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Shedding light on the existence of Furan fatty acids in latex lipids across a wide diversity of Hevea brasiliensis genotypes
No full textInternational audienceFuran fatty acids produced by plants and bacteria, and present in some edible resources, have attracted significant scientific attention for their health benefits. They include 10,13-epoxy-11methyl-octadecan-10,12-dienoic acid, which has been identified in the lipid fraction of latex from two Hevea brasiliensis genotypes commonly known as the source of natural rubber. Those two genotypes, namely RRIM501 and PB235, are from Rubber Research Institute of Malaysia (RRIM) and Prang Besar, Malaysia (PB), respectively. This research aimed to undertake the first ever investigation into the existence of this potential high value-added co-product in the lipid fraction of 48 Hevea brasiliensis genotypes, seeking to study the widest possible clonal variability. The results showed furan fatty acid exists in all lipid fractions of their latices. Its content varied significantly, ranging from 0.01 % to 0.71 % ( w / w in latex), the highest concentrations were found in genotypes from the Institut de Recherche sur le Caoutchouc (IRCA) in Côte d'Ivoire, Prang Besar (PB) in Malaysia, and Rubber Research Institute of Vietnam (RRIV) in Vietnam breeding programs. A positive correlation with total fatty acid content was observed when its content exceeded 0.10 %, suggesting an additive rather than a substitutive role with the other fatty acids present. Interestingly, linoleic and palmitoleic acids strongly correlated with the furan fatty acid concentration, indicating a possible biosynthetic pathway linkage. In terms of yield per tapping PB235, RRIV4, RRIV2, IRCA41, IRCA18, PB324, IRCA814, IRCA323, and IRCA109 genotypes showed the highest production potential, with yields range of 1 367-2 446 mg furan fatty acid per tree per tapping
Century-old herbarium specimen provides insights into Pierce’s disease of grapevines emergence in the Americas
No full textInternational audienceFossils and other preserved specimens are integral for informing timing and evolutionary history in every biological system. By isolating a plant pathogen genome from herbarium-preserved diseased grapevine material from 1906 (Herb_1906), we were able to answer questions about an enigmatic system. The emergence of Pierce’s disease (PD) of grapevine has shaped viticultural production in North America; yet, there are uncertainties about the geographic origin of the pathogen (Xylella fastidiosa subsp. fastidiosa, Xff) and the timing and route of its introduction. We produced a high-quality, de novo genome assembly of this historical plant pathogen and confirmed degradation patterns unique to ancient DNA. Due to the inclusion of the Herb_1906 sample, we were able to generate a significant temporal signal in the genomic data. This allowed us to build a time-calibrated phylogeny, where we estimate the introduction of Xff into the US between 1734 and 1741 CE, an earlier time frame than previously inferred. In a large collection of >300 Xff genomes, the Herb_1906 sample was genetically most similar to a small population from Northern California but not basal to the entire Xff California clade. Based on phylogenetic placement and a phylogeographic reconstruction, our data support a single introduction of Xff into the Southeastern US from Central America, with multiple subsequent introductions into California
Tephra fallout and dispersal modeling of phreatic eruptions: Implications for volcanic hazard assessment in Martinique and Guadeloupe (Lesser Antilles)
No full textInternational audienceA phreatic eruption is the most probable future scenario for the onset of eruptive activity at Montagne Pelée (Martinique) and La Soufrière (Guadeloupe) volcanoes. Despite the potential mortality from this type of non-magmatic eruption, the phreatic scenario is often not considered during hazard assessment. Both Montagne Pelée and La Soufrière are in volcanic alert level yellow (vigilance). Here we used the tephra fallout dispersal model HAZMAP to create hazard maps for tephra fallout during phreatic events in Martinique and Guadeloupe. We first simulated a single scenario based on the historical eruptions of May 2-3, 1902 at Montagne Pelée, and July 8, 1976 at La Soufrière. We then used a multi-scenario approach using three sets of eruptive conditions combined with the 43-year wind ERA5 reanalysis database. The latter maps show that the entire islands of Martinique and Guadeloupe could be impacted by tephra fallout from a future phreatic eruption. We then used a Monte Carlo method to sample a series of eruptive scenarios associated with three different grain-size distributions that we simulated using the complete 43-year wind database. The resulting probabilistic maps for Montagne Pelée and La Soufrière allow us to assess the maximum extent of phreatic tephra dispersal and compare it to historical eruptions of both volcanoes. Calculated probabilities of exceeding impact thresholds for key infrastructure on both islands suggest that Guadeloupe has a higher exposure than Martinique to a future phreatic eruption. The single-scenario, multiple-scenario and probabilistic hazard maps were all shared and evaluated with the local authorities in Martinique in order to improve the efficacy and relevance of the final map. These discussions led to the incorporation of an integrated phreatic scenario considering multiple phenomena into the newly revised 2022 volcano emergency plan for Montagne Pelée. Our results will be integrated in the future revised emergency response plan (ORSEC, Préfecture de Guadeloupe) for La Soufrière
Une approche collaborative globale innovante de la formation continue des enseignants du post-fondamental à Madagascar : le dispositif PERFORM
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Diversity and adoption constraints of agroforestry practices in the Sudanese Zone, north region of Cameroon
No full textSource Agritrop Cirad (https://agritrop.cirad.fr/616782/)International audienceIn the Sudanese region of northern Cameroon, development projects have promoted various agroforestry and forestry practices, including improved fallow, live fences, planting of anti- erosion grass strips, orchards, and woodlots. However, the adoption of these practices has been limited, and the tree density on cultivated land is gradually decreasing. To propose new directions for agroforestry, the study analyzed prevailing agroforestry practices and farmers' perceptions of the constraints to tree management on agricultural land. The study was conducted in five villages in the old agrarian area south of Garoua, where natural vegetation is scarce and highly degraded. These villages include Mafa-Kilda, Laïnde Massa, and Bame, on the one hand, and Gouna and Bawan, on the other, which are located in a zone close to the Benoue National Park. Three socio-professional groups were identified: male farmers, female farmers, and sedentary pastoralists. In each village, focus group discussions were held with each group, followed by individual interviews with 194 household heads (87 male farmers, 73 female farmers, and 34 sedentary pastoralists). The demographic characteristics of the respondents, land tenure status of the fields, agroforestry practices implemented, and constraints to the adoption of these practices were identified. Cultivation in agroforestry parklands and farmer-managed natural regeneration (FMNR) of trees were practiced by 98% and 62% of all respondents, respectively, with no significant differences between zones. On the other hand, planting trees along field boundaries, in orchards, and in live fences was practiced by 35%, 28%, and 22% of all respondents, respectively. There was low adoption of tree fallows (7%) and woodlots (10%) despite project support. Planting of anti- erosion grass strips and live fences was more common in the old agricultural zone (22% and 24%, respectively) than near the protected area (5% and 11%, respectively). Tree planting was more common among male farmers (24%) than female farmers (15%) and sedentary pastoralists (11%), due to better access to land and project support. The main constraints to the adoption of agroforestry practices in both areas were: animal damage (reported by 95% of respondents), lack of access to land (89%), bushfires (87%), tree cutting and pruning by livestock farmers, and unknown reasons (81%). In addition, 95% of respondents in the old agricultural zone perceived taxes on the pruning of native trees as a significant constraint, while only 28% of respondents in the area near the protected area mentioned this. The availability of seedlings, cited by only 5% of respondents, did not appear to be a constraint, as projects often provided seedlings. The FMNR of young trees and shrubs in fields is well-known and, to some extent, practiced by the vast majority of farmers and sedentary pastoralists in the North Cameroon region. Nevertheless, it deserves to be promoted to increase tree density on agricultural land by recognizing farmers' tree management practices and by removing constraints to its adoption, in particular, unrestricted grazing, difficult access to land, and penalties for farmers who prune native trees in their fields. Finally, land restoration projects should take greater account of women and pastoralists in their support
Evaluation of the Nutritional Status of Children under 5 Years Old Hospitalized in the Kabezi Health District Hospital in Burundi during the Period from 2015 to 2022
No full textInternational audienceA study on the assessment of the nutritional status of children under 5 years old was carried out in the Kabezi Health District. Data recorded at the Therapeutic Stabilization Service (SST) on cases of malnutrition, in the period from 2015 to 2021, were analyzed. It was revealed that 9 health centers out of 23 in the Kabezi Health District (HD) had cases of malnutrition. The most affected was the Kabezi health center, which alone accounted for 19% of the cases identified. The entropometric parameters made it possible to know the extent and severity of the nutritional status of children under 5 years old. The Body Mass Index highlighted the minimum weigh registered was 5 kg/m 2 while the general average was 10 kg/m 2 . The analysis of the presence of edema showed that 51% suffered from kwashiorkor while 49% suffered from marasmus. The study of the evolution over time revealed that the trend of the decrease in cases and severity is positive but with a low rhythm. The estimated projections indicate that 0 cases of marasmus and kwashiokor will be reached in 2046. Thus, this study shows how much decision-makers can make efforts to completely eradicate these sufferings in children under 5 years old and which have consequences on the overall development of the country.</div
Technopolitique et pouvoir prétorien dans l’Afrique postcoloniale : le cas du Cameroun face à Boko Haram
No full textInternational audienceCet article analyse l’usage des technologies militaires dans la lutte contre Boko Haram au Cameroun, en interrogeant leur rôle à la fois comme outils stratégiques de défense et comme instruments de contrôle politique. À partir d’une approche empirique et théorique, l’étude montre que si les innovations technologiques (drones, surveillance électronique, cybersécurité) ont permis d’améliorer l’efficacité opérationnelle des forces armées dans un contexte de guerre asymétrique, elles ont également contribué à la militarisation de l’espace civil et au renforcement du pouvoir exécutif. Le cas emblématique du Bataillon d’intervention rapide (BIR), unité d’élite directement rattachée à la présidence, illustre cette double fonction : combattre le terrorisme tout en sécurisant le régime. L’intégration de technologies avancées, souvent fournies par des partenaires étrangers (États-Unis, Israël, Chine), s’est faite dans un contexte de faible encadrement juridique, générant bavures, violations des droits humains et défiance citoyenne. Cette stratégie techno-sécuritaire, efficace à court terme, comporte ainsi des effets pervers sur le long terme : dépendance technologique, répression politique, fragilisation du lien social. Au-delà du cas camerounais, l’article ouvre un débat théorique sur le brouillage croissant entre sécurité intérieure et extérieure dans les États postcoloniaux, et sur les implications politiques de la technologisation du pouvoir. Il plaide pour une redéfinition démocratique des politiques sécuritaires, articulant souveraineté, transparence et participation, afin d’éviter que la technologie ne devienne un vecteur d’autoritarisme masqué sous l’argument sécuritaire
Partage Equitable: Règle Proportionnelle Corrigée
No full textInternational audienceIn this paper, we intend to present and apply the Corrected Proportional rule (PCo) as a fair division rule in its own right, which constitutes with the methods PRRC (Resources Distribution Process based on the results of the Clustering) and PRRG (Resources Distribution Process at Group level) the three main methods of the Fair Division Approach based on Clustering and Reduction of inequalities (APCR).The PCO rule reduces inequalities between individuals to a single level, that of the population considered as a single class. The originality of this paper is due to the fact that PCo rule is a fair division rule in its own right because of its results and is not used at all in the literature.Dans cet article, nous comptons présenter et appliquer la règle Proportionnelle Corrigée (PCo) comme une règle de partage équitable à part entière, laquelle constitue, avec les méthodes PRRC (Procédé de la Répartition des Ressources basé sur les Résultats de la Classification) et PRRG (Procédé de la Répartition des Ressources au niveau des Groupes), les trois principales méthodes de l’Approche de Partage équitable basée sur la Classification et la Réduction des inégalités (APCR).La règle PCo réduit les inégalités entre individus à un seul niveau, celui de la population considérée comme une classe unique. L’originalité de cet article tient au fait que la règle PCo est une règle de partage équitable à part entière en raison de ses résultats, et qu’elle n’est pas du tout utilisée dans la littérature
Stratégie d’Adoption de l’Intelligence Artificielle dans la transformation numérique des Collectivités Territoriales Décentralisées du Cameroun : Une approche fondée sur la Méthodologie DSR de Nunamaker
No full textDigital transformation represents a major strategic challenge for Cameroon’s Decentralised Territorial Collectivities (DTCs), which face growing expectations regarding the modernisation of public services, transparency, and citizen participation. In this context, Artificial Intelligence (AI) emerges as an opportunity to enhance governance, facilitate decision-making, anticipate citizens’ needs, and foster civic engagement. However, the adoption of AI remains limited due to various technological, institutional, human, and cultural constraints, such as the lack of technical expertise and inadequate infrastructure.This thesis therefore focuses on the strategy for adopting AI within Cameroon’s DTCs, which must address major challenges related to modernisation and equitable access to digital services. In an environment characterised by limited institutional capacities and increasing demand for innovative public services, AI constitutes a strategic lever for transforming local governance.To address this issue, the research adopts Nunamaker’s Design Science Research (DSR) methodology, tailored to complex organisational settings. This four-phase approach—problematisation, modelling, experimentation, and evaluation—enables the construction of a realistic, participatory, and gradual strategic model for AI adoption.The thesis also draws on the OECD AI Readiness Framework, which provides guidelines for assessing the capacity to adopt AI in a responsible and effective manner. The research findings highlight that the success of this adoption depends on several key factors:•Strengthening the skills of local stakeholders;•Responsible data governance;•Co-designing digital tools with end-users;•Sustained political commitment.Finally, the thesis proposes operational prototypes, including applications, tools, and a deployment approach to support the progressive adoption of AI within Cameroonian DTCs. It also offers concrete recommendations for policymakers, thus contributing to the development of territorial engineering for digital innovation grounded in ethics and collective intelligence.Stratégie d'Adoption de l'Intelligence Artificielle dans la transformation numérique des Collectivités Territoriales Décentralisées du Cameroun : Une approche fondée sur la Méthodologie DSR de Nunamaker Résumé La transformation numérique 1 représente un enjeu stratégique majeur pour les collectivités territoriales décentralisées (CTD) du Cameroun, confrontées à des attentes croissantes en matière de modernisation des services publics, de transparence et de participation citoyenne. Dans ce contexte, l'intelligence artificielle (IA) se présente comme une opportunité pour améliorer la gouvernance, faciliter la prise de décision, anticiper les besoins des citoyens et encourager leur engagement. Toutefois, l'adoption de l'IA demeure limitée en raison de divers freins technologiques, institutionnels, humains et culturels, tels que le manque de compétences techniques et les infrastructures inadaptées.Ainsi, cette thèse se concentre sur la stratégie d'adoption de l'IA dans les CTD du Cameroun, qui doivent relever des défis majeurs de modernisation et d'équité d'accès au numérique. Dans un environnement marqué par des capacités institutionnelles limitées et une demande croissante pour des services publics innovants, l'IA se présente comme un levier stratégique pour transformer la gouvernance locale.Pour répondre à cette problématique, la recherche adopte la méthodologie Design Science Research de Nunamaker, adaptée aux environnements organisationnels complexes. Cette approche en quatre phases, problématisation, modélisation, expérimentation et évaluation, permet de construire un modèle stratégique d'adoption de l'IA réaliste, participatif et progressif.La thèse s'appuie également sur le cadre de préparation à l'IA de l'OCDE, qui fournit des lignes directrices pour évaluer la capacité à adopter l'IA de manière responsable et efficace. Les résultats de la recherche mettent en lumière que la réussite de cette adoption repose sur plusieurs facteurs clés : Le renforcement des compétences des acteurs locaux. Une gouvernance des données responsable. La co-construction des outils numériques avec les usagers. Un engagement politique soutenu.1 La transformation numérique désigne les conséquences économiques et sociales de la numérisation et du développement du numérique (OCDE (2019), Vers le numérique : forger des politiques au service de vies meilleures, Éditions: OCDE, Paris, https://doi.org/10.1787/7cba1873-fr).Enfin, cette thèse propose des prototypes opérationnels, comprenant des applications, des outils et une démarche de déploiement des solutions pour une adoption progressive de l'IA dans les CTD camerounaises. Elle formule également des recommandations concrètes à destination des décideurs, contribuant ainsi à structurer une ingénierie territoriale de l'innovation numérique, fondée sur des principes d'éthique et d'intelligence collective.</div
Optimisation de la production des systèmes photovoltaïques à l'aide des commandes adaptatives et des systèmes autonettoyants.
No full textThe effectiveness of a photovoltaic (PV) system can be increased by using maximum power point tracking (MPPT). The literature has suggested a number of methods for tracking the maximum power point (MPP). However, this number of methods most often presents a high convergence speed in reaching the MPP, complexity under their implementation, power fluctuations, overshoots, and great difficulty in reaching the MPP under fast-changing atmospheric conditions, thus influencing the efficiency of PV systems. Intending to improve the performance of PV systems under rapid changes in the atmosphere, this paper proposes model reference adaptive control (MRAC) as a technique for tracking the MPP based on the employ of reference models such as optimal voltage and current at the MPP ( V MPP and I MPP ). The MATLAB/Simulink environment is used to produce the simulation results; the Kyocera Solar KC 130 GT module is used here as a photovoltaic power plant, connected to a boost converter, supplying a resistive load. The Lyapunov theory was used to demonstrate the stability of the system. The simulation outcomes obtained using the suggested method are compared with those obtained by techniques such as perturb and observe (P&O), incremental conductance (INC), variable step incremental conductance (VSINC), particle swarm optimization (PSO), and grey wolf optimization (GWO), thus showing a very large improvement under standard test and fast-changing atmospheric conditions of the technique proposed on the other techniques in terms of convergence speed and tracking efficiency. The simulation results prove that the suggested method has great tracking effectiveness (>99.88%), less time for convergence (<0.01 s), and simple implementation complexity under fast-changing atmospheric conditions without both transient and steady-state power oscillations, overshoots, and chattering effects, thus causing a great minimization of energy losses, and the proposed technique reaches exactly the MPP under fast-changing atmospheric conditions.L'efficacité d'un système photovoltaïque (PV) peut être augmentée en utilisant le suivi du point de puissance maximal (MPPT). La littérature a proposé un certain nombre de méthodes pour suivre le point de puissance maximal (MPP). Cependant, ce nombre de méthodes présente souvent une vitesse de convergence élevée pour atteindre le MPP, une complexité dans leur mise en œuvre, des fluctuations de puissance, des dépassements et de grandes difficultés à atteindre le MPP dans des conditions atmosphériques changeantes rapidement, influençant ainsi l'efficacité des systèmes PV. Dans le but d'améliorer la performance des systèmes PV sous des changements rapides dans l'atmosphère, cet article propose le contrôle adaptatif de référence de modèle (MRAC) comme technique de suivi du MPP, basé sur l'utilisation de modèles de référence tels que la tension et le courant optimaux au MPP (V_MPP et I_MPP). L'environnement MATLAB/Simulink est utilisé pour produire les résultats de simulation; le module photovoltaïque Kyocera Solar KC 130 GT est utilisé ici comme une centrale photovoltaïque, connecté à un convertisseur élévateur, fournissant une charge résistive. La théorie de Lyapunov a été utilisée pour démontrer la stabilité du système. Les résultats de simulation obtenus grâce à la méthode suggérée sont comparés à ceux obtenus par des techniques telles que la perturbation et observation (P&O), la conductance incrémentale (INC), la conductance incrémentale à pas variable (VSINC), l'optimisation par essaim de particules (PSO) et l'optimisation par loup gris (GWO), montrant ainsi une très grande amélioration dans des conditions standard de test et des conditions atmosphériques changeantes rapidement de la technique proposée par rapport aux autres techniques en termes de vitesse de convergence et d'efficacité de suivi. Les résultats de simulation prouvent que la méthode suggérée a une grande efficacité de suivi (>99,88 %), un temps de convergence court (<0,01 s) et une complexité d'implémentation simple sous des conditions atmosphériques changeantes rapidement, sans oscillations de puissance transitoires et stationnaires, ni dépassements, ni effets de chatter, causant ainsi une grande minimisation des pertes d'énergie. La technique proposée atteint exactement le MPP sous des conditions atmosphériques changeantes rapidement