TY - THES A1 - Taleb, Aiham T1 - Self-supervised deep learning methods for medical image analysis T1 - Selbstüberwachte Deep Learning Methoden für die medizinische Bildanalyse N2 - 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. N2 - Deep Learning findet in vielen Bereichen breite Anwendung, vor allem wegen seiner Fähigkeit, Datenrepräsentationen aus rohen Eingabedaten zu lernen. Dennoch war der Erfolg bisher an die Verfügbarkeit großer annotatierter Datensätze geknüpft. Dies ist eine Anforderung, die in verschiedenen Bereichen, z. B. in der medizinischen Bildgebung, schwer zu erfüllen ist. Die Kosten für die Annotation stellen ein Hindernis für die Ausweitung des Deep Learning auf klinisch relevante Anwendungsfälle dar. Die mit medizinischen Bildern verbundenen Annotationen sind rar, da die Erstellung von Experten Annotationen für multimodale Patientendaten in großem Umfang nicht trivial, teuer und zeitaufwändig ist. Dies unterstreicht den Bedarf an Algorithmen, die aus den wachsenden Mengen an unbeschrifteten Daten lernen. Selbstüberwachte Algorithmen für das Repräsentationslernen bieten eine mögliche Lösung, da sie die Lösung realer (nachgelagerter) Deep-Learning-Aufgaben mit weniger Annotationen ermöglichen. Selbstüberwachte Ansätze nutzen unannotierte Stichproben, um generisches Eigenschaften über verschiedene Konzepte zu erlangen und ermöglichen so eine annotationseffiziente Lösung nachgelagerter Aufgaben. Medizinische Bilder stellen mehrere einzigartige und inhärente Herausforderungen für existierende selbstüberwachte Lernansätze dar, die wir in dieser Arbeit angehen wollen: (i) medizinische Bilder sind multimodal, und ihre verschiedenen Modalitäten sind von Natur aus heterogen und in ihren Mengen unausgewogen, z.B. (ii) medizinische Scans sind mehrdimensional, oft in 3D statt in 2D; (iii) Krankheitsmuster in medizinischen Scans sind zahlreich und ihre Häufigkeit weist eine Long-Tail-Verteilung auf, so dass es oft unerlässlich ist, Wissen aus verschiedenen Datenmodalitäten, z. B. Genomik oder klinische Daten, zu verschmelzen, um Krankheitsmerkmale umfassender zu erfassen; (iv) medizinische Scans weisen in der Regel eine gleichmäßigere Farbdichteverteilung auf, z. B. in zahnmedizinischen Röntgenaufnahmen, als natürliche Bilder. Die von uns vorgeschlagenen selbstüberwachten Methoden adressieren diese Herausforderungen und reduzieren zudem die Menge der erforderlichen Annotationen erheblich. Wir evaluieren unsere selbstüberwachten Methoden in verschiedenen Anwendungen und Aufgaben der medizinischen Bildgebung. Unsere experimentellen Ergebnisse zeigen, dass die von uns vorgeschlagenen Methoden sowohl die Effizienz der Annotation als auch die Leistung steigern und viele Ansätze aus der verwandten Literatur übertreffen. Darüber hinaus ermöglichen unsere Methoden im Falle der Fusion mit genetischen Modalitäten auch eine modalübergreifende Interpretierbarkeit. In dieser Arbeit zeigen wir nicht nur, dass selbstüberwachtes Lernen in der Lage ist, die Kosten für manuelle Annotationen zu senken, sondern auch, wie man es in der medizinischen Bildgebung besser nutzen kann. Fortschritte beim selbstüberwachten Lernen haben das Potenzial, die Anwendung von Deep-Learning-Algorithmen auf klinische Szenarien auszuweiten. KW - Artificial Intelligence KW - machine learning KW - unsupervised learning KW - representation learning KW - Künstliche Intelligenz KW - maschinelles Lernen KW - Representationlernen KW - selbstüberwachtes Lernen Y1 - 2024 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-644089 ER - TY - JOUR A1 - Shams, Boshra A1 - Wang, Ziqian A1 - Roine, Timo A1 - Aydogan, Dogu Baran A1 - Vajkoczy, Peter A1 - Lippert, Christoph A1 - Picht, Thomas A1 - Fekonja, Lucius Samo T1 - Machine learning-based prediction of motor status in glioma patients using diffusion MRI metrics along the corticospinal tract JF - Brain communications N2 - Shams et al. report that glioma patients' motor status is predicted accurately by diffusion MRI metrics along the corticospinal tract based on support vector machine method, reaching an overall accuracy of 77%. They show that these metrics are more effective than demographic and clinical variables. Along tract statistics enables white matter characterization using various diffusion MRI metrics. These diffusion models reveal detailed insights into white matter microstructural changes with development, pathology and function. Here, we aim at assessing the clinical utility of diffusion MRI metrics along the corticospinal tract, investigating whether motor glioma patients can be classified with respect to their motor status. We retrospectively included 116 brain tumour patients suffering from either left or right supratentorial, unilateral World Health Organization Grades II, III and IV gliomas with a mean age of 53.51 +/- 16.32 years. Around 37% of patients presented with preoperative motor function deficits according to the Medical Research Council scale. At group level comparison, the highest non-overlapping diffusion MRI differences were detected in the superior portion of the tracts' profiles. Fractional anisotropy and fibre density decrease, apparent diffusion coefficient axial diffusivity and radial diffusivity increase. To predict motor deficits, we developed a method based on a support vector machine using histogram-based features of diffusion MRI tract profiles (e.g. mean, standard deviation, kurtosis and skewness), following a recursive feature elimination method. Our model achieved high performance (74% sensitivity, 75% specificity, 74% overall accuracy and 77% area under the curve). We found that apparent diffusion coefficient, fractional anisotropy and radial diffusivity contributed more than other features to the model. Incorporating the patient demographics and clinical features such as age, tumour World Health Organization grade, tumour location, gender and resting motor threshold did not affect the model's performance, revealing that these features were not as effective as microstructural measures. These results shed light on the potential patterns of tumour-related microstructural white matter changes in the prediction of functional deficits. KW - machine learning KW - support vector machine KW - tractography KW - diffusion MRI; KW - corticospinal tract Y1 - 2022 U6 - https://doi.org/10.1093/braincomms/fcac141 SN - 2632-1297 VL - 4 IS - 3 PB - Oxford University Press CY - Oxford ER - TY - BOOK A1 - Kuban, Robert A1 - Rotta, Randolf A1 - Nolte, Jörg A1 - Chromik, Jonas A1 - Beilharz, Jossekin Jakob A1 - Pirl, Lukas A1 - Friedrich, Tobias A1 - Lenzner, Pascal A1 - Weyand, Christopher A1 - Juiz, Carlos A1 - Bermejo, Belen A1 - Sauer, Joao A1 - Coelh, Leandro dos Santos A1 - Najafi, Pejman A1 - Pünter, Wenzel A1 - Cheng, Feng A1 - Meinel, Christoph A1 - Sidorova, Julia A1 - Lundberg, Lars A1 - Vogel, Thomas A1 - Tran, Chinh A1 - Moser, Irene A1 - Grunske, Lars A1 - Elsaid, Mohamed Esameldin Mohamed A1 - Abbas, Hazem M. A1 - Rula, Anisa A1 - Sejdiu, Gezim A1 - Maurino, Andrea A1 - Schmidt, Christopher A1 - Hügle, Johannes A1 - Uflacker, Matthias A1 - Nozza, Debora A1 - Messina, Enza A1 - Hoorn, André van A1 - Frank, Markus A1 - Schulz, Henning A1 - Alhosseini Almodarresi Yasin, Seyed Ali A1 - Nowicki, Marek A1 - Muite, Benson K. A1 - Boysan, Mehmet Can A1 - Bianchi, Federico A1 - Cremaschi, Marco A1 - Moussa, Rim A1 - Abdel-Karim, Benjamin M. A1 - Pfeuffer, Nicolas A1 - Hinz, Oliver A1 - Plauth, Max A1 - Polze, Andreas A1 - Huo, Da A1 - Melo, Gerard de A1 - Mendes Soares, Fábio A1 - Oliveira, Roberto Célio Limão de A1 - Benson, Lawrence A1 - Paul, Fabian A1 - Werling, Christian A1 - Windheuser, Fabian A1 - Stojanovic, Dragan A1 - Djordjevic, Igor A1 - Stojanovic, Natalija A1 - Stojnev Ilic, Aleksandra A1 - Weidmann, Vera A1 - Lowitzki, Leon A1 - Wagner, Markus A1 - Ifa, Abdessatar Ben A1 - Arlos, Patrik A1 - Megia, Ana A1 - Vendrell, Joan A1 - Pfitzner, Bjarne A1 - Redondo, Alberto A1 - Ríos Insua, David A1 - Albert, Justin Amadeus A1 - Zhou, Lin A1 - Arnrich, Bert A1 - Szabó, Ildikó A1 - Fodor, Szabina A1 - Ternai, Katalin A1 - Bhowmik, Rajarshi A1 - Campero Durand, Gabriel A1 - Shevchenko, Pavlo A1 - Malysheva, Milena A1 - Prymak, Ivan A1 - Saake, Gunter ED - Meinel, Christoph ED - Polze, Andreas ED - Beins, Karsten ED - Strotmann, Rolf ED - Seibold, Ulrich ED - Rödszus, Kurt ED - Müller, Jürgen T1 - HPI Future SOC Lab – Proceedings 2019 N2 - The “HPI Future SOC Lab” is a cooperation of the Hasso Plattner Institute (HPI) and industry partners. Its mission is to enable and promote exchange and interaction between the research community and the industry partners. The HPI Future SOC Lab provides researchers with free of charge access to a complete infrastructure of state of the art hard and software. This infrastructure includes components, which might be too expensive for an ordinary research environment, such as servers with up to 64 cores and 2 TB main memory. The offerings address researchers particularly from but not limited to the areas of computer science and business information systems. Main areas of research include cloud computing, parallelization, and In-Memory technologies. This technical report presents results of research projects executed in 2019. Selected projects have presented their results on April 9th and November 12th 2019 at the Future SOC Lab Day events. N2 - Das Future SOC Lab am HPI ist eine Kooperation des Hasso-Plattner-Instituts mit verschiedenen Industriepartnern. Seine Aufgabe ist die Ermöglichung und Förderung des Austausches zwischen Forschungsgemeinschaft und Industrie. Am Lab wird interessierten Wissenschaftlern eine Infrastruktur von neuester Hard- und Software kostenfrei für Forschungszwecke zur Verfügung gestellt. Dazu zählen teilweise noch nicht am Markt verfügbare Technologien, die im normalen Hochschulbereich in der Regel nicht zu finanzieren wären, bspw. Server mit bis zu 64 Cores und 2 TB Hauptspeicher. Diese Angebote richten sich insbesondere an Wissenschaftler in den Gebieten Informatik und Wirtschaftsinformatik. Einige der Schwerpunkte sind Cloud Computing, Parallelisierung und In-Memory Technologien. In diesem Technischen Bericht werden die Ergebnisse der Forschungsprojekte des Jahres 2019 vorgestellt. Ausgewählte Projekte stellten ihre Ergebnisse am 09. April und 12. November 2019 im Rahmen des Future SOC Lab Tags vor. T3 - Technische Berichte des Hasso-Plattner-Instituts für Digital Engineering an der Universität Potsdam - 158 KW - Future SOC Lab KW - research projects KW - multicore architectures KW - in-memory technology KW - cloud computing KW - machine learning KW - artifical intelligence KW - Future SOC Lab KW - Forschungsprojekte KW - Multicore Architekturen KW - In-Memory Technologie KW - Cloud Computing KW - maschinelles Lernen KW - künstliche Intelligenz Y1 - 2023 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-597915 SN - 978-3-86956-564-4 SN - 1613-5652 SN - 2191-1665 IS - 158 PB - Universitätsverlag Potsdam CY - Potsdam ER - TY - JOUR A1 - Kappattanavar, Arpita Mallikarjuna A1 - Hecker, Pascal A1 - Moontaha, Sidratul A1 - Steckhan, Nico A1 - Arnrich, Bert T1 - Food choices after cognitive load BT - an affective computing approach JF - Sensors N2 - Psychology and nutritional science research has highlighted the impact of negative emotions and cognitive load on calorie consumption behaviour using subjective questionnaires. Isolated studies in other domains objectively assess cognitive load without considering its effects on eating behaviour. This study aims to explore the potential for developing an integrated eating behaviour assistant system that incorporates cognitive load factors. Two experimental sessions were conducted using custom-developed experimentation software to induce different stimuli. During these sessions, we collected 30 h of physiological, food consumption, and affective states questionnaires data to automatically detect cognitive load and analyse its effect on food choice. Utilising grid search optimisation and leave-one-subject-out cross-validation, a support vector machine model achieved a mean classification accuracy of 85.12% for the two cognitive load tasks using eight relevant features. Statistical analysis was performed on calorie consumption and questionnaire data. Furthermore, 75% of the subjects with higher negative affect significantly increased consumption of specific foods after high-cognitive-load tasks. These findings offer insights into the intricate relationship between cognitive load, affective states, and food choice, paving the way for an eating behaviour assistant system to manage food choices during cognitive load. Future research should enhance system capabilities and explore real-world applications. KW - cognitive load KW - eating behaviour KW - machine learning KW - physiological signals KW - photoplethysmography KW - electrodermal activity KW - sensors Y1 - 2023 U6 - https://doi.org/10.3390/s23146597 SN - 1424-8220 VL - 23 IS - 14 PB - MDPI CY - Basel ER - TY - JOUR A1 - Hollenstein, Nora A1 - Trondle, Marius A1 - Plomecka, Martyna A1 - Kiegeland, Samuel A1 - Ozyurt, Yilmazcan A1 - Jäger, Lena Ann A1 - Langer, Nicolas T1 - The ZuCo benchmark on cross-subject reading task classification with EEG and eye-tracking data JF - Frontiers in psychology N2 - We present a new machine learning benchmark for reading task classification with the goal of advancing EEG and eye-tracking research at the intersection between computational language processing and cognitive neuroscience. The benchmark task consists of a cross-subject classification to distinguish between two reading paradigms: normal reading and task-specific reading. The data for the benchmark is based on the Zurich Cognitive Language Processing Corpus (ZuCo 2.0), which provides simultaneous eye-tracking and EEG signals from natural reading of English sentences. The training dataset is publicly available, and we present a newly recorded hidden testset. We provide multiple solid baseline methods for this task and discuss future improvements. We release our code and provide an easy-to-use interface to evaluate new approaches with an accompanying public leaderboard: . KW - reading task classification KW - eye-tracking KW - EEG KW - machine learning KW - reading research KW - cross-subject evaluation Y1 - 2023 U6 - https://doi.org/10.3389/fpsyg.2022.1028824 SN - 1664-1078 VL - 13 PB - Frontiers Media CY - Lausanne ER - TY - JOUR A1 - Rosso, Pablo A1 - Nendel, Claas A1 - Gilardi, Nicolas A1 - Udroiu, Cosmin A1 - Chlebowski, Florent T1 - Processing of remote sensing information to retrieve leaf area index in barley BT - a comparison of methods JF - Precision agriculture N2 - Leaf area index (LAI) is a key variable in understanding and modeling crop-environment interactions. With the advent of increasingly higher spatial resolution satellites and sensors mounted on remotely piloted aircrafts (RPAs), the use of remote sensing in precision agriculture is becoming more common. Since also the availability of methods to retrieve LAI from image data have also drastically expanded, it is necessary to test simultaneously as many methods as possible to understand the advantages and disadvantages of each approach. Ground-based LAI data from three years of barley experiments were related to remote sensing information using vegetation indices (VI), machine learning (ML) and radiative transfer models (RTM), to assess the relative accuracy and efficacy of these methods. The optimized soil adjusted vegetation index and a modified version of the Weighted Difference Vegetation Index performed slightly better than any other retrieval method. However, all methods yielded coefficients of determination of around 0.7 to 0.9. The best performing machine learning algorithms achieved higher accuracies when four Sentinel-2 bands instead of 12 were used. Also, the good performance of VIs and the satisfactory performance of the 4-band RTM, strongly support the synergistic use of satellites and RPAs in precision agriculture. One of the methods used, Sen2-Agri, an open source ML-RTM-based operational system, was also able to accurately retrieve LAI, although it is restricted to Sentinel-2 and Landsat data. This study shows the benefits of testing simultaneously a broad range of retrieval methods to monitor crops for precision agriculture. KW - leaf area index KW - vegetation indices KW - machine learning KW - radiative transfer models Y1 - 2022 U6 - https://doi.org/10.1007/s11119-022-09893-4 SN - 1385-2256 SN - 1573-1618 VL - 23 IS - 4 SP - 1449 EP - 1472 PB - Springer CY - Dordrecht ER - TY - JOUR A1 - Baumgart, Lene A1 - Boos, Pauline A1 - Eckstein, Bernd T1 - Datafication and algorithmic contingency BT - how agile organisations deal with technical systems JF - Work organisation, labour & globalisation N2 - In the context of persistent images of self-perpetuated technologies, we discuss the interplay of digital technologies and organisational dynamics against the backdrop of systems theory. Building on the case of an international corporation that, during an agile reorganisation, introduced an AI-based personnel management platform, we show how technical systems produce a form of algorithmic contingency that subsequently leads to the emergence of formal and informal interaction systems. Using the concept of datafication, we explain how these interactions are barriers to the self-perpetuation of data-based decision-making, making it possible to take into consideration further decision factors and complementing the output of the platform. The research was carried out within the scope of the research project ‘Organisational Implications of Digitalisation: The Development of (Post-)Bureaucratic Organisational Structures in the Context of Digital Transformation’ funded by the German Research Foundation (DFG). KW - digitalisation KW - datafication KW - organisation KW - agile KW - technical system KW - systems theory KW - interaction KW - algorithmic contingency KW - machine learning KW - platform Y1 - 2023 U6 - https://doi.org/10.13169/workorgalaboglob.17.1.0061 SN - 1745-641X SN - 1745-6428 VL - 17 IS - 1 SP - 61 EP - 73 PB - Pluto Journals CY - London ER - TY - RPRT A1 - Andres, Maximilian A1 - Bruttel, Lisa T1 - Communicating Cartel Intentions T2 - CEPA Discussion Papers N2 - While the economic harm of cartels is caused by their price-increasing effect, sanctioning by courts rather targets at the underlying process of firms reaching a price-fixing agreement. This paper provides experimental evidence on the question whether such sanctioning meets the economic target, i.e., whether evidence of a collusive meeting of the firms and of the content of their communication reliably predicts subsequent prices. We find that already the mere mutual agreement to meet predicts a strong increase in prices. Conversely, express distancing from communication completely nullifies its otherwise price-increasing effect. Using machine learning, we show that communication only increases prices if it is very explicit about how the cartel plans to behave. T3 - CEPA Discussion Papers - 77 KW - cartel KW - collusion KW - communication KW - machine learning KW - experiment Y1 - 2024 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-638469 SN - 2628-653X IS - 77 ER - TY - GEN A1 - Panzer, Marcel A1 - Bender, Benedict A1 - Gronau, Norbert T1 - Deep reinforcement learning in production planning and control BT - A systematic literature review T2 - Zweitveröffentlichungen der Universität Potsdam : Wirtschafts- und Sozialwissenschaftliche Reihe N2 - Increasingly fast development cycles and individualized products pose major challenges for today's smart production systems in times of industry 4.0. The systems must be flexible and continuously adapt to changing conditions while still guaranteeing high throughputs and robustness against external disruptions. Deep reinforcement learning (RL) algorithms, which already reached impressive success with Google DeepMind's AlphaGo, are increasingly transferred to production systems to meet related requirements. Unlike supervised and unsupervised machine learning techniques, deep RL algorithms learn based on recently collected sensorand process-data in direct interaction with the environment and are able to perform decisions in real-time. As such, deep RL algorithms seem promising given their potential to provide decision support in complex environments, as production systems, and simultaneously adapt to changing circumstances. While different use-cases for deep RL emerged, a structured overview and integration of findings on their application are missing. To address this gap, this contribution provides a systematic literature review of existing deep RL applications in the field of production planning and control as well as production logistics. From a performance perspective, it became evident that deep RL can beat heuristics significantly in their overall performance and provides superior solutions to various industrial use-cases. Nevertheless, safety and reliability concerns must be overcome before the widespread use of deep RL is possible which presumes more intensive testing of deep RL in real world applications besides the already ongoing intensive simulations. T3 - Zweitveröffentlichungen der Universität Potsdam : Wirtschafts- und Sozialwissenschaftliche Reihe - 198 KW - deep reinforcement learning KW - machine learning KW - production planning KW - production control KW - systematic literature review Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-605722 SN - 2701-6277 SN - 1867-5808 ER - TY - GEN A1 - Panzer, Marcel A1 - Bender, Benedict A1 - Gronau, Norbert T1 - Neural agent-based production planning and control BT - an architectural review T2 - Zweitveröffentlichungen der Universität Potsdam : Wirtschafts- und Sozialwissenschaftliche Reihe N2 - Nowadays, production planning and control must cope with mass customization, increased fluctuations in demand, and high competition pressures. Despite prevailing market risks, planning accuracy and increased adaptability in the event of disruptions or failures must be ensured, while simultaneously optimizing key process indicators. To manage that complex task, neural networks that can process large quantities of high-dimensional data in real time have been widely adopted in recent years. Although these are already extensively deployed in production systems, a systematic review of applications and implemented agent embeddings and architectures has not yet been conducted. The main contribution of this paper is to provide researchers and practitioners with an overview of applications and applied embeddings and to motivate further research in neural agent-based production. Findings indicate that neural agents are not only deployed in diverse applications, but are also increasingly implemented in multi-agent environments or in combination with conventional methods — leveraging performances compared to benchmarks and reducing dependence on human experience. This not only implies a more sophisticated focus on distributed production resources, but also broadening the perspective from a local to a global scale. Nevertheless, future research must further increase scalability and reproducibility to guarantee a simplified transfer of results to reality. T3 - Zweitveröffentlichungen der Universität Potsdam : Wirtschafts- und Sozialwissenschaftliche Reihe - 172 KW - production planning and control KW - machine learning KW - neural networks KW - systematic literature review KW - taxonomy Y1 - 2022 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-604777 SN - 1867-5808 ER -