Abdou Moumouni University

About: Abdou Moumouni University is a education organization based out in Niamey, Niamey, Niger. It is known for research contribution in the topics: Population & Agriculture. The organization has 796 authors who have published 808 publications receiving 17478 citations. The organization is also known as: University of Niamey & Abdou Moumouni Dioffo University.

Integrative taxonomy of a poorly known Sahelian rodent, Gerbillus nancillus (Muridae, Gerbillinae)

Abstract: a b s t r a c t Aridification processes that affected the Sahelian area of West Africa during the last decades have induced significant changes in plant and animal communities of this region. In rodents, the genus Gerbillus char- acteristic of North African and Asian arid habitats has been affected by this climatic and environmental trends. Several species of this genus showed a southward range expansion in recent years into the Sahelian bioclimatic zone. Recent sampling in several localities of West Africa (Mali, Niger and Senegal) enabled us to collect numerous specimens of small gerbils. An integrative study of these samples using molecu- lar, morphological and cytogenetical methods revealed that many of them were attributable to Gerbillus nancillus, a secretive and poorly known species. Gerbillus nancillus appears characterized by a well dif- ferentiated karyotype with 2n = 56 chromosomes, and to represent a unique genetic lineage within this genus. Body and skull measurements of G. nancillus were compared with those of the morphologically similar Gerbillus henleyi, which provided diagnostic clues between them. These new data significantly expand the distribution area of G. nancillus, which now ranges from Sudan in the East to Senegal in the West. G. nancillus is here reported from numerous new localities in Niger and Mali, and for the first time in Senegal, which raises questions about the origin of its presence and the colonization routes it followed to get there. We also show that G. henleyi and G. nancillus are sympatric and apparently often syntopic in the sub-Saharan part of the distribution of G. henleyi.

Comparison of Mass Azithromycin Coverage Targets of Children in Niger: A Cluster-Randomized Trachoma Trial

Abstract: Repeated oral azithromycin distribution targeted only to children has proven effective in reducing the ocular Chlamydia that causes trachoma. Here, we assess whether an enhanced coverage target of at least 90% of children is superior to the World Health Organization recommendation of at least 80%. Twenty-four trachoma-endemic communities in Matameye, Niger, were randomized to a single day of azithromycin distribution aiming for at least 80% coverage or up to 4 days of treatment and > 90% coverage of children under age 12. All distributions were biannual. Children 15 years were monitored for ocular Chlamydia infection by polymerase chain reaction every 6 months for 36 months in children and at baseline and 36 months in adults. Ocular Chlamydia prevalence in children decreased from 24.9% (95% confidence interval [CI] 15.9-33.8%) to 4.4% (95% CI 0.6-8.2%, P < 0.001) at 36 months in the standard coverage arm and from 15.6% (95% CI 10.0-21.2%) to 3.3% (95% CI 1.0-5.5%; P < 0.001) in the enhanced coverage arm. Enhanced coverage reduced ocular Chlamydia prevalence in children more quickly over time compared with standard (P = 0.04). There was no difference between arms at 36 months in children (2.4% lower with enhanced coverage, 95% CI 7.7-12.5%; P = 0.60). No infection was detected in adults at 36 months. Increasing antibiotic coverage among children from 80% to 90% may yield only short term improvements for trachoma control programs. Targeting treatment to children alone may be sufficient for trachoma control in this setting.

Study of Surface and Interface Roughness of GaN-Based Films Using Spectral Reflectance Measurements

Abstract: GaN films were grown using SiN treatment of sapphire substrate by metalorganic vapor-phase epitaxy in a home-made vertical reactor at atmospheric pressure The growth was interrupted at different stages to investigate the impact of interface and surface roughness on the optical properties of the GaN layers A transition from a three-dimensional (3D) to two-dimensional (2D) growth mode was revealed by real-time in situ laser reflectometry (λ = 6328 nm) as well as by atomic force microscopy images A theoretical model is proposed to determine the refractive index evolution during GaN layer growth based on the Bruggeman effective medium approximation Ex situ multiwavelength reflectivity signals were fit to the thin-film interference equations to derive the evolution of the effective refractive indexes for the surface and interface GaN layer, thereby determining the refractive index of the GaN layer during growth Ex situ spectroscopic ellipsometry measurements of the GaN layer refractive indexes at different growth stages were compared with calculated results Moreover, an empirical law was developed to fit the refractive index evolution during GaN layer growth and used for in situ reflectivity signal simulation in order to deduce the growth rate Finally, good agreement was observed between the experimental and theoretical findings

Probing iron at Super-Earth core conditions

Abstract: In this paper, we report on the quasi-isentropic compression of an iron sample using ramp shaped laser irradiation. This technique allows us to quasi-isentropically compress iron up to 700 GPa and 8500 K. To our knowledge, these data are the highest pressures reached on iron in off-Hugoniot conditions and the closest to the thermodynamic states thought to exist in Earth-like planetary cores. The experiment was performed on the Ligne d'Integration laser facility at CESTA, Bordeaux, France.