HAL-Artois
Not a member yet
27242 research outputs found
Sort by
Influence du statut pondéral sur l’atténuation du signal ultrasonique mesuré au niveau du calcanéum chez un groupe de jeunes femmes
No full textInternational audienceIntroductionThe aim of our study was to investigate the effect of weight status on broadband ultrasound attenuation (BUA) measured at the calcaneus in a group of young women.Summary of facts and resultsThree hundred and twenty-nine young women (238 normal-weight women, body mass index [BMI] < 25 kg/m2) and 91 overweight women (BMI > 25 kg/m2)] with an average age of 20.3 years participated in this study. Height, fat mass, lean mass, hip circumference and waist circumference were measured. Validated questionnaires were used to assess physical activity level, sleep quality and daily calcium intake. Broadband ultrasound attenuation (BUA) of the calcaneus was measured using a valid ultrasonometry device (Pegasus Smart Medlink®). BUA values were significantly higher (P < 0.01) in the overweight group (76.43 ± 6.6) compared to the normal-weight group (74.42 ± 5.5).ConclusionOur study suggests that being overweight is associated with greater BMD values at the calcaneus level in young women. Therefore, being overweight seems to protect against osteoporotic fractures at the calcaneus in women.IntroductionLe but de notre étude était d’étudier l’effet du statut pondéral sur l’atténuation du signal ultrasonique (BUA) mesurée au niveau du calcanéum chez un groupe de jeunes femmes.Synthèse des faits et résultatsTrois cent vingt-neuf jeunes femmes (238 normo-pondérées, indice de masse corporel [IMC] < 25 kg/m2) et 91 en surpoids (IMC > 25 kg/m2) âgées en moyenne de 20,3 ans ont participé à cette étude. La taille, la masse grasse, la masse maigre, le tour de hanche et le tour de taille ont été mesurés. Des questionnaires validés ont été utilisés pour évaluer le niveau d’activité physique, la qualité de sommeil et la consommation calcique journalière. L’atténuation du signal ultrasonique (BUA) du calcanéum a été mesurée à l’aide d’un appareil d’ultrasonométrie valide (Pegasus Smart Medlink®). Les valeurs de la BUA étaient significativement supérieures (p < 0,01) dans le groupe en surpoids (76,43 ± 6,62) par rapport au groupe normo-pondéré (74,42 ± 5,5).ConclusionNotre étude suggère que la surcharge pondérale est associée à des valeurs de DMO plus élevées au niveau du calcanéum chez les jeunes femmes. Ainsi, la surcharge pondérale semble protéger contre les fractures ostéoporotiques du calcanéum chez les femmes
Impact des choix méthodologiques sur l’estimation de la variation du stock de carbone organique du sol
No full textEngineering schoolIn response to the rising atmospheric concentration of greenhouse gases, which is one of the main drivers of global warming, soils are increasingly recognized as a strategic lever in climate mitigation efforts. As the largest terrestrial carbon sink, they hold potential for storing carbon. It is within this context that the “4 per 1000” initiative was launched, aiming to increase soil organic carbon stocks in order to help reduce anthropogenic emissions. However, it is essential to quantify the impact of soil management practices on their carbon storage capacity. This allows us to identify which practices effectively promote sequestration and could contribute to achieving the initiative’s targets. In this study, we assessed the evolution of soil organic carbon stocks over a six-year period, corresponding to a full crop rotation, on an agricultural plot at the ICOS FR EM2 site in northern France. Two methodological approaches were employed. The first was based on soil sampling to measure changes in carbon stocks, and the second relied on carbon balance calculations using CO₂ fluxes measured through the Eddy Covariance technique. The study aimed to compare the results obtained, analyze the influence of methodological choices on the estimates, and discuss the potential of this cropping system to contribute to carbon sequestration. Our analysis examined changes in soil carbon stocks using both methods and their respective implementation variants. It highlighted the importance of corrections applied to Eddy Covariance measurements, with differences in carbon balance estimates reaching up to 1 t C/ha over six years depending on the treatment. It also emphasized the critical role of methodological choices in the soil sampling approach, with an estimated range of carbon loss between 2 and 6 t C/ha. Despite these discrepancies, both methods led to the same conclusion. The plot acts as a carbon source, with significant depletion of soil organic carbon. This finding is consistent with results from other studies conducted on cropland. However, the cropping system studied appears to have a lower emission potential, particularly due to the presence of alfalfa, a crop that is rarely represented in the agricultural systems examined in the literature.Face à l’augmentation de la concentration atmosphérique en gaz à effet de serre, principale cause du réchauffement climatique, les sols, premier puits de carbone terrestre, apparaissent comme un levier stratégique dans la lutte contre ce phénomène. C’est dans cette perspective qu’est née l’initiative « 4 pour 1000 », visant à accroître les stocks de carbone organique du sol afin de contribuer à la réduction des émissions anthropiques. Toutefois, il est essentiel de pouvoir quantifier l’impact des pratiques de gestion des sols sur leur capacité de stockage du carbone, afin d’identifier celles qui favorisent réellement cette séquestration et qui pourraient permettre d’atteindre les objectifs fixés par cette initiative. Dans ce contexte, nous avons évalué l’évolution des stocks de COS sur une parcelle agricole du site ICOS FR-EM2 dans le nord de la France sur une période de six ans, correspondant à une rotation culturale. Deux approches méthodologiques ont été mobilisées : la méthode de mesure de l’évolution du stock de COS basée sur les prélèvements de sol et le bilan carbone basé sur les flux de CO₂ mesurés par Eddy Covariance. L’étude vise à comparer les résultats obtenus, à analyser l’impact des choix méthodologiques sur les estimations, et à discuter du potentiel de ce système de culture à contribuer à la séquestration du carbone. Notre étude a examiné l’évolution des stocks de carbone dans le sol à partir de ces deux méthodes et de leurs variantes de mise en œuvre. Elle met en évidence l’importance des corrections appliquées aux mesures par Eddy Covariance, avec des écarts d’estimation du bilan carbone pouvant atteindre 1 t C/ha sur six ans selon les traitements. De même, elle souligne le rôle déterminant des choix méthodologiques dans l’approche par prélèvements de sol, avec un déstockage estimé entre 2 et 6 t C/ha. Malgré ces divergences, les deux méthodes convergent vers une même conclusion : la parcelle agit comme une source de carbone, avec un déstockage important de carbone organique du sol. Ce constat rejoint les résultats d’autres études menées sur des terres arables. Toutefois, le système de culture étudié semble présenter un potentiel d’émission moindre, notamment grâce à la présence de luzerne, une culture peu représentée dans les systèmes agricoles analysés dans la littérature
La Mécanique des Fluides à Lille : entre politiques nationales et réalités locales dans l’entre-deux-guerres
No full textModelling the finite deformation of thermoplastic polymers via hyperinelasticity, Part II: An amorphous polymer with varying rubber content-, rate- and temperature-dependency
No full textInternational audienc
Recent developments in the field of MOF-based catalytic systems: A review
No full textInternational audienceA compilation of recent advancements in the field of MOF derived catalytic systems, together with innovative synthesis and modification techniques, are presented in this comprehensive review with a focus on societal and environmental demands-driven developments of more efficient functional materials and processes. The incorporation of alternative materials such as enzymes, polymers, and metal complexes into MOFs is probed as it enables tuning and upgrading key properties such as stability, activity and selectivity. Most significantly, the tremendous potential contribution of MOF-based catalysts in converting the industrial sector into a contemporary energy production system is demonstrated by discussing several key applications in sustainable development, including valorization of CO2, biofuel manufacture, and hydrogen generation
Neural non-canonical Hamiltonian dynamics for long-time simulations
No full textThis work focuses on learning non-canonical Hamiltonian dynamics from data, where long-term predictions require the preservation of structure both in the learned model and in numerical schemes. Previous research focused on either facet, respectively with a potential-based architecture and with degenerate variational integrators, but new issues arise when combining both. In experiments, the learnt model is sometimes numerically unstable due to the gauge dependency of the scheme, rendering long-time simulations impossible. In this paper, we identify this problem and propose two different training strategies to address it, either by directly learning the vector field or by learning a time-discrete dynamics through the scheme. Several numerical test cases assess the ability of the methods to learn complex physical dynamics, like the guiding center from gyrokinetic plasma physics
Innovative advanced processes for treatment of multiple emerging pesticides from water: Performance, statistical design, QuEChERS-GC-MS/MS sensitive identification and degradation mechanism.
No full textInternational audienceThe objective of this study is the degradation of a mixture of three pesticides from three distinct families: Metalaxyl (fungicide), Metolachlor (herbicide), and Diazinon (organophosphate Insecticide). In this work, the enhanced advanced oxidation process known as "Photo-Fenton" was first optimized, and the mineralization step was determined. The experimental design and response surface "three-parameter Doehlert design" were employed as the experimental methodology to modeling and optimizing the experimental parameters. Hydrogen peroxide, ferrous iron, and pH were the factors examined in this investigation. The mathematical model obtained was also validated. In the optimal conditions mg L−1, = 395.2 mg L−1 and pH=3.47, an 81 % mineralization rate was achieved. By combining the QuEChERS extraction method (Quick, Easy, Cheap, Effective, Rugged, and Safe), pre-concentration with the evaporation protocol, and GC–MS/MS analysis, a novel analytical methodology for determination of three analytes and the by-products of photo-degradation was developed. It was observed that this approach performed well for all analytes and the by-products detection at trace and ultra-trace levels. MTCh produced 12 by-products, DZN produced six, and MTX produced five intermediates after 15 min of degradation. Under the same ideal operating conditions, other alternative processes were tested to boost the mineralization yield: Fenton with an efficiency of 70 %, Photo-Fenton with two lamps 85 %. The yield for the adsorption procedure was 72 %. However, the cyclic approach, which started with Photo-Fenton and proceeded with adsorption, achieved a 90 % yield, and with the hybrid process (adsorption and Photo-Fenton process), the mineralization reached 99 % after just 60 min and was able to attain nearly complete mineralization by combining the processes of degradation and removal simultaneously