Effet de l’amélioration du pâturage naturel par l’introduction de Chamaecrista rotundifolia sur les propriétés chimiques du sol, la structure du pâturage, la production de biomasse et le stock semencier du sol

Land degradation is evident in arid ecosystems already weakened by climate variability. The natural rangelands that provide the bulk of livestock feed are no exception to this situation. Exploring strategies to improve the productivity of these natural rangelands is a palliative solution for livestock feeding. The overall objective of this study is to improve forage production by introducing a forage legume, Chamaecrista rotundifolia. Two experiments were carried out, one on a ferruginous soil and the other on a ferralitic soil. Two seeding densities of C. rotundifolia seeds were used. Fertilization of 100 kg/ha of triple superphosphate (46% P) was chosen for the plots. The results indicated that soil type, weeding at sowing and sowing density of the legume had significant effects on the number of C. rotundifolia plants/m² in the natural pasture three years after its introduction. The control treatments did not have seeds of C. rotundifolia in the two soil horizons surveyed (H0-10 cm and H 10-20 cm). The production of C. rotundifolia biomass was higher in august compared to the evaluation in july with an average production of 1811 kg DM/ha against a maximum of 1070 kg DM/ha in the month of july. The results of the biomass analysis showed a higher nitrogen content in C. rotundifolia compared to the other species on the same soils, which denotes the ability of C. rotundifolia to fix atmospheric nitrogen. Keywords: Fodder, Natural pastures, Restoration, Seed stock, Chamaecrista rotundifoliaLa dégradation des terres est une évidence dans les écosystèmes arides déjà fragilisés par la variabilité climatique. Les parcours naturels qui assurent l’essentiel de l’alimentation du bétail n’échappent pas à cette situation. Explorer des stratégies d’amélioration de la productivité de ces parcours naturels est une solution palliative à la résolution de l’alimentation du bétail. Cette étude a pour objectif global d’améliorer la production fourragère par l’introduction d’une légumineuse fourragère, Chamaecrista rotundifolia. Pour ce faire, deux dispositifs expérimentaux ont été installés, l'un sur un sol ferrugineux et l’autre sur un sol ferralitique. Deux densités de semis C. rotundifolia ont été utilisées. La fertilisation de 100 kg/ha de triple superphosphate (46% P) a été retenue pour les parcelles concernées. Les résultats indiquent que le type de sol, le désherbage au semis et la densité de semis de la légumineuse ont eu des effets significatifs sur le nombre de pieds de C. rotundifolia /m² dans le pâturage naturel trois ans après son introduction. Les traitements témoins ne comportent pas de semences de C. rotundifolia dans les deux horizons du sol prospectés (H0-10 cm et H 10-20 cm). La production de biomasse C. rotundifolia, a été plus élevée au mois d’août comparativement à l’évaluation au mois de juillet avec une production moyenne de 1811 kg MS/ha contre un maximum de 1070 kg MS/ha dans le mois de juillet. Les résultats de l’analyse de la biomasse montrent une teneur plus élevée en azote chez C. rotundifolia par rapport aux autres espèces et ce sur les mêmes sols, ce qui dénote de la capacité de C. rotundifolia à fixer l’azote atmosphérique. Mots-clés: Fourrage, Pâturages naturels, Restauration, Stock semencier, Chamaecrista rotundifoli

Effet de l’amélioration du pâturage naturel par l’introduction de Chamaecrista rotundifolia sur les propriétés chimiques du sol, la structure du pâturage, la production de biomasse et le stock semencier du sol

La dégradation des terres est une évidence dans les écosystèmes arides déjà fragilisés par la variabilité climatique. Les parcours naturels qui assurent l’essentiel de l’alimentation du bétail n’échappent pas à cette situation. Explorer des stratégies d’amélioration de la productivité de ces parcours naturels est une solution palliative à la résolution de l’alimentation du bétail. Cette étude a pour objectif global d’améliorer la production fourragère par l’introduction d’une légumineuse fourragère, Chamaecrista rotundifolia. Pour ce faire, deux dispositifs expérimentaux ont été installés, l'un sur un sol ferrugineux et l’autre sur un sol ferralitique. Deux densités de semis C. rotundifolia ont été utilisées. La fertilisation de 100 kg/ha de triple superphosphate (46% P) a été retenue pour les parcelles concernées. Les résultats indiquent que le type de sol, le désherbage au semis et la densité de semis de la légumineuse ont eu des effets significatifs sur le nombre de pieds de C. rotundifolia /m² dans le pâturage naturel trois ans après son introduction. Les traitements témoins ne comportent pas de semences de C. rotundifolia dans les deux horizons du sol prospectés (H0-10 cm et H 10-20 cm). La production de biomasse C. rotundifolia, a été plus élevée au mois d’août comparativement à l’évaluation au mois de juillet avec une production moyenne de 1811 kg MS/ha contre un maximum de 1070 kg MS/ha dans le mois de juillet. Les résultats de l’analyse de la biomasse montrent une teneur plus élevée en azote chez C. rotundifolia par rapport aux autres espèces et ce sur les mêmes sols, ce qui dénote de la capacité de C. rotundifolia à fixer l’azote atmosphérique. Mots-clés: Fourrage, Pâturages naturels, Restauration, Stock semencier, Chamaecrista rotundifoli

Containing Aircraft Noise Levels at take-off: A Mathematical Programming Approach

The sustained growth of air transportation traffic along the last decades has induced increasing noise exposure for the areas surrounding large and medium airports. This study concentrates on the optimization of the take-off and departure flight phase for a transportation aircraft. A general aircraft trajectory generation problem is first formulated as an optimal control problem where a global cost, including noise penalties, is to be minimized. Since aircraft operators and communities have conflictive objectives, a noise index is introduced. Airlines operations costs and community noise levels are expressed as complex functions of the aircraft trajectory geometry resulting in a complex optimization problem. It is observed that flight dynamics present a differential flatness property and it is discussed how to take advantage of this to solve the trajectory generation problem and assess adequately the resulting surrounding noise exposure. Then, the case of a particular standard take-off/initial climb trajectory is considered. It appears that the noise level constraints turn the resulting mathematical programming problem numerically intricate and that this problem should be approached as a parameter optimization problem through a systematic evaluation process.Peer Reviewe

Chapitre 21. Analyse des flux d’eau dans les systèmes de culture à base de sorgho dans un contexte de changement climatique (N’Tarla, Mali)

Dans les régions arides, l’eau est, par définition, le facteur limitant le plus courant de la production alimentaire. Au Mali, la zone cotonnière est située en zone soudano-sahélienne, entre les isohyètes 800 et 1 200 mm (FAO, 2001). Dans la zone dite sèche (900 mm), les cultures vivrières sont principalement le sorgho et le mil (Bazile et al., 2000). Les besoins en eau du sorgho varient entre 500 et 850 mm en fonction de la longueur du cycle (Gandah, 1991). Le cumul enregistré pendant l’anné..

Contribution à l'analyse, l'évaluation et la mise en œuvre des nouveaux moyens de contrôle du trafic aérien (application à l'Afrique occidentale)

TOULOUSE2-BUC Mirail (315552102) / SudocSudocFranceF

Chapitre 24. Effet de la période d’application du compost sur les rendements du sorgho et la productivité de l’eau de pluie

Introduction Au Burkina Faso, le secteur agricole occupe plus de 86 % de la population active et contribue à environ 40 % au PIB. Malgré cette importance et sa forte domination par les cultures céréalières, il peine à nourrir la population burkinabée du fait de sa très faible productivité. Les principales céréales cultivées sont le sorgho, le mil, le maïs et le riz. Elles constituent l’aliment de base de la population. Les faibles rendements de ces cultures sont souvent dus aux conditions plu..

Minimum time trajectory generation for relative guidance of aircraft

International audienceIn this communication is considered the problem of on line generation of minimum time trajectories to be followed by an aircraft to achieve relative convergence maneuvers. Here the trajectory generation problem is first considered as a minimum time control problem. The analysis of the resulting set of complex optimality conditions shows that the minimum time trajectories are produced by bang-bang control laws and can be characterized by some few geometric parameters. Then regular minimum time convergence trajectories can be defined. For practical considerations it appears necessary to solve on line this problem. Taking into consideration the structure of the regular minimum time convergence trajectories, an equivalent mathematical programming problem is formulated. . An off line exhaustive solution approach, based on reverse dynamic programming, is proposed to cover a large set of initial relative positions. Then a feed forward neural network can be trained to associate to an initial relative position the parameters of an optimal regular minimum time convergence trajectory

Containing Aircraft Noise Levels at take-off: A Mathematical Programming Approach

The sustained growth of air transportation traffic along the last decades has induced increasing noise exposure for the areas surrounding large and medium airports. This study concentrates on the optimization of the take-off and departure flight phase for a transportation aircraft. A general aircraft trajectory generation problem is first formulated as an optimal control problem where a global cost, including noise penalties, is to be minimized. Since aircraft operators and communities have conflictive objectives, a noise index is introduced. Airlines operations costs and community noise levels are expressed as complex functions of the aircraft trajectory geometry resulting in a complex optimization problem. It is observed that flight dynamics present a differential flatness property and it is discussed how to take advantage of this to solve the trajectory generation problem and assess adequately the resulting surrounding noise exposure. Then, the case of a particular standard take-off/initial climb trajectory is considered. It appears that the noise level constraints turn the resulting mathematical programming problem numerically intricate and that this problem should be approached as a parameter optimization problem through a systematic evaluation process.Peer Reviewe

Containing Aircraft Noise Levels at take-off: A Mathematical Programming Approach

The sustained growth of air transportation traffic along the last decades has induced increasing noise exposure for the areas surrounding large and medium airports. This study concentrates on the optimization of the take-off and departure flight phase for a transportation aircraft. A general aircraft trajectory generation problem is first formulated as an optimal control problem where a global cost, including noise penalties, is to be minimized. Since aircraft operators and communities have conflictive objectives, a noise index is introduced. Airlines operations costs and community noise levels are expressed as complex functions of the aircraft trajectory geometry resulting in a complex optimization problem. It is observed that flight dynamics present a differential flatness property and it is discussed how to take advantage of this to solve the trajectory generation problem and assess adequately the resulting surrounding noise exposure. Then, the case of a particular standard take-off/initial climb trajectory is considered. It appears that the noise level constraints turn the resulting mathematical programming problem numerically intricate and that this problem should be approached as a parameter optimization problem through a systematic evaluation process.Peer Reviewe

Malaria parasite clearance from patients following artemisinin-based combination therapy in Côte d'Ivoire

International audienceIntroduction:Parasite clearance is useful to detect artemisinin resistance. The aim of this study was to investigate parasite clearance in patients treated with artesunate + amodiaquine (AS + AQ) and artemether + lumefantrine (AL): the two artemisinin-based combination therapies (ACTs) recommended in the first-line treatment of uncomplicated malaria in Côte d'Ivoire.Methods:This study was conducted in Bouaké, Côte d'Ivoire, from April to June 2016. Patients aged at least 6 months with uncomplicated malaria and treated with AS + AQ or AL were hospitalized for 3 days, and follow-up assessments were performed on days 3, 7, 14, 21, 28, 35, and 42. Blood smears were collected at the time of screening, pre-dose, and 6-hour intervals following the first dose of administration until two consecutive negative smears were recorded, thereafter at day 3 and follow-up visits. Parasite clearance was determined using the Worldwide Antimalarial Resistance Network's parasite clearance estimator. The primary end points were parasite clearance rate and time.Results:A total of 120 patients (57 in the AS + AQ group and 63 in the AL group) were randomized among 298 patients screened. The median parasite clearance time was 30 hours (IQR, 24-36 hours), for each ACT. The median parasite clearance rate had a slope half-life of 2.36 hours (IQR, 1.85-2.88 hours) and 2.23 hours (IQR, 1.74-2.63 hours) for AS + AQ and AL, respectively. The polymerase chain reaction-corrected adequate clinical and parasitological response was 100% and 98.07% at day 42 for AS + AQ and AL, respectively.Conclusion:Patients treated with AS + AQ and AL had cleared parasites rapidly. ACTs are still efficacious in Bouaké, Côte d'Ivoire, but continued efficacy monitoring of ACTs is needed