arXiv subjects

Jan Gruber

Publications and source records attributed to Jan Gruber.

6 recordsLinked to original sources

arXiv2026

Development of a Proton Therapy Research Beamline with FLASH and Minibeam Capabilities at the 18 MeV Bern Medical Cyclotron

Advanced radiotherapy approaches such as FLASH irradiation and spatially fractionated radiotherapy (SFRT) show potential to improve the therapeutic ratio, yet their biological mechanisms and optimal delivery parameters remain uncertain. Progress requires accessible proton research platforms with flexible temporal and spatial dose delivery. We report on the adaptation of the Beam Transfer Line (BTL) of the Bern Medical Cyclotron (BMC) for radiobiology research with FLASH and proton minibeam capabilities. The BMC is optimized for the production of radionuclides for medical imaging, and is able to extract currents up to 150 $ \mathrm{\mu A}$. The 18 MeV proton beam was passively shaped using collimators, scattering foils, and extended drift space to generate irradiation fields. A dosimetric framework was implemented using an in-beam ionization chamber and radiochromic film with LET-dependent corrections. Beam uniformity and SFRT profiles with various grid spacings were evaluated at realistic target distances. The developed beamline enables stable delivery under controlled conditions in both conventional and FLASH regimes, spanning dose rates from 0.01 to 100 Gy/s. Dose uniformity within a 20 mm radius was below 8\%. Film measurements confirmed the need for LET-dependent corrections and indicated that quantitative dosimetry in in-vitro setups is achievable with appropriate LET corrections. The low proton energy (15.54(12) MeV extracted into air, 8.14(28) MeV delivered to cells in flask) facilitates compact SFRT implementation with well-resolved minibeams. The adapted BMC provides a flexible and accessible platform for systematic pre-clinical proton radiobiology studies under varied dose-rate and spatial delivery conditions. This supports optimization of emerging modalities such as proton FLASH and SFRT and helps bridge accelerator technology and radiobiology.

physics.med-ph↗

arXiv2026

Foundations for Agentic AI Investigations from the Forensic Analysis of OpenClaw

Agentic Al systems are increasingly deployed as personal assistants and are likely to become a common object of digital investigations. However, little is known about how their internal state and actions can be reconstructed during forensic analysis. Despite growing popularity, systematic forensic approaches for such systems remain largely unexplored. This paper presents an empirical study of OpenClaw a widely used single-agent assistant. We examine OpenClaw's technical design via static code analysis and apply differential forensic analysis to identify recoverable traces across stages of the agent interaction loop. We classify and correlate these traces to assess their investigative value in a systematic way. Based on these observations, we propose an agent artifact taxonomy that captures recurring investigative patterns. Finally, we highlight a foundational challenge for agentic Al forensics: agent-mediated execution introduces an additional layer of abstraction and substantial nondeterminism in trace generation. The large language model (LLM), the execution environment, and the evolving context can influence tool choice and state transitions in ways that are largely absent from rule-based software. Overall, our results provide an initial foundation for the systematic investigation of agentic Al and outline implications for digital forensic practice and future research.

cs.CR↗

arXiv2026

SoK: Understanding Anti-Forensics Concepts and Research Practices Across Forensic Subdomains

Anti-forensics includes a growing set of techniques designed to obstruct forensic analysis. While cybercriminals increasingly rely on these methods, they also help researchers identify and remedy weaknesses in forensic tools, advancing the overall robustness of digital forensics. Despite repeated efforts to define it, anti-forensics remains vague and inconsistent in its use. It also poses ethical challenges regarding the appropriateness of research practices and the legitimacy of the field itself. This article presents a systematic analysis of 123 publications on anti-forensics, combining qualitative and quantitative methods. We quantify the main techniques and attack vectors, examine their occurrence in different digital forensic subdomains, and identify typical research methods, motivations, and applications. This work also discusses what these findings mean for future research and proposes directions for building a more coherent and ethically grounded understanding of anti-forensics.

cs.CR↗

arXiv2025

Open problems in ageing science: A roadmap for biogerontology

The field of ageing science has gone through remarkable progress in recent decades, yet many fundamental questions remain unanswered or unexplored. Here we present a curated list of 100 open problems in ageing and longevity science. These questions were collected through community engagement and further analysed using Natural Language Processing to assess their prevalence in the literature and to identify both well-established and emerging research gaps. The final list is categorized into different topics, including molecular and cellular mechanisms of ageing, comparative biology and the use of model organisms, biomarkers, and the development of therapeutic interventions. Both long-standing questions and more recent and specific questions are featured. Our comprehensive compilation is available to the biogerontology community on our website (www.longevityknowledge.app). Overall, this work highlights current key research questions in ageing biology and offers a roadmap for fostering future progress in biogerontology.

q-bio.OT↗

arXiv2024

Strategies and Challenges of Timestamp Tampering for Improved Digital Forensic Event Reconstruction (extended version)

Timestamps play a pivotal role in digital forensic event reconstruction, but due to their non-essential nature, tampering or manipulation of timestamps is possible by users in multiple ways, even on running systems. This has a significant effect on the reliability of the results from applying a timeline analysis as part of an investigation. In this paper, we investigate the problem of users tampering with timestamps on a running (``live'') system. While prior work has shown that digital evidence tampering is hard, we focus on the question of \emph{why} this is so. By performing a qualitative user study with advanced university students, we observe, for example, a commonly applied multi-step approach in order to deal with second-order traces (traces of traces). We also derive factors that influence the reliability of successful tampering, such as the individual knowledge about temporal traces, and technical restrictions to change them. These insights help to assess the reliability of timestamps from individual artifacts that are relied on for event reconstruction and subsequently reduce the risk of incorrect event reconstruction during investigations.

cs.CR↗

arXiv2023

Argumentation Schemes for Blockchain Deanonymization

Cryptocurrency forensics became standard tools for law enforcement. Their basic idea is to deanonymise cryptocurrency transactions to identify the people behind them. Cryptocurrency deanonymisation techniques are often based on premises that largely remain implicit, especially in legal practice. On the one hand, this implicitness complicates investigations. On the other hand, it can have far-reaching consequences for the rights of those affected. Argumentation schemes could remedy this untenable situation by rendering underlying premises transparent. Additionally, they can aid in critically evaluating the probative value of any results obtained by cryptocurrency deanonymisation techniques. In the argumentation theory and AI community, argumentation schemes are influential as they state implicit premises for different types of arguments. Through their critical questions, they aid the argumentation participants in critically evaluating arguments. We specialise the notion of argumentation schemes to legal reasoning about cryptocurrency deanonymisation. Furthermore, we demonstrate the applicability of the resulting schemes through an exemplary real-world case. Ultimately, we envision that using our schemes in legal practice can solidify the evidential value of blockchain investigations as well as uncover and help address uncertainty in underlying premises - thus contributing to protect the rights of those affected by cryptocurrency forensics.

cs.AI↗