269 research outputs found
Effet de la fertilisation azotĂ©e et phosphorĂ©e sur le dĂ©veloppement de la Panachure jaune en riziculture aquatique en CĂŽte dâIvoire
La crise mondiale du riz survenue en 2008 a montrĂ© lâimpĂ©rative nĂ©cessitĂ© pour les pays tributaires des importations comme la CĂŽte dâIvoire, dâassurer leur autosuffisance. La fertilisation minĂ©rale figure parmiles cinq axes stratĂ©giques dĂ©finis pour lâaccroissement de la production rizicole en CĂŽte dâIvoire. Sachant lâeffet stimulateur de lâengrais azotĂ© sur le dĂ©veloppement de certaines maladies telle que la Pyriculariose duriz, un essai a Ă©tĂ© conduit dans le but de savoir lâinfluence dâune application optimale de lâazote sur lâĂ©pidĂ©mie de la Panachure jaune du riz ou Rice Yellow Mottle Virus (RYMV). LâĂ©tude a Ă©tĂ© rĂ©alisĂ©e selon un dispositif expĂ©rimental en SPLIT-PLOT comportant quatre niveaux dâazote (0 kg N Ha-1, 30 kg N Ha-1, 60 kg N Ha-1, 120 kg N Ha-1), trois niveaux de phosphore (0 kg P Ha-1, 13 kg P Ha-1, 26 kg N Ha-1) et 10 gĂ©notypes de riz irriguĂ©. Les rĂ©sultats ont montrĂ© que le phosphore et lâinteraction NxP nâont aucun effet significatif sur lâĂ©pidĂ©mie de RYMV. A lâopposĂ©, les analyses ont mis en Ă©vidence un effet significatif de lâazote sur lâincidence de la Panachure jaune Ă des doses comprises entre 0 et 30 Kg N Ha-1. Cet intervalle de doses Ă©tant en deçà de celui des doses recommandĂ©es en CĂŽte dâIvoire, lâintensification de la riziculture aquatique par unefertilisation azotĂ©e optimale, nâaura pas dâincidence significative sur le dĂ©veloppement de la Panachure jaune. Il faudra cependant sensibiliser les riziculteurs sur lâintĂ©rĂȘt dâappliquer des doses dâengrais recommandĂ©es dans la lutte contre la virose.Mots clĂ©s: Riz irriguĂ©, fertilisation minĂ©rale, Ă©pidĂ©mie, RYMV, incidence
Effet du paillage par des residus de pois dâangole (cajanus cajan l.) sur le rendement du riz (oryza sativa) pluvial en zone forestiere de CĂŽte dâIvoire
La riziculture pluviale, en zone forestiÚre de la CÎte d'Ivoire, est confrontée à plusieurs contraintes, dont, notamment la baisse de fertilité du sol et l'enherbement excessif. L'effet du paillage de Cajanus cajan comme engrais organique pour le riz pluvial, NERICA 1(Bonfani), a été évalué, en termes de rendement du riz. Cette étude a été conduite de 2003 à 2005 à la station de recherche du Centre National de Recherche Agronomique (CNRA) de Gagnoa. Deux rotations, à base de riz, avec les jachÚres à C. cajan de 6 mois et de 12 mois ont été testées et comparées, à celle avec la jachÚre naturelle. La biomasse des précédentes jachÚres est restée sur le sol comme mulch. Les résultats montrent que C. cajan ùgé de 12 mois a produit une biomasse sÚche de 17 t ha-1, en moyenne sur deux ans contre 1,7 t.ha-1 en 6 mois. La rotation riz avec C. cajan de 12 mois a amélioré significativement le rendement du riz, avec un gain de paddy qui a varié entre 700 et 900 kg ha-1, par rapport à la jachÚre naturelle. En plus, cette jachÚre à cajanus de 12 mois a permis de maintenir un minimum de rendement 1t ha-1. Cette technique offre une alternative de gestion durable des systÚmes traditionnels de riziculture pluviale
Synthesis of New Benzylic Di-, Tri-, and Tetraphosphonic Acids as Potential Chelating Agents
Abstract New di-, tri-, and tetraphosphonic acids were synthesized starting from four o-hydroxymethyl phenol derivatives and obtained in three steps in good overall yield. The phosphonic acids were isolated and purified using semi-preparative C18 HPLC column. The new compounds were characterized using different spectroscopic methods (1H, 13C, and 31P NMR; ESI MS; and MSn, IR). GRAPHICAL ABSTRAC
Producing red clover seeds for organic agriculture
This tool is a data sheet that can be used by French farmers who produce or want to produce red clover seeds in organic conditions.
It provides advice starting from the contract signing to the seed drying, going through the specificities of the crop, the sowing, irrigation, specific pests and their management, and the harvest
Securing virtual network function placement with high availability guarantees
Virtual Network Functions as a Service (VNFaaS) is currently under attentive study by telecommunications and cloud stakeholders as a promising business and technical direction consisting of providing network functions as a service on a cloud (NFV Infrastructure), instead of delivering standalone network appliances, in order to provide higher scalability and reduce maintenance costs. However, the functioning of such NFVI hosting the VNFs is fundamental for all the services and applications running on top of it, forcing to guarantee a high availability level against attacks and software failures. Indeed the availability of an VNFaaS relies on the failure rate of its single components, namely the servers, the virtualization software, and the communication network. The proper assignment of the virtual machines implementing network functions to NFVI servers and their protection from both endogenous and exogenous threats is essential to guarantee high availability. We model the High Availability Virtual Network Function Placement (HA- VNFP) as the problem of finding the best assignment of virtual machines to servers guaranteeing protection by replication. We propose a probabilistic approach to measure the real availability of a system and design both efficient and effective algorithms that can be used by stakeholders for both online and offline planning
Gamma oscillations in V1 are correlated with GABA(A) receptor density: A multi-modal MEG and Flumazenil-PET study.
High-frequency oscillations in the gamma-band reflect rhythmic synchronization of spike timing in active neural networks. The modulation of gamma oscillations is a widely established mechanism in a variety of neurobiological processes, yet its neurochemical basis is not fully understood. Modeling, in-vitro and in-vivo animal studies suggest that gamma oscillation properties depend on GABAergic inhibition. In humans, search for evidence linking total GABA concentration to gamma oscillations has led to promising -but also to partly diverging- observations. Here, we provide the first evidence of a direct relationship between the density of GABA(A) receptors and gamma oscillatory gamma responses in human primary visual cortex (V1). By combining Flumazenil-PET (to measure resting-levels of GABA(A) receptor density) and MEG (to measure visually-induced gamma oscillations), we found that GABA(A) receptor densities correlated positively with the frequency and negatively with amplitude of visually-induced gamma oscillations in V1. Our findings demonstrate that gamma-band response profiles of primary visual cortex across healthy individuals are shaped by GABA(A)-receptor-mediated inhibitory neurotransmission. These results bridge the gap with in-vitro and animal studies and may have future clinical implications given that altered GABAergic function, including dysregulation of GABA(A) receptors, has been related to psychiatric disorders including schizophrenia and depression
Temporal variability of mineral dust in southern Tunisia : analysis of 2 years of PM10 concentration, aerosol optical depth, and meteorology monitoring
International audienceThe south of Tunisia is a region very prone to wind erosion. During the last decades, changes in soil management have led to an increase in wind erosion. In February 2013, a ground-based station dedicated to the monitoring of mineral dust (that can be seen in this region as a proxy of the erosion of soils by wind) was installed at the Institut des RĂ©gions Arides (IRA) of MĂ©denine (Tunisia) to document the temporal variability of mineral dust concentrations. This station allows continuous measurements of surface PM10 concentration (TEOMâą), aerosol optical depth (CIMEL sunphotometer), and total atmospheric deposition of insoluble dust (CARAGA automatic sampler). The simultaneous monitoring of meteorological parameters (wind speed and direction, relative humidity, air temperature, atmospheric pressure, and precipitations) allows to analyse the factors controlling the variations of mineral dust concentration from the sub-daily to the annual scale. The results from the two first years of measurements of PM10 concentration are presented and discussed. In average on year 2014, PM10 concentration is 56 ”g/m3. However, mineral dust concentration highly varies throughout the year: very high PM10 concentrations (up to 1,000 ”g/m3 in daily mean) are frequently observed during wintertime and springtime, hardly ever in summer. These episodes of high PM10 concentration (when daily average PM10 concentration is higher than 240 ”g/m3) sometimes last several days. By combining local meteorological data, air-masses trajectories, sunphotometer measurements, and satellite imagery, the part of the high PM10 concentration due to local emissions and those linked to an advection of dusty air masses by medium and long range transport from the Sahara desert is quantified
Kak's three-stage protocol of secure quantum communication revisited: Hitherto unknown strengths and weaknesses of the protocol
Kak's three-stage protocol for quantum key distribution is revisited with
special focus on its hitherto unknown strengths and weaknesses. It is shown
that this protocol can be used for secure direct quantum communication.
Further, the implementability of this protocol in the realistic situation is
analyzed by considering various Markovian noise models. It is found that the
Kak's protocol and its variants in their original form can be implemented only
in a restricted class of noisy channels, where the protocols can be transformed
to corresponding protocols based on logical qubits in decoherence free
subspace. Specifically, it is observed that Kak's protocol can be implemented
in the presence of collective rotation and collective dephasing noise, but
cannot be implemented in its original form in the presence of other types of
noise, like amplitude damping and phase damping noise. Further, the performance
of the protocol in the noisy environment is quantified by computing average
fidelity under various noise models, and subsequently a set of preferred states
for secure communication in noisy environment have also been identified.Comment: Kak's protocol is not suitable for quantum cryptography in presence
of nois
Synthesis, characterization and antifungal activity of a series of manganese(II) and copper(II) complexes with ligands derived from reduced N,NâČ-O-phenylenebis(salicylideneimine)
A series of manganese(II) and copper(II) complexes with reduced Schiff bases derived from o-phenylenediamine has been prepared and characterized by elemental analysis, TG measurements, ESR, magnetic measurements, FTIR, UVâVisible spectra and conductivity. These complexes were found to be [MnL(H2O)n] and [CuL](H2O)n species with n = 0â2. Their antifungal activity was evaluated on different human fungi including yeasts of the Candida genus (C. albicans, C. glabrata, C. tropicalis and C. parapsilopsis) some opportunistic moulds belonging to the Aspergillus (A. fumigatus, A. terreus and A. flavus), Scedosporium genus (S. apiospermum and S. prolificans) and some dermatophytes (M. gypseum, M. persicolor, T. mentagrophytes, M. canis and T. tonsurans). The manganese complexes showed a significant growth inhibition of the dermatophytes tested and fungi of the genus Scedosporium. This is very interesting as these fungi are usually poorly susceptible to current antifungal including Amphotericin B and Itraconazole chosen as reference in this study
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