5,406 research outputs found

    Reduction of Soil-Borne Plant Pathogens Using Lime and Ammonia Evolved from Broiler Litter

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    In laboratory and micro-plots simulations and in a commercial greenhouse, soil ammonia (NH3) and pH were manipulated as means to control soil-borne fungal pathogens and nematodes. Soil ammonification capacity was increased by applying low C/N ratio broiler litter at 1–8% (w/w). Soil pH was increased using lime at 0.5–1% (w/w). This reduced fungi (Fusarium oxysporum f. sp. dianthi and Sclerotium rolfsii) and root-knot nematode (Meloidogyne javanica) in lab tests below detection. In a commercial greenhouse, broiler litter (25 Mg ha−1) and lime (12.5 Mg ha−1) addition to soil in combination with solarization significantly reduced M. javanica induced root galling of tomato test plants from 47% in the control plots (solarization only) to 7% in treated plots. Root galling index of pepper plants, measured 178 days after planting in the treated and control plots, were 0.8 and 1.5, respectively, which was statistically significantly different. However, the numbers of nematode juveniles in the root zone soil counted 83 and 127 days after pepper planting were not significantly different between treatments. Pepper fruit yield was not different between treatments. Soil disinfection and curing was completed within one month, and by the time of bell-pepper planting the pH and ammonia values were normal

    The nuclear contacts and short range correlations in nuclei

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    Atomic nuclei are complex strongly interacting systems and their exact theoretical description is a long-standing challenge. An approximate description of nuclei can be achieved by separating its short and long range structure. This separation of scales stands at the heart of the nuclear shell model and effective field theories that describe the long-range structure of the nucleus using a mean- field approximation. We present here an effective description of the complementary short-range structure using contact terms and stylized two-body asymptotic wave functions. The possibility to extract the nuclear contacts from experimental data is presented. Regions in the two-body momentum distribution dominated by high-momentum, close-proximity, nucleon pairs are identified and compared to experimental data. The amount of short-range correlated (SRC) nucleon pairs is determined and compared to measurements. Non-combinatorial isospin symmetry for SRC pairs is identified. The obtained one-body momentum distributions indicate dominance of SRC pairs above the nuclear Fermi-momentum.Comment: Accepted for publication in Physics Letters. 6 pages, 2 figure

    Fast self-stabilizing byzantine tolerant digital clock synchronization

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    Consider a distributed network in which up to a third of the nodes may be Byzantine, and in which the non-faulty nodes may be subject to transient faults that alter their memory in an arbitrary fashion. Within the context of this model, we are interested in the digital clock synchronization problem; which consists of agreeing on bounded integer counters, and increasing these counters regularly. It has been postulated in the past that synchronization cannot be solved in a Byzantine tolerant and self-stabilizing manner. The first solution to this problem had an expected exponential convergence time. Later, a deterministic solution was published with linear convergence time, which is optimal for deterministic solutions. In the current paper we achieve an expected constant convergence time. We thus obtain the optimal probabilistic solution, both in terms of convergence time and in terms of resilience to Byzantine adversaries

    Evaluation de l’efficacite de quatre formulations de chlorpyriphos ethyl contre la cochenille Farineuse du manguier Rastrococcus invadens Williams (Homoptera : Pseudococcidae) : bilan de dix annees d’experimentation en Côte D’Ivoire

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    La cochenille farineuse du manguier, Rastrococcus invadens (Homoptera : Pseudococcidae) est l’un des principaux ravageurs du manguier en Côte d’Ivoire, particulièrement dans la région nord qui fournit les mangues exportées. En attendant la mise en place de la lutte biologique envisagée, et devant l’ampleur des dégâts pouvant favoriser des traitements abusifs de la part des producteurs, des expérimentations ont été initiées pour sélectionner des insecticides efficaces en vue de leur homologation. Sur station de recherche, le premier screening a concerné 8 formulations d’insecticides appliquées à doses fortes (2 litres / ha) sur 100 m² de parcelle élémentaire de manguiers. Ensuite, pour chaque formulation retenue, trois doses ont été testées (2 litres / ha, 1 litre / ha et 0,5 litre / ha) sur 200 m². En milieu paysan, la dose optimale a été confirmée sur au moins 20 ha dans des essais couples. Le screening préliminaire a mis en évidence l’efficacité des formulations à base de chlorpyrifos éthyl avec une rémanence de 4 semaines. L’évaluation de 3 doses de ces formulations en station a permis de retenir la dose efficace de 1 litre / ha soit 480 g dechlorpyrifos-éthyl / ha. Les tests réalisés en milieu paysan ont confirmé l’efficacité des 4 formulations de chlorpyrifos-éthyl contre le ravageur : Dursban 4 E, Cyren 480 EC, Pyriforce 480 EC et Pyrical 480 EC. L’exécution raisonnée des traitements permet à la lutte chimique de s’intégrer harmonieusement dans un programme de gestion intégrée de la cochenille farineuse.Mots clés : Rastrococcus invadens, cochenille farineuse du manguier, lutte chimique, chlorpyrifos-éthyl.EVALUATION OF FOUR FORMULATIONS OF CHLORPYRIPHOS ETHYL AGAINST THE MANGO MEALY BUG Rastrococcus invadensWILLIAMS  (HOMOPTERA : PSEUDOCOCCIDAE) : ASSESSMENTOF TEN YEARS  EXPERIMENTATION IN CÔTE D’IVOIREThe mango mealy bug, Rastrococcus invadens (Homoptera,  Pseudococcidae) is one of the main pests of mango in Côte d’Ivoire,  particularly in the northern region that provides the exported mangoes. Before the using of biological control considered, and faced with the extent of damages that may promote abusive treatment by the producers,  experiments were initiated to select effective insecticides for their approval. On research station, the first screening has involved eight formulations of insecticides applied at high doses (2 L / ha) of 100 m² plot of mango trees. Then, for each formulation selected, three doses were tested (2 liters / ha, 1 liter / ha and 0.5 l / ha) on 200 m². On-farm, the optimal dose was confirmed at least 20 ha in trials couples. The preliminary  screening has shown the effectiveness of formulations containing  chlorpyrifos ethyl with a remanence of 4 weeks. The evaluation of three  doses of these formulations on station allowed to retain the effective dose of 1 l / ha or 480 g of chlorpyrifos-ethyl / ha. The on-farm tests have  confirmed the effectiveness of four formulations of chlorpyrifos-ethyl against the pest: Dursban 4 E, Cyren 480 EC, Pyriforce 480 EC and Pyrical 480 EC. The rational treatment allows to chemical control to integrate  seamlessly into an integrated management program against the mealy  bug.Key words : Rastrococcus invadens, mango mealy bug, chemical control, chlorpyrifos ethyl

    Shrinkage behaviour of semi-crystalline polymers in laser sintering: PEKK and PA12

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    This is the author accepted manuscript. The final version is available from Elsevier via the DOI in this recordShrinkage is extensively mentioned in the literature as one of the main causes for dimensional instability or poor performance in Laser Sintering (LS). This study proposes and examines a methodology to describe shrinkage in cooling from a material perspective. Thermal behaviour and crystallisation effects were measured to determine the influence of powder structure and density on overall LS shrinkage. PEKK and PA12 powders were used to assess such behaviour in LS. The shrinkage parameter associated with powder bulk properties has the greatest impact in PEKK, contributing to 57% of the total shrinkage observed in cooling for this material as supported by the low values of bulk density, irregular morphology and internal porosity observed for these particles. For PA12, crystallisation is responsible for 60% of the overall shrinkage observed. In LS, PEKK shows an overall shrinkage approximately 30% lower than PA12, which makes it a promising material for maintaining final part dimensions.Arkema Innovations Chemistr

    Methods for evaluating particle coalescence and their implications in laser sintering

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    This is the author accepted manuscript. The final version is available from Elsevier via the DOI in this recordAn experimental study on the melt and coalescence of different Poly(aryl ether ketones) (PAEK) powders was carried out. The study consisted of evaluating individual particles and neck growth using a hot stage platform. Three different methods of assessing particles dimensions were evaluated, and the coalescence was compared for the grades on three different substrates: glass, glass coated silicone and amorphous PEKK films, the last substrate with the intent to relate with the laser sintering process. It was found that all individual particles shrink prior to melting, achieving up to 30% reduction in perimeter at temperatures just above melting. This shrinkage is followed by an increase in size, mostly driven by viscous flow. Shrinkage is expected to affect neck growth by delaying coalescence, as particles are pulled away whilst neck increases. This is a plausible explanation for why neck growth occurs at a lower rate than predicted by most coalescence models. The use of different substrates does not seem to affect particle coalescence or change in dimension. Viscosity and particle size influence overall particle behaviour and melt, whilst morphology and porosity do not have a great impact in particles coalescence.The authors would like to acknowledge the financial support of Arkema Innovations Chemistry for this study

    Israeli germplasm: phenotyping and genotyping of native grapevines (Vitis vinifera L.)

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    In this study 32 grapevine accessions from Israel were phenotyped according to O.I.V descriptors and phyllometry, furthermore genotyped with seven microsatellite loci for the first time for further clarification of their potential biodiversity and phylogenetic grapevine analysis. The results according to the SSR microsatellites suggest that the majority of the studied Israeli grapevine accessions, compared to the international reference varieties, show considerably different genotypes - nine accessions showed a unique (individual) genotype, further three accessions represented a first group, four accessions represent a second group and eight groups contained two different accessions. The significant differences among the studied grapevine accessions were observed also in most of the 17 phyllometric measurements of significant leaf characteristics, especially in the leaf area, vein length (L1, L2, L3 and L4), depth of lateral sinuses (OS, OI), petiol length (Lp) and vein angles (β, β’). The observed grapevine characteristics according to the O.I.V. descriptors suggested that more than three-quarters of the studied accessions showed characteristics of table grapes

    Profil anthropometrique des enfants scolarises tananariviens

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    Les enfants tananariviens sont en état de malnutrition chronique. Notre objectif est d'évaluer l'indice de masse corporelle (IMC) pour estimer lesenfants apparemment "sains". Une enquête et une mesure de la taille et du poids des enfants scolarisés tananariviens de 6 à 11 ans ont été réalisées. Après leur accord, la taille et l'indice de masse corporelle des 442 enfants tirés au hasard ont été ainsi obtenus. L'analyse de la moyenne de la taille a révélé une différence significative à 8 ans, une différence non évidente sur l'indice de masse corporelle. La comparaison avec les valeurs de référence (OMS 2006) a montré un retard statural de 34% avec une tendance globale à la hausse et un déficit pondéral égal à 5,5% selon le z score. Ainsi, au sein d'une population malnutrie, l'indice de masse corporelle pourrait être utilisé comme un des paramètres à considérer dans l'évaluation de l'état de santé pour classer ces enfants en bonne santé apparente

    A simple proof of the unconditional security of quantum key distribution

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    Quantum key distribution is the most well-known application of quantum cryptography. Previous proposed proofs of security of quantum key distribution contain various technical subtleties. Here, a conceptually simpler proof of security of quantum key distribution is presented. The new insight is the invariance of the error rate of a teleportation channel: We show that the error rate of a teleportation channel is independent of the signals being transmitted. This is because the non-trivial error patterns are permuted under teleportation. This new insight is combined with the recently proposed quantum to classical reduction theorem. Our result shows that assuming that Alice and Bob have fault-tolerant quantum computers, quantum key distribution can be made unconditionally secure over arbitrarily long distances even against the most general type of eavesdropping attacks and in the presence of all types of noises.Comment: 13 pages, extended abstract. Comments will be appreciate
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