Search results for "sahara"
showing 10 items of 125 documents
ATR–FTIR Spectral Analysis and Soluble Components of PM10 And PM2.5 Particulate Matter over the Urban Area of Palermo (Italy) during Normal Days and …
2019
Several epidemiological studies have shown a close relationship between the mass of particulate matter (PM) and its effects on human health. This study reports the identification of inorganic and organic components by attenuated total reflectance-Fourier-transform infrared spectroscopy (ATR-FTIR) analysis in PM10 and PM2.5 filters collected from three air quality monitoring stations in the city of Palermo (Sicily, Italy) during non-Saharan dust events and Saharan events. It also provides information on the abundance and types of water-soluble species. ATR-FTIR analysis identified sulfate, ammonium, nitrate, and carbonate matter characterized by vibrational frequencies at 603, 615, 670, and …
Alu insertion polymorphisms in the African Sahel and the origin of Fulani pastoralists.
2017
The origin of Western African pastoralism, represented today by the Fulani nomads, has been a highly debated issue for the past decades, and has not yet been conclusively resolved.This study focused on Alu polymorphisms in sedentary and nomadic populations across the African Sahel to investigate patterns of diversity that can complement the existing results and contribute to resolving issues concerning the origin of West African pastoralism.A new dataset of 21 Alu biallelic markers covering a substantial part of the African Sahel has been analysed jointly with several published North African populations.Interestingly, with regard to Alu variation, the relationship of Fulani pastoralists to …
Evolutionary history of two cryptic species of northern African jerboas
2020
Abstract Background: Climatic variation and geologic change both play significant roles in shaping species distributions, thus affecting their evolutionary history. In Sahara-Sahel, climatic oscillations shifted the desert extent during the Pliocene-Pleistocene interval, triggering the diversification of several species. Here, we investigated how these biogeographical and ecological events have shaped patterns of genetic diversity and divergence in African Jerboas, desert specialist rodents. We focused on two sister and cryptic species, Jaculus jaculus and J. hirtipes, where we (1) evaluated their genetic differentiation, (2) reconstructed their evolutionary and demographic history; (3) tes…
Evolutionary relationships, biogeography and morphological characters of Glinus (Molluginaceae), with special emphasis on the genus composition in Su…
2021
Glinus is a small genus of Molluginaceae with 8–10 species mostly distributed in the tropics of the World. Its composition and evolutionary relationships were poorly studied. A new molecular phylogeny constructed here using nuclear (ITS) and chloroplast (rbcL, trnK-matK) markers confirmed the monophyly of the genus. Based on ITS analysis, the following well-supported lineages are present within Glinus: the G. bainesii lineage is recovered as sister to the remainder of the genus followed by G. oppositifolius. Three other clades are: G. hirtus with G. orygioides; G. radiatus and G. lotoides; the latter is represented by a sample from North America, and G. zambesiacus as sister to G. setifloru…
Long-term mineral fertiliser use and maize residue incorporation do not compensate for carbon and nutrient losses from a Ferralsol under continuous m…
2015
9 pages; International audience; It has been repeatedly argued that mineral fertiliser application combined with in situ retention of crop residue biomass can sustain long-term productivity of West African soils. Using 20-year experimental data from southern Togo, a biannual rainfall area, we analysed the effect of two rates of mineral NPK fertiliser application to maize–cotton rotation on the long-term dynamics of soil C and nutrient contents, as compared with two control treatments. Mineral fertiliser treatments consisted of application to both maize (first season) and cotton (second season) the research-recommended NPK rates (Fertiliser-RR) and 1.5 times these rates (Fertiliser-1.5 RR). …
Performance of a rapid diagnostic test for the detection of Cryptosporidium spp. in African children admitted to hospital with diarrhea
2020
Background Cryptosporidium is a protozoan parasite that causes mild to severe diarrhoeal disease in humans. To date, several commercial companies have developed rapid immunoassays for the detection of Cryptosporidium infection. However, the challenge is to identify an accurate, simple and rapid diagnostic tool for the estimation of cryptosporidiosis burden. This study aims at evaluating the accuracy of CerTest Crypto, a commercialized rapid diagnostic test (RDT) for the detection of Cryptosporidium antigens in the stool of children presenting with diarrhoea. Methods A cross-sectional study was conducted in four study sites in Sub-Saharan Africa (Gabon, Ghana, Madagascar, and Tanzania), from…
Subnational mapping of HIV incidence and mortality among individuals aged 15-49 years in sub-Saharan Africa, 2000-18: a modelling study
2021
Background. High-resolution estimates of HIV burden across space and time provide an important tool for tracking and monitoring the progress of prevention and control efforts and assist with improving the precision and efficiency of targeting efforts. We aimed to assess HIV incidence and HIV mortality for all second-level administrative units across sub-Saharan Africa. Methods. In this modelling study, we developed a framework that used the geographically specific HIV prevalence data collected in seroprevalence surveys and antenatal care clinics to train a model that estimates HIV incidence and mortality among individuals aged 15–49 years. We used a model-based geostatistical framework to e…
An integrated model of condom use in Sub-Saharan African youth: A meta-analysis.
2017
Objective: We tested an integrated social–cognitive model derived from multiple theories of the determinants of young people's condom use in Sub-Saharan Africa. The model comprised seven social–cognitive antecedents of condom use: Attitudes, norms, control, risk perceptions, barriers, intentions, and previous condom use. Method: We conducted a systematic search of studies including effects between at least one model construct and intended or actual condom use in young people from sub-Saharan African countries. Fifty-five studies comprising 72 independent data sets were included and subjected to random-effects meta-analysis. Demographic and methodological variables were coded as moderators. …
Disparités sociales en éducation en Afrique sub-saharienne : Genre, localisation géographique et revenu du ménage
2006
06017; Dans ce texte, nous poursuivons deux objectifs complémentaires : le premier consiste à offrir une description de l'ampleur des disparités sociales qui existent dans les systèmes éducatifs des pays de l'Afrique au Sud du Sahara principalement dans la période actuelle mais aussi en lui donnant une perspective temporelle; le second cherche à identifier certains des facteurs qui peuvent rendre compte des disparités constatées ou des actions qui ont visé à les réduire.
Cost and Financing of Education and its Impact on Coverage and Quality of Services and Efficiency and Equity in Sub-Saharan African Countries
2007
07052; In this chapter, we take mostly an international comparative perspective limited to Sub-Saharan African countries. First, we analyse first the macro picture and the public finance dimension, analyzing the systemic choices made in the distribution of public resources across levels and types of education. Second, we move to unit cost estimates and the factors accounting for their level in a given country and to their variation across the different countries of the region. Finally, we examine the implication of the choices made in the financial dimension upon outcomes (coverage and quality of educationl services), birnging issues of efficiency and equity into the analysis.