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Enhanced diffusion over a periodic trap by hydrodynamic coupling to an elastic mode
No full textInternational audienceIn many physical systems, degrees of freedom are coupled \emph{via} hydrodynamic forces, even in the absence of Hamiltonian interactions. A particularly important and widespread example concerns the transport of microscopic particles in fluids near deformable boundaries. In such a situation, the influence of elastohydrodynamic couplings on Brownian motion remains to be understood. Unfortunately, the temporal and spatial scales associated with the thermal fluctuations of usual surfaces are often so small that their deformations are difficult to monitor experimentally, together with the much slower and larger particle motion at stake. Here, we propose a minimal model describing the hydrodynamic coupling of a colloidal particle to a fluctuating elastic mode, in presence of an external periodic potential. We demonstrate that the late-time diffusion coefficient of the particle increases with the compliance of the elastic mode. Remarkably, our results reveal that, and quantify how: i) spontaneous microscopic transport in complex environnements can be affected by soft boundaries -- a situation with numerous practical implications in nanoscale and biological physics; ii) the effects of fast and tiny surface deformations are imprinted over the long-term and large-distance colloidal mobility -- and are hence measurable in practice
Impact des altérations taphonomiques surfaciques de l’os sur les études en morphométriegéométrique.
No full textInternational audienceTaphonomic alterations on bioarchaeological remains are common and can have amajor impact on osteological collections. During geometric morphometric analyses, the bonesused may be more or less well preserved, and studies may be limited due to these alterations. Weinvestigated the impact of taphonomic surface alterations on bone shape studies. To this end, weselected 19 humeri from the La Granède site (a medieval funerary complex in Millau, 12) in anexcellent state of preservation. In our study, we virtually applied taphonomic shrinkage andmaterial addition to this reference population. These two types of virtual degradation weredesigned to mimic the effects of roots and concretions on bone. We then compared themorphologies of the bones before and after alteration using a geometric morphometry protocol.We were able to see that, when there is a fairly slight removal of material that can be compared tothe action of roots on a bone, the data remain usable and similar to those of the reference group.On the contrary, when sediment is added, the data are unreliable and the difference with thereference group is significant. These results therefore call into question the use of archaeologicaldata with taphonomic alterations in morphological studies, while demonstrating the possibility ofretaining bones with certain types of alteration in studies.Les altérations taphonomiques des vestiges bioarchéologiques sont courantes etpeuvent grandement impacter les collections ostéologiques. Lors d’analyses en morphométriegéométrique, les os utilisés peuvent présenter une conservation plus ou moins satisfaisante et lesétudes peuvent être limitées en raison de ces altérations. Nous nous sommes intéressés àl’impact des altérations taphonomiques surfaciques des os sur les études de forme. Pour cela,nous avons sélectionné 19 humérus d’individus issus du site de La Granède (ensemble funérairemédiéval situé à Millau, 12) présentant un excellent état de conservation. À travers l’étude quenous avons menée, nous avons appliqué virtuellement des altérations taphonomiques en retrait eten ajout de matière sur cette population de référence. Ces deux types de dégradations virtuellesont eu pour but de mimer les effets de racines et de concrétions sur l’os. Nous avons ensuitecomparé les morphologies des os avant et après altération par un protocole en morphométriegéométrique. Nous avons donc pu voir que, lorsqu'il y a un retrait de matière assez léger qui peutêtre comparé à l'action des racines sur un os, les données restent exploitables et similaires àcelles du groupe de référence. Au contraire, lorsqu'il y a un ajout de matière, les données ne sontpas fiables et la différence avec le groupe de référence est importante. Ces résultats questionnentdonc sur l’utilisation de données archéologiques avec des modifications taphonomiques dans lesétudes morphologiques tout en démontrant la possibilité de conserver, dans les études, des osprésentant certains types d’altérations
Clarifications about upscaling diffusion with heterogeneous reaction in porous media
No full textInternational audienceThe upscaling process of coupled (single- and two-species) diffusion with heterogeneous chemical reaction in homogeneous porous media is revisited in this work with several important clarifications following the article from Bourbatache et al. (Acta Mech 234: 2293-2314, 2023. https://doi.org/10.1007/s00707-023-03501-w). It is shown that the upscaled model obtained from the volume averaging method (VAM) or, equivalently, following an adjoint and Green’s formulation technique provides a closed model without any a priori assumption on the form of the solution for the pore-scale concentration involved in the spectral approach used in the periodic homogenization method (PHM) reported in the above reference. Through comparison with direct pore-scale simulations, the VAM model is shown to outperform the predictions of the average concentration and average flux profiles for the simple two-dimensional configuration considered in Bourbatache et al. (Acta Mech 234: 2293-2314, 2023. https://doi.org/10.1007/s00707-023-03501-w) in comparison with the model obtained from PHM in this reference. Finally, identification of the apparent effective diffusion coefficient from these pore-scale simulations, which serve as in silico experiments, proves that the correct dependence upon the Damkhöler number is the one predicted by the model obtained with VAM, in contradiction with the conclusion put forth in Bourbatache et al. (Acta Mech 234: 2293-2314, 2023. https://doi.org/10.1007/s00707-023-03501-w). The physical explanation lies in the corrective contribution of the reactive part to the apparent effective diffusion coefficient, which is positive and adds up to the pure intrinsic diffusive part. The discrepancy between PHM and VAM approaches is proved to originate from the choice of changes of variables in the pore-scale concentration used in the spectral approach while employing PHM
Aidants : les salariés premiers concernés
No full textEn 2030, un salarié sur quatre sera aidant. Longtemps invisibilisée, la question de l’aidance s’invite aujourd’hui au cœur de l’entreprise
DOP076 Translational and preclinical study validating anterior gradient 2 as a novel epithelial therapeutic target in Inflammatory Bowel Disease (IBD) involved in inflammation, fibrosis, and intestinal barrier integrity
No full textInternational audienc
Nature-based solutions to increase sustainability and resilience of vineyard-dominated landscapes
No full textInternational audienceVineyards are highly intensive systems very often located in biodiversity hotspots at the global scale. These ecosystems are now facing major environmental, agronomical and economic issues that challenge their sustainability. Based on multiple evidence, I illustrate here how biodiversity and several nature-based solutions across scales, from manipulating within-field plant communities to landscape-scale diversification, can provide benefits related to key societal challenges that vineyard socio-ecosystems are facing. These findings support the idea that biodiversity and ecosystem services play a key role in the functioning of these landscapes and that nature-based solutions offer a sustainable pathway for the future of vineyard agroecosystems. This literature review also highlights several gaps of knowledge that define a research agenda for nature-based solutions to strengthen multifunctionality of vineyard landscapes
Prevalence and risk factors of maternal dissatisfaction after vaginal delivery: A multicenter prospective study
No full textInternational audienceTo evaluate the prevalence and risk factors of maternal dissatisfaction 2 days after a singleton vaginal delivery at or near term. We conducted a planned ancillary cohort study of the TRanexamic Acid for Preventing Postpartum Hemorrhage After Vaginal Delivery (TRAAP) randomized controlled trial. Maternal dissatisfaction, related to the birth and to the subsequent hospital stay, was assessed 2 days postpartum by two self-administered questions: "Are you satisfied with the care you received during your child's birth?" and "Are you satisfied with the care you have received during your hospital stay?". Satisfaction was defined by answers of "extremely satisfied" or "very satisfied," and dissatisfaction by the responses "moderately satisfied," "not very satisfied," or "not at all satisfied". Their association with maternal dissatisfaction was analyzed by random-effects logistic regression. The prevalence of maternal dissatisfaction with the birth was 2.9%, and with the hospital stay 9.5%. Characteristics associated with a higher risk of maternal dissatisfaction with the birth were labor exceeding 6 h, bad memories of the birth and, only for women without complicated deliveries, manual examination of the uterine cavity. The only characteristic associated with a higher risk of dissatisfaction with the hospital stay was non-French nationality. None of the postpartum hemorrhage, third- or fourth-degree perineal lacerations, operative vaginal delivery, episiotomy and uterine massage were associated with a higher risk of maternal dissatisfaction. Maternal dissatisfaction was low after singleton vaginal deliveries at or near term. Strategies aiming to avoid labor longer than 6 h and manual examination of the uterine cavity may decrease maternal dissatisfaction after delivery
Elucidating assembly and function of VirB8 cell wall subunits refines the DNA translocation model in Gram-positive T4SSs: Unveiling a functional cell wall complex in Gram-positive T4SSs
No full textInternational audienceBacterial type IV secretion systems (T4SSs) are widespread nanomachines specialized in the transport across the cell envelope of various types of molecules including mobile genetic elements during conjugation. Despite their prevalence in Gram-positive bacteria, including relevant pathogens, their assembly and functioning remain unknown. This study addresses these gaps by investigating VirB8 proteins, known to be central components of conjugative T4SSs in Gram-positive bacteria. However, the functional packing and precise role of VirB8 in T4SSs biology remain undefined. Our findings elucidate the nature of VirB8 proteins as cell wall components, where they multimerize and exhibit a conserved assembly pattern, distinct from VirB8 in Gram-negative bacteria. We also demonstrate that VirB8 proteins interact with other T4SS subunits and DNA, indicating their pivotal role in the building of the DNA translocation channel across the cell wall. We lastly propose a distinct architecture for conjugative T4SSs in Gram-positive bacteria compared to their Gram-negative counterparts, possibly attributed to the differences in the cell wall structure.</div
Differential cardiovascular impacts of sodium salts: unveiling the distinct roles of sodium chloride and sodium bicarbonate-consequences for heart failure patients.
No full textInternational audienceMisconceptions surrounding sodium compounds, particularly the interchangeable use of sodium and sodium chloride (table salt), persist within the medical community, influencing dietary recommendations and patient management especially in heart failure (HF) patients with chronic kidney disease (CKD). This narrative review aims to dissect these misconceptions and discusses the physiological impacts of sodium, chloride, and sodium bicarbonate on cardiovascular (CV) physiology. The conflation of sodium and sodium chloride in dietary recommendations has obscured critical differences in their physiological effects. While sodium chloride is traditionally linked to hypertension, emerging evidence suggests that chloride, rather than sodium, may be the primary driver of hypertension and activation of the renin-angiotensin-aldosterone system. In contrast, sodium bicarbonate, when administered orally, seems to exert minimal effects on blood pressure and plasma volume, offering a promising and safe way for managing HF patients with renal insufficiency. Indeed, the therapeutic benefits of sodium bicarbonate in CKD patients, including preservation of muscle mass, slowing of renal function decline, lowering of all-cause mortality, and improved nutritional status, are quite proven; this underscores its potential utility in patients suffering from both HF and renal insufficiency. Despite concerns about metabolic alkalosis, recent studies suggest that judicious sodium bicarbonate therapy may mitigate major adverse cardiac events without exacerbating HF. This review advocates for a paradigm shift in CV medicine, urging clinicians to discern between sodium chloride and other sodium salts, particularly sodium bicarbonate, in patient care. By elucidating these distinctions, clinicians can tailor dietary recommendations and therapeutic interventions to optimize outcomes for HF patients with CKD and address the multi-faceted complexities of atherosclerotic disease. This review clarifies the physiological differences between sodium chloride and sodium bicarbonate, advocating for a nuanced approach in managing cardiovascular (CV) health in patients with heart failure (HF) and chronic kidney disease (CKD). Sodium chloride (table salt) is commonly associated with hypertension, whereas chloride, rather than sodium itself, appears to be the primary factor influencing blood pressure and activation of the renin-angiotensin-aldosterone system.Sodium bicarbonate shows promise in managing CKD by preserving muscle mass, slowing renal decline, reducing all-cause mortality, and improving nutritional status without significantly impacting blood pressure or plasma volume, making it secure in patients with HF. By distinguishing between these sodium compounds, clinicians can better tailor dietary recommendations and treatments to improve outcomes for patients with HF and CKD, advancing the management of CV diseases