International Journal of Agricultural Research, Innovation and Technology (IJARIT)
International Journal of Agricultural Research, Innovation and Technology (IJARIT)Not a member yet
12720 research outputs found
Sort by
Coexistence of Two Dune Growth Mechanisms in a Landscape-Scale Experiment
No full textInternational audienceIn landscape-scale experiments at the edge of the Gobi desert, we show that various dune types develop simultaneously under natural wind conditions. Using 4 years of high-resolution topographic data, we demonstrate that, depending on sand availability, the same wind regime can lead to two different dune orientations, which reflect two independent dune growth mechanisms. As periodic oblique dunes emerge from a sand bed and develop to 2 m in height, we analyze defect dynamics that drive the non-linear phase of pattern coarsening. Starting from conical sand heaps deposited on gravels, we observe the transition from dome to barchan and asymmetric barchan shapes. We identify a minimum size for arm elongation and evaluate the contribution of wind reversals to its longitudinal alignment. These experimental field observations support existing theoretical models of dune dynamics boosting confidence in their applicability for quantitative predictions of dune evolution under various wind regimes and bed conditions
Discovery and Genomic Characterization of a Novel Henipavirus, Angavokely Virus, from Fruit Bats in Madagascar
No full textInternational audienceThe genus Henipavirus (family Paramyxoviridae) currently comprises seven viruses, four of which have demonstrated prior evidence of zoonotic capacity. These include the biosafety level 4 agents Hendra (HeV) and Nipah (NiV) viruses, which circulate naturally in pteropodid fruit bats. Here, we describe and characterize Angavokely virus (AngV), a divergent henipavirus identified in urine samples from wild, Madagascar fruit bats. We report the nearly complete 16,740-nucleotide genome of AngV, which encodes the six major henipavirus structural proteins (nucleocapsid, phosphoprotein, matrix, fusion, glycoprotein, and L polymerase). Within the phosphoprotein (P) gene, we identify an alternative start codon encoding the AngV C protein and a putative mRNA editing site where the insertion of one or two guanine residues encodes, respectively, additional V and W proteins. In other paramyxovirus systems, C, V, and W are accessory proteins involved in antagonism of host immune responses during infection. Phylogenetic analysis suggests that AngV is ancestral to all four previously described bat henipaviruses—HeV, NiV, Cedar virus (CedV), and Ghanaian bat virus (GhV)—but evolved more recently than rodent- and shrew-derived henipaviruses, Mojiang (MojV), Gamak (GAKV), and Daeryong (DARV) viruses. Predictive structure-based alignments suggest that AngV is unlikely to bind ephrin receptors, which mediate cell entry for all other known bat henipaviruses. Identification of the AngV receptor is needed to clarify the virus’s potential host range. The presence of V and W proteins in the AngV genome suggest that the virus could be pathogenic following zoonotic spillover.IMPORTANCE Henipaviruses include highly pathogenic emerging zoonotic viruses, derived from bat, rodent, and shrew reservoirs. Bat-borne Hendra (HeV) and Nipah (NiV) are the most well-known henipaviruses, for which no effective antivirals or vaccines for humans have been described. Here, we report the discovery and characterization of a novel henipavirus, Angavokely virus (AngV), isolated from wild fruit bats in Madagascar. Genomic characterization of AngV reveals all major features associated with pathogenicity in other henipaviruses, suggesting that AngV could be pathogenic following spillover to human hosts. Our work suggests that AngV is an ancestral bat henipavirus that likely uses viral entry pathways distinct from those previously described for HeV and NiV. In Madagascar, bats are consumed as a source of human food, presenting opportunities for cross-species transmission. Characterization of novel henipaviruses and documentation of their pathogenic and zoonotic potential are essential to predicting and preventing the emergence of future zoonoses that cause pandemics
Les espaces des musiques hip-hop
No full textInternational audienceDepuis plusieurs années, des recherches interdisciplinaires montrent comment les musiques interagissent avec les espaces où elles se produisent et participent à leur transformation. Du fait de leur globalisation et de leurs nombreuses adaptations locales, les musiques hip-hop sont un prisme particulièrement pertinent pour analyser les co-constructions entre musiques, espaces et identités. Les musiques hip-hop révèlent et agissent en effet sur les modes d’organisation des villes, des régions ou pays dans lesquels elles s’implantent. Quels sont les processus de territorialisation du rap en différents lieux du monde ?Ce chapitre répond à cette question en montrant d’abord comment le hip-hop se développe en lien avec des pratiques et des représentations associées aux villes. En observant les diverses formes d’appropriation de ces musiques à l’échelle des États, il donne ensuite à voir la manière dont s'y développent des rapports entre centres et périphéries, ainsi que des hiérarchies spatiales. Finalement, en analysant la diffusion transnationale du hip-hop, il montre comment cette musique met en mouvement l'existence de relations inégalitaires à l’échelle du globe
Thermal Regime of Slow and Ultraslow Spreading Ridges Controlled by Melt Supply and Modes of Emplacement
No full textInternational audienceMelt supply at slow-ultraslow spreading ridges is overall reduced and highly variable. Magma cooling and crystallization substantially shape the axial thermal regime by providing heat that is lost to the ocean through conduction and hydrothermal convection. Geological data suggest that melt is emplaced over a wide depth range, variably accessible to hydrothermal cooling, and that periods of higher and lower melt supply may alternate at a given location. Until now, numerical models focused on steady-state thermal regimes controlled by either spreading rate or melt supply, falling short at slow-ultraslow ridges. Here we present results from a 2-D numerical thermal model that couples repeated melt injections and hydrothermal convection. We first constrain thermal regimes inferred from two ultraslow-spreading endmembers in melt supply at the Southwest Indian Ridge (SWIR): a magmatically robust endmember at 50°28'E and a nearly amagmatic endmember at 64°30'E. We adjust parameters associated with melt supply (the melt injection frequency and the temperature of the host rocks upon melt emplacement) and hydrothermal circulation (the extent and permeability of the hydrothermal system). Our simulations predict that greater melt injection frequencies unsurprisingly produce hotter thermal regimes. However, at a given frequency, melt emplacement in cooler host rocks (e.g., <800°C) causes cooler thermal regimes with transient black smoker-type hydrothermal circulation that extracts heat efficiently. Periodic waxing and waning magma supply, as proposed from geological data at the SWIR 50°28'E, induces an oscillatory thermal regime. Transience in the axial thermo-mechanical state may be an integral part of lower-crustal construction at magmatically robust sections of slow-ultraslow ridges
High resolution optical seismometer for real-time monitoring of ocean-bottom seismicity
No full textInternational audienc
Dating Low-Grade Deformation: Role of Lithology and Strain Partitioning on Ar Isotope Records in the Alpi Apuane of Northern Apennines (Italy)
No full textInternational audienceThe Alpi Apuane (northern Apennines) represent a key area for understanding the processes related to the Apennines building and geodynamic evolution of the central Mediterranean, but the timing of tectono-metamorphic events is still debated. White mica from cover rocks of the Massa and Apuane units was investigated by the 40Ar-39Ar in situ and step-heating techniques. Samples recorded several episodes of deformation developed under low-grade conditions and resulting in a D1 composite schistosity followed by a variably developed D2 retrograde crenulation. In the Massa Unit, D2 crenulation was accompanied by replacement of muscovite-phengite by paragonite, whereas the composition of phengite from the Apuane Unit does not vary noticeably, irrespective of whether phengite is aligned along D1 or D2 schistosities. Both units exhibit a significant intrasample scatter of in situ ages and variably discordant age spectra from step-heating data, due to partial reequilibration of white mica along a deformation path lasting ≥10 Ma, with dates approaching the time of younger events as retrogression becomes more pervasive. The onset of deformation has a minimum age of ∼20 Ma, as documented by 40Ar-39Ar data for the composite D1 foliation in the Massa Unit. D2 deformation shows a common temporal evolution at the scale of the region and is recorded for at least ∼2.5 Ma, starting not after ∼12.5 Ma and ending at ∼10.5 Ma. Results highlight the importance of a detailed microscale characterization and of a careful preselection of samples, as compositionally different domains a few millimeters apart may yield different results because of compositionally driven strain partitioning
Les engagements internationaux des pays d'Afrique centrale en réponse aux changements climatiques
No full textInternational audienc
SWORD2: hierarchical analysis of protein 3D structures
No full textInternational audienceUnderstanding the functions and origins of proteins requires splitting these macromolecules into fragments that could be independent in terms of folding, activity, or evolution. For that purpose, structural domains are the typical level of analysis, but shorter segments, such as subdomains and supersecondary structures, are insightful as well. Here, we propose SWORD2, a web server for exploring how an input protein structure may be decomposed into ‘Protein Units’ that can be hierarchically assembled to delimit structural domains. For each partitioning solution, the relevance of the identified substructures is estimated through different measures. This multilevel analysis is achieved by integrating our previous work on domain delineation, ‘protein peeling’ and model quality assessment. We hope that SWORD2 will be useful to biologists searching for key regions in their proteins of interest and to bioinformaticians building datasets of protein structures. The web server is freely available online: https://www.dsimb.inserm.fr/SWORD2
« Impact du dividende démographique sur la croissance économique en République Démocratique du Congo (RDC) ; une approche par la modélisation AutoRegressive Distributed Lag (ARDL) »
No full textAuthentification de l'utilisateur par la dynamique de frappe au clavier basée sur une approche d'apprentissage d'ensemble
No full textInternational audienceToday, we live in a ubiquitous networked world, with the ability to connect to network systems regardless of time and place, using a variety of information technology devices. This increase in connectivity has raised concerns about the security of systems in protecting users' personal information and private data. The password has been the most common solution for user authentication. But it becomes vulnerable when a third party acquires it illegally. In order to increase security during authentication, several methods have been used such as keystroke dynamics which is a behavioral biometric. Previous works have demonstrated the feasibility of user authentication using keystroke dynamics. In this research, we propose an authentication method based on Bagging classifier set. This method is composed of three Bagging ensembles formed by SVM, KNN and decision tree classifiers. The outputs of these three ensembles are then merged and a majority vote was applied to obtain the final result. The proposed approach was evaluated using the CMU dataset. The final result obtained by our approach is promising, achieving an accuracy of 95.65%..Aujourd'hui, nous vivons dans un monde en réseau omniprésent, avec la possibilité de se connecter à des systèmes de réseau quels que soient l'heure et l'endroit, à l'aide de divers dispositifs informatiques. Cette augmentation de la connectivité a suscité des inquiétudes quant à la sécurité des systèmes de protection des informations personnelles et des données privées des utilisateurs. Le mot de passe a été la solution la plus courante pour l'authentification des utilisateurs. Mais il devient vulnérable lorsqu'un tiers l'acquiert illégalement. Afin de renforcer la sécurité lors de l'authentification, plusieurs méthodes ont été utilisées, a l'instar de la dynamique de la frappe au clavier qui est une biométrie comportementale. Des travaux antérieurs ont démontré la faisabilité de l'authentification des utilisateurs en utilisant la dynamique de la frappe. Dans cette recherche, nous proposons une méthode d'authentification basée sur un ensemble de classifieurs Bagging. Cette méthode est composée de trois ensembles Bagging formés par les classifieurs SVM, KNN et arbre de décision. Les sorties de ces trois ensembles sont ensuite fusionnées et un vote majoritaire a été appliqué pour obtenir le résultat final. L'approche proposée a été évaluée en utilisant le jeu de données CMU. Le résultat final obtenu par notre approche est prometteur, avec une précision de 95,65 %