Simulating maize water productivity at deficit irrigated field in north west Ethiopia.

Irrigation agriculture in Ethiopia can be improved by applying appropriate irrigation levels. Since water scarcity is the major problem in Ethiopia, and farmers apply water without knowledge of the amount of water to be applied, appropriate irrigation levels for maize crops should be investigated in the central Gondar zone, Ethiopia. This paper aims to investigate the effect of deficit levels of irrigation on crop parameters and evaluate the AquaCrop model for its predictability potential of water productivity. The experiment has four levels of water application (Full Irrigation (100%), 75%, 50%, and 25% of crop evapotranspiration) at 10 days of irrigation interval using Randomized Complete Block Design with three replications. Data collected in two experiments in the different seasons were soil moisture, canopy cover, biomass, and final yield. As high R 2 (0.93) and Nash-Sutcliffe Efficiency (NSE) (0.91) values indicated, the model performed well in simulating canopy cover, above-ground biomass, and yield in all treatments except 25% full irrigation (FI) with prolonged water deficit. Grain yield measured from experiment 2 was within the range of 4.6 t/ha to 7.4 t/ha. Even though a high yield was found from FI, the measured water use efficiency was better in 75% FI treatment, indicating a potential for water-saving by this treatment than FI. Higher grain yield was observed for maize sown in January at experiment 1. This was attributed to the rainfall impact on the experiment since it was spring season in Ethiopia at which some rainfall in the region is pronounced. In addition, AquaCrop thoroughly underestimated the seasonal evapotranspiration values and the deviations were commonly bigger as stress levels increased. Therefore, AquaCrop can be used in the simulation of crop parameters, prediction of irrigated outputs, and assessing the impact of irrigation scheduling.

Modeling and optimization method of an indirectly irradiated solar receiver.

This work presents the modeling and optimization of an indirectly irradiated solar receiver. A numerical model of the cavity-absorber block is put forward with the coupling of the net-radiation method using infinitesimal areas and a CFD code. An iterative method with a relaxation factor made it possible to obtain the temperature distribution and the developed code was implemented in the form of UDF and used as boundary conditions in the CFD model of the absorber to simulate the flow of air and heat transfer. The good ability of the receiver to transfer heat to the fluid is proved with a 92% thermal efficiency obtained. Then the combination of the Kriging surface response method and the MOGA allowed the mathematical optimization of the receiver. The multi-objective optimization made it possible to obtain 3 candidates giving the best combinations of design parameters from the fixed objectives. Three bullet points, highlighting the customization of the procedure. •A practical analysis using the net-radiation method using infinitesimal areas is applied for cavity radiative exchange model.•The code developed for the cavity is implemented in the boundary conditions at the level of the ANSYS Fluent CFD model allowing the simulation of the conjugated transfers within the absorber.•The optimization method proposed is the combination of the Kriging surface response method for quantitative and qualitative analysis of the design parameters and MOGA to obtain different combinations seeking to maximize or to minimize the chosen parameters.

Isolement et caracterisation de Burkholderia cepacia lors d'infections hospitalieres

"Le developpement des techniques de reanimation et d'explorations fonctionnelles a entraine une ""explosion des infections nosocomiales"". Cette etude porte sur les souches de Burkholderia cepacia isolees en 1996 dans un hopital pediatrique du CHU de Dakar; suite a l'installation d'aspirateurs tracheo-bronchiques servant au desencombrement des enfants. Les 44 souches de B.cepacia etudiees proviennent de 42 hemocultures pratiquees chez 29 garcons et 13 filles ages de 5 jours a 7 ans et de 2 aspirateurs. Les aspirateurs constituent la source de contamination. Toutes les souches produisent un pigment jaune-orange. Un seul biotype a ete identifie. Le profil de sensibilite aux antibiotiques est presque univoque pour les 44 souches testees. La transmission de B. cepacia resulte de l'installation d'appareil de reanimation medicale dont l'entretien pose probleme. Les infections nosocomiales constatees sont jusqu'ici des bacteriemies simples. L'identification phenotypique et genotypique des souches a montre la circulation d'un seul clone. Le renforcement des mesures d'hygiene est la meilleure solution a ces infections nosocomiales."

Salmonelloses non typhoidiques en milieu pediatrique africain

A l'hopital pediatrique Albert Royer de Dakar; l'etude des salmonelles non typhoidiques de (1985-1989) a permis de colliger 35 dossiers. Elles representent 0;4 pour cent des hospitalisations et sont survenues essentiellement (83 pour cent) chez l'enfant age de moins de 3 ans; presentant surtout un terrain pathologique sous-jacent. Les principales formes cliniques ont ete septicemiques (46 pour cent) et digestives (31 pour cent). Parmi les formes localisees (23 pour cent) ; les meningites purulentes ont represente 45 pour cent. Un seul portage asymptomatique a ete decele. Les 17 serotypes de Salmonella isoles appartiennent a 8 serogroupes. S. enteridis et S. typhimurium ont constitue 51 pour cent des isolats. La sensibilite aux antibiotiques des differents serotypes a ete variable; les cephalosporines de troisieme generation et la gentamycine ayant inhibe plus de 80 pour cent des souches. La duree moyenne de l'antibiotherapie a ete de 21 jours avec une mortalite s'elevant a 17 pour cent. L'association ampicilline-gentamycine; bien que critiquable; garde son indication en traitement de 1ere intention a cause des disponibilites en produits

Pleuresies purulentes de l'enfant

122 cas de pleuresies purulentes de l'enfant sont rapportes. L'age moyen est de 3 ans. 33 pour cent des cas sont survenus sur un terrain de malnutrition proteino-calorique. 60 pour cent des enfants avaient un epanchement de grande abondance et 56 pour cent une pneumopathie associee. Le Staphylococcus aureus (51 pour cent) et le Streptococcus pneumoniae (18 pour cent) ont domine la bacteriologie du liquide pleural. Le taux de deces est de 6;5 pour cent. Le drainage pleural est pratique chez 53 pour cent des patients. L'exploration fonctionnelle n'a retrouve que des anomalies mineures. Le traitement de choix des pleuresies purulentes de l'enfant doit comprendre outre le drainage pleural; une association d'antibiotiques comportant un anti-staphylococcique