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Lower limb compensation in adult spinal deformity: can we identify different patterns?
No full textInternational audienceObjective Lower limbs can play a major compensating role for sagittal malalignment; however, little is known about the different types of compensation. This study aimed to identify different patterns of lower limb compensation and to determine which parameters may affect the recruitment of knee flexion versus hip extension. Methods This study included adult spinal deformity (ASD) patients with full-body X-rays in erect position from a multicentric prospective database. All parameters were measured at baseline: demographics, clinical scores and radiographic parameters: pelvic parameters, pelvic incidence-lumbar lordosis (PI-LL) mismatch, T1 pelvic angle (TPA), sacro-femoral angle (SFA), knee flexion angle (KA), ankle dorsi-flexion angle (AA), pelvic shift (PSh), hip and knee osteoarthritis (OA) grade. A K-means cluster analysis was conducted to identify patterns of lower limb compensation based on SFA and KA. The optimal number of clusters was determined using the silhouette score. The different parameters were then compared across clusters. Results 871 ASD patients were included, of whom 66.9% were females. Mean age was 62.3±14.6 years, mean BMI was 27.7±5.5 kg.m -2 . Four patterns of lower limb compensations were identified: "No compensators", "Recliners" (mainly hip extension), "Squatters" (mainly knee flexion) and "Mixed compensators" (both)."Mixed" and "Squatters" had significantly larger BMI. The proportion of females was the least in the "Squatters" cluster (47.0%) while it was the highest in the "Recliners" group (79.3%) (p<0.001). The proportion of patients with severe hip OA was the lowest in the "Recliners" (38.5%) while it was the highest in the "Squatters" group (71.9%). Knee OA rate was the highest in the"Squatters" group (72.7%). "Mixed compensators" had the greatest PI-LL mismatch (30.4±20.0°) and "No compensators" the lowest (5.3±21.3°). Pelvic incidence values were the highest in "Recliners" and "Mixed compensators" (59.2±13.1° and 57.0±14.1° respectively). TPA values were the highest in the "Mixed compensators" and the lowest in the "No compensators" (33.3±11.7° versus 16.1±11.5°). The "Squatters" presented the significantly poorest values for disability, frailty, and SRS score. Conclusions Cluster analysis determined four types of lower limb compensation:"Recliners" using only hip extension, "Squatters" using only knee flexion,"Mixed compensators" and "No compensators". Lower limb compensatory mechanisms recruitment is multifactorial and varies with age, sex, BMI, frailty, knee and hip OA, pelvic incidence, and spinal alignment
Experimental and theoretical study of metal combustion in oxygen flows
No full textThe effects of oxygen flow speed and pressure on the iron and mild steel combustion are investigated experimentally and theoretically. The studied specimens are vertical cylindrical rods subjected to an axial oxygen flow and ignited at the upper end by laser irradiation. Three main stages of the combustion process have been identified experimentally: (1) Induction period, during which the rod is heated until an intensive metal oxidation begins at its upper end; (2) Static combustion, during which a laminar liquid "cap" slowly grows on the upper rod end; and, after the liquid cap detachment from the sample, (3) Dynamic combustion, which is characterized by a rapid metal consumption and turbulent liquid motions. An analytical description of these stages is given. In particular, a model of the dynamic combustion is constructed based on the turbulent oxygen transport through the liquid metal-oxide flow. This model yields a simple expression for the fraction of metal burned in the process, and allows one to calculate the normal propagation speed of the solid metal--liquid interface as a function of the oxygen flow speed and pressure. A comparison of the theory with the experimental results is made
Identifying and understanding obstacles to heating sobriety and thermal comfort in collective housing: Insights from a survey in France
No full textInternational audienceIn many countries, central heating systems are widely used in multifamily housing allowing maintenance and costs to be shared. However, these systems often limit residents’ control over their own consumption, complicating efforts to reduce energy use and maintain comfort. Despite the growing importance of household energy savings in national and European climate targets, little research has examined user experiences with these systems. This study addresses that gap through an exploratory survey conducted in France.Grounded in scientific literature, technical analyses, and current policy frameworks, the survey was distributed through various channels—including public institutions, online platforms, and field outreach—and collected 403 responses. It examined user difficulties in managing heating, including challenges with controls, bill comprehension, and communication with landlords. It also explored behaviours with high energy-savings impact: reducing heating at night or during absences, window opening, and shutter use.Findings show that many residents face barriers to energy-efficient heating, often due to difficult-to-use controls, limited feedback on consumption, and poor support from landlords or property managers. Those who do not reduce heating at night or when away frequently report these challenges. Participants expressed strong interest in solutions such as personalized advice, real-time feedback, and connected radiator valves to improve comfort, control, and energy management.This work highlights the need to better integrate user experience into multifamily housing energy policies. It provides actionable insights for policymakers and housing providers seeking to enhance comfort and energy savings while supporting France and Europe’s broader energy transition goals
A Comparison of the Effects of a Digital Adoption Platform on Product Lifecycle Management Software
No full textInternational audienceProduct Lifecycle Management (PLM) emerged from the growing need for companies to oversee their products throughout their entire lifecycle-from design and production to usage, and even disposal. This responsibility includes managing product data, regardless of whether the product remains within the company, is in use by customers, or has reached the end of its life in a landfill. PLM systems aim to centralize and allow editing of all product-related data across departments and stages. However, integrating such comprehensive tools into industrial environments is often challenging. The diversity of professional roles each with distinct cultures, expertise, and technical languages complicates seamless adoption and efficient use of PLM systems. To address this challenge, Digital Adoption Platforms (DAPs) have emerged as complementary tools. DAPs are software layers that integrate with existing applications to guide users through processes via stepby-step tutorials, contextual tooltips, and input suggestions. While DAPs have proven effective in many enterprise software domains by easing onboarding and increasing productivity, their use within PLM systems remains limited and under-researched. Particularly, there is a lack of data on how DAPs affect the usability of complex PLM systems and whether they offer tangible improvements for novice users. This study aims to evaluate the usability of PLM systems enhanced by DAPs. By analyzing the user experience and measuring performance, the research seeks to determine whether DAP assistance leads to better adoption, reduced training time, and improved user satisfaction. The findings will also help identify the underlying reasons behind any observed benefits or limitations
A framework for the sustainability evaluation of smart and connected products concepts during early product design.
No full textInternational audienceThe integration of electronic components into physical products to enable advanced data-driven functionalities has led to the emergence of Smart Connected Products (SCP). Due to their complex hybrid nature, SCP can have both positive and negative impacts on the environmental, economic and social pillars. They can thus pose ambiguous sustainability challenges. Recognizing that a product's sustainability impact is in part determined during the early design phases, this study proposes a framework to evaluate the sustainability impacts of SCP concepts after their generation in the creative design stages. The framework objective is to provide a structured and accessible method to select the relevant concepts to consider for the subsequent phase of the design process. Thus, the framework comprises three successive steps: (1) formalizing generated concepts into a common format, (2) evaluating them with regard to 18 sustainability indicators and (3) ranking them based on their scores. The proposed set of 18 actionable indicators was established on the basis of a systematic literature review. The framework scientific robustness and utility were validated through expert interviews. Results highlight the framework's relevance, transparency, and applicability within the SCP domain, though limitations were noted in its exhaustiveness and adaptability to other domains. Regarding the usability of the framework, it was validated through a design workshop. Results demonstrated that the framework was appreciated by the participants and they were satisfied by its outcomes. However, its directive structure seemed to hinder immersion in the evaluation task
What is the carbon footprint of a 100% digital pathology scenario in France?
No full textInternational audienceHealthcare systems contribute to 5-10% of annual greenhouse gas (GHG) emissions and must reduce them to meet the 2016 Paris Agreement targets. Workflows in many areas of medicine are digitised, including surgical pathology. This is the case in France, the second most populous country in the European Union (68 million inhabitants/ 0•8% of world population) with an energy supply that is primarily sourced from nuclear power. We aimed to evaluate the carbon footprint (CF) in a theoretical scenario where all French surgical pathology laboratories implement full digitisation. Data on annual surgical pathology activities were obtained from the French National College of Pathologists. We defined the steps required by histological slide digitisation (scanning, image management software (IMS), data workflow, desktop tools, and storage) and inventoried the tools and their CF using a specific database and bibliography. This study was extrapolated to a national digitisation scenario without artificial intelligence (AI). Digitisation of a single French laboratory was also compared to the same laboratory, nondigitised. In 2021, 28,932,624 slides were generated, corresponding to more than 43PB (1•5 GB per whole-slide image (WSI)) shared by 250 surgical pathology laboratories using 500 scanners (i.e., two per laboratory working 12 hours per day). Digitising pathology resulted in 1,103 to 1,259 tons of carbon dioxide equivalent (CO2eq) for three months compared to 2,116 to 2,923 t CO2eq for one year of digital storage. This is equivalent to the GHG emissions of a combustion-powered car travelling around the Earth 145 times and 336 times, respectively. Data storage was the main contributor to the CF, regardless of storage type and duration (local or external for three months or one year). The other contributors included in decreasing order were desktop tools, scanners, and IMS. Finally, for one French surgical pathology laboratory, the CF of full digitisation increased by 4% to 8% (three months to one year of digital storage) compared to the current non-digitised CF. Such additional impact was equivalent to adding 13 to 26 minus 80-degree freezers in the laboratory. Full digitisation of surgical pathology has a significant environmental impact on global warming, even without the use of AI. Reducing storage duration and increasing the lifespan of digital equipment are the main strategies to mitigate these impacts
The Koinos Model: compelling social interactions in Virtual Reality
No full textInternational audienceVirtual Reality (VR) has the potential to provide qualitative social interactions. The literature explores the Social Presence and Co-presence notions, which we propose to pursue with the definition of the Koinos concept, to name the perceived quality of social interactions in a mediated environment. This definition derives from the Predictive Coding Theory and Qualia Theory, which takes into account an individual's own subjective feelings. In a second time, we propose the Koinos model, which represents the dynamics of social interactions in VR, and can be used as a tool to predict the Koinos generated by a specific VR configuration. The model reflects the mediated message transmitted during social interactions in VR, taking into account the common ground between interlocutors
GPS effect : When attentional guiding is detrimental to learning
No full textInternational audienceThis study examines the effects of step-by-step attentional guidance during immersive virtual reality (VR) lesson. While such guidance can enhance task completion, it may simultaneously facilitate or impede learners' development of deep task understanding. In addition, the study evaluates the role of enactment, a generative learning strategy, in promoting meaningful learning outcomes following the VR lesson. Ninety-two master's students in engineering received instruction on a manufacturing process through an instructional scenario and video before participating in the VR lesson. Results indicate that attentional guidance can have contrasting effects depending on whether enactment is subsequently employed, particularly regarding procedural knowledge acquisition. These findings suggest that step-by-step guidance may hinder procedural knowledge development-analogous to a GPS directing users along predetermined steps without encouraging contextual understanding-whereas incorporating an enactment phase after guided VR instruction appears to enhance procedural learning.</div
On the importance of Ni–Au–Ga interdiffusion in the formation of a Ni–Au/p-GaN ohmic contact
No full textInternational audienceHigh-resolution transmission electron microscopy (TEM) coupled to energy dispersive X-ray spectroscopy (EDX) is used to clarify the exact role of Ni-Au-Ga interdiffusion mechanisms taking place during rapid thermal annealing under an oxygen atmosphere of a Ni-Au/p-GaN contact. It is shown that oxygen-assisted, Ni diffusion to the top surface of the metallic contact through the formation of a nickel oxide (NiO x ) is accompanied by Au diffusion down to the GaN surface and by Ga out-diffusion through the GaN/metal interface. Electrical characterizations of the contact by a transmission line method show that an ohmic contact is obtained as soon as a thin, Au-Ga interfacial layer is formed, even after complete diffusion of Ni or NiO x to the top surface of the contact. Our results clarify that the presence of Ni or NiO x at the interface is not the main origin of the ohmic-like behavior in such contacts. Auto-cleaning of the interface during the interdiffusion process may play a role, but TEM-EDX analysis evidences that the creation of Ga vacancies associated with the formation of a Ga-Au interfacial layer is crucial for reducing the Schottky barrier height and maximizing the amount of current flowing through the contact
Optimisation of a non contact coil / magnet actuator: geometry, nonlinearities and thermal heating
No full textInternational audienceThis article presents the optimisation of an electromagnetic actuator composed of a toroidal coil and a cylindrical magnet positioned along the coil’s axis that may be used for non-contact measurement of excitation of structures, for vibration testing, electromagnetic shunts or energy harvesting. The originality of this work lies in proposing a generalised optimisation of such electromagnetic systems to maximise the axial force for a given volume or mass, while aiming for the most linear behaviour possible. A semi-analytical and dimensionless computation method is introduced and compared with existing approaches. The influence of each geometric parameter of the coil and the magnet on the axial force is investigated. Furthermore, the non-linearities induced by the displacement of the magnet in the coil’s magnetic field are quantified, and the effect of design parameters on limiting these non-linearities is analysed to identify optimal geometries. The axial force and non-linearity computations are validated through finite element simulations and experimental measurements. Finally, a study on the influence of the coil wire diameter on the force output and allowable current is also presented