the studied methods did not have the same accuracy, and the automated methods can underestimate the root length. Overall, the results allow to conclude that different groups of plants arriving before others affected above and belowground biomass, roots may be key drivers during the creation of these priority effects, and interaction outcomes between plants depended on neighbour identity and location, modulated by the order they arrive in. Our results suggest that we can use priority effects by sowing different species or plant functional groups at different time to steer a community to a desired trajectory depending on the restoration goal (such as increasing biomass whilst maintaining diversity). However, there is a need to test contingency, potential, and long term impacts of such possible tools for restoration.