Barycentremetry, spine disorders, posture and motion analysis

International audiencePurpose of the research: Prevention of spine disorders and their management require better understanding of related biomechanical issues. While tremendous progress has been performed for musculoskeletal modelling of the spine, subject specific modelling of the gravitational loads and their effects on the spine is still an issue. Recently, 3D reconstruction of the skeleton from biplanar head to feet X-rays in erect position has been completed by the external body envelope. An approach named “barycentremetry” based on density models to estimate the mass and centre of mass of each body segment, yielding a force plate less estimation of the gravity line, together with the estimation of the gravitational loads and the associated lever arm at each vertebral level.Principal results: Due to vertebral pose, gravitational loads effect on intervertebral disc shows wide variation. Studies exploring barycentremetry clinical relevance were analysed, particularly for adolescent idiopathic scoliosis, adult spinal deformities and osteoporosis. They progressively yield a better comprehension of the potential vicious circles linking postural disorder to increase of spine loads to increase of postural disorder.Barycentremetry was also explored within gait and motion analysis research, allowing to estimate subject specific body segments inertial parameters for patient specific dynamic analysis. Indeed, 3D musculoskeletal modelling of posture and motion could benefit from subject specific dynamic analysis based on barycentremetry.Major conclusions: Such approaches progressively provide a better understanding of the stability of this complex system and compensation strategies that could be useful for early detection of disorders that are responsible of a biomechanical cascad

Analyse mathématique et numérique d’un contrôle optimal bilinéaire pour le systèmede Keller-Segel dégénéré

This thesis is dedicated to the theoretical and numerical study of an optimal control problem applied to a chemotaxis system of Keller–Segel type, characterized by a doubly degenerate diffusion.A bilinear control is introduced in the equation of the chemoattractant concentration in order to steer both the cell density and the chemical concentration toward desired target states, while minimizing a quadratic cost functional under the constraints imposed by the weak formulation of the controlled system. This new formulation circumvents the need for strong solution regularity.To establish the existence of solutions for the state system, the optimal solutions, and the adjoint problem associated with the Lagrange multipliers, an approach combining time semi-discretization with the Faedo–Galerkin method is implemented. This strategy allows the proof of existence of weak solutions for the problem in the non-degenerate case. By introducing two distinct types of degeneracy in the diffusion function, two suitable weak formulations are proposed to ensure the existence of solutions for the corresponding adjoint problem.Subsequently, the existence of Lagrange multipliers is established using two complementary techniques: the first relies on a direct analysis of the weak formulation of the adjoint problem, while the second is based on the Fréchet derivative of the linearized system, in conjunction with the regular point theorem, to ensure the necessary optimality conditions.On the numerical side, two distinct strategies are explored. The first, of the optimize-then-discretize type, relies on discretizing the state and adjoint problems using the finite element method in space and a semi-implicit Euler method in time. Optimization is carried out via the projected gradient method. This work led to the implementation of an advanced computational code using FreeFem++, allowing the validation of theoretical results through numerical simulations.The second strategy, of the discretize-then-optimize type, involves discretizing the state system using a finite volume method (TPFA or CVFE schemes), ensuring scheme stability and local conservation. The discrete adjoint system is then rigorously derived from the linearized system obtained by differentiating the discrete state problem.These contributions also open up numerical perspectives, particularly the exploration of more efficient optimization algorithms than the gradient method, in order to better handle degenerate models.Cette thèse est consacrée à l’étude théorique et numérique d’un problème de contrôle optimal appliqué à un système de chimiotaxie de type Keller–Segel, caractérisé par une diffusion doublement dégénérée. Un contrôlebilinéaire est introduit dans l’équation de la concentration du chimioattractant afin de guider la densité cellulaire et la concentration chimique vers des états cibles, tout en minimisant une fonction coût quadratique sous les contraintes imposées par la formulation faible du système contrôlé. Cette nouvelle formulations’affranchie de la régularité des solutions fortes. Afin d’établir l’existence de solutions pour le problème direct, des solutions optimales, ainsi que du problème adjoint associé aux multiplicateurs de Lagrange, une approche combinantla semi-discrétisation en temps avec la méthode de Faedo–Galerkin est mise enoeuvre. Cette stratégie permet de démontrer l’existence de solutions faibles pour le problème dans le cas non dégénéré. En introduisant deux types distincts de dégénérescence sur la fonction de diffusion, deux formulations faibles appropriées sont proposées afin d’assurer l’existence de solutions au problème adjoint correspondant. Par la suite, l’existence des multiplicateurs de Lagrange est établie à l’aide de deux techniques complémentaires : la première repose sur une analyse directe de la formulation faible du problème adjoint, tandis que la seconde s’appuie sur la dérivée de Fréchet du système linéarisé, en conjonction avec le théorème dupoint régulier, afin de garantir les conditions d’optimalité nécessaires. Sur le plan numérique, deux stratégies distincts sont étudiées. La première, de typeoptimiser puis discrétiser, repose la discrétisation du problème direct et adjoint par la méthode des éléments finis en espace et la méthode d’Euler semi-implicite en temps. L’optimisation est réalisée par la méthode du gradient avec projection. Ce travail a donné lieu à l’implémentation d’un code de calcul avancé sous FreeFem++, permettant de valider les résultats théoriques par des simulations numériques. La seconde stratégie, de type discrétiser puis optimiser. Le système direct est discrétisé par une méthode de type volumes (schéma TPFA ou CVFE), assurantla stabilité du schéma et la conservation locale. Ensuite, le système adjoint discret est dérivé rigoureusement à partir du système linéarisé obtenu par la dérivation du problème direct discret. Ces travaux ouvrent également des perspectives numériques, notamment l’exploration d’algorithmes d’optimisation plus performants que la méthode du gradient, afin de mieux traiter les modèles dégénérés

Impact du traitement thermique réglementaire (70°C, 1 heure) sur les enterocoques et les clostridies lors de la digestion anaérobie mésophile et thermophile

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A Multinational Study on the Mediating Effect of TikTok Addiction Between Psychological Distress and Academic Self-Efficacy Among University Students

International audienceWith the rapid rise in TikTok usage among youth, concerns regarding its addictive usage and impact on mental health and academic performance have emerged. The present study was undertaken to evaluate whether TikTok addiction mediates the relationship between psychological distress (depression and anxiety) and academic self-efficacy (ASE) of Arab university students. A cross-sectional survey was conducted among 3257 university students in Egypt, Jordan, Lebanon, Palestine, and Oman. Students completed validated Arabic translations of measures of our variables of interest. Mediation analyses were carried out using the PROCESS macro in SPSS, after adjusting for relevant covariates. TikTok addiction significantly mediated the relationship between psychological distress and ASE. Specifically, it partially mediated the link of anxiety (indirect effect: Beta = - 0.28 (indicating a moderate negative association); Boot SE = 0.04; Boot 95% CI - 0.35, - 0.20) and depression (indirect effect: Beta = - 0.28 (indicating a moderate negative association); Boot SE = 0.04; Boot 95% CI - 0.35, - 0.20) to ASE. Higher depression and anxiety were significantly associated with higher TikTok addiction, and higher TikTok addiction was significantly associated with lower ASE. In addition, higher depression and anxiety were significantly and directly associated with lower ASE. Conversely, when TikTok addiction was modeled as the independent variable, both anxiety (indirect effect: Beta = - 0.05; Boot SE = 0.01; 95% CI - 0.08; - 0.03) and depression (indirect effect: Beta = - 0.05; Boot SE = 0.01; 95% CI - 0.08; - 0.03) mediated its negative association with ASE. Problematic TikTok use and psychological distress appear to reinforce one another in diminishing students' academic confidence. This reciprocal mediation highlights a harmful cycle in which TikTok addiction and internalizing symptoms jointly erode ASE. Interventions targeting social media addiction could enhance students' academic functioning and well-being in Arab university settings

Environmental aldehydes exposure and the health implications among a cohort of traffic police in Lebanon

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Blue Light's Impact on Skin Barrier Components: Insights from NP-LC/HR-MS n and Raman Analyses

International audienceSkin health relies heavily on a well-maintained cutaneous barrier. While the detrimental effects of UV radiation on the epidermis are established, the impact of blue light, a significant component of sunlight and artificial sources, is less clear. This study aims to explore blue light’s influence on the reconstructed human epidermis (RHE) using two complementary analytical approaches: Raman microspectroscopy and normal phase liquid chromatography coupled with high-resolution mass spectrometry (NPLC/HR-MSn). RHE samples were exposed to blue light (415 nm and 455 nm) during different stages of their maturation.Raman spectra were acquired for both irradiated and non-irradiated (control) samples. Raman descriptors were analyzed to assess potential alterations in the structural organization of proteins and lipids’ conformational changes. Additionally, lipids from RHE samples were extracted and analyzed using NPLC/ HR-MSn. Blue light exposure led to changes in the structural organization of RHE lipids and proteins, as well as changes in the lipid composition. These changes varied depending on the wavelength and exposure dose. Exposure to blue light could disrupt the integrity of the skin’s protective barrier, leading to increased sensitivity to environmental stressors and potential skin damage

The relative contribution of discs and vertebral bodies to thoracic kyphosis in healthy volunteers

International audienceIntroduction : Understanding the normal anatomy of thoracic kyphosis (TK) in healthy subjects is essential for evaluating sagittal malalignment and planning the surgery accordingly. The aim of this study was to identify the proportion of thoracic kyphosis originating from disc versus vertebral body shape and to describe its variation according to age and thoracic kyphosis magnitude.Methods : This study was a retrospective review of a prospective multicenter database of healthy volunteers aged 18 years or older. Vertebral body and disc sagittal Cobb angles were measured at each level and summed within each of the 3 TK regions (Upper, Middle and Lower TK). Relative contributions of discs and vertebral bodies to Upper, Middle, Lower, and total TK were assessed in the whole cohort, and according to age and TK groups, after stratification. Finally, a multivariate analysis including age and TK magnitude was conducted.Results : Among these 645 subjects, the mean age was 37.6 ± 16.3 years with 51% of females. Intervertebral discs were kyphotic in Upper and Middle TK with respective discs contribution to total TK of 4.2% and 9.6%, for a total of 13.8% of total kyphosis. Lower TK discs were lordotic, with a participation of -13.2% of total TK, leading to an overall discs contribution to TK of 0.6%. Vertebral bodies were all kyphotic with a contribution of 99.4% of total kyphosis. Vertebral bodies kyphosis increased across age groups for Middle TK (p = 0.004), Lower TK (p < 0.001), and Total TK (p < 0.001). Discs contributions to total TK increased significantly with increasing TK (-13.8% for Low TK, -1.5% for Average-Low TK, 5.7% for Average-High TK and 9.1% for High TK), (p < 0.001). Finally, discs contribution was significantly greater in males than in females, with respective values of 2.6% and -1.8% (p = 0.01).Conclusion : This study highlights the predominant role of vertebral bodies contribution to thoracic kyphosis, 99.4% on average. The contribution of disc to thoracic kyphosis (values ranging from -13.8% to 9.1%) increases significantly with increasing thoracic kyphosis magnitude. The association of age with thoracic kyphosis was greater for vertebral bodies than discs, particularly in Middle and Lower TK

Survival of Ceramic Veneers: Impact of Dentin Exposure and Tooth Vitality After 1 to 15 Years of Follow‐Up

International audienceObjective: This retrospective clinical study aimed to evaluate the survival rates of ceramic laminate veneers in relation to dentin exposure, endodontic treatment, preparation design, and the type of dual-cure resin cement used. Materials and Methods: A total of 672 veneers were placed in 189 patients and followed for 1 to 15 years. Veneer supporting teeth were categorized after etching based on the degree of dentin exposure into three groups: GA1 (enamel only), GA2 (&lt; 30% dentin), and GA3 (&gt; 30% dentin). Additional variables included endodontic treatment, preparation design, and the resin cement system used. Kaplan-Meier survival analysis, Log-Rank tests (α = 0.05), and Odds Ratios (ORs) were computed. All procedures were performed by a single clinician, veneers were fabricated by a single ceramist, and the study was performed by a different, single examiner. Results: The cumulative 15-year estimated survival rate was 96%, mean survival 5.98 years. Veneers in the GA1 group showed an estimated survival rate of 96.7%, compared to 95.3% in GA2 and 93.9% in GA3. A statistically significant difference was found between GA1 and GA3 (p = 0.033). Endodontically treated teeth and those with dentin exposure exhibited higher risks of failure (OR = 1.68 and 3.47, respectively). Endodontic treatment, preparation design, and resin cement type did not significantly affect survival (p &gt; 0.05).Conclusions: The extent of dentin exposure significantly impacts the survival of bonded ceramic veneers after 1 to 15 years of follow-up. Preservation of enamel is critical for optimizing outcomes. Clinical Significance: These findings suggest that meticulous patient selection, preparation techniques, optimal bonding protocols, and bonding exclusively to enamel, whenever possible, are essential for ensuring the clinical success of CLV bonded with dual-cured resi

Dans les archives du Père René Mouterde

International audienceThe archives of Father René Mouterde s.j., one of the founders of the Inscriptions grecques et latines de la Syrie (IGLS) project, are preserved in the photo library of the Bibliothèque Orientale of Université Saint-Joseph of Beirut and at the Maison de l’Orient et de la Méditerranée in Lyon. Three examples illustrate their scientific potential. Firstly, with the help of this documentation, two funerary reliefs from the Roman imperial period are attributed to the Middle Euphrates region rather than to Palmyra or Seriane. Then, an unpublished bronze plaque from the protobyzantine period is identified and published. It was used as a mark of ownership for beasts of burden belonging to a Palestinian monastery.Les archives du père René Mouterde s.j., l’un des fondateurs du programme des Inscriptions grecques et latines de la Syrie (IGLS), sont conservées à la photothèque de la Bibliothèque Orientale de l’Université Saint-Joseph de Beyrouth et à la Maison de l’Orient et de la Méditerranée à Lyon. Trois exemples illustrent leur potentiel scientifique. Tout d’abord, avec l’aide de cette documentation, deux reliefs funéraires d’époque impériale romaine sont attribués à la région du Moyen-Euphrate plutôt qu’à Palmyre ou Sériane. Ensuite, une plaquette de bronze inédite d’époque protobyzantine est identifiée et publiée. Elle servait de marque de propriété pour des bêtes de somme appartenant à un monastère palestinien

High-Throughput Analysis of the Flagella FliK-Dependent Surfaceome and Secretome in Bacillus thuringiensis

International audienceBacterial pathogens employ multiple strategies to invade and damage host tissues while evading immune defenses. Recent studies highlight flagella as crucial contributors to bacterial virulence, not only by facilitating motility, but also by regulating the secretion of virulence factors. However, the role of the flagella-dependent secretome remains largely unexplored. We have recently shown that FliK, a key regulator that defines substrate specificity in the flagellar export apparatus, is essential for the resistance of Bacillus thuringiensis (B. thuringiensis) against antimicrobial peptides (AMPs) and its virulence in a Drosophila infection model. In this study, we used liquid chromatography-tandem mass spectrometry to conduct a large-scale comparative analysis of the proteins secreted in culture supernatant or associated with the cell wall of the ΔfliK mutant and its reference strain. Our results reveal significant differences in the secretome and surfaceome of the ΔfliK mutant compared to the reference strain. These findings emphasize the role of FliK in regulating the production and secretion of several proteins, underscoring the importance of flagella in controlling various biological processes. This work provides valuable insights into the functional characterization of potential candidate proteins involved in B. thuringiensis virulence and AMP resistance mechanisms. Overall, these results open new perspectives for understanding the molecular processes that govern bacterial resistance to AMPs