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Monitoring tropical forests with light drones: ensuring spatial and temporal consistency in stereophotogrammetric products
No full textInternational audienceThis study benefited from an "Investissement d'Avenir" grant managed by the Agence Nationale de la Recherche (CEBA, ref. ANR-10-LABX-25-01), via project PHENOBS. We also acknowledge the support of the UE Biodiversa+ BiodivMon program (Project Coforfunc). We are thankful to Ilona Clocher, Jean-Louis Smock, Jean-Yves Goret, Florian Jeanne and Julien Engel for their help with drone data acquisition and/or processing. Access to the Paracou site and infrastructure (https://paracou.cirad.fr) was granted by CIRAD/Ecofog, and we thank Géraldine Derroire and all Phenobs project participants. We are grateful to Raphaël Pélissier for helping in the initial shaping of the Phenobs project and for his continued support
Across ancient oceans: Eocene dispersal routes of Asian terrestrial mammals to Europe, Afro-Arabia and South America
No full textInternational audienceDuring the middle and late Eocene, Asian terrestrial mammals dispersed to Europe, while primates and rodents dispersed across the 500-to-2000 km wide Neotethys Ocean and the 1500-to-2000 km wide Atlantic Ocean to colonize Afro-Arabia and South America. This study explores how these mammals have achieved such remarkable and enigmatic dispersals. We present high-resolution paleogeographic models for the middle to late Eocene based on updated plate kinematic reconstructions, paleo-bathymetry and paleo-topography data. With this, we evaluate landmass configurations and connectivity that may have facilitated faunal exchanges from Asia toward Europe, Afro-Arabia, and South America and discuss dispersal mechanisms between these biogeographic provinces. Our reconstructions reveal that during the Bartonian (~40–38 Ma), an overland dispersal corridor between Asia and Balkanatolia became available to terrestrial mammals and acted as a pivotal pathway for Asian faunas dispersing toward western Europe and Afro-Arabia. We identified two Balkanatolian island-hopping routes across the Western Neotethys potentially enabling the dispersal of small-bodied Asian primates, rodents and artiodactyls to Afro-Arabia. Alternatively, these taxa may have rafted across the Central Neotethys. By ~34 Ma, Balkanatolia fully connected with Western Europe, opening a southern “Grande Coupure” route for Asian faunas. In the Atlantic, we identify long-distance rafting as the most plausible mechanism for the 40–34 Ma transoceanic dispersal of the Asian-originated primates and rodents from Afro-Arabia to South America despite the likely presence of sparse islands along the Walvis Ridge and the Rio Grande Rise
Effet de l'augmentation de la température sur le virus de la dengue chez le vecteur Aedes aegypti en Nouvelle-Calédonie
No full textInternational audienceDengue virus (DENV) is a major public health concern in tropical and subtropical regions, including the Pacific. Temperature is recognised as a major driver of transmission under climate change. Understanding how higher temperatures may alter DENV transmission is essential to anticipate future dengue risk. Therefore, we assessed the effect of temperature on DENV-1 in Aedes aegypti from New Caledonia. Mosquitoes were orally infected and maintained for 14 days at 26.6 °C (average temperatures during recent outbreaks) or 31.1 °C (SSP5-8.5 scenario projected temperatures). Mosquito bodies, heads, and saliva were analysed separately to determine infection, dissemination, and transmission rates as well as transmission efficiencies. Infectious virus was detected by using a fluorescent focus assay, and viral titres were quantified via TCID50 assays. No significant differences were observed in infection, dissemination, and transmission rates or transmission efficiencies between the two temperatures. However, DENV titres in mosquito bodies and heads were significantly higher at 31.1 °C than 26.6 °C. Our results indicate that elevated temperature increases viral loads within the insect but not the proportion of infectious mosquitoes, highlighting the importance of considering temperature as a key parameter in assessing dengue risk under climate change. Further studies are needed to investigate the effects of temperature on virus–mosquito interactions.Le virus de la dengue (DENV) est un problème majeur de santé publique dans les régions tropicales et subtropicales, y compris dans le Pacifique. La température est reconnue comme un facteur majeur de transmission dans le contexte du changement climatique. Il est essentiel de comprendre comment la hausse des températures peut modifier la transmission du DENV afin d'anticiper les risques futurs liés à la dengue. Nous avons donc évalué l'effet de la température sur le DENV-1 chez les moustiques Aedes aegypti de Nouvelle-Calédonie. Les moustiques ont été infectés par voie orale et maintenus pendant 14 jours à une température de 26,6 °C (température moyenne lors des récentes épidémies) ou de 31,1 °C (température prévue selon le scénario SSP5-8,5). Le corps, la tête et la salive des moustiques ont été analysés séparément afin de déterminer les taux d'infection, de dissémination et de transmission, ainsi que l'efficacité de la transmission. Le virus infectieux a été détecté à l'aide d'un test de focalisation fluorescente, et les titres viraux ont été quantifiés à l'aide de tests TCID50. Aucune différence significative n'a été observée entre les deux températures en termes de taux d'infection, de dissémination et de transmission ou d'efficacité de transmission. Cependant, les titres DENV dans le corps et la tête des moustiques étaient significativement plus élevés à 31,1 °C qu'à 26,6 °C. Nos résultats indiquent qu'une température élevée augmente la charge virale chez l'insecte, mais pas la proportion de moustiques infectieux, soulignant l'importance de considérer la température comme un paramètre clé dans l'évaluation du risque de dengue dans le contexte du changement climatique. D'autres études sont nécessaires pour étudier les effets de la température sur les interactions entre le virus et les moustiques
Stabilisation opératoire d'agents fondés sur des modèles de langage : protocole expérimental et plateforme Hermes-HSF
No full textArtisanal Dried Mango Production in Chad: Process Characterization, Hygiene Challenges and Proposed Optimization
No full textInternational audienceDried mangoes are an essential socio-economic resource in Chad, with 80% of production done via artisanal solar drying. However, current methods are slow (2 to 3 days) and carried out at low temperatures (30–45∘C), which promotes microbial proliferation and alters product quality. The objective of this study is to evaluate production and sales practices in order to propose concrete solutions to transform this vulnerable sector into a hygienic, standardized, and economically viable industry. The sector suffers from a critical lack of capacity, infrastructure, and skilled labor. This study was conducted through surveys and observations of 100 female producers and vendors in the main production areas (Logone Oriental and Occidental, Mandoul, Mayo Kebbi) to characterize the processes and identify critical control points. The results confirm that this activity is exclusively female. Production takes place on rudimentary open-air supports (3–4 days), exposing products to contamination from insects, dust, and humidity. Most producers have received no training in Good Hygiene Practices (GHP). Poor personal hygiene and inadequate cleaning of equipment constitute major risks of cross-contamination. In conclusion, despite its vital role, the artisanal dried mango production in Chad is hindered by rudimentary methods and a critical lack of hygiene. To enhance this sector, it is imperative to adopt an optimized production diagram, implement GHP and Good Manufacturing Practices (GMP), and train stakeholders in effective drying techniques and hygiene standards. This approach is crucial for ensuring the production of a safe, nutritious, and high-quality food product.
Modèle de croissance endogène de Galor et Moav (2004): analyse et résolution
No full textCe document est un papier de travail (working paper) basé sur le modèle de Galor et Moav (2004). Il présente l’analyse et la résolution numérique de la transition entre le capital physique et le capital humain, ainsi que les implications pour les inégalités économiques. Ce travail est publié à titre académique et pédagogique sous licence CC-BY, autorisant toute réutilisation avec citation de l’auteur.This document presents a solution to the Galor and Moav (2004) model, focusing on the transition from physical capital accumulation to human capital accumulation during the development process. The analysis emphasizes the micro-foundations of household decisions, particularly the trade-off between bequests in the form of physical capital and investment in education.The solution highlights the crucial role of credit constraints and demonstrates how the economy converges to a steady state where human capital becomes the endogenous driver of growth. This work provides, to some extent, an understanding of the historical shift in productive forces and the evolution of inequalities during this structural transition.Ce document présente une résolution du modèle de Galor et Moav (2004) portant sur latransition de l'accumulation du capital physique vers le capital humain au cours du processusde développement. L'analyse se concentre sur les micro-fondations des décisions des ménages, enparticulier l'arbitrage entre la transmission de legs sous forme de capital physique et l'investis-sement dans l'éducation.La résolution met en lumière le rôle crucial des contraintes de crédit et montre commentl'économie converge vers un état stationnaire où le capital humain devient le moteur endogènede la croissance. Ce travail permet tant soit peu de comprendre le basculement historique desforces productives et l'évolution des inégalités au cours de cette transition structurelle
Changes in Cooking and Breadmaking Properties of IR 841 Paddy Rice During Storage in West Africa
No full textInternational audienceTemperature and relative humidity can significantly affect quality of paddy rice during storage. Limited studies established the link between storage time, environmental fluctuations, changes in grain and flour physicochemical properties, and culinary performances. In a West African context, IR 841 paddy rice variety was stored under humid-sub-humid (HSH), and dry (DRY) conditions for 12 months. Over 12 months, rice stored under DRY conditions experienced greater environmental fluctuations than rice stored under HSH conditions. Grain water absorption capacity (WAC) increased during storage under DRY conditions, rising from 3.3 ± 0.3 to 3.8 ± 0.3 g/g DM between 0 and 12 months. Flour amylose content and soluble solids remained relatively stable from month 0 to 6 in all conditions, and further under HSH conditions. The observed changes led to improved grain cooking performance after 6 months of storage under DRY conditions. After 12 months, a decrease in rice flour WAC and a peak in viscosity were observed, while mean particle size increased from 42 ± 1 to 67 ± 3 µm under HSH conditions and from 31 ± 3 to 83 ± 3 µm under DRY conditions. Storage time may reduce the breadmaking capacity of rice flour. Overall, environmental fluctuations under DRY conditions strongly affected rice grain and flour properties.</div
Simultaneous estimation of radiance and its sensitivities to radiative properties in a spherical-heterogeneous atmospheric radiative transfer model by Monte Carlo method: Application to Titan
No full textInternational audienceWe propose a control variates technique to reduce the variance of null-collision Monte Carlo algorithms used for solving the Radiative Transfer Equation (RTE) in highly heterogeneous media. The method complements the classical spatially partitioned overestimate approach by additionally recording the minimum absorption coefficient within each voxel during preprocessing. During path tracing, the attenuation due to this minimum absorption is evaluated analytically, while the residual part is handled by path-samplings. This analytical treatment significantly improves convergence particularly in strongly absorbing media such as the planetary atmospheres in infrared absorbing band. The mathematical equivalence between the original and control-variates estimators is demonstrated, and numerical applications for Earth's and Titan's atmospheres confirm the expected variance reduction.</div
Charcoal Prepared from Detarium Microcarpum Peel is an Effective, Low-Cost Adsorbent for the Removal of Methylene Blue (MB) Dye from Aqueous Solutions
No full textInternational audienceIn an effort to promote the valorization of organic waste, Detarium microcarpum—an important fruit species in southern Chad whose use is generally limited to food consumption and traditional medicinal applications owing to its therapeutic properties—was employed as a precursor for the synthesis of activated carbon. Chemical activation was carried out using potassium hydroxide (KOH). Adsorption experiments conducted with methylene blue, a cationic dye, demonstrated a removal efficiency of 98.43% at pH 11 within 10 minutes at a temperature of 35 °C. The effects of various experimental parameters, including adsorbent mass, point of zero charge (pHPZC), solution pH, contact time, initial dye concentration, and temperature, were systematically investigated These analyses confirmed the basic nature of the reaction upon activation. This material has good porosity and a very high methylene blue decolorization capacity, which suggests the possibility of obtaining high-quality activated carbons from this biomass for the depollution of pollutants and especially for the treatment of wastewater
Regulation of Aldosterone Secretion by Substance P and the Neurokinin Type 1 Receptor in Aldosterone‐Producing Adenomas
No full textInternational audienceBackground Aldosterone‐producing adenoma (APA) is a major cause of primary aldosteronism, the most frequent form of secondary hypertension. Although somatic mutations in ion channels within APA have been shown to activate Ca 2+ signaling and drive aldosterone production, the pathophysiology of primary aldosteronism remains partially understood. SP (Substance P), encoded by the TAC1 gene, is a neuropeptide of the tachykinin family, known for its role in stimulating aldosterone production through activation of the neurokinin 1 receptor (NK1R) in the human adrenal cortex. The aim of our work was to investigate the presence of SP nerve fibers and the NK1R in a large series of APA to assess the potential role of tachykinins in the pathophysiology of primary aldosteronism. Methods Using molecular, immunohistochemical, and functional techniques, 56 APA tissues were analyzed to assess the expression of SP and NK1R and their impact on aldosterone secretion. Results SP‐positive nerve fibers were detected in 90% of the APA tissues, localized both within and around the adenomas, which also showed strong NK1R expression. Functional studies revealed that SP stimulated aldosterone secretion in 6 of 10 APA cultures. The NK1R antagonist aprepitant inhibited SP‐induced aldosterone secretion in 3 of the 4 SP‐responsive APA cultures on which the antagonist was tested. Additionally, in perifused APA explants, SP influenced aldosterone pulsatility, resulting in enhanced mineralocorticoid secretion. Conclusions These findings suggest that the SP‐NK1R signaling pathway may contribute to APA pathophysiology and represent a novel potential target for the pharmacological treatment of PA in a subset of patients