Group closeness effects on co-owned information sharing: A multilevel perspective

Co-owned information contains personal details about multiple individuals, often nested within a social group. It is important to study the sharing of such information because its careless disclosure can violate the privacy of all co-owners. What makes such sharing decisions unique is that they are often conducted within a tight social context, the attributes of which can systematically affect the decisions of all individuals nested within the group. This necessitates multi-level theorizing and testing. Doing so, we theorize the impact of group closeness (a group-level attribute) on co-owned information sharing by the group members (individual-level reflections and behaviors). We tested our ideas through a deceptive procedure: ninety participants in 40 groups were asked to voluntarily share a co-owned photo of 2–3 group members, for algorithm training purposes (cover story). Hierarchical Linear Modeling revealed (1) the retained relevance of self-centered private information sharing motivators and deterrents in group contexts, and (2) a cross-level effect of group closeness: it weakened the negative effect of privacy concerns on actual co-owned information sharing. The findings underscore the role of social context in determining the potency of privacy concerns to drive the privacy behaviors of individuals nested within this context

Correlating spatially resolved catalysis and Raman spectroscopy during CO oxidation over Cu/CeO₂ catalysts

Spatially resolved analysis allows for the development of accurate structure–property correlations in regimes of high catalytic conversion. We report on the novel combination of a compact profile reactor with IR spectroscopy for spatially resolved gas-phase analysis and with Raman spectroscopy for spatially resolved structural analysis. The potential of this combined approach is illustrated for the CO oxidation over low-loaded Cu/CeO₂ catalysts at atmospheric pressure but the use of higher pressures is feasible. Spatially resolved operando Raman spectroscopy of Cu/CeO₂ at 150 °C reveals structural changes directly correlated with the catalytic conversion. With increasing conversion an increase in the consumption of surface lattice oxygen is observed which is accompanied by the formation of oxygen vacancies and ceria reduction. Our mechanistic findings demonstrate the participation of the ceria support in the CO oxidation over low-loaded Cu/CeO₂ catalysts at high conversions. The presented setup provides high versatility for spatially dependent mechanistic analysis of catalysts as a function of varying gas environments and their influence on the structural changes

Simultaneous Bacteria Sensing and On-demand Antimicrobial Peptide Release

A material able to simultaneously sense a bacterial presence and to on-demand release antimicrobial peptides (AMP) in a tunable amount was developed. Simultaneous sensing and release were achieved by the combination of a bacteria-sensing hydrogel with antimicrobial peptide-carrying mesoporous silica particles or coatings. The mesoporous silica with a mesopore diameter of 22 nm was functionalized with a covalently grafted green light-sensitive linker to which antimicrobial peptides were covalently attached. The gelatin-based hydrogel, which contains C14R functionalized mesoporous silica particles, is designed to respond to bacteria presence as it may occur e.g. in a wound's microbiological environment. In the presence of bacteria and 0.1 % trypsin, a protease enzyme simulating bacterial presence, the hydrogel, deposited in a donut shape, undergoes a shape loss as the bacteria cleave cross-linking bonds within the hydrogel. When observing hydrogel shape loss after 2 hours as a readout of a bacterial infection subsequent irradiation triggers the release of antimicrobial peptides on demand with adjustable concentration-time profiles. The sensing and on-demand release are integrated into commercially available wound dressing fabrics demonstrating an application proof-of-concept. Characterization using ATR-IR spectroscopy, TGA, and BCA validate the successful fabrication and release. The H1.6P composite released antimicrobial agents, reaching concentrations of up to 298 μg/mL at pH 7.4 from a 300 μL sample. The efficacy of the released C14R against E. coli BL21(DE3) is illustrated. Overall, the multifunctionality of this approach presents a promising step towards on-demand wound care and thus for reducing side effects and antibiotic resistance

Shining New Light on the Mechanism of Selective Oxidation Catalysis Using Method Development in Transient Spectroscopy

Selective oxidation reactions are some of the most important chemical processes, with enormous economic and environmental contributions. Controlling the selectivity remains the greatest challenge, owing to their complexity, with both parallel and consecutive reaction pathways leading to by-products. Their mode of operation over supported and bulk oxide catalysts has been the subject of debate for decades, largely influenced by phenomenological principles. Recently, direct evidence from transient spectroscopy has provided insight into the dynamical nature of selective oxidation catalysts as well as the actively participating surface species and sites of the catalysts, while highlighting important functions of the supporting structure. This perspective presents the implications of these findings for a scientific understanding of the characteristics of selective oxidation reactions as a basis for rational catalyst design. First, the potential of the transient spectroscopic approach is illustrated based on the available literature on selective oxidation reactions. When moving from supported catalysts to bulk oxide systems with their increased level of structural complexity, additional challenges concerning the determination of structure–performance relationships emerge, but these may be tackled successfully in the future in view of current method development

Terahertz photonic spectrum analyser

The volume of data transmitted via wireless communication will further increase in the upcoming years, eventually surpassing the bandwidth capabilities provided by existing technologies. Increasing the carrier frequency used for the data transmission also increases the available bandwidth and makes new, yet unused bands available. Current technologies use frequencies below 100 GHz but are said to expand into the terahertz (THz) frequencies (100 GHz - 10 THz) with 6G technologies and beyond. THz radiation is non-ionising and, therefore, interesting for medical applications on living organisms like cancer detection. THz fingerprinting detects materials based on their absorption which security applications use to identify substances like drugs or explosives. Most of the THz applications require a THz source in their measurement equipment. Current sources are still either bulky, expensive or low in output power requiring further research for improvements in all categories. For the spectral signal output characterisation, accurate and reliable spectrum analysers are required. The only currently commercially available spectrum analysers for the THz frequency range are electronic spectrum analysers with extender modules. Each of these covers a bandwidth of approximately 42 % of their centre frequency limited by the typically employed rectangular metallic hollow waveguides. Measuring harmonics of a signal already requires several extender modules. Covering the full frequency range from 100 GHz up to 1.5 THz, which is simultaneously the highest yet commercially reachable frequency, necessitates at least seven extender modules. The investment costs for the full frequency range easily exceed half a million Euros. An alternative to reaching the THz frequencies is photonic technology. Tuning a telecom-wavelength (1550 nm) laser by 1 THz equals a tuning by only 0.5 % and is easily accessible with commercial equipment. This thesis introduces several variants of a THz photonic spectrum analyser based on the difference frequency of two continuous-wave optical telecom-wavelength signals. A photoconductive mixer generates the optical difference frequency acting as a local oscillator and mixes it with the signal of a THz source. The mixing process transfers the spectral information of the source into the intermediate frequency, typically kHz or MHz, where an analog-digital converter acquires the data. The thesis introduces four measurement variants for the optical difference frequency generation and the data acquisition: 1.) The frequency sweep uses a continuously increasing difference frequency and measures all components falling within the bandwidth of a low-pass filter in the intermediate frequency chain. 2.) The offset frequency sweep employs a band-pass filter instead of the low-pass filter in order to reduce 1/f-noise. Each frequency component of the source is displayed twice. A deconvolution regains the original spectrum of the source. 3.) The Fourier transformation mode measures a time trace of the downconverted signal and transforms it to the frequency domain with a Fourier transformation. The resulting frequency information equals the spectrum surrounding the optical difference frequency. 4.) The final measurement mode is based on in-phase and quadrature demodulation. The signal is split into two paths and each downconverted within its respective photoconductive mixer. Both paths use the same optical difference frequency, yet with a relative phase difference of 90°. Experimentally, this thesis demonstrates three different implementations of the photonic THz spectrum analyser, each with its own way of generating the difference frequency. The first variant uses two free-running, temperature controlled distributed-feedback laser diodes and ErAs:InGaAs or low-temperature grown InGaAs:Be photoconductive mixers. We demonstrate operation between 100 GHz and 1.05 THz, yet may cover frequencies beyond 2.7 THz with a minimum resolution bandwidth of 1.2 MHz. The system reaches displayed average noise levels of -111.8 dBm/Hz at a frequency of 100 GHz and -98.0 dBm/Hz at a frequency of 1 THz. Using photoconductive mixers with planar, end-fire Vivaldi antennas, this photonic spectrum analyser variant extends to signals in dielectric waveguides and rectangular metallic hollow waveguides. The second photonic spectrum analyser implementation uses an electro-optical THz comb that generates the two required optical frequency components form a single laser with an electro-optical modulator. The electro-optical THz comb shows a phase noise of -108.6 dBc/Hz at an offset frequency of 1 MHz at a centre frequency of 40 GHz and a linewidth of 1.8 Hz at a frequency of 100 GHz. We used it for frequencies up to 110 GHz while frequencies up to 1 THz are currently possible. The third photonic spectrum analyser examined in this thesis utilises two continuous-wave lasers, both locked to the same frequency-comb and further to a global positioning system (GPS) signal, in combination with an InGaAs:Rh photoconductive mixer. This variant covers frequencies up to at least 6.5 THz with linewidths below 1 Hz at a frequency of 100 GHz and below 20 Hz at a frequency of 1 THz. Simultaneously, it offers a displayed average noise level of -145.6 dBm/Hz at a frequency of 100 GHz, -133.7 dBm/Hz at 1 THz and -111.5 dBm/Hz at a frequency of 4.5 THz

25 Jahre Forschung am S-DALINAC

Als am 18. Oktober 1991 der »Supraleitende Darmstädter Linear-Accelerator«, kurz S-DALINAC, mit einem Festakt eingeweiht wurde, begann eine neue Epoche der Grundlagenforschung an der TH Darmstadt

Experimental observation of N00N state Bloch oscillations

Bloch oscillations of quantum particles manifest themselves as periodic spreading and relocalization of the associated wave functions when traversing lattice potentials subject to external gradient forces. Albeit this phenomenon is deeply rooted into the very foundations of quantum mechanics, all experimental observations so far have only contemplated dynamics of one and two particles initially prepared in separable local states. Evidently, a more general description of genuinely quantum Bloch oscillations will be achieved on excitation of a Bloch oscillator by nonlocal states. Here we report the observation of Bloch oscillations of two-particle N00N states, and discuss the nonlocality on the ground of Bell-like inequalities. The time evolution of two-photon N00N states in Bloch oscillators, whether symmetric, antisymmetric or partially symmetric, reveals transitions from particle antibunching to bunching. Consequently, the initial states can be tailored to produce spatial correlations akin to those of bosons, fermions and anyons, presenting potential applications in photonic quantum simulation

Production and electromagnetic decay of hyperons: a feasibility study with HADES as a phase-0 experiment at FAIR

A feasibility study has been performed in order to investigate the performance of the HADES detector to measure the electromagnetic decays of the hyperon resonances Σ(1385)⁰, Λ(1405) and Λ(1520) as well as the production of double strange baryon systems Ξ⁻ and Λ Λ in p + p reactions at a beam kinetic energy of 4.5 GeV. The existing HADES detector will be upgraded by a new Forward Detector, which extends the detector acceptance into a range of polar angles that plays a crucial role for these investigations. The analysis of each channel is preceded by a consideration of the production cross-sections. Afterwards the expected signal count rates using a target consisting of either liquid hydrogen or polyethylene are summarized

Retrieval methods for legal question answering in German

This thesis investigates the effectiveness of various Information Retrieval (IR) Systems in addressing legal questions formulated in layman’s terms within the German legal domain. The study utilizes the GerLayQA[3] dataset, comprising legal questions sourced from the popular online platform “Frag-einen-Anwalt.de” aiming to evaluate the capability of IR systems to retrieve relevant paragraphs from German legal texts in response to these queries. The research employs a diverse range of retrieval methods, including baseline approaches such as TF-IDF and BM25 and more advanced techniques based on state-of-the-art language models. A significant focus is placed on comparing the performance of pre-trained and fine-tuned Bi-Encoder models and highlighting the impact of domain-specific training on retrieval accuracy. Furthermore, the study explores the potential of a Retrieve-and-Re-Rank pipeline combining the efficiency of Bi-Encoders with the precision of Cross-Encoders. This approach is evaluated against single-stage retrieval methods to assess its viability in the legal domain. This work makes a novel contribution by developing and evaluating a Majority Vote IR model, which aggregates results from multiple retrieval methods through a majority voting mechanism and thereby tries to minimize the effect of any single IR system weakness. This ensemble approach is compared against individual models to determine its effectiveness in improving retrieval performance. The performance of these systems is rigorously evaluated using standard information retrieval metrics, including the Precision@k, Recall@k, F1@k-Score, and the Normalized Discounted Cumulative Gain (NDCG). The results are critically analyzed to identify the strengths and limitations of each approach within the context of German Legal Information Retrieval. This research aims to contribute to the growing field of legal AI by providing insights into the applicability and challenges of various IR techniques for processing German layman legal queries. The findings have implications for developing more accessible and efficient legal information systems, potentially closing the gap between complex legal language and public understanding