@phdthesis{Bubeck2024, author = {Bubeck, Philip}, title = {Flood impacts, behavioural responses of individuals, and integrated risk management}, school = {Universit{\"a}t Potsdam}, pages = {328}, year = {2024}, language = {en} } @phdthesis{Frank2024, author = {Frank, Mario}, title = {On synthesising Linux kernel module components from Coq formalisations}, doi = {10.25932/publishup-64255}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-642558}, school = {Universit{\"a}t Potsdam}, pages = {IX, 78}, year = {2024}, abstract = {This thesis presents an attempt to use source code synthesised from Coq formalisations of device drivers for existing (micro)kernel operating systems, with a particular focus on the Linux Kernel. In the first part, the technical background and related work are described. The focus is here on the possible approaches to synthesising certified software with Coq, namely the extraction to functional languages using the Coq extraction plugin and the extraction to Clight code using the CertiCoq plugin. It is noted that the implementation of CertiCoq is verified, whereas this is not the case for the Coq extraction plugin. Consequently, there is a correctness guarantee for the generated Clight code which does not hold for the code being generated by the Coq extraction plugin. Furthermore, the differences between user space and kernel space software are discussed in relation to Linux device drivers. It is elaborated that it is not possible to generate working Linux kernel module components using the Coq extraction plugin without significant modifications. In contrast, it is possible to produce working user space drivers both with the Coq extraction plugin and CertiCoq. The subsequent parts describe the main contributions of the thesis. In the second part, it is demonstrated how to extend the Coq extraction plugin to synthesise foreign function calls between the functional language OCaml and the imperative language C. This approach has the potential to improve the type-safety of user space drivers. Furthermore, it is shown that the code being synthesised by CertiCoq cannot be used in kernel space without modifications to the necessary runtime. Consequently, the necessary modifications to the runtimes of CertiCoq and VeriFFI are introduced, resulting in the runtimes becoming compatible components of a Linux kernel module. Furthermore, justifications for the transformations are provided and possible further extensions to both plugins and solutions to failing garbage collection calls in kernel space are discussed. The third part presents a proof of concept device driver for the Linux Kernel. To achieve this, the event handler of the original PC Speaker driver is partially formalised in Coq. Furthermore, some relevant formal properties of the formalised functionality are discussed. Subsequently, a kernel module is defined, utilising the modified variants of CertiCoq and VeriFFI to compile a working device driver. It is furthermore shown that it is possible to compile the synthesised code with CompCert, thereby extending the guarantee of correctness to the assembly layer. This is followed by a performance evaluation that compares a naive formalisation of the PC speaker functionality with the original PC Speaker driver pointing out the weaknesses in the formalisation and possible improvements. The part closes with a summary of the results, their implications and open questions being raised. The last part lists all used sources, separated into scientific literature, documentations or reference manuals and artifacts, i.e. source code.}, language = {en} } @incollection{SchladebachBarsa2024, author = {Schladebach, Marcus and B{\^a}rsa, Catinca Cristiana}, title = {\S 70 Hohe See}, series = {Handbuch Bev{\"o}lkerungsschutz}, booktitle = {Handbuch Bev{\"o}lkerungsschutz}, editor = {Freudenberg, Dirk and von Lewinski, Kai}, publisher = {C.H. Beck}, address = {M{\"u}nchen}, isbn = {978-3-406-80741-1}, pages = {1201 -- 1208}, year = {2024}, language = {de} } @phdthesis{Taleb2024, author = {Taleb, Aiham}, title = {Self-supervised deep learning methods for medical image analysis}, doi = {10.25932/publishup-64408}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-644089}, school = {Universit{\"a}t Potsdam}, pages = {xii, 171}, year = {2024}, abstract = {Deep learning has seen widespread application in many domains, mainly for its ability to learn data representations from raw input data. Nevertheless, its success has so far been coupled with the availability of large annotated (labelled) datasets. This is a requirement that is difficult to fulfil in several domains, such as in medical imaging. Annotation costs form a barrier in extending deep learning to clinically-relevant use cases. The labels associated with medical images are scarce, since the generation of expert annotations of multimodal patient data at scale is non-trivial, expensive, and time-consuming. This substantiates the need for algorithms that learn from the increasing amounts of unlabeled data. Self-supervised representation learning algorithms offer a pertinent solution, as they allow solving real-world (downstream) deep learning tasks with fewer annotations. Self-supervised approaches leverage unlabeled samples to acquire generic features about different concepts, enabling annotation-efficient downstream task solving subsequently. Nevertheless, medical images present multiple unique and inherent challenges for existing self-supervised learning approaches, which we seek to address in this thesis: (i) medical images are multimodal, and their multiple modalities are heterogeneous in nature and imbalanced in quantities, e.g. MRI and CT; (ii) medical scans are multi-dimensional, often in 3D instead of 2D; (iii) disease patterns in medical scans are numerous and their incidence exhibits a long-tail distribution, so it is oftentimes essential to fuse knowledge from different data modalities, e.g. genomics or clinical data, to capture disease traits more comprehensively; (iv) Medical scans usually exhibit more uniform color density distributions, e.g. in dental X-Rays, than natural images. Our proposed self-supervised methods meet these challenges, besides significantly reducing the amounts of required annotations. We evaluate our self-supervised methods on a wide array of medical imaging applications and tasks. Our experimental results demonstrate the obtained gains in both annotation-efficiency and performance; our proposed methods outperform many approaches from related literature. Additionally, in case of fusion with genetic modalities, our methods also allow for cross-modal interpretability. In this thesis, not only we show that self-supervised learning is capable of mitigating manual annotation costs, but also our proposed solutions demonstrate how to better utilize it in the medical imaging domain. Progress in self-supervised learning has the potential to extend deep learning algorithms application to clinical scenarios.}, language = {en} } @techreport{StieglitzZerfassWlokaetal.2024, author = {Stieglitz, Stefan and Zerfaß, Ansgar and Wloka, Michelle and Clausen, S{\"u}nje}, title = {Communications trend radar 2024}, series = {Communication insights}, volume = {20}, journal = {Communication insights}, publisher = {Academic Society for Management \& Communication}, address = {Leipzig}, issn = {2749-893X}, doi = {10419/284410}, pages = {43}, year = {2024}, abstract = {What does the future hold for corporate communications? The Communications Trend Radar is an applied research project. On an annual basis, it identifies relevant trends for corporate communications from the fields of society, management, and technology. The research team at the University of Potsdam (Professor Stefan Stieglitz, S{\"u}nje Clausen, MS.) and Leipzig University (Professor Ansgar Zerfass, Dr Michelle Wloka) identified the following trends for 2024: Information Inflation, AI Literacy, Workforce Shift, Content Integrity, Decoding Humans. More information on the trends can be found in the Communications Trend Radar Report 2024}, language = {en} } @article{FrommStieglitzMirbabaie2024, author = {Fromm, Jennifer and Stieglitz, Stefan and Mirbabaie, Milad}, title = {Virtual reality in digital education}, series = {ACM SIGMIS database}, volume = {55}, journal = {ACM SIGMIS database}, number = {2}, publisher = {ACM}, address = {New York, NY}, issn = {0095-0033}, doi = {10.1145/3663682.3663685}, pages = {14 -- 41}, year = {2024}, abstract = {Virtual reality promises high potential as an immersive, hands-on learning tool for training 21st-century skills. However, previous research revealed that the mere use of digital tools in higher education does not automatically translate into learning outcomes. Instead, information systems studies emphasized the importance of effective use behavior to achieve technology usage goals. Applying the affordance network approach, we investigated what constitutes effective usage behavior regarding a virtual reality collaboration system in digital education. Therefore, we conducted 18 interviews with students and observations of six course sessions. The results uncover how affordance actualization contributed to the achievement of learning goals. A comparison with findings of previous studies on other information systems (i.e., electronic medical record systems, big data analytics, fitness wearables) allowed us to highlight system-specific differences in effective use behavior. We also demonstrated a clear distinction between concepts surrounding effective use theory facilitating the application of the affordance network approach in information systems research.}, language = {en} } @inproceedings{MarxBruenkerMirbabaieetal.2024, author = {Marx, Julian and Br{\"u}nker, Felix and Mirbabaie, Milad and Stieglitz, Stefan}, title = {Digital activism on social media}, series = {Proceedings of the 57th Annual Hawaii International Conference on System Sciences}, booktitle = {Proceedings of the 57th Annual Hawaii International Conference on System Sciences}, editor = {Bui, Tung X.}, publisher = {Department of IT Management Shidler College of Business University of Hawaii}, address = {Honolulu, HI}, isbn = {978-0-99813-317-1}, pages = {7205 -- 7214}, year = {2024}, abstract = {Social media constitute an important arena for public debates and steady interchange of issues relevant to society. To boost their reputation, commercial organizations also engage in political, social, or environmental debates on social media. To engage in this type of digital activism, organizations increasingly utilize the social media profiles of executive employees and other brand ambassadors. However, the relationship between brand ambassadors' digital activism and corporate reputation is only vaguely understood. The results of a qualitative inquiry suggest that digital activism via brand ambassadors can be risky (e.g., creating additional surface for firestorms, financial loss) and rewarding (e.g., emitting authenticity, employing 'megaphones' for industry change) at the same time. The paper informs both scholarship and practitioners about strategic trade-offs that need to be considered when employing brand ambassadors for digital activism.}, language = {en} } @inproceedings{MirbabaieRieskampHofeditzetal.2024, author = {Mirbabaie, Milad and Rieskamp, Jonas and Hofeditz, Lennart and Stieglitz, Stefan}, title = {Breaking down barriers}, series = {Proceedings of the 57th Annual Hawaii International Conference on System Sciences}, booktitle = {Proceedings of the 57th Annual Hawaii International Conference on System Sciences}, editor = {Bui, Tung X.}, publisher = {Department of IT Management Shidler College of Business University of Hawaii}, address = {Honolulu, HI}, isbn = {978-0-99813-317-1}, pages = {672 -- 681}, year = {2024}, abstract = {Many researchers hesitate to provide full access to their datasets due to a lack of knowledge about research data management (RDM) tools and perceived fears, such as losing the value of one's own data. Existing tools and approaches often do not take into account these fears and missing knowledge. In this study, we examined how conversational agents (CAs) can provide a natural way of guidance through RDM processes and nudge researchers towards more data sharing. This work offers an online experiment in which researchers interacted with a CA on a self-developed RDM platform and a survey on participants' data sharing behavior. Our findings indicate that the presence of a guiding and enlightening CA on an RDM platform has a constructive influence on both the intention to share data and the actual behavior of data sharing. Notably, individual factors do not appear to impede or hinder this effect.}, language = {en} } @article{FuhrhopLeubner2024, author = {Fuhrhop, Nanna and Leubner, Martin}, title = {Kafkas Sprache unter der Lupe}, series = {Praxis Deutsch : Kafka}, volume = {51}, journal = {Praxis Deutsch : Kafka}, number = {305}, publisher = {Friedrich}, address = {Hannover}, issn = {0341-5279}, pages = {55 -- 59}, year = {2024}, abstract = {Die Unterrichtsanregungen zeigen exemplarisch den Nutzen von sprachlichen Zug{\"a}ngen im Literaturunterricht. Die Lernenden erschließen den Text Vor dem Gesetz unter Ber{\"u}cksichtigung des Machtgef{\"a}lles zwischen den Figuren und beachten insbesondere sprachliche Mittel.}, language = {de} } @phdthesis{Poerschke2024, author = {P{\"o}rschke, Alexander}, title = {Koalitionsbildung und Gesetzgebung im Semi-Parlamentarismus}, doi = {10.25932/publishup-63449}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-634498}, school = {Universit{\"a}t Potsdam}, pages = {xvi, 265}, year = {2024}, abstract = {Der Semi-Parlamentarismus beschreibt das Regierungssystem, in dem die Regierung von einem Teil des Parlaments gew{\"a}hlt wird und abberufen werden kann, von einem anderen Teil des Parlaments aber unabh{\"a}ngig ist. Beide Kammern m{\"u}ssen dabei der Gesetzgebung zustimmen. Dieses von Steffen Ganghof klassifizierte System erg{\"a}nzt g{\"a}ngige Regierungssystemtypologien, wie sie beispielsweise von David Samuels und Matthew Shugart genutzt werden. Der Semi-Parlamentarismus ist der logische Gegenpart zum Semi-Pr{\"a}sidentialismus, bei dem nur ein Teil der Exekutive von der Legislative abh{\"a}ngt, w{\"a}hrend im Semi-Parlamentarismus die Exekutive von nur einem Teil der Legislative abh{\"a}ngt. Der Semi-Parlamentarismus verk{\"o}rpert so ein System der Gewaltenteilung ohne einen exekutiven Personalismus, wie er durch die Direktwahl und Unabh{\"a}ngigkeit der Regierungchef:in im Pr{\"a}sidentialismus hervorgerufen wird. Dadurch ist der Semi-Parlamentarismus geeignet, Unterschiede zwischen Parlamentarismus und Pr{\"a}sidentialismus auf den separaten Einfluss der Gewaltenteilung und des exekutiven Personalismus zur{\"u}ckzuf{\"u}hren. Die Untersuchung des Semi-Parlamentarismus ist daher f{\"u}r die Regierungssystemliteratur insgesamt von Bedeutung. Der Semi-Parlamentarismus ist dabei kein rein theoretisches Konstrukt, sondern existiert im australischen Bundesstaat, den australischen Substaaten und Japan. Die vorliegende Dissertation untersucht erstmals umfassend die Gesetzgebung der semi-parlamentarischen Staaten als solchen. Der Fokus liegt dabei auf den zweiten Kammern, da diese durch die Unabh{\"a}ngigkeit von der Regierung der eigentliche Ort der Gesetzgebung sind. Die Gesetzgebung in Parlamentarismus und Pr{\"a}sidentialismus unterscheidet sich insbesondere in der Geschlossenheit der Parteien, der Koalitionsbildung und dem legislativen Erfolg der Regierungen. Diese Punkte sind daher auch von besonderem Interesse bei der Analyse des Semi-Parlamentarismus. Die semi-parlamentarischen Staaten unterscheiden sich auch untereinander teilweise erheblich in der institutionellen Ausgestaltung wie den Wahlsystemen oder den verf{\"u}gbaren Mitteln zur {\"U}berwindung von Blockadesituationen. Die Darstellung und die Analyse der Auswirkungen dieser Unterschiede auf die Gesetzgebung ist neben dem Vergleich des Semi-Parlamentarismus mit anderen Systemen das zweite wesentliche Ziel dieser Arbeit. Als Fundament der Analyse habe ich einen umfangreichen Datensatz erhoben, der alle Legislaturperioden der australischen Staaten zwischen 1997 und 2019 umfasst. Wesentliche Bestandteile des Datensatzes sind alle namentlichen Abstimmungen beider Kammern, alle eingebrachten und verabschiedeten Gesetzen der Regierung sowie die mit Hilfe eines Expert-Surveys erhobenen Parteipositionen in den relevanten Politikfeldern auf substaatlicher Ebene. Haupts{\"a}chlich mit der Hilfe von Mixed-Effects- und Fractional-Response-Analysen kann ich so zeigen, dass der Semi-Parlamentarismus in vielen Aspekten eher parlamentarischen als pr{\"a}sidentiellen Systemen gleicht. Nur die Koalitionsbildung erfolgt deutlich flexibler und unterscheidet sich daher von der typischen parlamentarischen Koalitionsbildung. Die Analysen legen nahe, dass wesentliche Unterschiede zwischen Parlamentarismus und Pr{\"a}sidentialismus eher auf den exekutiven Personalismus als auf die Gewaltenteilung zur{\"u}ckzuf{\"u}hren sind. Zwischen den semi-parlamentarischen Staaten scheinen vor allem die Kontrolle des Medians beider Parlamentskammern durch die Regierung und die M{\"o}glichkeit der Regierung, die zweite Kammer mitaufzul{\"o}sen, zu entscheidenden Unterschieden in der Gesetzgebung zu f{\"u}hren. Die Kontrolle des Medians erm{\"o}glicht eine flexible Koalitionsbildung und f{\"u}hrt zu h{\"o}heren legislativen Erfolgsraten. Ebenso f{\"u}hrt eine m{\"o}glichst leichte Aufl{\"o}sungsm{\"o}glichkeit der zweiten Kammern zu h{\"o}heren legislativen Erfolgsraten. Die Parteigeschlossenheit ist unabh{\"a}ngig von diesen Aspekten in beiden Kammern der semi-parlamentarischen Parlamente sehr hoch.}, language = {de} }