Sorghum responses to different forms of Tilemsi rock phosphate combined with soluble fertilizers in a low-input production system in Mali

The deficiency in bioavailable phosphorus is one of the major constraints to cereal production in Mali. The objective of this study was to assess the combined effects of Tilemsi rock phosphate (PNT) with different doses of soluble fertilizers on the solubility of rock phosphate, the agronomic performance of sorghum and the chemical properties of the soil. The study consisted of the comparison of four (4) types of fertilization at three (3) levels of variation 0 kg.ha-1; 11 kg.ha-1, and 16 kg.ha-1 of phosphorus arranged in a complete randomized block with three replicates. The combination of PNT with sulfate ammonium (NH4) 2SO4 resulted in a significant increase in grain and biomass yields during the two years of the study. The increase of the rate of phosphate rock application lead to improve the sorghum grain yield by an average of 29%. The combined application of sulfate ammonium (NH4) 2SO4 with PNT significantly increased the phosphorus uptake indices from PNT. These results show that there is a possibility of improving the productivity of sorghum in Mali with the combined use of Tilemsi rock phosphate and soluble fertilizers, particularly sulfate ammonium. La déficience en phosphore assimilable du sol est l’une des contraintes majeures à la production céréalière au Mali. L’objectif de cette étude est d’évaluer les effets de différentes formules de fumures à base du phosphore naturel de tilemsi (PNT) et d’engrais azotés et potassiques sur les propriétés chimiques du sol et les performances agronomiques du sorgho. Pour ce faire, un dispositif factoriel en blocs complètement randomisés a été implanté. Le premier facteur est composé des 4 formules de fumures (PNT granule (P), PNT granule avec KCl , PNT granule avec (NH4)2SO4 et PNT granule avec KCl et (NH4)2SO4 ) et le second facteur les niveaux de doses de phosphore (0 kg.ha-1; 11 kg.ha-1, et 16 kg.ha-1). L’association du PNT avec le sulfate d’ammonium (NH4)2SO4 a entraîné une augmentation significative des rendements grain et biomasse pendant les deux annéesd’étude. L’augmentation de la dose d’apport du phosphore a amélioré le rendement grain de 29% en moyenne. L’application combinée du sulfate d’ammonium (NH4)2SO4 avec le PNT a augmenté significativement l’efficacité agronomique du PNT. Ces résultats montrent qu’il y a une possibilité d’améliorer la productivité du sorgho au Mali avec l’utilisation combinée de phosphore naturel de Tilemsi à la dose de 16 kg.ha-1 et les engrais solubles notamment le sulfate d’ammonium. Ainsi cette formulation pourrait être recommandée en culture de sorgho pour les producteurs à faible revenu en zone Sahélienne du Mali

Viral and bacterial etiology of severe acute respiratory illness among children < 5 years of age without influenza in Niger.

International audienceGlobally, pneumonia is the leading cause of morbidity and mortality in children, with the highest burden experienced in sub-Saharan Africa and Asia. However, there is a dearth of information on the etiology of severe acute respiratory illness (SARI) in Africa, including Niger. We implemented a retrospective study as part of national influenza sentinel surveillance in Niger. We randomly selected a sample of nasopharyngeal specimens collected from children <5 years of age hospitalized with SARI from January 2010 through December 2012 in Niger. The samples were selected from individuals that tested negative by real-time reverse transcription polymerase chain reaction (rRT-PCR) for influenza A and B virus. The samples were analyzed using the Fast Track Diagnostic Respiratory Pathogens 21plus Kit (BioMérieux, Luxemburg), which detects 23 respiratory pathogens including 18 viral and 5 bacterial agents. Among the 160 samples tested, 138 (86%) tested positive for at least one viral or bacterial pathogen; in 22 (16%) sample, only one pathogen was detected. We detected at least one respiratory virus in 126 (78%) samples and at least one bacterium in 102 (64%) samples. Respiratory syncytial virus (56/160; 35%), rhinovirus (47/160; 29%) and parainfluenza virus (39/160; 24%) were the most common viral pathogens detected. Among bacterial pathogens, Streptococcus pneumoniae (90/160; 56%) and Haemophilus influenzae type b (20/160; 12%) predominated. The high prevalence of certain viral and bacterial pathogens among children <5 years of age with SARI highlights the need for continued and expanded surveillance in Niger

Identification of hydraulic parameters influencing the hydraulic erodibility of spillway flow channels

The rock mass erosion of dam spillways, a phenomenon involving the interaction between the hydraulic load of water and the capability of the rock mass to resist its destruction, remains a critical safety issue. The erosion resistance of a rock mass can be estimated through several erodibility indices, including those of Kirsten, Pells or Bollaert. Several indices have been developed to link rock resistance to the hydraulic parameters of water, i.e., the hydraulic load applied on a rock mass. The developed indices use the average flow velocity, the average shear stress on the bottom of the flow channel, the stress applied to the internal joints of fractured rock mass, the dynamic impulse force, and the power dissipation of water to represent the erosive force of water. From these indices, several methods of assessing hydraulic erosion have been developed, and all use the threshold line concept. Nonetheless, several uncertainties are associated with these methods. This paper presents and discusses the various means of calculating the erosive force of water as a hazard parameter for predicting potential rock erosion. The representativeness of these approaches is also discussed, and we clarify nuances associated with each method. We then provide guidelines for future research aimed at improving estimates of the erosive force of the water within spillway flow channels

A Reduced-Scale Physical Model of a Spillway to Evaluate the Hydraulic Erodibility of a Fractured Rock Mass

The hydraulic erosion of the rock mass within dam spillways must be considered when assessing the stability of dam infrastructures. As this erosion results from the interaction between water and the rock mass, commonly applied methods to evaluate this phenomenon use the notion of a threshold line, a correlation between the water’s erosive force and the resistance of the rock mass against erosion. These methods are empirical or semi-empirical, and they have limitations regarding the characterization of this phenomenon. These methods are based on specific hydraulic and rock mass parameters, including a number of parameters that are irrelevant to the erosion process; thus, there is a need to upgrade the existing methods or to seek new solutions to characterize hydraulic erosion. We present a laboratory-scale physical model to determine the effects of rock mass parameters on erosion. This model is designed to determine individual and interactive effects of several hydraulic and rock mass parameters on erosion, including joint opening, block size, joint shear strength, and the nature of potentially erodible surfaces, as well as water pressure (static and dynamic), variations of flow rate and velocity, and channel roughness

Characterization, at Partial Loads, of the Combustion and Emissions of a Dual-Fuel Engine Burning Diesel and a Lean Gas Surrogate

For decentralized power generation in West Africa, gas from a small biomass gasification unit can be used as the main fuel in a dual-fuel engine with diesel as the pilot fuel. To study the combustion in this type of engine (Lister Petter), experiments were conducted with a surrogate gas composed of liquefied petroleum gas and nitrogen (LPGN2), the energy context of which is similar to that of syngas. The tests were conducted at different loads and for different diesel substitution rates. The combustion analysis showed that the LPGN2 mixture had an overall behaviour similar to neat diesel, while the pressure peaks were lower in dual-fuel mode. The results also indicated a longer ignition delay and a pronounced diffusive combustion phase leading to a lower indicated mean effective pressure with gas. The fuel efficiencies remained low in both mono- and dual-fuel operation. The relative instability of the combustion in dual-fuel mode gave rise to an increase in the coefficient of variation (COVIMEP). Compared to neat diesel, the engine running at low loads in dual-fuel mode showed higher emission levels of CO, a slight reduction of 2.5% of CO2 and a sub-stantial decrease of 73% for nitrogen oxides

Advancements in rock block volume calculation by analytical method for geological engineering applications

The shape, the volume, and the distribution of the rock blocks represent important geomechanical factors of a rock mass behavior in engineering works. Several methods have been developed for estimating these parameters, including numerical models, as well as analytical and empirical methods. However, their determination in actual in-situ conditions can be quite challenging. The existing analytical methods show limitations in determining the in-situ rock blocks volume. Numerical models provide more reliable estimates of these parameters, but they are not accessible to all, and they require a good working knowledge. Increasing the accuracy of existing analytical methods, or developing more reliable and accessible methods, are more realistic approaches to obtain better estimates of rock block volumes. This paper presents a new method to obtain more accurate estimates of in-situ rock block volume. The method is developed for rock a mass consisting of three persistent joint sets, each set having constant spacing and orientation values. It is based on vector products to obtain exact block volumes, an improvement as compared to previous methods. The volumes of the rock blocks are calculated through the multiplication of the blocks’ edge vector. The results of the developed equation are validated with the output of numerical simulations using 3DEC version 7.0 software, and the results indicate that the developed method makes it possible to determine in-situ rock block volume more reliably than the existing methods

Evaluation of response strategies against epidemics due to Neisseria meningitidis C in Niger

International audienceOBJECTIVE: To inform public health recommendations, we evaluated the effectiveness and efficiency of current and hypothetical surveillance and vaccine response strategies against Neisseria meningitidis C meningitis epidemics in 2015 in Niger.METHODS : We analysed reports of suspected and confirmed cases of meningitis from the region of Dosso during 2014 and 2015. Based on a definition of epidemic signals, the effectiveness and efficiency of surveillance and vaccine response strategies were evaluated by calculating the number of potentially vaccine-preventable cases and number of vaccine doses needed per epidemic signal.RESULTS : A total of 4763 weekly health area reports, collected in 90 health areas with 1282 suspected meningitis cases, were included. At a threshold of 10 per 100 000, the total number of estimated vaccine-preventable cases was 29 with district-level surveillance and vaccine response, 141 with health area-level surveillance and vaccination and 339 with health area-level surveillance and district-level vaccination. While being most effective, the latter strategy required the largest number of vaccine doses (1.8 million), similar to the strategy of surveillance and vaccination at district level (1.3 million), whereas the strategy of surveillance and vaccination at health area level would have required only 0.8 million doses. Thus, efficiency was lowest for district-level surveillance and highest for health area-level surveillance with district-level vaccination.CONCLUSION : In this analysis, we found that effectiveness and efficiency were higher at health area-level surveillance and district-level vaccination than for other strategies. Use of N. meningitidis C vaccines in a preventive strategy thus should be considered, in particular as most reactive vaccine response strategies in our analysis had little impact on disease burden

Influenza Sentinel Surveillance among Patients with Influenza-Like-Illness and Severe Acute Respiratory Illness within the Framework of the National Reference Laboratory, Niger, 2009-2013.

Little is known about the epidemiology of influenza in Africa, including Niger. We documented the epidemiology of seasonal and pandemic influenza among outpatients with influenza-like-illness (ILI) and inpatients with severe acute respiratory illness (SARI) presenting at selected sentinel sites in Niger from April 2009 through April 2013.Patients meeting the ILI or the SARI case definitions and presenting at the outpatient or inpatient departments of selected sentinel sites were enrolled. Epidemiological data and nasopharyngeal swabs were collected. The respiratory samples were tested by real-time reverse transcription polymerase chain reaction.From April 2009 to April 2013, laboratory results were obtained from 1176 ILI and 952 SARI cases, of which 146 (12%) and 54 (6%) tested positive for influenza virus, respectively. The influenza positivity rate was highest in the 5-14 year age-group (32/130; 24% among ILI patients and 6/61; 10% among SARI patients) followed by the 1-4 year age-group (69/438; 16% among ILI patients and 32/333; 9% among SARI patients). Of the 200 influenza positive cases 104 (52%) were A(H1N1)pdm09, 62 (31%) were A(H3N2) and 34 (17%) were B. Influenza viruses were detected predominantly from November to April with peak viral activity observed in February.The Niger sentinel surveillance system allowed to monitor the circulation of seasonal influenza as well as the introduction and spread of influenza A(H1N1)pdm09 in the country. Continuous influenza surveillance is needed to better understand the epidemiology of seasonal influenza and monitor the emergence of influenza strains with pandemic potential

Characteristics of influenza-like illness (ILI) and severe acute respiratory illness (SARI) cases, Niger, 2009–2013.

<p>The p—value is for the comparison of the characteristics of patients with ILI and patients with SARI</p><p>Characteristics of influenza-like illness (ILI) and severe acute respiratory illness (SARI) cases, Niger, 2009–2013.</p

Number (and percent) of samples tested positive for influenza virus among influenza-like illness (ILI) and severe acute respiratory illness (SARI) cases, Niger, 2009–2013.

<p><b>٭</b> Comparison of the influenza detection rate among patients with ILI and patients with SARI</p><p>The p—value is for the comparison of the influenza detection rate among patients with ILI and patients with SARI</p><p>Number (and percent) of samples tested positive for influenza virus among influenza-like illness (ILI) and severe acute respiratory illness (SARI) cases, Niger, 2009–2013.</p