International Journal of Agricultural Research, Innovation and Technology (IJARIT)
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High resolution optical displacement sensor: Development and qualification for remote applications in seismology and volcanology
No full textInternational audienceWe present here the design, performance and in situ demonstration of an innovative, high resolution, low-cost optical (laser) seismometer. After a brief outline of the context and purposes, we present the optoelectronic interrogator designed and built by the ESEO team, its developments and performance. We also present the evolution of the associated geophone. Finally, we detail the deployment and qualification campaigns that led to the PREST project
Geodynamic framework of the magmatic activity of Cretaceous Léré basin (Southwestern Chad, Central Africa)
No full textInternational audienceNumerous 5 to 20 m-wide dolerite dykes crosscut vertically to sub-vertically basement granitoids around and within the Cretaceous Léré basin, SW Chad (Central Africa). They extend along strike on several hundred meters length. Léré dolerites exhibit various textures, from classical doleritic texture to sub-ophitic via ophitic and intersertal textures. They are composed of euhedral and subhedral crystals of andesine and labradorite, anorthoclase, augite, olivine, ilmenite and Ti-magnetite. Calcite and amphibole are present. Estimated crystallization temperatures are between 1050 and 1105 ± 50 °C. Occurrence of dyke swarms in Léré basin is controlled by Pan-African strike-slip faults created during an extensional tectonic phase during Paleozoic to Early Mesozoic. These lavas, analyzed with ICP-MS and ICP-AES, are basalt, trachybasalt and basaltic trachyandesite with some continental tholeiite affinity. Dolerites of Léré basin have evolved by limited fractional crystallization differentiation, accompanying by minor assimilation process. Three groups of rocks are identified (according to Y/Nb ratios), linked to different mantle sources which have intermediate compositions between E-MORB and OIB
Techno-critique et techno-réalisme contextuels : des clefs vers une Recherche durable
No full textInternational audiencePartant du contexte socio-écologique de contraction de la disponibilité en ressources énergétiques et minérales, cette affiche invite à réfléchir au sens et à la nature de la « durabilité » d’une instrumentation scientifique en prenant comme repères les concepts fondateurs de la démarche low-tech, descendante d’un courant techno-critique historique. Ainsi, les questions de consommation de ressources, de pollution, de durabilité, utilité et accessibilité, confrontées à des briques conceptuels issues de la philosophie des techniques et des sciences de la durabilité, permettent d’identifier des concepts à fort potentiel et des pièges trop souvent passés sous silence. Dans sa globalité, cette prise de recul invite à réfléchir l’instrumentation du futur dans une démarche radicalement transdisciplinaire en impliquant citoyens, historiens et philosophes des techniques dans le montage et la réalisation des projets scientifiques et techniques
The interplay of disturbance, vegetation structure, and propagule pressure contributes to Pinus kesiya invasion in Tapia woodland, Madagascar
No full textInternational audiencePinus are among the highly invasive species that have spread outside their plantation area after their introduction in the Southern Hemisphere. The case of Pinus kesiya invasion is observed in the high plateau of Madagascar, inside the sclerophyll Tapia woodland which is dominated by the endemic Uapaca bojeri tree species. The analysis of this invasion was carried out using 375 plots of 100 m(2) each in Tapia woodland. Data on the vegetation structure, the plot characteristics and the propagule pressure were collected. We recorded a total of 740 pines distributed in 29.8% of the plots. The generalized linear model built on P. kesiya at the three different life stages allowed us to highlight a different explicative variable on the species' presence and abundance separately. The factors explaining pine occurrence varied according to the pine life stage. In the seedling stage, the distance of the plot from the propagule source combined with the longitudinal position of the plot explained 18% of the pine presence. In the sapling and adult stages, the vegetation structure was the main important factor (22% and 11% of variation explained regarding presence and abundance). The frequency of U. bojeri and the degree of disturbance were the most important factors characterizing this vegetation structure. Based on these results, a strategy to control pine invasion in the Tapia woodland may focus on enrichment with U. bojeri and limitation of the plantation of P. kesiya in proximity
Les « influenceurs web » à l’épreuve de l’économie numérique au Cameroun : contribution au développement des industries culturelles en plein essor
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Active packaging films containing antioxidant extracts from green coffee oil by-products to prevent lipid oxidation
No full textInternational audienceThe residual biomass of cold-pressed green coffee oil (GCO), rich in chlorogenic acids (CGA), was reused by incorporating the press cake (CE) and sediment (SE) extracts into carboxymethyl cellulose (CMC) films. The effect of these extracts combined with GCO was investigated on the physicochemical, barrier, and antioxidant properties, and on the ability of the active films to delay fish oil oxidation. The films with added CE and GCO (C-CE) or SE and GCO (C-SE) showed high antioxidant activity, 3.61 ± 0.01 and 2.03 ± 0.01 mmol Trolox eq/g dry film, respectively. These findings are in line with the CGA content in CE and SE (9.8 and 9.0% w/w, respectively), as determined by HPLC. The addition of SE and GCO slightly affects the oxygen barrier of CMC films, while providing them with high Ultraviolet–Visible (UV–Vis) absorption. The evolution of peroxide value (PV) and thiobarbituric acid reactive substances (TBARS) in fish oil samples covered by C-CE and C-SE films and inert headspace was significantly lower than those of controls (storage at 40 °C for 16 days). The antioxidant release from films with added CE and SE showed an antagonistic behaviour into the food simulants. Although both active films are promising for active packaging, the C-SE film appeared as more advantageous for oil-rich food protection
Food security and natural resources: diversification strategies
No full textInternational audienceThis chapter deals with two major issues rural households face in tropical areas: preserving natural resources and guaranteeing food security. Tackling these two challenges simultaneously may require developing profitable production systems that can both guarantee food security for farmers, while also ensuring sustainable management of natural resources
To Be or Not to Be International: Geographic Knowledge, Globalization and the Question of Languages
No full textInternational audience"Even before geographers started to conceive the global world and the way it affected established worlds, their own scientific world has already changed. As IGU congresses show, starting in the 1960s English became the language of global science. However, this process did not go without questions and worries about languages from IGU prominent geographers; there has been recently a renewed interest among geographers. The authors focus here on the questions of production and transposition of knowledge, although the latter cannot be dissociated from its publication. The central question is: Can the global scale, which may offer a way out of, say, regional or national normative grips, have become itself normative. Say differently: does the acceptance of English as the international communication device ends all discussions on the hegemonic normative position it has on scientific productions? Is going global the same as being international? Does meeting the global scientific standards suffice for your research to be considered, “universal”? The authors do not pretend here to be able to answer all those questions completely and satisfactory, the merit of their contribution might simply be to shed a new light on some of them." (source éditeur