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Uncertainty-Aware Micromobility Rebalancing With Censored Demand Reconstruction
No full textInternational audienceShared micromobility systems face persistent vehicle availability challenges due to spatio-temporal imbalances. These challenges are amplified by demand uncertainty and censored (unobserved) demand, trips that fail to occur due to stock-outs and thus remain invisible to traditional forecasting models. This paper presents an integrated framework for short-horizon micromobility rebalancing that accounts for both forecast uncertainty and censored demand. Censored demand is inferred by identifying short taxi and bus trips occurring during cycling-favorable conditions and station shortages, which likely reflect suppressed micromobility intent. We use a Conditional Variational Autoencoder (CVAE) to reconstruct latent micromobility flows from these observations, conditioned on weather, traffic, and temporal factors. Forecast and censored demand are integrated into a DRO model to generate rebalancing actions. To execute relocations, we develop a hybrid logistics layer combining operator trucks with dynamically available crowdsourced vehicles. Reinforcement learning (RL) refines dispatch by adapting to task failures and anticipated demand. Using a large-scale case study in New York City, we demonstrate that incorporating censored demand and uncertainty significantly reduces unmet demand and improves alignment with true demand distributions. Results show up to a 40% reduction in service loss compared to baselines
Unraveling "waves" in liner shipping. A 2D method for visualizing individual vessel trajectories with AIS data
No full textInternational audienceLiner shipping is often marked by operational regularities, with vessels operating on designated services calling at specific ports at specific times. Deviations from these patterns can be small and confined in space and in time, but they can also be much more consequential, like recent disruptions tied to the COVID-19 pandemic, the Red Sea crisis or the Panama Canal bottleneck. This underscores the necessity of understanding individual vessel trajectory configurations, monitoring vessel trajectories and identifying deviations from usual patterns prior to conducting aggregated analyses of vessel movements. This paper examines various visualization methods, including traditional 2D mapping and 3D space-time cubes, and concludes that the latter are often inadequate for visualizing vessel loops and deviations over extended time periods with enough detail to inform about vessel operations, shipping operators' strategies, and the scope of disruptions to supply chains. To overcome the limitations of existing methods, this paper introduces a novel approach based on linear referencing. Instead of relying on geographic coordinates, ports are sequenced by relative positions along a line feature that follows the coasts of various world regions consecutively. The resulting wave-like patterns, which represent time on one axis and a linear referencing of ports on the other, enable rapid identification of regular "waves" and of deviations in vessel trajectories and their magnitude within their geographic and temporal context. The new visualization method complements existing ones, as illustrated by select cases of vessels discussed in the paper.</div
Salvage of Failed Patellofemoral Arthroplasty Due to Instability: Combined Medial Patellofemoral Ligament Reconstruction, Tibial Tubercle Osteotomy, and Vastus Medialis Obliquus Advancement - Case Report and Algorithm-Based
No full textInternational audienceIntroduction/Objectives: Patellofemoral arthroplasty (PFA) is a joint-sparing alternative to total knee arthroplasty (TKA) for isolated patellofemoral osteoarthritis, offering symptom relief while preserving tibiofemoral compartments and bone stock compared with TKA, particularly in younger and active patients. However, persistent anterior knee pain and patellar instability remain leading causes of early failure, even when prosthetic components are stable and tibiofemoral degeneration is absent. This study aimed to describe a combined, non-prosthetic surgical strategy for symptomatic PFA failure due to patellar instability and to propose an algorithm-based framework for clinical decision-making. Methods: A 54-year-old woman presented with chronic anterior knee pain and recurrent instability four years after isolated PFA. Imaging confirmed stable and well-aligned prosthetic components with preserved tibiofemoral compartments but consistent lateral patellar subluxation. The patient was treated using a joint-preserving approach combining medial patellofemoral ligament (MPFL) reconstruction with hamstring autograft, anteromedial tibial tubercle osteotomy, and vastus medialis obliquus (VMO) advancement. Clinical outcomes were assessed with the Kujala and International Knee Documentation Committee (IKDC) scores at six weeks and three months. Results:At three months, the Kujala score improved from 54 to 78, and the IKDC subjective score increased from 38 to 69. The patient reported significant pain reduction, restoration of patellar stability, and functional recovery. No recurrent instability, surgical complications, or implant-related problems were observed. Radiographs confirmed correct alignment and congruent prosthetic components.Conclusion:A combined approach addressing soft-tissue, bony, and dynamic stabilizers may provide an effective, joint-preserving alternative to total knee arthroplasty in selected patients with symptomatic PFA failure caused by instability. The algorithm presented may assist in surgical decision-making and optimize patient outcomes
Evaluating the flexural performance of bio-based concrete with different types of bio-aggregate and binder
No full textInternational audienceThis study investigates the influence of bio-aggregate type (hemp, bamboo, and reed) and binder type (CEMIV, LC3, and PNC) on the flexural performance of bio-based concrete, with the objective of identifying optimized formulations for construction applications. The term 'optimization' refers to the identification of favorable aggregate-binder combinations based on a comparative assessment of flexural strength, stiffness, deformation behavior, and cracking characteristics. Digital image correlation was employed to analyze deformation and cracking behavior. The results indicate that hemp-based concretes combined with CEMIV exhibit the highest flexural performance, benefiting from effective crack-bridging mechanisms. Reed-based concretes demonstrate a more stable and homogeneous flexural response, particularly when combined with higher-performance binders such as CEMIV and LC3. In contrast, bamboo-based concretes show pronounced interfacial debonding, especially when paired with lower-strength binders (such as PNC), leading to early strain localization. Binders with high fineness, such as PNC, promote the development of finer and more uniformly distributed cracks, despite lower global flexural performance. These findings provide fundamental insights into the intrinsic flexural behavior of bio-based concretes, indicating that the complementary combination of the dimensional stability of reed aggregates and the favorable mechanical performance of hemp shives can form a robust basis for the future development of reinforced bio-based composites, such as fabric-reinforced cementitious matrix (FRCM) systems, where optimized substrate performance is essential
Better understanding of the maleinization of oils using model fatty compounds: Insights from NMR, SEC, and HRMS analyses
No full textInternational audienceThe chemical modification of vegetable oils through maleinization reaction offers a promising route to sustainable bio-based materials for diverse industrial applications. However, the underlying mechanisms of the maleinization reaction such as the ene, Diels-Alder, and radical pathways, remain insufficiently understood, limiting process optimization and broader adoption. In this study, we employed a model compound approach using methyl oleate (C18:1), methyl linoleate (C18:2), and their corresponding triglycerides to systematically investigate the maleinization reaction with maleic anhydride (MA) under controlled conditions. Advanced analytical techniques, including nuclear magnetic resonance (NMR) spectroscopy, size-exclusion chromatography (SEC), and Fourier-transform ion cyclotron resonance mass spectrometry (FT-ICR MS) were performed to elucidate reaction mechanisms, quantify product distributions (when possible), and assess structural modifications. Our results demonstrated that the ene reaction is the predominant pathway for C18:1 substrates while radical mechanisms contribute to minor products. The Diels-Alder cycloaddition is negligible under the studied conditions. The extent of maleinization increases with MA equivalents, as confirmed by quantitative 13C NMR and FT-ICR MS analyses while SEC reveals some polymerization
Your home, my home, our home ? The appropriability of shared domestic spaces in the context of intergenerational coresidence
No full textInternational audienceAccess to housing is nowadays an issue for young people. Simultaneously many elderly people are experiencing loneliness. In this context, intergenerational coresidence services and platforms are developed, with the promise of addressing these issues. Their success depends on the desire of both target audiences to engage in co-housing practices with members of a different age-group. This raises the question of the appropriability (or not) of intergenerational shared spaces and the conditions under which their (dis)appropriation can be carried out by young and older individuals. Based on a qualitative study conducted with ten respondents belonging to two contrasting age groups, we highlight the similarities and differences in the meaning given to the concepts of home and intergenerational shared home. We identify the modalities under which shared domestic spaces can become different kinds of home (my place, your place, our place). This research contributes to the growing body of literature on contemporary modifications of the home by shedding light on generational approaches to home appropriation
Co-culturing with bacteria modulates fatty acid composition in benthic diatom biofilms for lipid-based biotechnologies: A case study of Amphora sp.
No full textInternational audienceDespite being recognized as promising oleaginous microalgal resources, benthic diatom biofilms remain overlooked in microalgal biotechnology. To enhance their industrial potential, bacterial interactions can exploit to boost biomass, increase lipid yields and tailor lipid profiles. Given the complexity of natural biofilms, our study adopted a reductionist approach to investigate the impact of bacteria on the metabolism of a marine benthic diatom, Amphora sp., through binary co-cultures. Bacteria were isolated from non-axenic Amphora sp. biofilm cultures during the exponential phase in a lab-scale porous substrate biofilm photobioreactor. A bacterial biofilm assay was conducted to select biofilm-forming strains, followed by co-culturing them with Amphora sp. in bottle culture flasks, assuming these strains would persist and interact within the Amphora biofilm. All cultures were maintained for 6 days in F/2-enriched artificial seawater at 16 • C, under a 12:12 light:dark cycle (100 μmol photons.m -2 .s -1 ). Biomass and lipid contents were quantified using the gravimetric method, while fatty acid profiles were analysed using GC-MS. Results showed that some bacterial strains reduced Amphora sp. biomass, while Nitratireductor sp. and Sulfitobacter sp. had no noticeable effect. However, significant shifts in fatty acid profile of Amphora sp. were observed in most co-cultures while none of the individual bacterial strains substantially affected lipid production compared to its axenic and non-axenic counterparts. Co-cultures with Nitratireductor sp. and Sulfitobacter sp. yielded 50-55 % saturated, 40-50 % monounsaturated, and 1-6 % polyunsaturated fatty acids, indicating favourable biodiesel properties. Thus, modifying the microbiome of microalgal biofilms could be an innovative strategy for tailoring fatty acid composition for lipid-based applications
How to perform Unilateral Pectineal Suspension for apical prolapse by robotic assistance: A technical note with Video
No full textInternational audienceSacrocolpopexy remains the gold-standard surgical technique for the management of apical prolapse, whether performed with or without concomitant hysterectomy. However, the use of synthetic mesh has become increasingly debated owing to concerns regarding postoperative complications. Robotic-assisted unilateral pectineal suspension (UPS) has emerged as an innovative, safe, and effective alternative for apical prolapse repair. This minimally invasive, mesh-free procedure achieves uterine suspension by anchoring the anterior cervical surface to Cooper’s iliopectineal ligament. Indications include women of reproductive age seeking a uterus-preserving approach, obese patients, and those unwilling to undergo procedures involving synthetic prostheses; it may also represent a suitable option in selected cases of recurrence following laparoscopic sacrocolpopexy or vaginal repair. We describe the standardized steps of this surgical procedure, along with the specific advantages of the robotic approach, illustrated by a detailed video demonstration to support implementation among surgeons
Comparative investigation of numerical methods for incorporating real climate data into thermal quadrupole models for building wall applications: fitting techniques, and Laplace inversion algorithms
No full textInternational audienceThe thermal quadrupole method provides the advantage of expressing the partial differential formulation of the heat equation as a linear system in transformed time (Laplace transform) and space (integral transforms) domains. It allows faster computations compared to standard techniques such as Finite Element Methods. The following work concerns the incorporation of climate data recordings of hourly external temperature and solar heat flux in the thermal quadrupole method for solving the heat equation through a multilayered building wall.Two methods are proposed for the purpose of applying Laplace transforms to the discrete sets of climate data: a global Fourier series fit, accounting for severe fluctuations and peaks with the number of harmonics depending on dataset size; and a discrete Laplace transform methodology applied to a global series of linearly computed sub-series over defined intervals. Two models are investigated, a 1D heat transfer problem in Cartesian coordinates and a 2D axisymmetric representation in cylindrical coordinates, the latter dictating Hankel transforms for the space domain. After solving in the transformed domains, the challenge lies in accurately retrieving time-domain results. Three Laplace inversion algorithms—Stehfest, De Hoog, and Den Iseger—are investigated for their numerical stability, accuracy, and efficiency. A parametric analysis related to parameters of the data fitting and Laplace inversion methods is carried out. Results of different combinations of the fitting method/inversion algorithm (or a coupling of algorithms) are provided and compared with a finite element resolution of the thermal problems (FreeFEM++ and COMSOL) with an emphasis on computational time enhancements. The main objective of this work is to develop a numerically efficient direct model suitable for future application in inverse methods