Hier werden digitale Dissertationen und Habilitationen gespeichert, erschlossen und veröffentlicht.
Einrichtungen in ePub
Wählen Sie eine Sektion, um deren Inhalt anzusehen.
Aktuellste Veröffentlichungen
Metabolic and cellular factors determining the therapeutic effects of dimethyl fumarate
(2025-06-12) Kosińska, Joanna
Security analysis of confidential VMs on modern server architectures
(2025-06-24) Wilke, Luca
Cloud computing has transformed data management and IT practices for organizations and individuals alike, offering unmatched scalability, flexibility, and cost-efficiency.
However, it comes with privacy concerns, as the cloud service providers can access all processed data.
Trusted Execution Environments (TEEs) are one potential solution, offering a new form of isolation that even locks out the infrastructure operator.
Attacks from any software component outside the TEE are thwarted by novel access restrictions while
physical attacks are prevented by memory encryption.
Even the operating system or hypervisor cannot overcome these restrictions.
With Intel SGX, Intel TDX, and AMD SEV-SNP, both major x86 CPU vendors offer TEEs on their server CPUs.
This thesis scrutinizes the extent to which the current TEE generation delivers on their security promises.
We start this thesis by describing the isolation mechanisms implemented by SGX, TDX, and SEV-SNP.
Building on these insights, we demonstrate that the trend to use deterministic memory encryption without integrity or freshness has several shortcomings.
We show that monitoring deterministic ciphertexts for changes allows leaking information about the plaintext, which we exploit on SEV-SNP.
SGX and TDX prevent straightforward exploitation by restricting software attackers from reading and writing the ciphertext, while SEV-SNP only restricts writing.
Next, we challenge the security of such access restrictions by showing that an attacker with brief physical access to the memory modules can create aliases in the address space that bypass these safeguards.
We exploit this on SEV-SNP to re-enable write access for software attackers, culminating in a devastating attack that forges attestation reports, undermining all trust in SEV-SNP.
On SGX and TDX, such attacks are mitigated by a dedicated alias check at boot time.
Finally, we examine the security of VM-based TEEs against single-stepping attacks, which allow instruction-granular tracing and have led to numerous high-stakes attacks on SGX.
We show that SEV-SNP is also vulnerable to single-stepping and provide a software framework enabling easy access to single-stepping on SEV for future research.
Next, we analyze the single-stepping security of Intel TDX, which comes with a built-in mitigation comprising a detection heuristic and a prevention mode.
We uncover a flaw in the heuristic that stops the activation of the prevention mode, thereby re-enabling single-stepping on TDX.
Furthermore, we unveil an inherent flaw in the prevention mode that
leaks fine-grained information about the control flow.
Integrated methodology for enhanced low-dose PET imaging
(2025) Elmoujarkach, Ezzat A.
Interprofessionelle perioperative Betreuung von chronischen Dialysepatienten
(2025) Köhli, Sandra
Die komplexe Pharmakotherapie von Dialysepatienten erhöht das Risiko für arzneimittelbezogene Probleme (ABP) sowie die Mortalität und das kardiovaskuläre Risiko im Zusammenhang mit operativen Eingriffen.
Ziel des BMG geförderten Projektes war es zu prüfen, ob eine intensivierte, interdisziplinäre Betreuung durch ein Stewardship Team aus Pharmazeuten, Nephrologe und Infektiologe die ABP im Vergleich zum Standard of care verringert.
Novel Machine Learning Methods for Video Understanding and Medical Analysis
(2025-06-26) Hu, Yaxin
Artificial intelligence has developed rapidly over the past decade and has penetrated into nearly every aspect of life. New applications in areas such as human-computer interaction, virtual reality, autonomous driving and intelligent medical systems have emerged in large numbers. Video is a kind of high-dimensional data, which has one more dimension than images, requiring more computing resources. As more and more high-quality large-scale video datasets are released, video understanding has become a cutting-edge research direction in the computer vision community. Action recognition is one of the most important tasks in video understanding. There are many successful network architectures for video action recognition.
In our work, we focus on proposing new designs and architectures for video understanding and investigating their applications in medicine. We introduce a novel RGBt sampling strategy to fuse temporal information into single frames without increasing the computational load and explore different color sampling strategies to further improve network performance. We find that frames with temporal information obtained by fusing the green channels from different frames achieve the best results. We use tubes of different sizes to embed richer temporal information into tokens without increasing the computational load. We also introduce a novel bio-inspired neuron model, the MinBlock, to make the network more information selective. Furthermore, we propose a spatiotemporal architecture that slices videos in space-time and thus enables 2D-CNNs to directly extract temporal information. All the above methods are evaluated on at least two benchmark datasets and all perform better than the baselines.
We also focus on applying our networks in medicine. We use our slicing 2D-CNN architecture for glaucoma and visual impairments analysis. And we find that visual impairments may affect walking patterns of humans thus making the video analysis relevant for diagnosis. We also design a machine learning model to diagnose psychosis and show that it is possible to predict whether clinical high-risk patients would actually develop a psychosis.
Physiotherapie in Deutschland
(2025) Stöckl, Martina
Die Fragestellung der vorliegenden Arbeit lautet: Wie gestalten sich die Entwicklungsmöglichkeiten der Physiotherapie am Beispiel von Deutschland? Diese resultiert aus einem Forschungsinteresse hinsichtlich zweier Blickrichtungen. Eine empirische, für welche die beiden Checklisten CROSS und COREQ verwendet werden. Die zweite Blickrichtung fokussiert den theoretischen Rahmen der Physiotherapie. Zuerst werden mit dem Fragebogen des sequentiell vertiefenden Mixed-Methods-Designs Informationen über die Durchführbarkeit von physiotherapeutischen Tätigkeiten gesammelt. Dafür werden 120 Physiotherapeut*innen befragt, welche zusätzlich zur Bedeutung der Physiotherapie als Profession Auskunft geben. Sechs Experteninterviews vervollständigen den Datensatz und tragen zur gesamtheitlichen Darstellung der physiotherapeutischen Realität in Deutschland bei. Diese Auswertung erfolgt anhand einer strukturierenden qualitativen Inhaltsanalyse nach Kuckartz mit dem Programm MAXQDA. Zusätzlich wird eine Triangulation aller erhobenen Daten vorgenommen. Die Ergebnisse des Surveys zeigen viele unausgeschöpfte Potenziale im beruflichen Alltag sowie eine enge Sicht auf die Vorstellung der Profession. Die Antworten der befragten Expert*innen bestätigen: Die Physiotherapie ist ein hochkomplexes Gebiet. Mithilfe des in der Arbeit entwickelten dreidimensionalen Pyramidenmodells kann eine Verortung der physiotherapeutischen Realität in ihrer Gesamtheit erfolgen. Zudem kristallisieren sich vielfältige Entwicklungsmöglichkeiten in Richtung Professionalisierung und wissenschaftlicher Disziplinbildung heraus. Eine Übertragung des entwickelten Modells auf andere Berufsgruppen zur Vereinfachung interprofessioneller Zusammenarbeit ist denkbar, ebenso wie eine Anwendung auf internationaler Ebene.
Performance of transcatheter heart valves in severely calcified aortic valve stenoses
(2025-06-12) Bisht, Osama
Non-invasive estimation of respiratory effort
(2025) Graßhoff, Jan
Kalorienarme Saccharidzusammensetzung vor der Hauptmahlzeit reduziert die nachfolgende Kalorienaufnahme
(2025) Thordsen, Narona Liza
Behandlung der Harnsäurelithiasis in Deutschland
(2025) Genske, Tobias Frank
Die Komplexität moralischer Erfahrungen mit Palliativer Sedierung
(2025) Rau, Franziska Juliana
Effizienzevaluation von Diagnostikempfehlungen eines molekularen Tumorboards
(2025) Tiemann, Paul Lennart
Cutting-edge precision
(2025) Erben, Niclas
Molecular characterization of breast cancer in patients aged 50 years and older with respect to prognostication, genomic instability, and tumor heterogeneity
(2025) Liegmann, Anna-Sophie
Despite the majority (70%) of female breast cancer cases being diagnosed in women aged 55 years and older and an increasing population of older breast cancer patients due to demographic change, older patients lack adequate representation in cancer research. Thus, this doctoral thesis focused on breast cancer patients aged 50 years and older, aiming to elucidate the role of intratumor heterogeneity, ploidy, and genomic instability and their influences on disease outcome.
Therefore, a breast cancer collective of 39 patients with short (median 2.4 years) and long survival (median 19 years) were selected. Multiplex interphase fluorescence in situ hybridization (miFISH) was carried out to analyze copy number alterations (CNAs) of eight breast cancer-associated genes for their potential as biomarkers, as well as assessing genomic instability and tumor heterogeneity. Furthermore, image cytometry was performed to detect ploidy and phylogenetic tree modeling to gain more information about tumor development. Supplementary, targeted next-generation sequencing of 563 breast cancer-associated genes was carried out externally, and the obtained mutation status was statistically analyzed, compared to the miFISH results, and interpreted as part of this thesis.
The experimental part of this work revealed several CNAs of breast cancer-specific genes, as well as gene mutations frequently reported in breast carcinomas. The copy number gain of COX2 occurred most frequently (in 72% of the cases), followed by MYC (69%), whereas losses were more common for CDH1 (74%) and TP53 (69%). Comparing aneuploid with diploid tumor samples, significantly higher average signal numbers, CNAs, and instability indices, reflecting the degree of genomic instability, were revealed in the aneuploid tumors. In 16 cases, the signal pattern indicated the formation of an isochromosome 8q and in 14 cases of an isochromosome 17q. Supporting the hypothesis of an isochromosome formation, CNAs of DBC2/MYC and HER2/TP53 significantly co-occurred. Moreover, significant co-occurrence of CNA of HER2/DBC2 was detected, and CNAs for HER2 and PIK3CA mutations and CNAs for CCND1 and PIK3CA mutations were significantly mutually exclusive.
Overall, the distribution of gene mutations of the 563-breast cancer-associated genes, as well as the pattern of CNAs in the eight breast cancer-related genes (miFISH) detected in the 39 patients aged 50 years and older, were comparable to results of the age-unbiased TCGA-cohort. Notably, neither the quantity of CNAs, the tumor ploidy, nor the degree of intratumor heterogeneity revealed an association with the survival time, indicating that for patients above the age of 50, these criteria do not seem to have a substantial effect on disease prognosis.