University of Regensburg

We apply the semiclassical theory including the Berry curvature dipole, side jumps and skew scattering for a quantitative description of the circular photogalvanic effect (CPGE) in Weyl semimetals at intraband absorption. In contrast to gapped systems where they completely exhaust all contributions to the CPGE current, all previously known semiclassical mechanisms give a result different from that obtained using a complete quantum-mechanical approach. We show that this difference in the existing quasiclassical and full quantum-mechanical approaches persists at all spatial ranges of the disorder potential. Apparently, the implementation of another microscopic mechanism into the quasiclassical description of the CPGE is required.

The synthesis of aromatic amines, especially anilines, is crucial in organic chemistry because of their significance in pharmaceuticals and high-value chemicals. However, traditional methods for producing aniline involve pre-functionalization and/or several high-energy-demanding steps. Therefore, the development of direct protocols towards aniline has attracted significant interest. We introduce a direct photocatalytic method for synthesizing aniline using hydroxylamine and vanadium complexes. While previous studies describe vanadium complexes and hydroxylamine in thermally driven reactions, our research utilizes photochemistry, providing milder reaction conditions for the efficient benzene amination. Mechanistic investigations using 51V-NMR support coordination of hydroxylamine to vanadium and the multifaceted role of acetic acid as solvent, acid, and ligand. X-band EPR and 51V-NMR demonstrated the time-dependent reduction of vanadium by hydroxylamine. The same excess experiments and 15N-NMR coordination studies identified product inhibition by aniline. 1H-NMR kinetic experiments, enabled through a broad peak suppression, suggest a paramagnetic V+4-hydroxylamine complex as the key intermediate, and 51V-NMR kinetics support the photocatalyst's role in maintaining the redox cycle and reducing the active V+4-hydroxylamine intermediate. Our direct photocatalytic method not only enables the selective synthesis of aniline under mild conditions, but also allows easy scaling through its compatibility with flow systems.

Short tandem repeats (STRs) are low-entropy regions in the genome, consisting of a short (1-6 bp) unit that is consecutively repeated multiple times. They are known for high mutational instability, due to so-called stutter-mutations, in which the number of units in the run increases or descreases. In particular, STRs with repeat unit length of 1-2 bp are prone to mutate even within several cell divisions. The extremely rapid accumulation of variation makes them interesting phylogenetic markers for retrospective single-cell lineage reconstruction. Here we model their mutational dynamics at the level of individual repeat unit type and then aggregate length variations over many STR loci with the aim of obtaining a very fast ``molecular clock''. We calibrate our model based on several datasets with known lineage structure prepared from cultured cells. We find that the mutational dynamics of STRs are reasonably consistent for a given cell line, but vary among different ones. This suggests that the dynamics are not entirely explained by mutations in caretaker genes, rather, various other factors play a role -- possibly tissue origin and differentiation state. Further data and research is necessary to asses their relative effects.

We study how consumers express sustainability-related needs in online product search and how query autocompletion (QAC) systems mediate this intent. Using a 1% random sample (3.95 M queries) from the AmazonQAC dataset, we identify sustainable- and consumption-oriented vocabulary through a hybrid lexicon-based approach and analyse how QAC preserves, removes, or introduces such terms. Only about 1% of queries contain explicit sustainability intent, concentrated in categories like Food & Grocery and Health & Beauty. QAC preserves users’ sustainable intent in 60% of cases and adds sustainability-related tokens in a further 40%, indicating that it can reinforce rather than suppress ethical consumption cues. Regression analyses show that these additions occur more often in longer and more frequent queries. Our findings challenge the assumption that digital search infrastructures inherently bias users toward unsustainable consumption and highlight opportunities for QAC design to support responsible shopping behaviour.

Many users struggle with effective online search and critical evaluation, especially in high-stakes domains like health, while often overestimating their digital literacy. Thus, in this demo, we present an interactive search companion that seamlessly integrates expert search strategies into existing search engine result pages. Providing context-aware tips on clarifying information needs, improving query formulation, encouraging result exploration, and mitigating biases, our companion aims to foster reflective search behaviour while minimising cognitive burden. A user study demonstrates the companion’s successful encouragement of more active and exploratory search, leading users to submit 75% more queries and view roughly twice as many results, as well as performance gains in difficult tasks. This demo illustrates how lightweight, contextual guidance can enhance search literacy and empower users through micro-learning opportunities. While the vision involves real-time LLM adaptivity, this study utilises a controlled implementation to test the underlying intervention strategies.

Understanding and classifying query intents can improve retrieval effectiveness by helping align search results with the motivations behind user queries. However, existing intent taxonomies are typically derived from system log data and capture mostly isolated information needs, while the broader task context often remains unaddressed. This limitation becomes increasingly relevant as interactions with Large Language Models (LLMs) expand user expectations from simple query answering toward comprehensive task support, for example, with purchasing decisions or in travel planning. At the same time, current LLMs still struggle to fully interpret complex and multifaceted tasks. To address this gap, we argue for a stronger task-based perspective on query intent. Drawing on a grounded-theory-based interview study with airport information clerks, we present a taxonomy of task-based information request intents that bridges the gap between traditional query-focused approaches and the emerging demands of AI-driven task-oriented search.

Hereditary Hemorrhagic Telangiectasia (HHT) is a rare vascular disorder with mucocutaneous telangiectasia. Hormones are hypothesized to play a role in reducing bleeding in these patients; however, clear evidence is currently lacking. The aim of this study was to further investigate this hypothesis by assessing the impact of altered hormonal status on HHT severity. This cross-sectional electronic questionnaire, available in English and German, was distributed with the support of various self-help groups. It included sections on the general medical history of HHT and the influence of hormones on disease symptoms. Data were collected between March 2016 and August 2017. Of the 477 respondents with HHT, 326 were female (68%). With increasing age, female patients experienced more severe epistaxis compared to male patients, with a mean age of 54 years (standard deviation ± 11.5 years, range [28,83]). Of the 228 female patients who reported having taken hormones, 73% used them for contraception and 57% for hyper- or dysmenorrhea. Regarding hormone intake, 52% of the patients taking combined estrogen and progestin therapy experienced less epistaxis. Most female patients stated an increase in epistaxis during puberty (41%) and pregnancy (39%), predominantly in the second trimester. In HHT, variation in levels of hormone concentrations seem to contribute to symptom severity. Off-label use of hormonal products in women with HHT may be considered. Clinicaltrials.gov: NCT02690246, Registration Date: 2016–02-09.

In trauma, even therapeutic apixaban levels can significantly exacerbate bleeding. In cases of overdose, the risk of prolonged, life-threatening hemorrhage increases substantially, necessitating targeted interventions, such as pharmacological reversal agents. Rapid identification of elevated anticoagulant levels is crucial to initiate specific countermeasures and limit blood loss, and point-of-care testing may facilitate timely treatment. In our case of an extreme overdose of apixaban (max 5664.24 ng/mL, first report of such high amount) has resulted in serious and life-threatening clinical symptoms due to sustained multiple injuries. It is still a debate which therapies prove the most efficacious, whereby the vast surplus of apixaban and the short half-life of andexanet alfa must be considered. This case, in which high apixaban concentration persisted, might help to shed light on these issues.

BackgroundVagus nerve stimulation (VNS) is a well-established treatment option for treatment-resistant affective disorders. Due to potential concerns about increased cardiac innervation on the right side, devices are almost exclusively implanted on the left cervical vagus nerve. Clinical data on right-sided VNS for psychiatric indications are often very scarce.MethodsWe present a case series involving three patients—two with MDD and one with bipolar depression—each with extensive prior unsuccessful treatments, frequent hospitalizations, and severe psychiatric and medical comorbidities. In each case, the right cervical side was chosen for primary implantation or re-implantation due to cardiac disease, pre-existing devices, or anatomical constraints (including high-grade atrioventricular block with pacemaker and recurrent laryngeal nerve palsy). All patients underwent standard titration of stimulation parameters and long-term clinical follow-up.ResultsAll three patients showed significant and lasting mood stabilization within approximately 12 months after right-sided VNS implantation. Hospital admission rates decreased markedly, and in two cases, maintenance electroconvulsive therapy (ECT) was discontinued or notably reduced. In all cases, VNS was generally well tolerated. During right-sided stimulation, no clinically significant bradyarrhythmia, device interactions, or other serious cardiac adverse events were observed.ConclusionsThis series highlights the usefulness of right-sided VNS in sustaining long-term mood stability and reducing hospitalizations for patients with highly treatment-resistant, comorbid mood disorders. The findings expand existing epilepsy-focused data on right-sided VNS to the psychiatric field and support systematic evaluation of this approach in future prospective studies. Multidisciplinary coordination is essential to minimize risks and improve outcomes. Additional long-term research is needed to assess its lasting effectiveness, optimal candidate selection, and cost-efficiency in routine clinical practice.

Each year, several thousand tons of microplastics (MPs) end up in the environment. While available techniques for the identification and quantitative characterization of microplastics are getting more elaborate, studies investigating the fate and ecotoxicological impact of MPs face a major challenge: differentiating between naturally occurring and artificial MPs once they are released into the environment. This issue can be addressed by labeling the artificial MPs; however, there is currently a lack of surrogates that combine labeling with a close resemblance to MPs found in the environment. Most studies use labeled polystyrene microspheres as surrogates, but these differ considerably from environmental MPs in terms of shape, chemical composition, and surface charge. In this study, we aim to address this challenge by introducing electrospun microfibers as a precursor for irregularly shaped, optically labeled MPs. The labels were directly embedded into the microfibers, which were then broken down by shear-force exfoliation and ball milling, yielding irregularly shaped fibers and fragments. The resulting MPs exhibited a heterogeneous morphology much closer to that of environmental MPs than commercially available spherical MP surrogates commonly used. In addition to organic fluorophores, we introduced lanthanide-doped upconversion nanoparticles (UCNPs) as optical labels. This special class of luminophores combines excitation in the near infrared (NIR) with high photostability, multiple sharp emissions in the UV/visible and NIR ranges, and versatility in doping composition. The low abundance of lanthanides in the environment also enables the quantitative detection of UCNP-doped MPs using element-specific analytical methods. Overall, this new type of artificial MP offers exciting opportunities for biological and environmental studies.