International Journal of Agricultural Research, Innovation and Technology (IJARIT)
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A multi-seasonal model of plant-pest interactions: the coffee berry borer
No full textInternational audienceThe coffee berry borer (CBB), Hypothenemus hampei (Coleoptera: Scolytidae) is the most devastating insect pest of coffee throughout the world, causing a lot of economic damage in all regions where commercial coffee is grown. In this work, we formulate and study a model describing multi-seasonal infestation dynamics of coffee berries by CBB in a rainy/dry season regime, with the aim of identifying how sanitation measures can be applied to ensure CBB eradication. We employ a semi-discrete formalism to describe these dynamics as the epidemiological dynamics are best represented by a continuous model in ODE, while the remaining dynamics, that connect one season to the next, are better or more simply described by discrete-time events: berry harvest and plantation sanitation. During the rainy season, the infestation dynamics of coffee berries by CBB are described as proposed in Fotso Fotso et al (2021) with the coffee berry production rate depending on time. During the dry season, the dynamics are very similar , except that no berry growth takes place and mortality rates are higher as the environment is less favorable. The model is then completed by the discrete events that take place at the end of the rainy season and at the end of the dry season, that correspond to harvesting and plantation cleaning respectively. Based on that model, we first obtain a periodic CBB-free solution, that will be the desirable behaviour of the system. Linearising the dynamics around that solution and applying Floquet theory, we obtain stability conditions for this solution, that give threshold values for the harvesting and cleaning parameters below which asymptotic stability is ensured, hence CBB eradication. Note however that, even with perfect harvesting and cleaning, CBB could still persist through the survival of the colonising forms over the dry season.Finally, with perfect harvesting of the healthy berries at the end of the cropping season, we obtain conditions on harvesting and cleaning of the infested berries, that ensures CBB eradication at the minimum cost, for two versions of the cost
Analysis of temporal consistency management protocols for resource-constrained multi-agent systems
No full textInternational audienceMulti-Agent Systems (MAS) are distributed system composed of a set of connected nodes, that communicate and share data. Since nodes do not have access to a central clock, the consistency of shared data is one of the important issues raised by this type of system. Approaches to establish temporal consistency of these shared data have been designed and implemented in the past. This paper presents and analyses existing protocols for managing temporal consistency in order to identify those that are in line with the specificities of weakly adjoining MAS with limited resources and connectivity. We propose a classification and a comparative analysis of these protocols for use within this category of MAS
Potato virus Y adaptation to various resistance QTL combinations in pepper and impact on host tolerance
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La laïcité scolaire à La Réunion : une créolisation de la loi de 2004 ?
No full textInternational audienceThe French law of 15 March 2004 forbidding state school pupils from wearing visible religious signs is particularly interesting to research in Reunion Island, as it was only properly applied in the region since 2018. In this context, what positions and strategies do education professionals adopt when facing visible religious signs? How do they negotiate the tension between this new norm in schools and the distinctive Réunion identity as regards laicity? What resources do they mobilize, according to what logic and on the basis of what “principles of justice” (Boltanski and Thévenot, 1991)? A sociologic investigation conducted in 2019 reveals a singular implementation of secular education in secondary schools which leads to considerations of creolization.La loi du 15 mars 2004 interdisant le port des signes ostensibles aux élèves des établissements scolaires publics en France apparaît particulièrement intéressante à étudier à La Réunion puisqu'elle n’a véritablement été mise en œuvre qu’à partir de 2018. Dans ce contexte, quels positionnements et quelles stratégies adoptent les professionnels de l’éducation face aux expressions visibles du religieux ? Comment négocient-ils la tension entre la nouvelle norme scolaire et « le particularisme réunionnais » en matière de laïcité ? Quelles ressources mobilisent-ils, selon quelles logiques et sur la base de quels « principes de justice » (Boltanski et Thévenot, 1991) ? Une enquête sociologique menée en 2019 témoigne d’une mise en œuvre singulière de la laïcité scolaire à La Réunion qui incite à penser sa créolisation
Composition, Roughness, and Topography from Radar Backscatter at Selk Crater, the Dragonfly Landing Site
No full textInternational audienceThe Selk crater region is the future landing site of NASA's Dragonfly mission to Titan. The region was imaged by the Cassini RADAR at incidence angles from 5°to 72°and at various polarization angles. Using this data set, we mapped six terrain units and assembled a backscatter curve for each, providing normalized backscatter cross section (σ 0) as a function of incidence angle. By fitting these backscatter curves with a sum of a quasi-specular and diffuse terms and evaluating three alternative formulations of the first and two for the second, we extracted the best-fit surface effective dielectric constant, rms slope, and scattering albedo. Although the parameters' absolute values are model dependent, relative values between terrains indicate real variations in surface properties. The results are consistent with the impact exposing and fracturing a low-loss tangent material such as the water-ice bedrock, which is likely also present in the hummocky terrains and to a lesser degree in the plains and interdune regions. The dunes and dark terrains are composed of smooth, uniform material with low dielectric constant (1.5-2.3 median values for all models) compatible with organic sand. A diffuse single-scattering model enabled independent derivation of the dielectric constant from high-incidence observations, leading to low values (<2) over all terrains, indicating a depolarizing (sub)surface. Finally, radarclinometry revealed lateral variations in rim height, which remains below 300 m along the SARTopo profile but reaches up to 600 m at other locations, hinting at a rim less eroded than previously thought
Red-Absorbing Ru(II) Polypyridyl Complexes with Biotin Targeting Spontaneously Assemble into Nanoparticles in Biological Media
No full textInternational audienceFour new ruthenium(II) polypyridyl complexes were synthesized to study the effect of poly(ethylene glycol) and/or biotin conjugation on their physical and biological properties, including their hydrophilicity, their cellular uptake, and their phototoxicity. Unexpectedly, these complexes selfassembled into nanoparticles upon dilution in biological media. This behavior leads to their accumulation in lysosomes following their internalization by cells. While a significant increase in cellular uptake was observed for the biotin-conjugated complexes, it did not result in an increase in their phototoxicity. However, their high phototoxicity upon irradiation at long wavelengths (645-670) and their self-assembling behavior make them a promising backbone for the development of new lysosome-targeted photosensitizers for photodynamic therapy
Discours radiophoniques, cartographies épidémiques et représentations locales de la COVID-19 en Guinée
No full textInternational audienceIf COVID-19 epidemics confirmed social sciences’ interest for the study of social media (Lee Hugues et Pale, 2009) and infodemic (Vosoughi et alii, 2018) in epidemic contexts, it also excluded a large part of the population still important in Africa from the production of knowledge: those who cannot access internet because of lack of connection and/or illiteracy. This paper fills this gap by analyzing local representations of COVID-19, drawing on the longitudinal study of radiophonic discourses in national languages and face-to-face ethnography led by anthropologists among the population. It examines how COVID-19 was appropriated and interpreted by Guinean population through the mobilization of epidemic, political and historic local experiences. It also considers how the evolution of local representations of the pandemics, over time and over political and economic perturbations, illustrates a progressive cognitive and practical lack of public interest in the virus. To do so, radio shows in national languages including participation from the public on COVID-19 topic were systematically recorded, transcribed and translated in French from March to August 2021. National languages included sosoxui for Basse-Côte, pulaar for Moyenne Guinée, kissiye and kpɛlɛɛwoo for the Forest region, and maninkakan for Haute-Guinée. Long-term participant observation and face-to-face interviews were led in the cities of Conakry and Mamou, and in the rural areas of Forécariah from May 2020 to December 2021 among health professionals and general population. These data were analysed thematically and chronologically to examine how the epidemics was discussed and the restriction measures commented by the population through time. From March to May 2020, the massive diffusion of information about COVID-19, both at international and national level, led the Guinean to take ownership of the protection measures against the epidemic – the traumatic memory of Ebola playing a major role. However, as the epidemic event merged with the 2020 controversial electoral process, local populations began to question the relevance of the epidemic management policies and restriction measures. The reduced number of positive cases led to a trivialization of COVID-19 and to a rising popular resistance against restriction measures such as confinement and wearing a mask. The virus appeared exogenous and concerning only national elites and populations of Northern countries. The representation of the epidemic, first powered by the trauma of Ebola, rapidly turned to the register of coercion: now called the “Screwdriver epidemic”, COVID-19 in Guinea appears for the local populations as the reproduction of the unequal relation binding them to their elites, as Guinea is bound to the rest of the world.Avec la COVID-19, faute de pouvoir mener des ethnographies classiques, les enquêtes réalisées via l’internet, le téléphone ou les réseaux sociaux ont participé à exclure de la production des connaissances un large pan de la population africaine qui souffre de la fracture numérique et/ou d’analphabétisme. Le présent article comble ce vide en analysant les discours populaires sur l’épidémie via les radios émettant en langues nationales en Guinée et au travers de données ethnographiques recueillies dans les régions de Conakry, Mamou et Forécariah par des chercheurs guinéens et français auprès d’agents de santé et de la population, de mars 2020 à décembre 2021. Les discours populaires ont été recueillis en français, sosoxui (Basse-Côte), pulaar (Moyenne Guinée), kissiye et kpɛlɛɛwoo (région forestière), et maninkakan (Haute-Guinée). Ils mettent en avant une crainte initiale de la contamination puis une altérisation et un discrédit de la maladie, témoignant d’un désengagement cognitif et pratique des Guinéens face à la COVID-19 au cours de l’épidémie. La diffusion massive d’informations sur la COVID-19 a conduit la population à d’abord s’approprier les mesures de protection contre l'épidémie, le souvenir d'Ebola jouant un rôle majeur. Mais, lorsque le temps épidémique s’est confondu avec le processus électoral controversé de 2020, la portée politique de la réponse et le nombre réduit de cas enregistrés ont mené à une résistance populaire croissante contre les mesures de restriction (confinement, port du masque). Le virus est apparu comme exogène et ne concernant que les élites nationales et les populations des pays du Nord. L’imaginaire de l’épidémie, alimenté par le traumatisme d’Ebola, s’est nourri du registre de la coercition : désormais « épidémie tournevis », la COVID-19 en Guinée apparaît pour la majorité silencieuse de la population comme la reproduction du rapport inégal qui la lie à ses élites, comme la Guinée au reste du monde
Semantic segmentation of high-resolution aerial imagery using a fully convolutional network
No full textInternational audienceSemantic segmentation applied to aerial imagery allows the extraction of terrestrial objects such as roads, buildings and even vegetation. Having large, detailed datasets of navigable roads, is of paramount importance in several application fields; namely urban planning, automatic navigation, disaster management. To reach this goal, extracting all roads in a given territory area is the first step. This paper presents a modern method to semantically segment aerial images for a road network extraction. We employ an encoder-decoder architecture to approach the problem of disconnected road regions faced by some existing methods. Using an FCN approach, the localization information was combined to the semantic one, to enable the reconstruction of the road by the proposed model, while being consistent with following the spatial alignment. The method was implemented and evaluated on the public dataset Massassuchets Roads. Results appear to be in full agreement with the theorical predictions and a significant improvement in road connectivity over some previous works; the proposed network achieved a precision of 87.86% and a recall of 87.89%
Two secure online steganography schemes based on HTTP request sequences
No full textProceedings of CARI 2022International audienceThe interest of steganography is to find ways to leak confidential information without being detected. Several methods proposed in the literature implement strategies for secret embedding in one or more covert media with increased security performance, by enhancing alteration resistance. Nevertheless, these embedding strategies are vulnerable to detection with blind universal steganalysis. This paper sheds light on two new secure covert channels, perfectly driven by online web operations that do not leave fingerprints. The design features of this undetectable scheme are based on lightweight requests for secret encoding coupled to the cover media independence. Experiments on this new approach have shown remarkable security results compared to existing ones. The results are significant and present promising research contributions
Système de recommandation avec prise en compte de la prévision de disponibilité des catégories de produits
No full textInternational audienceRecommending suitable products to users is crucial in e-commerce and streaming platforms. In some situations, a customer has a preference for a product based on the product features and the current temporal context. It is therefore wise to take these aspects into account in order to improve the quality of the recommendations. In this paper, we propose recommender systems based on the availability prediction of product categories according to the temporal context. Indeed, the classification of the Top-N recommendations proposed by the initial recommender system is updated in such a way as to favor products with categories predicted available. Furthermore, we propose an algorithm for the choice of the appropriate temporal context to consider for the availability prediction of categories. Experiments are carried out on four datasets and comparisons are made on the results of three basic recommender systems with and without integration of availability forecasts, according to the Hit-ratio, MAP and F1-score evaluation metrics. We note that in 75% of cases, to have the best performance, it is necessary to integrate the availabilities prediction of the categories. This gain can even go to more than 12% regardless of the dataset. All this confirms the relevance of our contribution.Recommander des articles appropriés aux utilisateurs est crucial dans les plateformes de commerce électronique et de streaming. Dans certaines situations, un client a une préférence pour un produit en fonction des caractéristiques du produit et du contexte temporel courant. Il est donc judicieux de prendre en compte ces aspects afin d'améliorer la qualité des recommandations. Dans cet article, nous proposons des systèmes de recommandation basés sur la prédiction de disponibilité des catégories des produits en fonction du contexte temporel. En effet, le classement des recommandations Top-N proposées par le système de recommandation initial est mis à jour de manière à favoriser les produits aux catégories prédites disponibles. Par ailleurs, nous proposons un algorithme pour le choix du contexte temporel adéquat à la considération de la prédiction de disponibilité des catégories. Des expérimentations sont menées sur quatre jeux de données et des comparaisons sont effectuées sur les résultats de trois systèmes de recommandation de base avec et sans intégration des prédictions de disponibilité, suivant les métriques d'évaluation Hit-ratio, MAP et F1-score. On constate que dans 75% des cas, pour avoir la meilleure performance, il est nécessaire d'intégrer les prédictions de disponibilité des catégories. Ce gain peut même aller à plus de 12% quel que soit le jeu de données. Tout ceci confirme la pertinence de notre contribution