International Journal of Agricultural Research, Innovation and Technology (IJARIT)
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L’égalité filles/garçons au cycle 3
No full textEquality is a strong value of the French motto : « Liberty, Equality, Fraternity » which applies to all persons living on French territory. It has been enshrined in the Constitution since 1946 and this fundamental principle condemns all forms of discrimination, in particular those related to sex. Even if progress has been made in society, the fact remains that the differentiated socialisation of girls and boys from a very early age leads to the formation of gender stereotypes. Thus, in the framework of our research, we were mainly interested in the role of the teacher in the deconstruction of gender stereotypes because the school is a determining factor in this struggle. Our research question is therefore : How can school teachers act to change mentalities about gender stereotypes and develop critical thinking in cycle 3 ? This questioning leads us to state two hypotheses and in order to verify them, we conducted a survey among cycle 3 pupils in the Académie de La Réunion to gather their initial representations. Following this, we set up a learning sequence to change their ways of acting and thinking. The results obtained enabled us to demonstrate that developing pupils' critical thinking skills enables them to deconstruct gender stereotypes and to form their own opinions for greater gender equality.L’égalité est une valeur forte de la devise française : « Liberté, Egalité, Fraternité » qui s’applique à toutes personnes vivant sur le territoire Français. Elle est inscrite dans la Constitution depuis 1946 et ce principe fondamental condamne toutes les discriminations, en particulier celles liées au sexe. Même si des avancées ont eu lieu dans la société, il n’en demeure pas moins que la socialisation différenciée dès le plus jeune âge entre les filles et les garçons aboutit à la formation de stéréotypes de genre. Ainsi, dans le cadre de nos recherches, nous nous sommes principalement intéressées au rôle de l’enseignant dans la déconstruction des stéréotypes genrés car l’école est un facteur déterminant dans cette lutte. Notre question de recherche vise donc à savoir : Comment les professeurs des écoles peuvent-ils agir pour faire évoluer les mentalités sur les stéréotypes de genre et développer l’esprit critique au cycle 3 ? Ce questionnement nous amène à énoncer deux hypothèses et afin de les vérifier, nous avons réalisé une enquête auprès des élèves du cycle 3 de l'académie de La Réunion pour recueillir leurs représentations initiales. Suite à cela, nous avons mis en place une séquence d’apprentissage pour faire évoluer leurs manières d’agir et de penser. Les résultats obtenus nous ont permis de démontrer que développer l’esprit critique des élèves permet de déconstruire les stéréotypes de genre et de forger leur propre opinion pour plus d’égalité entre les sexes
Analysis of CO2, CH4, and CO surface and column concentrations observed at Réunion Island by assessing WRF-Chem simulations
No full textInternational audienceRéunion Island is situated in the Indian Ocean and holds one of the very few atmospheric observatories in the tropical Southern Hemisphere. Moreover, it hosts experiments providing both ground-based surface and column observations of CO 2 , CH 4 , and CO atmospheric concentrations. This work presents a comprehensive study of these observations made in the capital Saint-Denis and at the high-altitude Maïdo Observatory. We used simulations of the Weather Research and Forecasting model coupled with Chemistry (WRF-Chem), in its passive tracer option (WRF-GHG), to gain more insight to the factors that determine the observed concentrations. Additionally, this study provides an evaluation of the WRF-GHG performance in a region of the globe where it has not yet been applied. A comparison of the basic meteorological fields near the surface and along atmospheric profiles showed that WRF-GHG has decent skill in reproducing these meteorological measurements, especially temperature. Furthermore, a distinct diurnal CO 2 cycle with values up to 450 ppm was found near the surface in Saint-Denis, driven by local anthropogenic emissions, boundary layer dynamics, and accumulation due to low wind speed at night. Due to an overestimation of local wind speed, WRF-GHG underestimates this nocturnal buildup. At Maïdo, a similar diurnal cycle is found but with much smaller amplitude. There, surface CO 2 is essentially driven by the surrounding vegetation. The hourly column-averaged mole fractions of CO 2 (XCO 2) of WRF-GHG and the corresponding TCCON observations were highly correlated with a Pearson correlation coefficient of 0.90. These observations represent different air masses to those near the surface; they are influenced by processes from Madagascar, Africa, and further away. The model shows contributions from fires during the Southern Hemisphere biomass burning season but also biogenic enhancements associated with the dry season. Due to a seasonal bias in the boundary conditions, WRF-GHG fails to accurately reproduce the CH 4 observations at Réunion Island. Furthermore, local anthropogenic fluxes are the largest source influencing the surface CH 4 observations. However, these are likely overestimated. Furthermore, WRF-GHG is capable of simulating CO levels on Réunion Island with a high precision. As to the observed CO column (XCO), we confirmed that biomass burning plumes from Africa and elsewhere are important for explaining the observed variability. The in situ observations at the Maïdo Observatory can characterize both anthropogenic signals from the coastal region
Evolution of the East African Rift System from trap-scale to plate-scale rifting
No full textInternational audienceMany continental rifts are subjected to volcanism in tandem with rifting, which has raised a long-standing debate about whether magmatism is the cause or the consequence of plate fragmentation. To re-evaluate this chickenand-egg question, we took advantage of five decades of research on the East African Rift System (EARS), the largest active continental rift on Earth, to explore the spatial and temporal relationship between rifting and magmatism. By comparing the co-occurrence of tectonics and volcanism since the Eocene with the present-day seismicity, we delimit the EARS as a ~ 5000 km-wide zone of volcano-tectonics made of four branches affecting not only East Africa but also the Mozambique channel and Madagascar. We then developed a quality filtering procedure of published radiometric ages in order to build two independent, robust, and comprehensive age compilations for magmatism and rifting over this extended EARS. Our thorough quality-checked selection of ages reveals that the EARS presents two distinct regimes of volcanism. Since the Upper Eocene, the rift system was affected by (1) pulses of volcanism in 500-1000 km-wide areas, and (2) a discontinuous but remarkably simultaneous volcanic activity, scattered along the four branches of the EARS since 25-27 Ma. Combining this spatio-temporal evolution of volcanism with a critical review of the timing of rifting, we show that the tectonics of the EARS evolves through time from trap-scale to plate-scale rifting. Until the Middle Miocene, extension structures first developed following flood basalt events and plateau uplifts. Then, volcanism resumed synchronously all over the EARS at ca. 12-12.5 Ma, followed by a general extensional deformation. This evolution, which cannot be explained by the sole action of a plume or of tectonics, is therefore interpreted in an intermediate way in which the EARS results from (1) extensive stresses acting on the African lithosphere in the longlived context of the Gondwana breakup and (2) an overall complex mantle upwelling dynamics arising from the African Large Low Shear Velocity Province (LLSVP). We propose that extension stresses affecting the African lithosphere also modulate the melting of mantle anomalies and/or the collection of magma through the Pan-African belts. This influence explains the synchronous occurrence of many magmatic and tectonic events in the EARS and at the boundaries of the Nubia and Somali plates. Finally, our results suggest that the source of extension stresses affecting the African plate probably evolved from a dominant far-field origin to prevailing variations of gravitational potential energy (GPE) and a diverging basal shear of the Nubia and Somali lithosphere. This change would stem from an increase of the mantle flux in the Middle Miocene, yielding a change in the EARS' dynamics from trap-scale to plate scale rifting
New Low-Cost Ceramic Microfiltration Membranes for Bacteria Removal
No full textInternational audienceSafe water provision in low-income countries is constrained by limited financial resources, and the problem is worsened during natural disasters. Thus, there is a need to develop efficient low-cost technologies for point-of-use water treatment. This work reports on the development of new ceramic microfiltration membranes made from mixtures of inexpensive raw materials available locally (kaolin, bentonite and limestone) and their efficiency in rejecting bacteria such as Escherichia coli and Staphylococcus aureus. Thermogravimetric analysis, differential scanning calorimetry, Fourier-transform infrared spectroscopy, X-ray diffraction, mercury intrusion porosimetry, flexural strength and water uptake were used to characterize the raw materials and membranes. The addition of limestone in the membrane fabrication increased the pore size, the porosity and, thus, the permeability of the membranes but at the expense of the rejection performance. Among the different compositions studied, the membrane made of 83% kaolin, 10% bentonite and 7% limestone showed the best performance compromise with water permeability of 566 L·h−1·m−2·bar−1 and 100% rejection of both Escherichia coli and Staphylococcus aureus. These new low-cost microfiltration membranes are expected to have potential applications in water treatment and household applications. © 2022 by the authors. Licensee MDPI, Basel, Switzerland
Nouvelles approches thérapeutiques pour réduire les réponses au stress associées aux dysfonctions cérébrovasculaires et réparatrices en situation diabétique par des principes actifs vectorisés
No full textDiabetes is a major health issue worldwide. It is characterized by hyperglycemia, insulin resistance and is associated with many microvascular and macrovascular complications. In diabetic conditions, methylglyoxal (MGO) levels are increased. MGO is a major precursor of advanced glycation end products (AGE) formation and it induces cellular oxidative stress, inflammation and endoplasmic reticulum (ER) stress. These cellular stresses play a crucial role in endothelial and blood brain barrier (BBB) dysfunctions and also delay the wound healing. My thesis objective was to improve the drug delivery of a plant derived compound (Curcumin). Curcumin has several beneficial properties such as antioxidant and anti-inflammatory properties but its effects are limited due to its hydrophobic nature. Nanovectors such as High Density Lipoprotein (HDL) or micelles may help to improve the delivery of curcumin. Curcumin vectorized by HDL or micelles were evaluated in two different models: in vitro brain endothelial cell protection from methylglyoxal and in vivo tail regeneration in Zebra fish. Curcumin loaded rHDL nanoparticles (Cur-rHDLs) were prepared by mixing HDL and curcumin briefly followed by ultracentrifugation. Amount of curcumin loaded was quantified by LC-MS/MS analysis. Brain endothelial cells (Bend3), were pre-treated with rHDL, curcumin and Cur-rHDLs for 1h before co-incubating with MGO. Cur-rHDLs showed a protective effect by reducing the cytotoxicity, reactive oxygen species (ROS) production, ER stress, and chromatin condensation induced by MGO. It also improved the endothelial cell integrity impaired by MGO. Cur-rHDLs showed a synergistic effect compared to curcumin or rHDL alone. Curcumin loaded carrageenan polysaccharide micelles (Cur-micelles) were prepared by using oligocarrageenan (digested carrageenan) copolymerized with polycaprolactone. Curcumin was loaded by acetone volatilization method. Cur-micelles were characterized by nuclear magnetic resonance analysis and dynamic light scattering analysis. On the Zebrafish tail amputation model, Cur-micelles increased macrophages and neutrophils recruitment to the site of tail injuryand had a positive impact on the tail regeneration by increasing the tail regenerative area. Curmicelles also showed a synergistic effect compared to curcumin or micelles alone. These studies show the potential beneficial effects of Cur-rHDLs and Cur-micelles on MGO stimulated endothelial cells and on zebrafish tail regeneration, respectively. They open new research perspectives to further investigate and understand the mechanisms that can be used to develop therapeutics for diabetic vascular complications.Le diabète est un problème majeur de santé publique. Il est caractérisé par une hyperglycémie, une résistance à l’insuline et est associé à des complications macro et micro vasculaires. En situation de diabètes, la concentration de méthylglyoxal (MGO) est augmentée. Le MGO est un précurseur des produits avancés de glycation (AGE) et il induit un stress oxydatif, une inflammation et un stress du réticulum endoplasmique. Ces stress jouent un rôle important dans les dysfonctions endothéliales et de la barrière hématoencéphalique ainsi que dans le retard de réparation des lésions. L’objectif de ma thèse a été d’améliorer la délivrance de curcumine, une molécule d’origine végétale. La curcumine a plusieurs effets bénéfiques tel que des activités anti oxydantes et anti inflammatoires, mais ces effets sont limités par son hydrophobicité. Des nanovecteurs tel que des protéines de hautes densités (HDL) ou des micelles peuvent améliorer la délivrance de la curcumine. L’effet de la curcumine, vectorisée par des HDL ou par des micelles, a été évaluée dans deux modèles différents : la protection de cellules endothéliales en présence de MGO in vitro et in vivo, la régénération de la nageoire caudale chez le poisson zèbre. Des nanoparticules de rHDL associées avec la curcumine (Cur-rHDLs) ont été préparées par ultracentrifugation après avoir mélangé brièvement les HDL avec la curcumine. Une analyse par LC-MS/MS a permis de quantifier la curcumine associée aux HDL. Les cellules endothéliales cérébrales Bend3 ont été prétraitées 1 heure en présence de rHDL, de curcumine ou de Cur-rHDLs puis incubées en présence de MGO. Sur des cellules traitées par du MGO, la Cur-rHDLs a montré un effet protecteur en réduisant la cytotoxicité, la production d’espèces radicalaires d’oxygène, le stress du réticulum endoplasmique et la condensation de la chromatine. Elle améliore également l’intégrité des cellules endothéliales compromise par le MGO. La Cur-rHDLs a un effet synergique en comparaison des effets de la curcumine ou des rHDLs seuls. Des micelles de polysaccharide d’algues (des carraghénanes) associées avec de la curcumine (Cur-micelles) ont été préparées en copolymérisant des oligocarraghénanes (carraghénanes digérées) avec du polycaprolactone. La curcumine a été associée aux micelles par la méthode d’évaporation de l’acétone. Les Cur-micelles ont été caractérisées par des analyses de spectroscopie de résonance magnétique nucléaire et de diffusion dynamique de la lumière. Dans ce modèle, les Cur-micelles augmentent le recrutement des macrophages et des neutrophiles au site de la lésion ainsi que la taille de la surface de la nageoire régénérée. Les Cur-micelles ont également un effet synergique en comparaison des effets de la curcumine ou des micelles seules. Ces travaux montrent les effets bénéfiques des Cur-rHDLs sur des cellules endothéliales en présence de MGO et des Cur-micelles sur la régénérescence de la nageoire caudale des poissons zèbres. Ils permettent une meilleure compréhension de ces approches et ouvrent de nouvelles perspectives de recherche pour le développement de thérapies dans le cadre de complications vasculaires associées au diabète
Optimal Renewable Resource Harvesting model using price and biomass stochastic variations: A Utility Based Approach
No full textInternational audienceIn this article, we provide a general framework for analyzing the optimal harvest of a renewable resource(i.e. fish, shrimp) assuming that the price and biomass evolve stochastically and harvesters have a constantrelative risk aversion (CRRA) . In order to take into account the impact of a sudden change in the environ-ment linked to the ecosystem, we assume that the biomass are governed by a stochastic differential equationof the ‘Gilpin-Ayala’ type, with regime change in the parameters of the drift and variance. Under the aboveassumptions, we find the optimal effort to be deployed by the collector (fishery for example) in order tomaximize the expected utility of its profit function. To do this, we give the proof of the existence anduniqueness of the value function, which is derived from the Hamilton-Jacobi-Bellman equations associatedwith this problem, by resorting to a definition of the viscosity solution
A coherent biogeographical framework for Old World Neogene and Pleistocene mammals
No full textInternational audienceAbstract: In order to understand mammalian evolution and compute a wide range of biodiversity indices, we commonly use the ‘bioregion’, a spatial division adapted to ecological and evolutionary constraints. While commonly conducted byneontologists, the establishment of bioregions in palaeontology is generally a secondary analysis, shaped on subjective time scales and areas specific to the investigated questions and groups. This heterogeneity, coupled with the scale dependency of biodiversity indices, prevents the clear identification of macroecological and macroevolutionary trends for large taxonomic groups like extinct mammals. Here we tackle this issue by providing a coherent framework for Neogene and Pleistocene mammals of the Old World following two steps: (1) a temporal scale adapted to mammalian evolutionary history (i.e. evolutionary fauna) is defined by poly-cohort analysis; (2) bioregions are then computed for each evolutionary fauna by clustering, ordination and intermediate approaches at multiples spatial scales (i.e. continental to regional) for Eurasia and Africa. Additionally, providing a coherent framework for a wide range of mammalian datasets, our results show: (1) the synchronous emergence and fall of five mammalian evolutionary faunas identified at chronological scales varying from the epoch to the geological stage; (2) a transition from a longitudinal to a latitudinal biogeographical structuring between the Miocene and Pliocene, especially in Europe; (3) the long-term affinity of southern Asian with African faunas, in sharp contrast with the modern Palaearctic bioregion extension; and (4) the establishment of a vast Mediterranean bioregion from fragmented areas in the Late Miocene to its full extent in the Pleistocene
No increased risk of Kaposi sarcoma relapse in patients with controlled HIV‐1 infection after switching protease inhibitor‐based antiretroviral therapy
No full textInternational audienceObjectives: Our aim was to assess if switching from a protease inhibitors (PI)-based regimen to a PI-free one is associated with an increased risk of Kaposi Sarcoma (KS) relapse among patients living with HIV (PLHIV) with history of KS and controlled HIV replication.Methods: In a retrospective analysis of the prospectively collected Dat'AIDS database we selected patients who both had a past KS history and a HIV-1 viral load below 200 copies/mL while being PI-treated. We searched for KS relapses while persistent virological success was maintained for at least 6 months, whether patients kept taking the PI, or switched to PI-free regimen.Results: Among the 216 patients with past KS event and a history of HIV-1 infection efficiently treated by a PI-based regimen, 148 patients (68.5%) later switched to a PI-sparing regimen. Their baseline characteristics were not different from non-switching patients. We described 7 cases of relapse (3.2% of the 216 patients). Five cases of relapse occurred in switching patients (3.4%). The remaining two relapses occurred in PI-treated patients (2.9%). At KS relapse, CD4 cell count was 459 cells/μL (range 225-560) for switching patients, compared with 362 and 136 cells/μL for the other two patients.Conclusions: In this large cohort of PLHIV with a history of KS and ART-controlled HIV replication, KS relapses were described in 3.2% of the patients, and were not more frequent when a PI-containing ART regimen has been switched to a PI-free regimen. Our results do not support a specific effect of PI on KS
« L’Âme des guerriers (1990) d’Alain Duff : un succès de scandale en Nouvelle-Zélande. » (Sylvie Largeaud-Ortega, Orientalisme ou défi postcolonial ? Le cas de L’Âme des Guerriers d’Alan Duff, Paris, Honoré Champion, coll. « Bibliothèque de littérature générale et comparée », 2021, 978-2-7453-5586-7, 270 p.) dans Acta fabula, volume 23, numéro 3, mars 2022.
No full textRecent Advances in Hybrid Energy Harvesting Technologies Using Roadway Pavements: A Review of the Technical Possibility of Using Piezo-thermoelectrical Combinations
No full textInternational audienceCurrently, we are facing an energy transition due to pollution and depletion issues related to fossil energy sources. Among all the efforts to develop alternative green energy sources, there are other energy sources that remain unexplored. Ambient energies present on roadway pavements are one example. Thermal energy from solar radiation and the mechanical vibrations induced by passing vehicles are promising ambient energy sources available from roadway pavements. The aim of this study is to examine the existing energy harvesting systems for these ambient energy sources. This paper also summarizes existing study efforts on hybrid (thermal and mechanical vibration) energy harvesting systems in general. This hybrid system can overcome the limitations of a single source-based system as intermittent and low power generation. Energy harvesting technologies can generate green energy without negative environmental impact during the conversion process. This article solely contains references to studies examining the technological feasibility of a road energy harvesting project. Despite their importance, this bibliographic research did not include attempts to address costs, life cycle analyses, or the impact of the systems on the road structure. The reasons for this omission are due to the difficulty of obtaining this information in the scientific literature for comparison with the suggested systems