@phdthesis{Ertel2026, author = {Ertel, Florence Laura Louise}, title = {Europapolitische Themen in Wahlk{\"a}mpfen: Chancen und Herausforderungen der Anwendung von Blended Reading-Verfahren f{\"u}r die Europ{\"a}ische Integrationsforschung}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:739-opus4-20504}, school = {Universit{\"a}t Passau}, pages = {71 Seiten, 132 unterschiedlich gez{\"a}hlte Seiten, XXIII Seiten}, year = {2026}, abstract = {Durch fortschreitende Digitalisierung w{\"a}chst die Verf{\"u}gbarkeit digitaler Textdaten europapolitischer Diskurse. Gleichzeitig werden algorithmusbasierte Verfahren zur Analyse dieser großen Menge an Textdaten stetig weiterentwickelt. F{\"u}r die europ{\"a}ische Integrationsforschung bietet die Vielfalt der Kommunikationsarten und -formen die M{\"o}glichkeit, gesellschaftliche, mediale und politische Diskurse zur europ{\"a}ischen Integration auf den verschiedensten Ebenen nachzuvollziehen. Chancen birgt dies insbesondere aus der integrationstheoretischen Perspektive des Postfunktionalismus. Dieser Ansatz r{\"u}ckt die vermehrte Politisierung der europ{\"a}ischen Integration in den Mittelpunkt. Denn mit der zunehmenden Vertiefung der europ{\"a}ischen Integration w{\"a}chst zugleich der europ{\"a}ische Einfluss auf nationale Policies und wirkt sich immer unmittelbarer auf das Leben der Europ{\"a}er:innen aus. Dies f{\"u}hrt zu verst{\"a}rkter Polarisierung und Mobilisierung innerhalb der Gesellschaft und spiegelt sich in einer wachsenden Spaltung zwischen proeurop{\"a}ischen und antieurop{\"a}ischen politischen Lagern wider. So werden Einstellung zur EU zu einer wichtigen strukturellen Spaltungslinie zwischen Parteien. Folgt man der GAL/TAN-These von Hooghe und Marks (2009), k{\"o}nnen Parteien in gr{\"u}ne, alternative, libert{\"a}re und grunds{\"a}tzlich proeurop{\"a}ische sowie traditionalistische, autorit{\"a}re, nationalistische und eher euroskeptische Parteien unterteilt werden. Letztere nutzen insbesondere digitale Kommunikationsr{\"a}ume verst{\"a}rkt und effektiv. Dies unterstreicht die Notwendigkeit, Datengrundlagen f{\"u}r Analysen auf den digitalen Raum auszuweiten und zu archivieren, um den Diskurs in seiner Breite erfassen zu k{\"o}nnen. Mit der Menge an digital verf{\"u}gbaren Textdaten w{\"a}chst allerdings auch die Un{\"u}bersichtlichkeit. Dies f{\"u}hrt zu methodischen Herausforderungen in Bezug auf die Art der Daten, die Datensammlung und -speicherung sowie die Datenvorverarbeitung und -analyse. Angesichts großer Textdatenmengen stoßen in der europ{\"a}ischen Integrationsforschung {\"u}bliche qualitative Analyseverfahren an ihre Grenzen. Quantitative Analyseverfahren ver{\"a}ndern das Verh{\"a}ltnis von Textdatenmaterial und Forscher:in. Die wissenschaftliche Debatte setzt sich mit der Frage auseinander, wie sich Analysen angesichts der wachsenden Textdatenmengen gestaltet und steuern lassen, damit das Verh{\"a}ltnis von Textdatenmaterial und Forscher:in nicht durch Algorithmen, die einen Black-Box-Effekt in der Datenanalyse erzeugen k{\"o}nnen, verzerrt wird. Daraus ergibt sich die Notwendigkeit einer Verbindung von quantitativen und qualitativen Analysenmethoden auf epistemologischer und methodologischer Ebene, um reliable und valide Forschungsergebnisse zu gew{\"a}hrleisten. Dies impliziert die {\"U}berwindung der so h{\"a}ufig diskutierten Gegens{\"a}tze von qualitativen und quantitative Analysen, datengeleiteten und theoriegeleiteten Analysen oder Close und Distant Reading. Allerdings existiert in der Politikwissenschaft bislang kein Best Practice-Workflow f{\"u}r die Analyse großer Textdatenmengen webbasierter Daten, mit dem intersubjektive Nachvollziehbarkeit und Reliabilit{\"a}t im Forschungsprozess gew{\"a}hrleistet werden k{\"o}nnen. An diese Forschungsl{\"u}cke kn{\"u}pft die kumulative Dissertation an. In sechs aufeinander aufbauenden Publikationen in deutscher, englischer und franz{\"o}sischer Sprache wird ein Best Practice-Workflow f{\"u}r Blended Reading entwickelt. Dieser Ansatz verbindet die Vorteile von quantitativer und qualitativer Forschung. Der starke methodische Schwerpunkt wird durch Fallstudien zu europ{\"a}ischen und nationalen Wahlk{\"a}mpfen in Deutschland, Frankreich und {\"O}sterreich kontextualisiert. Daf{\"u}r wird die Rolle europapolitischer Themen in der Wahlkampfkommunikation der vergangenen zwei Jahrzehnte aus postfunktionalistischer Perspektive analysiert.}, language = {mul} } @phdthesis{Wirth2026, author = {Wirth, Olivia}, title = {Digital Platforms and Mobile Technologies for Development: Essays on Firm Formalization, Financial Inclusion, and Agricultural Resilience in Sub-Saharan Africa}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:739-opus4-20049}, school = {Universit{\"a}t Passau}, pages = {xi, xv, 156 Seiten}, year = {2026}, abstract = {Mobile technologies and digital platforms have expanded rapidly across sub-Saharan Africa, creating opportunities to strengthen state capacity, broaden financial inclusion, and build agricultural resilience. This dissertation examines their development impacts across three settings. Chapter 1 combines novel administrative tax records with high resolution data on mobile network rollout in Uganda to estimate the effects of mobile internet access on firm tax behavior and public revenue. Exploiting plausibly exogenous rollout timing, we find that improved access increases firm formalization and expands the tax base, strengthening revenue collection. Chapter 2 presents a randomized controlled trial in Niger—the world's most financially excluded country—to identify barriers to adoption of a mobile money platform. Information provision raises awareness but not use, consistent with information being necessary but insufficient for diffusion. By contrast, a modest financial incentive significantly increases both adoption and usage. Chapter 3 uses a household panel collected before and after a severe drought in northern Ghana and exploits variation in rainfall in a differences-in-differences framework to estimate effects on production, income sources and adaptation plans. We find that increasing drought severity lowers soybean yields and revenues and decreases reliance on own-business income and remittances, reflecting broader livelihood impacts. Farmers who use mobile phones to access agricultural information make different input choices and adaptation plans. Taken together, these findings highlight the promise of mobile technologies and digital platforms for development. Their effectiveness, however, depends on complementary infrastructure and local capacity, underscoring the need for scalable, context-specific strategies to harness these tools for inclusive growth and resilience.}, language = {en} } @phdthesis{Khosravi2026, author = {Khosravi, Mohammad}, title = {Hard Instances, Improved Algorithms and New Interdiction Models for Robust Optimization}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:739-opus4-20399}, school = {Universit{\"a}t Passau}, pages = {vii, 197 Seiten}, year = {2026}, abstract = {Robust combinatorial optimization seeks solutions that remain effective across all possible realizations of an uncertainty set, making the choice of this set a crucial factor in both the complexity and practical applicability of robust models. A key challenge in this field is striking a balance between computational tractability and solution quality, particularly when dealing with large uncertainty sets. This dissertation advances the field of robust optimization by addressing three central themes: (i) methods for generating hard instances and establishing a benchmark library, (ii) high-quality exact solution methods and approximation algorithms, and (iii) the modeling of uncertainty sets and their impact on problem complexity. The absence of a benchmark library for robust optimization problems makes it difficult to conduct fair and effective comparisons of different solution methods. As a result, researchers often rely on randomly generated instances, which may hinder meaningful evaluations. To address this issue, this work develops optimization-based and heuristic methods for generating challenging instances of robust problems. Additionally, to facilitate more consistent and insightful comparisons of solution algorithms with minimal effort, we introduce a standardized benchmark library for use by the research community. To tackle the computational challenges posed by large uncertainty sets, this dissertation proposes scenario reduction techniques specifically designed for robust optimization. These methods aim to reduce the size of the uncertainty set while preserving the objective value as accurately as possible. Unlike traditional clustering approaches, this formulation treats scenario reduction as an optimization problem independent of the underlying decision-making model, enabling structured reductions with theoretical performance guarantees. Experimental results demonstrate that this approach produces solutions of comparable or superior quality compared to those obtained through general-purpose clustering techniques. Building on this framework, we further refine scenario reduction by incorporating information about the structure of feasible solutions. While previous reduction methods focused exclusively on the uncertainty set, we show that integrating knowledge of feasible solutions leads to improved uncertainty sets and more accurate robust models. Through a combination of theoretical analysis and computational experiments, we establish the effectiveness of this approach in enhancing both tractability and solution quality in robust combinatorial optimization. Finally, we introduce a novel variant of discrete budgeted uncertainty for cardinality-based constraints or objectives, incorporating a weight vector into the budget constraint. Our theoretical analysis reveals that while the adversarial problem can be solved in linear time, the robust problem becomes NP-hard and non-approximable. Nonetheless, we propose and evaluate alternative modeling approaches that demonstrate promising scalability in practice. This dissertation contributes to robust optimization by offering new perspectives on uncertainty modeling, algorithmic techniques for scenario reduction, and complexity analyses of key robust problems. The proposed methods provide both theoretical guarantees and practical advancements, paving the way for more efficient and scalable robust optimization models.}, language = {en} } @misc{BauerRoesslerKasperetal.2025, author = {Bauer, Matthias and R{\"o}ssler, Reto and Kasper, Nils and Ernst, Christoph}, title = {Diagrammatische Praktiken}, volume = {2025}, number = {14}, editor = {Bauer, Matthias and R{\"o}ssler, Reto and Nies, Martin}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:739-opus4-20417}, pages = {134}, year = {2025}, abstract = {Indem die Aufs{\"a}tze von Nils Kasper, Christoph Ernst, Reto R{\"o}ssler und Matthias Bauer sowohl wissens- und kulturgeschichtliche als auch medien- und verfahrenstechnische Fragestellungen behandeln, zeigen sie in ihrer Komplementarit{\"a}t das Spektrum an Denk- und Handlungsm{\"o}glichkeiten auf, das Diagramme bzw. diagrammatische Praktiken er{\"o}ffnen.}, language = {de} } @misc{Weithmann2025, author = {Weithmann, Michael}, title = {Passau und das Nibelungenlied}, series = {Altbayerische Heimatpost : Leben und Erleben in Bayern 27/2025}, volume = {2025}, journal = {Altbayerische Heimatpost : Leben und Erleben in Bayern 27/2025}, number = {27}, publisher = {Passauer Neue Presse}, address = {Passau}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:739-opus4-20349}, pages = {10 -- 12}, year = {2025}, abstract = {The Nibelungenlied is an epic poem written around 1200 in Middle High German. Its anonymous poet was likely from the region of Passau. The current theory of the creation of the poem emphasizes the poet's concentration on the region of Passau: for example, the poem highlights the relatively unimportant figure of Bishop Pilgrim of Passau, and the poet's geographical knowledge appears much more firm in this region than elsewhere. These facts, combined with the dating, have led scholars to believe that Wolfger von Erla, Bishop of Passau (reigned 1191-1204) was the patron of the poem.}, subject = {Nibelungenlied}, language = {de} } @misc{HarendarskiBrieseHallmannetal.2024, author = {Harendarski, Ulf and Briese, Joschka and Hallmann, Tiziana and Dettmann, Luc and Kitzerow, Tom}, title = {Kraft und Signifikanz}, volume = {2024}, number = {13}, editor = {Harendarski, Ulf and Briese, Joschka}, doi = {10.15475/skms.2024.1}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:739-opus4-20388}, pages = {162 Seiten}, year = {2024}, abstract = {Zuerst erschienen auf: https://www.kultursemiotik.com/forschung/publikationen/schriftenreihe-online/ Inhalt Vorwort Kraft und Signifikanz. Kultursemiotische Betrachtungen allt{\"a}glicher Darstellungen in der sprachbasierten Semiose Ulf Harendarski und Joschka Briese Signifikanz der Melancholie Zur diskursiven Konstitution Leonard Cohens Tiziana Hallmann Von gefallenen Helden Mythologische Umschriften und ihre semiotisierende Kraft Luc Dettmann Sprachliche Konstitutionen von Drittpersonalit{\"a}t Eine semantisch/pragmatische Analyse von distanzmarkierenden Verben in drittpersonalen Aussagen {\"o}ffentlicher Texte Tom Kitzerow Spuren diskursiver Interpretationsprozesse F{\"u}r ein elaboriertes Konzept von Signifikanz Joschka Briese Impressum}, language = {de} } @phdthesis{Rolvering2026, author = {Rolvering, Geske}, title = {Empirical Essays in Public Economics}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:739-opus4-20186}, school = {Universit{\"a}t Passau}, pages = {x, 159 Seiten}, year = {2026}, abstract = {This dissertation exploits quasi-experimental methods and rich microdata to identify causal effects of public interventions that speak directly to the goals outlined in the 2030 Agenda for Sustainable Development. Specifically, the first chapter analyzes the effect of public child care provision on mothers' career trajectories, focusing on the timing of labor market re-entry and the quality of occupational outcomes. It thereby contributes to the Sustainable Development Goals of "Gender Equality", "Reducing Inequalities", and "Decent Work and Economic Growth". The second chapter investigates the impact of all-day school programs on juvenile property, violent, and drug-related crime. By providing evidence on how school schedules can be structured to promote safe learning environments, it contributes in particular to the goal of "Quality Education". In addition, it also contributes to broader objectives related to "Good Health and Well-Being" as well as "Peace, Justice and Strong Institutions". The third chapter examines public attitudes toward climate change and carbon pricing in Germany and analyzes whether different types of information shift people's policy views. By exploring measures to reduce resistance to effective but politically unpopular environmental policies, this chapter contributes to the goal of "Climate Action".}, language = {en} } @misc{LukasBrehmDurdeletal.2023, author = {Lukas, Wolfang and Brehm, David and Durdel, Patrick and Papart, S{\"o}nke and Kreuter, Sara and Weinbach, Donata and Pfeifer, Lena and Assadsolimani, Jasmin and Wagner, Alexander}, title = {Zeichen des Fremden}, volume = {2023}, number = {9}, editor = {Lukas, Wolfgang and Nies, Martin}, doi = {10.15475/skms.2023.3}, url = {http://nbn-resolving.de/urn:nbn:de:101:1-2023081602100461706063}, pages = {189 Seiten}, year = {2023}, abstract = {Zuerst erschienen auf: https://www.kultursemiotik.com/forschung/publikationen/schriftenreihe-online/ Inhalt Zeichen des Fremden Einleitung Wolfgang Lukas / Martin Nies Wessen Rettung? Gefl{\"u}chtete Figuren, Sinnproduktion und implizite Poetik in Jenny Erpenbecks 'Gehen, ging, gegangen' und Bodo Kirchhoffs 'Widerfahrnis' David Brehm Der falsche Fremde Auto- und metafiktionale Reflexionen von Identit{\"a}t und Ethnizit{\"a}t in Abbas Khiders 'Der falsche Inder' S{\"o}nke Parpart „Ich habe kein Bild mehr von mir" (De-)Konstruktion von Identit{\"a}t und Fremdheit in Jenny Erpenbecks 'Gehen, ging, gegangen' (2015) und Olga Grjasnowas 'Gott ist nicht sch{\"u}chtern' (2018) Sara Kreuter Verfinsterungen des Eigenen Konstruktionen des Anderen in Wolfram Lotz' 'Die l{\"a}cherliche Finsternis' Patrick Durdel Die vertraute Fremdheit der Anthropophagie Franzobels 'Floß der Medusa' (2017) Donata Weinbach Intimate Weavings Tracing Urban and Corporeal Others in Sin{\´e}ad Morrissey's Poetry Lena Pfeifer Make America en vogue again Die Konstruktion einer nationalen Identit{\"a}t in der US-amerikanischen Vogue nach dem Trump-Wahlsieg Jasmin Assadsolimani Schweiz / Haiti / NEW WORLD PLAZA Individualgeschichte und Universalgeschichte in Dorothee Elmigers 'Aus der Zuckerfabrik' Alexander Wagner}, subject = {Einwanderung }, language = {mul} } @phdthesis{Hosseini2026, author = {Hosseini, Amir}, title = {Integrated Scheduling and Material Handling: Theory and Applications in Manufacturing Systems}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:739-opus4-20249}, school = {Universit{\"a}t Passau}, pages = {xv, 127 Seiten}, year = {2026}, abstract = {Scheduling concerns the allocation of limited resources to competing tasks over time and is central to manufacturing systems. In practice, production scheduling is tightly linked to material handling, as jobs must be transported between machines, buffers, and storage locations. However, transportation decisions have often been simplified or decoupled from classical scheduling models. This dissertation investigates the problem of Integrated Scheduling and Material Handling (ISMH), where processing and transportation decisions are jointly optimized to improve overall system performance. The thesis develops this objective in three steps. First, it provides a structured and unified classification of scheduling problems with transportation elements, organizing a fragmented body of literature and clarifying methodological foundations. Second, it studies scheduling in AGV-based material handling systems under battery constraints, proposing a novel mixed-integer programming formulation and an exact solution approach based on logic-based Benders decomposition. Third, it extends integrated models to a buffer-constrained flow shop setting with mobile buffering, introducing a decomposition-based algorithm that significantly improves scalability. Together, these contributions advance conceptual understanding, modeling frameworks, and exact solution methods for integrated production and internal logistics planning in modern manufacturing systems.}, language = {en} } @unpublished{Wehner2026, author = {Wehner, Stefanie}, title = {Regional and gendered aspects of migration: Data-exploration from a multi-local field survey in Ghana (Northern, Eastern and Greater Accra Region)}, doi = {10.15475/mitrawa.upa7}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:739-opus4-20299}, pages = {25 Seiten}, year = {2026}, abstract = {This study assesses the perception of migrants and migrant households on drivers and structures of translocal mobility and their consequences for livelihoods in Ghana. A bi-local survey was conducted to collect data on households and migrants in the area of origin (AoO) and individuals in the area of destination (AoD). The survey at the AoO was conducted in two research areas (Gushiegu Municipal District in the Northern Region and Fanteakwa District in the Eastern Region). Thesample then covered 75\% migrant households and 25\% non-migrant households, both randomly selected. The collected data provides information on almost 1,000 migrants and 2,000 non-migrants. Since Greater Accra Region was identified as one major destination, this region was selected as an Area of Destination. In Accra, 50 migrants from Eastern and Northern Region each were randomly selected from the previous survey database. The perception of migrant households and migrants themselves on migration was assessed using descriptive statistics. Over 95\% said migration is essential to secure their livelihood and that migration improves the standard of living of the households. The study elucidates the challenges encountered by rural households in agriculture and the strategies implemented to address these issues. The predominant challenges confronting farmers include the escalating costs of agricultural inputs, the prevalence of pests and diseases, and fluctuations in environmental conditions. Moreover, the research highlights robust translocal networks that extend beyond mere financial remittances, encompassing an intangible web of communication, emotions, and aspirations. By traversing spatial and gender dimensions, the study unveils the extensive diversity of migration aspects, demonstrating that migration exerts markedly different impacts on women compared to men and has varying implications for households in the Northern Region versus the Eastern Region. It is evident that female migrants from Northern Ghana constitute the most vulnerable group, grappling with severe food insecurity. In contrast, translocal networks in the Eastern Region facilitate families in leveraging remittances for diversification of their economic base, thereby enhancing their capacity for future development, while those in the Northern region are essential for addressing the existential needs of families.}, language = {en} } @phdthesis{Ryzhova2026, author = {Ryzhova, Anna}, title = {The Transnational News Diets of Russian Speakers in Germany: what news they use and trust}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:739-opus4-19867}, school = {Universit{\"a}t Passau}, pages = {187 Seiten}, year = {2026}, abstract = {The present cumulative dissertation consists of four articles, and is based on more than 70 semi-structured interviews with the Russian speakers in Germany. Forty two interviews were conducted before of the start of Russia's full-scale invasion of Ukraine, and the other twenty nine right after its beginning (out of which I used only twenty five for the final analysis, as I focused only on the Russian speakers, associated with agressor or neutral countries in Russia's war in Ukraine). The dissertation addresses a variety of issues, related to the media use of the Russian speakers in Germany, which was previously understudied both in general and from political communication perspective (Panagiotidis, 2023). In the strand of migrants and media research, scholars point the following gaps: the lack of political element in studies of how migrants use media (Leurs and Smets, 2018), the lack of studies how homeland and host society media are used simultaneously, not in isolation from each other, and the lack of studies on the influence of homeland media on migrants as such (Ramasubramanian et al., 2017), and finally, communication scholars not using migration studies frameworks in their research on migrants, which leads to fields existing in parallel (Leurs \& Smets 2018). This dissertation addresses all these gaps. Being the first study to apply the concepts of "news repertoires" and the latest theorization of "news literacy" for studying the migrant populations, as well as looking in-depth in the mechanisms of trust, I analyze the media diets of Russian speakers in Germany in their entirety, considering the contexts and roles, attributed to the German quality, Russian opposition, Russian state sponsored and other types of media, i.e. not analying them in isolation, and also looking at the motivations to use different media for different domains of their lives. Besides, for analysing the transformations of media diets of the Russian speakers in the aftermath of Russia's full-scale invasion of Ukraine, I use the concept of "sense of belonging" to Russia to examine the deep, underlying reasons for why news repertoires of these audiences changed, or did not change in the light of Russia's war crimes. As for the contribution to the German-language and Germany-focused literature on the Russian speakers, this is the first comprehensive study to scrutinize the media diets of Russian speakers in-depth with a special emphasis on their motivations, political affiliations and differentiating between the media these audiences "use" and the media they "trust", as previous research on Russian speakers in Germany and their media use was largely focused on integration, largely ignoring the political aspect and Russia's repetitive attempts to influence Russian speakers abroad (e.g.Hepp et al., 2011) or lacked nuance in their results (e.g. Boris Nemtsov Foundation Survey, which posed questions about "Russian media" without defining what it is, i.e. is that opposition media, Kremlin-sponsored media, etc. Finally, this thesis provides a comprehensive case study of audiences from an authoritarian context (or a former authoritarian context, for those, who migrated from Ukraine, but were socialized in the Soviet Union) who migrated to democracy and their media use, and also sheds light on the spectrum of motivations of audiences abroad to continue consuming media from an authoritarian homeland (in our case, Kremlin-sponsored media), which can provide important foundation for future research on other migrant groups from authoritarian contexts in democracies, such as Chinese migrants in Europe. Among the results of the present dissertation is an article on three types of news repertoires that these audiences have, and how political beliefs underpin them; an article on how they view the "truth" in media and why it is a concept of crucial importance for their news trust patterns; an article on news literacy and how migrant audiences need transnational news literacy knowledge in order to navigate complex media landscapes, in which authoritarian states actively try to reach them with their narratives; and finally, how a major crisis event, such as war in Ukraine, changed (or did not change) the news repertoires of the Russian speaking audiences in Germany and why the "sense of belonging" is at the core of these changes.}, language = {en} } @phdthesis{Kochendoerfer2026, author = {Kochend{\"o}rfer, Laura}, title = {Rethinking systems use in information systems research - theories on individuals' use of multiple information systems}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:739-opus4-20164}, school = {Universit{\"a}t Passau}, pages = {vi, 99 Seiten}, year = {2026}, abstract = {While individuals use multiple information systems (IS) every day, research on IS use predominantly investigates use with respect to only one information system at a time. In light of this "single-IS paradigm" (Gerlach \& Cenfetelli, 2022), theoretical and empirical insights into the nature and behavioral manifestations of multiple IS use remain limited. To advance the discipline's understanding of the multiple IS use reality, this dissertation theorizes mechanisms that are idiosyncratic to the context of individuals' multiple IS use. Based on grounded theory methodology and interview data from individuals using multiple IS, this dissertation contributes two theories on multiple IS use in two essays. The first essay introduces an analytical theory of eight different interdependencies-in-use as core mechanisms that emerge as users engage with multiple IS. The second essay builds on these interdependencies-in-use and examines how one type of interdependency manifests in behavior. The resulting process theory explains a behavioral phenomenon resulting from multiple IS use: users transferring usage behaviors from one IS to another. This dissertation contributes a theoretical framework for conceptualizing multiple IS use with its underlying mechanisms that enable future research to systematically investigate multiple IS use and related phenomena. It further enriches insights on usage behavior by a multiple IS perspective, indicating that multiple IS use contexts give rise to unique behavioral dynamics. With that, the current conversation in IS use research that focuses on single IS use is extended with new theoretical insights on the use of multiple IS. The dissertation offers additional recommendations for practitioners to consider the interdependent way individuals use multiple IS.}, language = {en} }