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
« Refoulé et recentré » : dynamiques touristiques et patrimoniales en Afrique du Sud et au Mozambique: Tome 3 : Position et Projet Scientifique (rapport de synthèse)
No full textM. Jean-Michel JAUZE, Pr en géographie, Université́ de La Réunion, garant de l'HDR. Madame FOURNET-GUÉRIN Catherine, Pr en géographie, Sorbonne Université - Madame GRAVARI-BARBAS Maria, Pr en géographie, Université Paris 1 Panthéon- Sorbonne, rapporteure - Monsieur LAJOIE Gilles, Pr en géographie, Université́ de La Réunion, rapporteur - Madame MAINET Hélène, Pr en géographie, Université́ de Clermont Auvergne, rapporteure - Monsieur TAGLIONI François,RésuméCe mémoire d’H.D.R. s’organise autour d’une pensée géographique ancrée sur les notions de refoulement et de recentrage/recodage.Le terrain concerné se situe en Afrique australe (Afrique du Sud et Mozambique), délimité par six espaces urbains prioritaires : Johannesburg et Pretoria sur les hautes terres sud-africaines ; Durban et Pietermaritzburg dans la province littorale du KwaZulu-Natal ; Maputo et Matola sis dans la partie méridionale mozambicaine.Le phénomène de « Dynamiques des marges patrimoniales » se situe au cœur du travail analytique et systémique mené, lequel repose sur plus d’une décennie de recherche.La réflexion porte sur les recompositions et la (re)valorisation de lieux géographiques et de faits historiques, par une mise en valeur à la fois touristique et patrimoniale.Elle cible la place et l’évolution de sujets tenant des « marge ». Ces dernières peuvent se considérer comme des objets-lieux périphériques et/ou refoulés au très fort potentiel mémoriel (soit aussi l’idée d’une ressource de territoire). Leur passé demeure effectivement attaché à une histoire pesante ou douloureuse ; il se voit ré-exalté sous diverses formes.Au final, la patrimonialisation touristique des matériaux « sensibles » met en interrelation enjeux et temporalités. Elle s’ouvre à un public très varié et permet d’apprécier différentes stratégies d’acteurs détenant un agenda précis. Elle finit aussi par exprimer des phénomènes de territorialisation et de mémorialisation.AbstractThis H.D.R. dissertation is organised around a geographical thought anchored on the notions of refoulement and recentering/recoding.The area of study is located in Southern Africa (South Africa and Mozambique), delimited by six major urban spaces: Johannesburg and Pretoria in the South African highlands; Durban and Pietermaritzburg in the coastal province of KwaZulu-Natal; Maputo and Matola located in the southern part of Mozambique.The phenomenon of 'Dynamics of Heritage Margins' lies at the heart of the analytical and systemic work carried out here, which is based on over a decade of research.The analysis focuses on the recompositions and (re)valorisation of geographical places and historical facts, through both tourism and cultural heritage enhancement.It targets the place and evolution of "margins" subjects, which can be considered as peripheral and/or repressed objects/places with a very strong memory-based potential. Their past remains attached to a dark or painful history; it is re-exalted in various forms.In the end, the tourist heritage of those "sensitive" materials brings together issues and temporalities. It opens up to a varied public and allow to appreciate strategies of actors with a specific agenda. It ends up expressing phenomena of territorialization and memorialization
Massive Volcanism May Have Foreshortened the Marinoan Snowball Earth
No full textInternational audienceThe Cryogenian Period (717-635 Ma) experienced two low-latitude "snowball Earth" glaciations, the Sturtian and the Marinoan of contrasting 57 and 2, as suggested by cap carbonates, specific geologic evidence linking volcanic events with deglaciation are lacking. Here, we present high-precision zircon geochronology with chemical abrasion-isotope-dilution isotope ratio mass spectrometry that indicates an extensive and thick sequence of rift-related magmatic rocks in South Qinling, Central China, erupted 2-6 Myr before the termination of the Marinoan. Climate modeling proposes a scenario explaining why the Marinoan was the shorter snowball and how volcanism may have driven the deglaciation
Le biocontrôle en France : de quoi parle-t-on ?
No full textInternational audienceThe use of synthetic chemical pesticides for crop protection has now clearly shown its limits: health risks, negative effects on the environment, ecological imbalances, loss of efficiency and high costs. Therefore, the goal of reducing the use of synthetic chemical pesticides in crop protection is now generally accepted by most professional and political actors. This paper focuses on the situation encountered in France, regarding the use of products of natural origin to manage populations and injuries of crop pests. In this field, the term “biocontrôle” has indeed appeared in France during the last decade; it is considered as a crop protection concept and it is presented as a solution to reduce the use of pesticides. This term “biocontrôle” is a French specificity; it does not have, to date, a single reference translation in English. This paper aims at providing an overview of what the term “biocontrôle” means in France. Behind an official definition, an examination of the definitions of “biocontrôle” in France shows significant terminological instability. The diversity of meanings of “biocontrôle” has led to varying interpretations by different French stakeholders. Furthermore, analysis of the use of the term “biocontrôle” in France over the last decade shows the growing interest of the general public, agricultural and agro-pharmaceutical professionals, policers and the scientific community. The increase in the use of the term “biocontrôle” has been observed in parallel with the decrease in the use of the French term “lutte biologique” (biological control or biocontrol in English), a recognized and stable concept for more than a century. Finally, this diversity of definitions of “biocontrôle” and the increase in the use of the term “biocontrôle” in France lead to issues in the field of crop protection that are discussed in this synthesis.L'utilisation des pesticides chimiques de synthèse dans la protection des cultures a aujourd'hui clairement montré ses limites : risques sanitaires, effets négatifs sur l'environnement, déséquilibres écologiques, pertes d'efficacité et coûts élevés. C'est pourquoi la forte réduction de ces pesticides est maintenant un objectif généralement admis par la plupart des acteurs professionnels et politiques. En France, le biocontrôle est un concept de protection des cultures apparu lors de la dernière décennie et présenté comme une solution permettant de réduire l'utilisation de pesticides. La présente synthèse vise à dresser un état des lieux de ce que recouvre le terme de « biocontrôle » en France. Derrière une définition officielle, la revue des définitions du biocontrôle en France montre une instabilité terminologique significative. La diversité des acceptions du terme de « biocontrôle » est à l'origine d'interprétations variables selon les acteurs. Par ailleurs, l'analyse de l'utilisation du terme « biocontrôle » en France au cours de la dernière décennie montre l'intérêt grandissant du biocontrôle auprès du grand public, des professionnels du monde agricole et agropharmaceutique, des politiques et de la communauté scientifique. L'augmentation de l'usage de ce terme a été observée parallèlement à la diminution de l'usage du terme « lutte biologique », un concept reconnu et stable depuis plus d'un siècle. Enfin, cette diversité des définitions du biocontrôle et cette augmentation de l'utilisation du terme « biocontrôle » induisent des problématiques dans le domaine de la protection des cultures qui sont évoquées dans cette synthèse. Mots clés : biocontrôle / produits de biocontrôle / protection des cultures / terminologie / instabilité dénominative Abstract-"Biocontrôle" in France: what are we talking about? The use of synthetic chemical pesticides for crop protection has now clearly shown its limits: health risks, negative effects on the environment, ecological imbalances, loss of efficiency and high costs. Therefore, the goal of reducing the use of synthetic chemical pesticides in crop protection is now generally accepted by most professional and political actors. This paper focuses on the situation encountered in France, regarding the use of products of natural origin to manage populations and injuries of crop pests. In this field, the term "biocontrôle" has indeed appeared in France during the last decade; it is considered as a crop protection concept and it is presented as a solution to reduce the use of pesticides. This term "biocontrôle" is a French specificity; it does not have, to date, a single reference translation in English. This paper aims at providing an overview of what the term "biocontrôle" means in France. Behind an official definition, an examination of the definitions of "biocontrôle" in France shows significant terminological instability. The diversity of meanings of "biocontrôle" has led to varying interpretations by different French stakeholders. Furthermore, analysis of the use of the term "biocontrôle" in France over the last decade shows the growing interest of the general public, agricultural and agropharmaceutical professionals, policers and the scientific community. The increase in the use of the term "biocontrôle" has been observed in parallel with the decrease in the use of the French term "lutte biologique" (biological control or biocontrol in English), a recognized and stable concept for more than a century. Finally, this diversity of definitions of "biocontrôle" and the increase in the use of the term "biocontrôle" in France lead to issues in the field of crop protection that are discussed in this synthesis
Comparison of quasi-geostrophic, hybrid and 3D models of planetary core convection
No full textInternational audienceWe present investigations of rapidly-rotating convection in a thick spherical shell geometry relevant to planetary cores, comparing results from Quasi-Geostrophic (QG), 3D and hybrid QG-3D models. The 170 reported calculations span Ekman numbers, Ek, between 10-4 and 10-10, Rayleigh numbers, Ra, between 2 and 150 times supercritical, and Prandtl numbers, Pr, between 10 and 10-2. The default boundary conditions are no-slip at both the ICB and the CMB for the velocity field, with fixed temperatures at the ICB and the CMB. Cases driven by both homogeneous and inhomogeneous CMB heat flux patterns are also explored, the latter including lateral variations, as measured by Q*, the peak-to-peak amplitude of the pattern divided by its mean, taking values up to 5. The Quasi-Geostrophic (QG) model is based on the open-source pizza code. We extend this in a hybrid approach to include the temperature field on a 3D grid. In general, we find convection is dominated by zonal jets at mid-depths in the shell, with thermal Rossby waves prominent close to the outer boundary when the driving is weaker. For the thick spherical shell geometry studied here the hybrid method is best suited for studying convection at modest forcing, Ra ≤ 10 Rac when Pr = 1, and departs from the 3D model results at higher Ra, displaying systematically lower heat transport characterized by lower Nusselt and Reynolds numbers. We find that the lack of equatorially anti-symmetric and z-correlations between temperature and velocity in the buoyancy force contributes to the weaker flows in the hybrid formulation. On the other hand, the QG models yield broadly similar results to the 3D models, for the specific aspect ratio and range of Rayleigh numbers explored here. We cannot point to major disagreements between these two datasets at Pr ≥ 0.1, although the QG model is effectively more strongly driven than the hybrid case due to its cylindrically-averaged thermal boundary conditions. When Pr is decreased, the range of agreement between the Hybrid and 3D models expands, e.g. up to Ra ≤ 15 Rac at Pr = 0.1, indicating the hybrid method may be better suited to study convection in the regime Pr ≪ 1. We effectively observe two regimes: (i) at Pr ≥ 0.1 the QG and 3D models agree in the studied range of Ra/Rac while the hybrid model fails when Ra > 10 Rac; (ii) at Pr = 0.01 the QG and 3D disagree above Ra/Rac = 10 while the hybrid and 3D models agree fairly well up to Ra ~ 20 Rac. Models that include laterally-varying heat flux at the outer boundary reproduce regional convection patterns that compare well with those found in similarly forced 3D models. Previously proposed scaling laws for rapidly-rotating convection are tested; our simulations are overall well described by a triple balance between Coriolis, inertia and Archimedean (CIA) forces with the length-scale of the convection following the diffusion-free Rhines-scaling. The Prandtl number, Pr, affects the number and the size of the jets with larger structures obtained at lower Pr; higher velocities and lower heat transport are also seen on decreasing Pr. The scaling behaviour of the convective velocity shows a strong dependence on Pr. This study is an intermediate step towards a hybrid model of core convection also including 3D magnetic effects
Pauvreté multidimensionnelle et inégalités en République Démocratique du Congo
No full textThis working paper proposes to examine the questions of poverty in the specific contexteof the DRC and in this dynamic, 2 techniques allowing the dissection of the poverty in itsmultiple dimensions have been used : The Alkir&Foster techniques and that of fuzzy sets,in order to determine the characteristics of poor households, the causes and the scope(incidence, intensity and depth) of that poverty. The author has looked at the singularityof the DRC by proposing an archetype of indicators that is able to build a poverty indexthat best embodies the particularity of this region. It also brings in the notion ofinequalities in order to broaden the sphere of réflexion around this phenomenon.B.P 4745 KIN 2, Université Protestante au Congo, Faculté d'administration des affaires et sciences économiques République Démocratique du Congo. RESUME Ce papier entend examiner la question de la pauvreté dans le contexte spécifique de la RDC et dans cette dynamique, 2 techniques permettant la dissection de la pauvreté dans ses multiples dimensions ont été mis à contribution : La technique Alkire&Foster et celle des ensembles flous, de manière à déterminer les caractéristiques des ménages pauvres, les causes et l'envergure (Incidence, intensité, profondeur) de cette pauvreté. L'auteur s'est penché sur la singularité de la RDC en proposant un archétype d'indicateurs qui soit à même de construire un indice de pauvreté incarnant le mieux la particularité dans cette contrée. Il fait également intervenir la notion des inégalités afin d'élargir la sphère de réflexion autour de ce phénomène
A taxonomy of simulated geomagnetic jerks
No full textInternational audienceGeomagnetic jerks—abrupt changes in the acceleration of Earth’s magnetic field that punctuate geomagnetic records— have been richly documented over the past decades by taking advantage of the complementary strengths of ground observatory and satellite measurements. It has recently been proposed that these events originate from the interplay and timescale separation between slow convection and rapid hydromagnetic wave propagation in Earth’s outer core, with these latter waves playing a key role in the generation of jerk signals. To assess the generality of this explanation, here we analyse a catalogue of 14 events obtained during a 14 000-yr-long temporal sequence from a numerical geodynamo simulation that is the closest to date to Earth’s core conditions regarding timescale separation. Events are classified according to their dynamic origin and the depth at which they are triggered in the outer core. The majority of jerk events are found to arise from intermittent local disruptions of the leading-order force balance between the pressure, Coriolis, buoyancy and Lorentz forces (the QG-MAC balance), that leads to an inertial compensation through the emission of rapid, non-axisymmetric, quasi-geostrophic Alfvén waves from the region where this force balance is disrupted. Jerk events of moderate strength arise from the arrival at low latitudes at the core surface of hydromagnetic wave packets emitted from convective plumes rooted at the inner core boundary. As in an earlier simulation, these account well for jerk features that have recently been documented by satellite and ground observations. The more realistic timescales in the simulation reported here allow further details to be distinguished, such as multiple temporal alternations of geomagnetic acceleration pulses at low latitudes, long-range synchronization of pulse foci in space and rapid longitudinal drift of these foci at the core surface. The strongest events in the catalogue arise from disruption of the leading-order force balance near or at the core surface, from the combined influence of the arrival of buoyancy plumes and magnetic field rearrangement. The hydromagnetic waves that are sent laterally and downwards generate signals that clearly illustrate the presence of nearly synchronous ‘V-shaped’ magnetic variation patterns over a wide portion of Earth’s surface and also at mid to high latitudes, despite the source being confined to low latitudes at the core surface. Other well-known characteristics of strong geomagnetic jerks such as surges in the intensity of the secular variation and inflexions in the length-of-day variations are also reproduced in these events. Irrespectively of the event strength, our results support the hypothesis of a single physical root cause—the emission of magneto-inertial waves following a disruption of the QG-MAC balance—for jerks observed throughout the geomagnetic record
The aesthetic value of reef fishes is globally mismatched to their conservation priorities
No full textInternational audienceReef fishes are closely connected to many human populations, yet their contributions to society are mostly considered through their economic and ecological values. Cultural and intrinsic values of reef fishes to the public can be critical drivers of conservation investment and success, but remain challenging to quantify. Aesthetic value represents one of the most immediate and direct means by which human societies engage with biodiversity, and can be evaluated from species to ecosystems. Here, we provide the aesthetic value of 2,417 ray-finned reef fish species by combining intensive evaluation of photographs of fishes by humans with predicted values from machine learning. We identified important biases in species’ aesthetic value relating to evolutionary history, ecological traits, and International Union for Conservation of Nature (IUCN) threat status. The most beautiful fishes are tightly packed into small parts of both the phylogenetic tree and the ecological trait space. In contrast, the less attractive fishes are the most ecologically and evolutionary distinct species and those recognized as threatened. Our study highlights likely important mismatches between potential public support for conservation and the species most in need of this support. It also provides a pathway for scaling-up our understanding of what are both an important nonmaterial facet of biodiversity and a key component of nature’s contribution to people, which could help better anticipate consequences of species loss and assist in developing appropriate communication strategies
Interfacial organization and phase behavior of mixed galactolipid-DPPC-phytosterol assemblies at the air-water interface and in hydrated mesophases
No full textInternational audienceThe structural behavior of model assemblies composed of monogalactosyldiacylglycerol (MGDG) and digalactosyldiacylglycerol (DGDG), the two main galactolipids found in plants, was investigated at the air/water interface and in aqueous dispersion. To approach the composition of the natural photosynthetic membranes, tunable Langmuir model membrane of galactolipids (GL) were used, and were complexified to form either heterogenous binary or ternary assemblies of GL, phospholipids (PL), and phytosterols (pS).The impact of pS, 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) or both on the structural properties of GL membrane was studied. The nature of the interactions between the different molecules was investigated using biophysical characterizations (ellipsometry, tensiometry, atomic force microscopy). In addition, the phase behavior was determined by SAXS analysis on the model assemblies in aqueous dispersions.Results revealed the good interfacial stability of these specific plant membrane lipids. The morphology of the GL film was characteristic of a fluid phase, with an interfacial roughness induced by the intercalation of monogalactosyl and digalactosyl polar heads of MGDG and DGDG, respectively. A phase heterogeneity in the monolayer was induced by the addition of DPPC and/or pS, which resulted in the modification of galactolipid organization and headgroup interactions. These structural changes were confirmed by SAXS analysis, showing more favorable interactions between MGDG and DPPC than between DGDG and DPPC in aqueous dispersion. This phenomenon was exacerbated in the presence of pS.HIGHLIGHTS • Plant polar lipids formed stable monolayers at the air/water interface. • Phytosterols reduced the lateral elasticity of galactolipid and DPPC monolayer. • DPPC has affected MGDG-DGDG interactions. • Results highlighted preferential phase miscibility between DPPC and MGDG
Coming from elsewhere: the preponderance of introduced plant species in agroforestry systems on the east coast of Madagascar
No full textInternational audienceAn inventory of the species in and around the clove agroforestry systems (AFS) on the east coast of Madagascar revealed that none of the currently grown species derive from the native Malagasy biodiversity: the herbaceous and woody plants which comprise planned agrobiodiversity, i.e. are deliberately planted by the farmer, are without exception, introduced species. The associated agrobiodiversity, including plants that grow spontaneously and are protected or tolerated by farmers, is composed of a mix of native and introduced species. This situation, which is paradoxical for an island with a very high level of endemicity is the result of a double process of species introduction. The first is associated with the waves of migration, which, during the past three thousand years or so, allowed colonisation of the island, previously devoid of human occupants. The migrant populations originating from Austronesia and then from Africa, introduced their own crops and associated growing practices and only exploited local biodiversity through gathering, which did not require planting or tending. This situation is therefore the result of a long process of farmers' strategies to manage natural resources in a context of subsistence agriculture. The second process is more recent and is associated with increasing occupation by Europeans from the 16th/eighteenth century onwards, which peaked at the end of the nineteenth century with the French colonisers, who introduced and then developed cash crops (coffee, cloves, vanilla). This long-term retrospective study sheds light on the dynamics at the origin of the biodiversity "melting pot" visible today in the AFS along the east coast of Madagascar. It shows the constant evolution and adaptation of farmers' strategies and cropping systems, but also their historical roots. The cohabitation between introduced and indigenous species, observed today in Madagascar, is found in other AFSs built around an introduced cash crop, in various tropical zones. Knowing the origins and determinants of this cohabitation could be useful to support future evolutions of these cropping systems in the current context of changing agricultural practices in response to ecological and macroeconomic pressures
Research and Measuring Technology Needs to Better Model and Measure Fatigue Crack Development of Thinly Surfaced Asphalt Road Pavements
No full textInternational audienceThe root cause of premature failures in relatively thin (<50 mm) asphalt surfaced roads is often a challenge to solve during forensic investigations in South Africa (SA). This description is based on peer review type discussions with forensic investigations experts as well as published research papers. The areas of ignorance or areas where research effort is needed are identified. These observations serve to identify areas of new knowledge needed in terms of actual verification with measurements, measurement technology, and modeling of the observed phenomena. The main objectives of this discussion paper are to highlight the evolution of distress development in asphalt layers starting from the identification and description of the kind of microcracks, effects of microcracks in the debonding of the asphalt layer from lower layer, and vehicle–pavement interactions (VPI) of moving truck wheels focusing on the thin asphalt layer. Specific reference is made to the need to measure and model the effects of bow waves in front of and next to the loaded rolling wheel