Search results for " Africa"
showing 10 items of 604 documents
Industrialization Strategies and Regional Actors
2021
Against the backdrop of the partly normative, partly empirical policy framework, the major regional industrial policy documents of the African Union, EAC, ECOWAS, SACU and SADC are examined as to their applicability. The empirical cases of the West African dairy and textile value chains are used to discuss the difficulties of regional priority-setting. The precise roles of (a) regional financial institutions, (b) regional development aid, including the panoply of ‘private sector development’ (PSD) projects and (c) regional business associations are defined. A concise summary of the essentials of common industrial policy concludes the chapter.
Spatial coherence of monsoon onset over Western and Central Sahel (1950-2000)
2009
Abstract The spatial coherence of boreal monsoon onset over the western and central Sahel (Senegal, Mali, Burkina Faso) is studied through the analysis of daily rainfall data for 103 stations from 1950 to 2000. Onset date is defined using a local agronomic definition, that is, the first wet day (>1 mm) of 1 or 2 consecutive days receiving at least 20 mm without a 7-day dry spell receiving less than 5 mm in the following 20 days. Changing either the length or the amplitude of the initial wet spell, or both, or the length of the following dry spell modifies the long-term mean of local-scale onset date but has only a weak impact either on its interannual variability or its spatial coher…
Seasonal evolution of boundary layer heat content in the West African monsoon from the NCEP/NCAR reanalysis (1968-1998)
2000
Using the National Center for Environmental Prediction (NCEP)/National Centre for Atmospheric Research (NCAR) dataset over the period 1968–1998, the basic relationships between July and September monsoon circulation variations over West Africa and monthly meridional distribution of moist static energy (MSE) content in the boundary layer are portrayed. Wet minus dry stratified analyses relative to Sudan–Sahel rainfall show that particular April–June meridional patterns of near-surface MSE contents, south of 10°N, could control the amplitude and timing of the monsoon rainy season. Relative to the driest July–September situations, the wettest ones have been, on average, preceded by delayed but…
Changes in the African monsoon region at medium-term time horizon using 12 AR4 coupled models under the A1b emissions scenario.
2011
This study documents simulated precipitation and circulation changes through the 20C3M and A1b scenarios. It portrays a robust pattern, associating rainfall deficits in subtropical regions with rainfall excesses over West Africa, except in Northern Senegal and Mauritania, with a significant enhancement of both the April–June rainy season in 10/12 models and of the July–September rainy season in 8/12 models. Eastward to 5°W a northward shift in the latitude of the moisture flux convergence at 850 hPa is evident in 10/11 models (+0.58° in mean) and a southward shift in 6/11 models in the western region (−0.24°) is observed. Copyright © 2011 Royal Meteorological Society
Comparison of rainfall structures between NCEP/NCAR reanalyses and observed data over tropical Africa
2000
A comparison is made between modelled (NCEP/NCAR reanalysis) and observed (CRC and CRU dataset) annual and monthly precipitation over tropical Africa during the period 1958–1997. The split moving-windows dissimilarity analysis (SMWDA) is used to locate abrupt changes in rainfall time series. In the NCEP reanalysis data, we identify a main abrupt shift, which occurs in 1967 and concerns more than 50% of grid points. In the observation, this shift is only found over parts of tropical North Africa. Three other NCEP abrupt shifts (1975, 1983 and 1987) in the reanalysis shown by the SMWDA, each concerning about 20% of tropical Africa, are not identified in the observation. One hypothesis concern…
Cross-hemispheric transport of central African biomass burning pollutants: implications for downwind ozone production
2010
Pollutant plumes with enhanced concentrations of trace gases and aerosols were observed over the southern coast of West Africa during August 2006 as part of the AMMA wet season field campaign. Plumes were observed both in the mid and upper troposphere. In this study we examined the origin of these pollutant plumes, and their potential to photochemically produce ozone (O<sub>3</sub>) downwind over the Atlantic Ocean. Their possible contribution to the Atlantic O<sub>3</sub> maximum is also discussed. Runs using the BOLAM mesoscale model including biomass burning carbon monoxide (CO) tracers were used to confirm an origin from central African biomass burning fires. The…
Cytotoxicity and modes of action of four Cameroonian dietary spices ethno-medically used to treat cancers: Echinops giganteus, Xylopia aethiopica, Im…
2013
Abstract Ethnopharmacological relevance. Echinops giganteus , Imperata cylindrica , Piper capense and Xylopia aethiopica are four medicinal spices used in Cameroon to treat cancers. Aim of the study The above plants previously displayed cytotoxicty against leukemia CCRF-CEM and CEM/ADR5000 cell lines as well as human pancreatic MiaPaCa-2 cells. The present study aims at emphasizing the study of the cytotoxicity and the modes of action of the above plants on a panel of ten cancer cell lines including various sensitive and drug-resistant phenotypes. The study has been extended to the isolation of the bioactive constituents from Echinops giganteus . Materials and methods The cytotoxicity of th…
Sul far del giorno
2016
Edizione critica dell'autobiografia del Premio Nobel per la Letteratura Wole Soyinka, corredata di Prefazione e Note della curatrice, che ne è anche la traduttrice, di una cronologia storica, di mappe geopolitiche della Nigeria dall'indipendenza, e di un apparato fotografico pubblicato in Italia in anteprima mondiale. Soyinka, classe 1934, drammaturgo, poeta, saggista, romanziere e attivista politico è stato il primo autore africano a essere insignito del Premio Nobel per la Letteratura. In questo avvincente memoir, racconta le proprie vicende di artista, intellettuale e attivista militante nella sua Nigeria e nel palcoscenico del mondo, in cui da sempre porta le voci dell'Africa. Nel lingu…
Notes on Afrotropical Cydnidae (Heteroptera) with emphasis on vehicle-mounted net samples and description of a new species from Liberia, West Africa
2019
Notes on the Cydnidae fauna in Liberia, sampled with a vehicle-mounted net, the species taxonomy and general distribution are reported, including the description of Chilocoris elongatus sp. nov. In addition, new country records are provided for Angola, Ethiopia, Gabon, Guine a-Bissau, Namibia, Niger, Republic of South Africa, Sierra Leone, Tanzania, Togo, Uganda, and Zimbabwe.
Seasonal reproducibility and predictability of the West African Monsoon in coupled GCMs
2009
In the framework of the ENSEMBLES FP6 project, an ensemble prediction system based on five different state-of-the-art European coupled models has been developed. This study evaluates the performance of these models for forecasting the West African monsoon (WAM) at the monthly time scale. From simulations started the 1 May of each year and covering the period 1991–2001, the reproducibility and potential predictability (PP) of key parameters of the WAM—rainfall, zonal and meridional wind at four levels from the surface to 200 hPa, and specific humidity, from July to September—are assessed. The Sahelian rainfall mode of variability is not accurately reproduced contrary to the Guinean rainfall …