里昂大学

When different individuals view the same image, their eye movements are often similar. The degree of this similarity is called interobserver congruency (IOC). We investigated how IOC is determined by three factors that impact gaze control: the visual features of an image, its semantic content, and the task observers perform when viewing it. We first quantified the low-level physical features and semantic complexity of images using a well-established measure of visual clutter and a novel measure based on a distributional semantic model, respectively. Then, we selected an image set in which these two measures were uncorrelated and used it in an eye-tracking experiment, in which observers either freely viewed the images or memorised their content. We assessed IOC using four metrics: two capturing purely spatial IOC and two sensitive to spatiotemporal IOC, i.e., considering both the locations and order of fixations. The values of the two spatial metrics decreased with increasing clutter and remained insensitive to the remaining factors we investigated. The two spatiotemporal metrics were sensitive to both clutter and semantic complexity, but, interestingly, in different ways. Specifically, according to a metric that was insensitive to the presence of objects in images, IOC decreased with clutter and increased with semantic complexity, while the metric sensitive to objects showed the opposite pattern. Additionally, we found that the memorization task rendered oculomotor behaviour more exploratory, which had modulatory effects on spatiotemporal – but not spatial – IOC. Together, our findings reveal how factors known to shape gaze behaviour determine IOC.

A comprehensive understanding of hydrogen-deformation interactions at the microscale is essential for revealing hydrogen embrittlement mechanisms. In situ micromechanics with simultaneous hydrogen (H-) charging has therefore gained traction in recent times. In the present study, we aim to address the drawbacks of current in situ H-charging setups by developing a more robust 3-electrode-based back-side charging system for a scanning electron microscope to perform various micromechanical tests, especially for thin samples (< 1 mm). The development of the setup is discussed and demonstrated through micropillar compression of an Fe-25Cr single crystal (011) during active H-charging. Results indicate that H increases the yield strength and the strain-hardening ability by activating multiple slip systems and significant dislocation entanglement, as revealed by electron microscopy, consistent with previous reports on BCC materials. Activation volume estimation from strain-rate jump tests suggests a possible competition between the solute-drag effect on dislocation mobility and dislocation forest hardening.

Introduction Autonomous buses, currently under development could improve the mobility of people. The objective of this study is to identify the perceptions, acceptability and expectations toward such buses of potential future users, including people with travel-limiting disabilities and older people. Methods A methods combining an online survey for potential users and a consultation with experts in mobility and disability was used with non-probability convenience sampling. Potential users were asked to report their eventual mobility limitations, to express their feelings toward autonomous buses, qualities these buses should have, their willingness to use them and their recommendations for the design of an autonomous bus. Experts were asked via email to respond to five open-ended questions on the benefits and disadvantages of an autonomous bus. Results 246 people participated to the online survey, 28 of whom (11%) reporting travel-limiting disabilities. Autonomous buses elicit positive expectations, in particular in relation to an improved mobility service. Main concerns were related to safety, security and accessibility issues, especially due to the lack of human presence. These concerns are more pronounced in people with travel-limiting disabilities. The nine experts' comments confirmed the survey's findings, while also detailing the types of problems anticipated as a result of the lack of driver. Conclusions These results allow to better understand the needs and expectations of potential users, including people with disabilities and older people with regard to the introduction of autonomous buses. Recommendations ensuring the accessibility, safety, and acceptability of autonomous buses for all are proposed.

Gas hydrates are solid compounds that form under high-pressure and low-temperature conditions, posing a major threat to oil and gas operations because of their tendency to agglomerate and block pipelines. One mitigation strategy is to allow hydrates to form under controlled conditions, enabling their transport as a slurry within the liquid phase. However, limited research on how such particles affect key multiphase flow parameters has been conducted. This study investigates the influence of particle concentration on slug flow characteristics, a common flow regime in oil and gas production. Experiments using air-water and air-oil systems with model polyethylene particles mimicking hydrate density were performed in a flow loop. The test section was composed of 50-mm ID, 34-m long horizontal pipe. Four particle concentrations were tested: 0%, 5%, 10% and 20% v/v. Except under flow conditions near the stratified-slug transition line, which lead to long elongated bubbles and low slug frequencies, particles were effectively dispersed and transported in both the film and slug regions. The presence of particles had a weak effect on the slug flow topology - structure lengths, flow frequency, bubble velocity and phase fraction remained almost unchanged. This was attributed to the minimal impact of the particles on the thermophysical properties of the mixture. In contrast, particles significantly increased the pressure drops in the oil system because of a higher mixture density and a particle size comparable to the viscous sublayer, what affects the apparent viscosity. An empirical correlation for pressure drop prediction was proposed, achieving deviations of about 5% compared to experimental data.

Fluctuation theorems, such as the Jarzynski equality and the Crooks relation, are effective tools connecting non-equilibrium work statistics and equilibrium free energy differences. However, detailed hands-on, reproducible protocols for implementing and analyzing these relations in real experiments remain scarce. This tutorial provides an end-to-end workflow for measuring, validating, and applying fluctuation theorems using a single-beam optical tweezers setup. It introduces the foundational ideas and consolidates practical calibration (PSD-based trap stiffness and position sensitivity), protocol design (forward/reverse finite-time drives over multiple amplitudes and durations), and robust estimators for free-energy difference and dissipated work, highlighting finite-sampling and rare-event effects. We demonstrate the procedures using an extensive set of measured trajectories under different conditions and provide openly accessible datasets and Python code, enabling new researchers or educators to reproduce the results with minimal effort. Beyond pedagogical validation, we discuss how these recipes translate to broader soft-matter and mesoscopic contexts. By combining user-friendly instruments with clear and transparent analysis, this work promotes the education and reliable adoption of stochastic thermodynamic methods in the curricula of physics and chemistry, as well as among emerging research teams.