|
| ||
|
|
||
Central Africa (central + africa)
Selected AbstractsHunting for Consensus: Reconciling Bushmeat Harvest, Conservation, and Development Policy in West and Central AfricaCONSERVATION BIOLOGY, Issue 3 2007ELIZABETH L. BENNETT First page of article [source] First record of Blastopsylla occidentalis Taylor, 1985 (Hemiptera: Psyllidae), a Eucalyptus psyllid in Cameroon, Central AfricaENTOMOLOGICAL RESEARCH, Issue 4 2010Joseph Lebel TAMESSE Abstract In order to investigate the biodiversity of psyllids in Cameroon, we collected a psyllid on Eucalyptus spp. (Myrtaceae) for the first time. Morphometric and morphological studies of this psyllid enable us to identify it as Blastopsylla occidentalis Taylor (Hemiptera: Psylloidea). Blastopsylla occidentalis lives on four Eucalyptus species (Eucalyptus globulus, E. saligna, E. deglupta, E. camaldulensis) in the Western and Central regions of the country. A description and illustration of the different developmental stages of B. occidentalis will allow the identification of this pest of Eucalyptus. [source] Effect of 13 single and eight mixed host plant diets on survival, post-embryonic development and morphology of variegated grasshopper in laboratoryENTOMOLOGICAL RESEARCH, Issue 1 2010Sévilor KEKEUNOU Abstract Zonocerus variegatus (Orthoptera: Pyrgomorphidae) is known as an agricultural pest in West and Central Africa. In this study, the effects of 13 single and eight mixed host plant diets on the survival, post-embryonic development and morphology of Z. variegatus in the laboratory were investigated. In each cage, 20 one-day larvae were provided with these diets and their survival monitored every two days, from August 2000 to September 2002, until all individuals died. Results showed that the number of larval stages varied from six to eight according to the diet. Six larval stages were most frequent. Development to the adult stage (complete development) was only noted with 52% of diets. All the mixed host plant diets induced complete development of Z. variegatus except that of Cajanus cajan + Synedrella nodiflora + Chromolaena odorata. Complete development was observed with four single host plant diets: Lablab purpurea, C. cajan, Manihot esculenta and S. nodiflora. Compared to leguminous species and Asteraceae, M. esculenta (Euphorbiaceae) was the species that resulted in the highest level of survival and development of Z. variegatus. Chromolaena odorata and S. nodiflora (Asteraceae) induced late appearance of the different Z. variegatus nymphal instars and the appearance time was shorter on legumes. The supernumerary stage 7 has the same color as the larva in stages 1,6, but this larva was significantly larger than stage 6 and smaller than the adult stage. These results indicate that legumes for short fallows affected the survival and post-embryonic development of Z. variegatus in the laboratory. [source] Do Poverty Reduction Strategies and Agricultural Policies Engage in West and Central Africa?IDS BULLETIN, Issue 2 2005Abdou Salam Fall First page of article [source] Evidence for genetic differentiation between the molecular forms M and S within the Forest chromosomal form of Anopheles gambiae in an area of sympatryINSECT MOLECULAR BIOLOGY, Issue 1 2002C. Wondji Abstract We studied genetic variation at ten microsatellite DNA loci in Anopheles gambiae populations from the Forest chromosomal form collected in four villages in Cameroon (Central Africa). Both recently described M and S molecular forms occur in sympatry in this area. Geographic differentiation within form was low (Fst < 0.017) despite geographical distance between collection sites ranging from 35 to 350 km. However, higher (Fst > 0.035) and statistically significant levels of genetic differentiation were observed between forms, being the highest between sympatric M and S populations collected within the same village. Results were consistent across all loci spread throughout the genome, therefore reflecting a genome-wide pattern. Considering previous findings of strong assortative mating within forms and general lack of hybrids in areas of sympatry, we propose that there is now sufficient direct and indirect evidence to consider both M and S molecular forms of An. gambiae as distinct species that have probably speciated recently. [source] A clonal cutaneous CD30+ lymphoproliferative eruption in a patient with evidence of past exposure to hepatitis EINTERNATIONAL JOURNAL OF DERMATOLOGY, Issue 7 2000Freddye M. Lemons-Estes CDR, MC USN The patient was a 52-year-old white man who had worked in remote areas of the world during the past 2 years, including an extended period in rural areas of Central Africa and in Central and South America. He had no acute illnesses during the 2-year period except for rare, mild, upper respiratory tract infections. For approximately 1 year, however, he had developed recurrent, papular-vesicular, slightly painful lesions on the fingers and palms, that spontaneously healed over weeks to months ( Fig. 1). The patient had no other concurrent illnesses and no abnormal laboratory findings, except for positive enzyme-linked immunoabsorbent assay (ELISA) for immunoglobulin G (IgG) antibodies for hepatitis E virus (HEV) using a recombinant expressed HEV antigen (Genelabs Technologies, Inc., San Antonio). Prolonged treatment with minocycline did not appear to moderate the lesions. At approximately 2.5 years after the development of his first cutaneous lesion, however, the patient reported that he had had no new lesions for over 3 months. Figure 1. Vesicular ,lesion on the finger which regressed over a period of weeks A biopsy specimen showed an intraepidermal vesicle with prominent epidermal necrosis and reticular degeneration ( Fig. 2). Within the epidermis, there was a dense infiltrate of lymphoid cells. The majority of these cells were pleomorphic with prominent nucleoli and frequent mitotic figures ( Fig. 3). Sheets of atypical cells were found in the subjacent dermis. The infiltrate extended down into the reticular dermis. With extension into the dermis, the infiltrate became more polymorphous with more small lymphoid cells, large numbers of eosinophils, and some plasma cells located more deeply. Figure 2. Intraepidermal ,blister showing reticular degeneration and marked epidermotrophism of large atypical cells with extension into the dermis with a mixed infiltrate containing eosinophils and plasma cells (30×) Figure 3. Intraepidermal ,infiltrate of large atypical cells with extension into the dermis with a mixed infiltrate containing eosinophils and plasma cells (400×) Immunohistochemical stains for CD3 (DAKO), CD4 (Becton Dickinson), CD8 (Becton Dickinson), CD15 (LeuM1, Becton Dickinson), CD20 (L-26, DAKO), CD30 (Ber-H2, DAKO), CD45RO (UCHL1, DAKO), S-100 protein (DAKO), T-cell intracellular antigen (TIA) (Coulter), epithelial membrane antigen (EMA) (DAKO), KP-1 (CD68, DAKO), MAC-387 (DAKO), Epstein,Barr virus (EBV) latent membrane antigen-1 (LMP-1, DAKO), and EBV-encoded nuclear antigen 2 (EBNA2, DAKO) were performed on formalin-fixed tissue using the ABC method with DABA as the chromagen. CD3 showed diffuse membrane staining of the large atypical lymphoid cells, as well as the majority of the small lymphoid cells ( Fig. 4). CD4 showed positive membrane staining of the large atypical lymphoid cells and the majority of the small lymphoid cells. CD8 showed only scattered light membrane staining of small lymphoid cells. CD15 was negative, and CD20 showed foci of groups of small lymphoid cells mainly within the reticular dermis. CD30 showed positive membrane and paranuclear staining of the large atypical cells, most abundant within the epidermis and papillary dermis ( Fig. 5). CD45RO showed positive membrane staining of the large atypical cells and the majority of the small lymphoid cells. S-100 protein showed increased dendritic cells within the surrounding viable epidermis and the subjacent papillary dermis ( Fig. 6). TIA showed granular staining in the large atypical lymphoid cells and only rare staining in small lymphoid cells ( Fig. 7). EMA staining was essentially negative. KP-1 showed only scattered positive cells mainly in the lower papillary and the reticular dermis. MAC-387 showed membrane staining in the viable epidermis ( Fig. 8). LMP-1 and EBNA2 for EBV were negative within the lymphoid cells as well as within the overlying epidermis. Figure 4. Immunohistochemical ,staining for CD3 showing diffuse staining of lymphoid cells within the epidermis and dermis (150×) Figure 5. Immunohistochemical ,staining for CD30 showing membrane and paranuclear staining of large atypical lymphoid cells within the epidermis and papillary dermis (a, 150× b, 400×) Figure 6. Immunohistochemical ,staining for S-100 protein within the epidermis and in the papillary dermis (a, 150× b, 300×) Figure 7. Immunohistochemical ,granular staining of large atypical lymphoid cells for TIA (200×) Figure 8. Immunohistochemical ,staining for MAC-387 showing epidermal staining (100×) Gene rearrangement studies showed a ,-T-cell receptor gene rearrangement. The monoclonal band was detected with VJ1, VJ2, and D1J2 primer sets. The T-cell receptor , rearrangement assay has a sensitivity of 61% and a specificity of 94% for the detection of a monoclonal rearrangement in T-cell lymphomas for which amplifiable DNA can be recovered. Electron microscopy was performed on formalin-fixed material, positive-fixed with 2.5% phosphate-buffered glutaraldehyde and further with 1% osmium tetroxide by standard techniques. Intracellular, 50,60-nm, cytoplasmic, spherical, viral-like particles were identified ( Fig. 9). Figure 9. Electron ,microscopy showing 50,60-nm diameter, intracellular, viral-like particles (arrows) (70,000×) [source] METHODOLOGICAL INSIGHTS: Using seismic sensors to detect elephants and other large mammals: a potential census techniqueJOURNAL OF APPLIED ECOLOGY, Issue 3 2005JASON D. WOOD Summary 1Large mammal populations are difficult to census and monitor in remote areas. In particular, elephant populations in Central Africa are difficult to census due to dense forest, making aerial surveys impractical. Conservation management would be improved by a census technique that was accurate and precise, did not require large efforts in the field, and could record numbers of animals over a period of time. 2We report a new detection technique that relies on sensing the footfalls of large mammals. A single geophone was used to record the footfalls of elephants and other large mammal species at a waterhole in Etosha National Park, Namibia. 3Temporal patterning of footfalls is evident for some species, but this pattern is lost when there is more than one individual present. 4We were able to discriminate between species using the spectral content of their footfalls with an 82% accuracy rate. 5An estimate of the energy created by passing elephants (the area under the amplitude envelope) can be used to estimate the number of elephants passing the geophone. Our best regression line explained 55% of the variance in the data. This could be improved upon by using an array of geophones. 6Synthesis and applications. This technique, when calibrated to specific sites, could be used to census elephants and other large terrestrial species that are difficult to count. It could also be used to monitor the temporal use of restricted resources, such as remote waterholes, by large terrestrial species. [source] ROADS AND RAILWAYS: Central AfricaAFRICA RESEARCH BULLETIN: ECONOMIC, FINANCIAL AND TECHNICAL SERIES, Issue 9 2009Article first published online: 2 NOV 200 No abstract is available for this article. [source] The inselberg flora of Atlantic Central Africa.JOURNAL OF BIOGEOGRAPHY, Issue 4 2005Abstract Aims, To identify the relative contributions of environmental determinism, dispersal limitation and historical factors in the spatial structure of the floristic data of inselbergs at the local and regional scales, and to test if the extent of species spatial aggregation is related to dispersal abilities. Location, Rain forest inselbergs of Equatorial Guinea, northern Gabon and southern Cameroon (western central Africa). Methods, We use phytosociological relevés and herbarium collections obtained from 27 inselbergs using a stratified sampling scheme considering six plant formations. Data analysis focused on Rubiaceae, Orchidaceae, Melastomataceae, Poaceae, Commelinaceae, Acanthaceae, Begoniaceae and Pteridophytes. Data were investigated using ordination methods (detrended correspondence analysis, DCA; canonical correspondence analysis, CCA), Sørensen's coefficient of similarity and spatial autocorrelation statistics. Comparisons were made at the local and regional scales using ordinations of life-form spectra and ordinations of species data. Results, At the local scale, the forest-inselberg ecotone is the main gradient structuring the floristic data. At the regional scale, this is still the main gradient in the ordination of life-form spectra, but other factors become predominant in analyses of species assemblages. CCA identified three environmental variables explaining a significant part of the variation in floristic data. Spatial autocorrelation analyses showed that both the flora and the environmental factors are spatially autocorrelated: the similarity of species compositions within plant formations decreasing approximately linearly with the logarithm of the spatial distance. The extent of species distribution was correlated with their a priori dispersal abilities as assessed by their diaspore types. Main conclusions, At a local scale, species composition is best explained by a continuous cline of edaphic conditions along the forest-inselberg ecotone, generating a wide array of ecological niches. At a regional scale, these ecological niches are occupied by different species depending on the available local species pool. These subregional species pools probably result from varying environmental conditions, dispersal limitation and the history of past vegetation changes due to climatic fluctuations. [source] Effects of climate and local aridity on the latitudinal and habitat distribution of Arvicanthis niloticus and Arvicanthis ansorgei (Rodentia, Murinae) in MaliJOURNAL OF BIOGEOGRAPHY, Issue 1 2004B. Sicard Abstract Introduction, The genus Arvicanthis (Lesson 1842) (Rodentia: Murinae), usually referred to as the unstriped grass rat, is mainly distributed in savanna and grassland habitats of Sub-Saharan Africa. Among the four chromosomal forms of Arvicanthis recently differentiated in Western and Central Africa, the one with a diploid chromosomal number (2n) of 62 and an autosomal fundamental number (NFa) of 62 or 64 is ascribed to Arvicanthis niloticus (Demarest 1822), while the one with 2n = 62 and a NFa between 74 and 76 is referred to A. ansorgei (Thomas 1910). Despite the broad area of sympatry recently uncovered along the inner delta of the Niger river in Mali [details in Volobouev et al. (2002) Cytogenetics and Genome Research, 96, 250,260], the distribution of the two species is largely parapatric and follows the latitudinal patterns of the West-African biogeographical domains, which are related to the latitudinal patterns of annual rainfall in this region. Here, we analyse the suggestion that the two species show specific adaptations to differences in climate aridity. Methods, Karyologically screened animals were sampled in 19 localities in seasonally flooded regions located along the ,Niger' river in Mali and extending from 1100 to 200 mm of mean annual rainfall. The analysis of trapping success (TS) data allowed us to investigate the respective effects of climate (i.e. annual rainfall) and local (i.e. duration of the green herbaceous vegetation) aridity on the latitudinal and habitat distribution of the two species. Conclusions, The broad zone of sympatry was found to correspond to a northward expansion of the recognized distribution area of A. ansorgei. TS values indicated that the two species responded very differently to climatic and local conditions of aridity. Arvicanthis ansorgei decreased in TS as regional conditions became more arid; a similar trend was also observed within regions where habitat occupancy decreased with local aridity. The higher TS observed in the most humid habitat relative to the others persisted throughout the latitudinal rainfall gradient. In contrast, TS of A. niloticus increased with latitudinal aridity. This species was present in more arid habitats than A. ansorgei from 1000 mm down to 400 mm of mean annual rainfall where a shift to the most humid habitat occurred. These opposite trends in TS distribution between species suggest that A. ansorgei is less adapted than A. niloticus to arid environments at both a regional and habitat level; thus, A. ansorgei would be able to invade dry regions only along the extensive floodplains bordering the inner delta of the ,Niger' river. Several biological traits that may be involved in limiting the southward distribution of A. niloticus are discussed. [source] Cercopithecus nictitans prey on air-borne termites in Gabon, Central AfricaAFRICAN JOURNAL OF ECOLOGY, Issue 2 2010Kathryn Jeffery No abstract is available for this article. [source] Counting elephants in Montane forests: some sources of errorAFRICAN JOURNAL OF ECOLOGY, Issue 2 2009Hilde Vanleeuwe Abstract The dung count method is widely used to estimate elephant numbers in forests. It was developed in the lowland forests of Central Africa but it is also used in Montane forests in eastern Africa. Using data collected on Mount Kenya and computer simulations, this paper explores the following issues associated with dung surveys in Montane forests: ,,High rainfall at 3000 m altitude on Mount Kenya was expected to accelerate dung pile decay but no significant difference was found between 3000 and 2500 m where less rain falls, possibly because high rainfall at 3000 m is counteracted by lower temperatures; ,,Physical obstacles make it difficult to walk long, straight transects in Montane forests. Deviating from a straight line pushes the distribution of distance measurements from dung piles to the transect centre line (pdist) towards a negative exponential (NE), which complicates data analysis and may give inaccurate estimates. Using short transects largely alleviate this problem; ,,Analysis of dung count simulations shows that the expected sightability curve of pdist pushes towards a NE with increasing numbers of obstacles blocking the view, even along perfectly straight transects; ,,Extrapolating measured dung density to map area on Mount Kenya resulted in an underestimate of c. 13%. An unstratified correction of map area to ground area for Montane areas would be biased because of the strong tendency for elephants to avoid steeply sloping areas. Résumé La méthode par comptage des crottes est largement utilisée pour estimer le nombre des éléphants en forêt. Elle a été mise au point dans les forêts de basse altitude d'Afrique centrale, mais elle est aussi employée dans les forêts de montagne d'Afrique de l'Est. Utilisant les données collectées sur le Mont Kenya et des simulations informatiques, cet article explore les questions suivantes liées au comptage des crottes dans les forêts de montagne: ,,Les fortes chutes de pluies à 3 000 mètres d'altitude sur le Mont Kenya étaient censées accélérer la décomposition des tas de crottes, mais on n'a pas trouvé de différence significative entre 3 000 et 2 500 mètres où il tombe moins de pluie, peut-être parce que les fortes pluies à 3 000 mètres sont compensées par de plus basses températures; ,,Les obstacles physiques rendent plus difficiles de marcher le long de transects rectilignes dans les forêts de montagne. Le fait de dévier de la ligne droite pousse la distribution des mesures des distances entre les tas de crottes et la ligne droite du transect (pdist) vers un modèle exponentiel négatif (EN) qui complique l'analyse des données et peut donner des estimations inexactes. Le fait de recourir à des transects courts réduit considérablement ce problème; ,,L'analyse des simulations de comptages de crottes montre que la courbe de visibilité attendue de pdist pousse vers un EN lorsque le nombre d'obstacles bloquant la vue augmente, même le long de transects parfaitement rectilignes; ,,L'extrapolation de la densité mesurée des crottes sur une carte du Mont Kenya a abouti à une sous-estimation d'environ 13%. Une correction non stratifiée de la surface cartographiée des zones montagneuses vers une surface plane serait biaisée étant donné que les éléphants ont fortement tendance àéviter les zones escarpées et glissantes. [source] Differentiation of morphology, genetics and electric signals in a region of sympatry between sister species of African electric fish (Mormyridae)JOURNAL OF EVOLUTIONARY BIOLOGY, Issue 4 2008S. LAVOUÉ Abstract Mormyrid fishes produce and sense weak electric organ discharges (EODs) for object detection and communication, and they have been increasingly recognized as useful model organisms for studying signal evolution and speciation. EOD waveform variation can provide important clues to sympatric species boundaries between otherwise similar or morphologically cryptic forms. Endemic to the watersheds of Gabon (Central Africa), Ivindomyrus marchei and Ivindomyrus opdenboschi are morphologically similar to one another. Using morphometric, electrophysiological and molecular characters [cytochrome b sequences and amplified fragment length polymorphism (AFLP) genotypes], we investigated to what extent these nominal mormyrid species have diverged into biological species. Our sampling covered the known distribution of each species with a focus on the Ivindo River, where the two taxa co-occur. An overall pattern of congruence among datasets suggests that I. opdenboschi and I. marchei are mostly distinct. Electric signal analysis showed that EODs of I. opdenboschi tend to have a smaller initial head-positive peak than those of I. marchei, and they often possess a small third waveform peak that is typically absent in EODs of I. marchei. Analysis of sympatric I. opdenboschi and I. marchei populations revealed slight, but significant, genetic partitioning between populations based on AFLP data (FST , 0.04). Taken separately, however, none of the characters we evaluated allowed us to discriminate two completely distinct or monophyletic groups. Lack of robust separation on the basis of any single character set may be a consequence of incomplete lineage sorting due to recent ancestry and/or introgressive hybridization. Incongruence between genetic datasets in one individual, which exhibited a mitochondrial haplotype characteristic of I. marchei but nevertheless fell within a genetic cluster of I. opdenboschi based on AFLP genotypes, suggests that a low level of recent hybridization may also be contributing to patterns of character variation in sympatry. Nevertheless, despite less than perfect separability based on any one dataset and inconclusive evidence for complete reproductive isolation between them in the Ivindo River, we find sufficient evidence to support the existence of two distinctive species, I. opdenboschi and I. marchei, even if not ,biological species' in the Mayrian sense. [source] Exploring strategic priorities for regional agricultural R&D investments in East and Central AfricaAGRICULTURAL ECONOMICS, Issue 2 2010Liangzhi You O13; O32; O55; Q16 Abstract The 11 countries of East and Central Africa have diverse but overlapping agroclimatic conditions, and could potentially benefit from spillovers of agricultural technology across country borders. This article uses high-resolution spatial data on actual and potential yields for 15 major products across 12 development domains to estimate the total benefits available from the spread of new agricultural technologies around the region. Market responses and welfare gains are estimated using the,Dynamic Research Evaluation for Management,model, taking account of current and future projections of local and international demand. Results suggest which crops, countries, and agroclimatic regions offer the largest total benefits. Downloadable data and program files permit different assumptions and additional information to be considered in the ongoing process of strategic priority setting. [source] The economic and poverty impacts of maize research in West and Central AfricaAGRICULTURAL ECONOMICS, Issue 5 2009Arega D. Alene Maize research; Economic surplus; Poverty reduction; West Africa Abstract This article assembles the results of three multicountry surveys on variety performance and adoption patterns to measure the impacts of maize research in West and Central Africa from 1981 to 2005, and uses cost data since 1971 to compute social rates of return on public investments in maize research in the region. Adoption of modern varieties increased from less than 5% of the maize area in the 1970s to about 60% in 2005, yielding an aggregate rate of return on research and development (R&D) investment of 43%. The estimated number of people moved out of poverty through adoption of new maize varieties rose gradually in the 1980s to more than one million people per year since the mid 1990s. Over half of these impacts can be attributed to international maize research at IITA and CIMMYT. The article concludes with a discussion of strategic options to enhance the impacts of maize research in the region. [source] Detection and molecular characterization of foamy viruses in Central African chimpanzees of the Pan troglodytes troglodytes and Pan troglodytes vellerosus subspeciesJOURNAL OF MEDICAL PRIMATOLOGY, Issue 2 2006Sara Calattini Abstract Background, Foamy viruses are exogenous retroviruses that are highly endemic in non-human primates (NHPs). Recent studies, mainly performed in North America, indicated frequent simian foamy virus (SFV) infection in persons occupationally exposed to NHPs. This zoonotic infection was demonstrated mainly after bites by chimpanzees [Pan troglodytes (P. t.)] of the West African P. t. verus subspecies in primatology centers or zoos in the USA. Methods, We studied 32 chimpanzees from the Central African subspecies P. t. troglodytes and P. t. vellerosus, originating from Cameroon (29 cases) or Gabon (3 cases). We screened first plasma or sera of the animals with a Western blot detecting the SFVs Gag doublet proteins. Then, we performed two nested polymerase chain reactions (PCRs) amplifying a fragment of the integrase and LTR regions and, finally, we made phylogenetical analyses on the sequences obtained from the integrase PCR products. Results, By serological and/or molecular assays, we detected foamy viruses (FVs) infection in 14 chimpanzees. Sequence comparison and phylogenetic analyses of a 425 bp fragment of the integrase gene obtained for 10 of the 14 positive apes, demonstrated a wide diversity of new FVs strains that belong phylogenetically either to the P. t. troglodytes or P. t. vellerosus foamy viral clade. Conclusions, This study shows that chimpanzees living in these areas of Central Africa are infected by several specific foamy viruses. This raises, in such regions, the potential risk of a human retroviral infection of zoonotic origin linked to chimpanzees contacts, as already exemplified for STLV-1 and SIV infections. [source] Viruses Associated with Cassava Mosaic Disease in Senegal and Guinea ConakryJOURNAL OF PHYTOPATHOLOGY, Issue 2 2004G. Okao-Okuja Abstract A survey in Senegal and Guinea Conakry established the presence and incidence of cassava mosaic virus disease (CMD) in both countries. CMD occurred in all the fields surveyed, although its incidence was higher in Senegal (83%) than in Guinea (64%). Populations of the whitefly vector, Bemisia tabaci, were low in both countries averaging 1.7 adults per shoot in Guinea and 3.2 in Senegal. Most infections were attributed to the use of infected cuttings, 86 and 83% in Senegal and Guinea, respectively, and there was no evidence of rapid current-season, whitefly-borne infection at any of the sampled locations. Disease severity was generally low in the two countries and averaged 2.5 in Guinea and 2.3 in Senegal. No plants with unusually severe CMD symptoms characteristic of the CMD pandemic in East and Central Africa were observed. Restriction fragment length polymorphism (RFLP)-based diagnostics revealed that African cassava mosaic virus (ACMV) is exclusively associated with CMD in both the countries. Neither East African cassava mosaic virus (EACMV), nor the recombinant Uganda variant (EACMV-UG2) was detected in any sample. These survey data indicate that CMD could be effectively controlled in both countries by phytosanitation, involving the use of CMD-free planting material and the removal of diseased plants. [source] Anglican High Churchmen and the Expansion of Empire,JOURNAL OF RELIGIOUS HISTORY, Issue 2 2008HOWARD LE COUTEURArticle first published online: 21 MAY 200 Postcolonial history has taken a great deal of interest in the missionary endeavours of the church throughout the Empire, especially the work of Protestant/evangelical mission societies. Apart from attention to organisations like the Universities Mission to Central Africa (UMCA) and to some extent the work of the Society for the Propagation of the Gospel (SPG), the work of Anglican High Churchmen has sometimes been overlooked.1 In fact, High Churchmen were very concerned about the role of the Church of England in the expanding empire during the mid-nineteenth century. They were keen to bring the extension of the church under institutional control and to co-operate with the imperial parliament as closely as possible. The activity of the SPG and the foundation of the Colonial Bishoprics Fund (CBF), which provided clergy, schoolmasters, catechists, and bishops as agents of Anglicanism and Englishness, can be seen as part of this strategy. [source] In Conrad's Footsteps: Critical Approaches to Africanist Travel WritingLITERATURE COMPASS (ELECTRONIC), Issue 4 2006Robert Burroughs Travel writing about Central Africa in English reverberates with the language of Joseph Conrad's Heart of Darkness. This essay considers how that canonical text, in shaping twentieth-century travellers' understandings of Central Africa and the travel genre, also shapes literary critics' understandings of the same subjects. [source] The role of mass spectrometry to study the Oklo,Bangombé natural reactors,MASS SPECTROMETRY REVIEWS, Issue 5 2007J.R. De Laeter Abstract The discovery of the existence of chain reactions at the Oklo natural reactors in Gabon, Central Africa in 1972 was a triumph for the accuracy of mass spectrometric measurements, in that a 0.5% anomaly in the 235U/238U ratio of certain U ore samples indicated a depletion in 235U. Mass spectrometric techniques thereafter played a dominant role in determining the nuclear parameters of the reactor zones themselves, and in deciphering the geochemical characteristics of various elements in the U-rich ore and in the surrounding rock strata. The variations in the isotopic composition of a large number of elements, caused by a combination of nuclear fission, neutron capture and radioactive decay, provide a powerful tool for investigating this unique geological environment. Mass spectrometry can be used to measure the present-day elemental and isotopic abundances of numerous elements, so as to decipher the past history of the reactors and examine the retentivity/mobility of these elements. Many of the fission products have a radioactive decay history that have been used to date the age and duration of the reactor zones, and to provide insight into their nuclear and geochemical behavior as a function of time. The Oklo fission reactors and their near neighbor at Bangombé, some 30 km to the south-east of Oklo, are unique in that not only did they become critical some 2,×,109 years ago, but also the deposits have been preserved over this period of geological time. The long-term geochemical behavior of actinides and fission products have been extensively studied by a variety of mass spectrometric techniques over the past 30 years to provide us with significant information on the mobility/retentivity of this material in a natural geological repository. The Oklo,Bangombé natural reactors are therefore geological analogs that can be evaluated in terms of possible radioactive waste containment sites. As more reactor zones were discovered, it was realized that they could be classified into two groups according to their burial depth in the Oklo mine-site. Reactor Zones 10, 13, and 16 were buried more deeply, and were therefore less weathered than the other zones. The less-weathered zones are of great importance in mobility/retentivity studies and therefore to the question of radioactive waste containment. Isotopic studies of these natural reactors are also of value in physics to examine possible variations in fundamental constants over the past 2 billion years. © 2007 Wiley Periodicals, Inc., Mass Spec Rev 26:683,712, 2007 [source] Kunyenga, "Real Sex," and Survival: Assessing the Risk of HIV Infection among Urban Street Boys in TanzaniaMEDICAL ANTHROPOLOGY QUARTERLY, Issue 3 2002Chris Lockhart This article examines possible avenues of HIV infection among urban street boys in Tanzania. In doing so, it questions the ways that AIDS researchers have defined and approached the phenomenon of "survival sex" in East and Central Africa. The article specifically examines the boys' sexual networks, sexual practices, and attitudes regarding their own sexual behavior, including their perceived risk of HIV/AIDS infection. Seventy-five street boys aged eight to 20 from the city ofMwanza were interviewed. Results suggest that almost all street boys are involved in a sexual network in which homosexual and heterosexual behavior occurs. Homosexual practices are rooted in a complex set of behaviors and ideologies known as kunyenga, which is a situated aspect of life on the streets and helps maintain the boys' strong dependence on one another. A key aspect of the boys' sexual careers involves a decrease in kunyenga activity as they approach the age of 18 and an increase in heterosexual encounters after the age of 11. There appears to be a critical period between these ages in which heterosexual and kunyenga activities overlap. It is suggested that boys between these ages represent a potential bridge for HIV/AIDS infection between the general population and the relatively enclosed sexual network of street boys. [Tanzania, street children, HIV/AIDS, sexual behavior] [source] Nachituti's Gift: Economy, Society, and Environment in Central AfricaAMERICAN ANTHROPOLOGIST, Issue 2 2007MARLOES KRAAN Nachituti's Gift: Economy, Society, and Environment in Central Africa. David M. Gordon. Madison: University of Wisconsin Press, 2006. 304 pp. [source] Tinea capitis due to Trichophyton soudanense mimicking bacterial folliculitisMYCOSES, Issue 2 2007A. Ghilardi Summary We report the case of a 36-year-old Senegalese male with non-scarring alopecia of the scalp, including nodules and pustules, diagnosed as tinea capitis caused by Trichophyton soudanense. This dermatophyte is endemic in Central Africa and is becoming more frequent in Europe because of immigration. It has seldom been isolated in Italy. Tinea capitis is common in childhood and it is rare in adults, in which female sex is preferred. In adults, alopecic patches have to be distinguished from those due to other dermatoses inducing alopecia. [source] Out of Our Minds: Reason and Madness in the Exploration of Central AfricaAMERICAN ETHNOLOGIST, Issue 3 2001A. Jamie Saris Out of Our Minds: Reason and Madness in the Exploration of Central Africa. Johannes Fabian. Berkeley: University of California Press, 2000. ix. 320 pp., maps, figures, appendix, notes, bibliography, index. [source] TECHNICAL EFFICIENCY AND PRODUCTIVITY POTENTIAL OF COCOA FARMERS IN WEST AFRICAN COUNTRIESTHE DEVELOPING ECONOMIES, Issue 3 2008Joachim Nyemeck BINAM D24; Q12; Q18; R58 This paper uses survey data to examine the technical efficiency and productivity potential of cocoa farmers in West and Central Africa. Separate stochastic frontier models are estimated for farmers in Cameroon, Ghana, Nigeria, and Côte d'Ivoire, along with a stochastic metaproduction frontier to obtain alternative estimates for the technical efficiencies of farmers in the different countries. The mean productivity potential of cocoa farmers is also estimated, by using a decomposition result applied to both the national and the metaproduction frontiers. The determinants of technical efficiency are assessed to identify the reasons for differences across countries. [source] Living on the edge: life-history of olive baboons at Gashaka-Gumti National Park, NigeriaAMERICAN JOURNAL OF PRIMATOLOGY, Issue 4 2009James P. Higham Abstract Baboons are the most successful and ubiquitous African primates, renowned for their behavioral and reproductive flexibility, which enable them to inhabit a wide variety of habitat types. Owing to a number of long-term field studies, comparative behavioral, developmental, demographic, and life-history data are available from several populations, but study sites show a heavy bias toward South and East African savannahs, with little research in West or Central Africa. Life-history data from such areas are important if we are fully to understand the nature of the environmental factors that limit baboon distribution. Here, we present demographic data for olive baboons at Gashaka-Gumti National Park (GGNP), Nigeria, collected from December 2000,February 2006, and use these data to test comparative models of baboon life-history. The GGNP habitat, which includes large areas of rainforest, is an environment in which baboons are little studied, and rainfall is much higher than at previous study sites. GGNP troop size data are presented from censuses, as well as life-history data for two troops, one of which is within the park and wild-feeding (Kwano troop), whereas the other dwells at the park edge, and supplements its diet by crop-raiding (Gamgam troop). Troop sizes at GGNP are small compared with other field sites, but fit within previously suggested ranges for baboons under these climatic conditions. Inter-birth intervals in Kwano troop were long compared with most studied populations, and values were not as predicted by comparative models. Consistent with known effects of food enhancement, Gamgam troop experienced shorter inter-birth intervals and lower infant mortality than Kwano troop. We indicate some possible factors that exclude baboons from true rainforest, and suggest that the clearing of forests in Central and West Africa for agricultural land may allow baboons to extend their range into regions from which they are currently excluded. Am. J. Primatol. 71:293,304, 2009. © 2009 Wiley-Liss, Inc. [source] Passive microwave radiometer channel selection basedoncloudandprecipitation information contentTHE QUARTERLY JOURNAL OF THE ROYAL METEOROLOGICAL SOCIETY, Issue 617 2006Sabatino Di Michele Abstract The information content of microwave frequencies between 5 and 200 GHz for rain, snow and cloud water retrievals over ocean and land surfaces was evaluated using optimal estimation theory. The study was based on large datasets representative of summer and winter meteorological conditions over North America, Europe, Central Africa, South America and the Atlantic obtained from short-range forecasts with the operational ECMWF model. The information content of rain, snow and cloud water was traded off against the uncertainties due to the natural variability of other variables that microwave observations are sensitive to. These are surface emissivity, land surface skin temperature, atmospheric temperature and moisture. The estimation of the underlying error statistics was based on ECMWF model forecast error statistics. The results suggest that a number of frequency bands are most suited for the retrieval of (i) rain over oceans: 15,18, 35,40, 80, 145, 118.75±10,14 GHz; rain over land: 85,100, 135,140 GHz, (ii) snow over land and oceans: 95,100, 140,150, 187 GHz, (iii) clouds over oceans: 40, 80,85 GHz; clouds over land: 90,100, 135,140 GHz. For radiometers designed for global and multi-season applications, several channels in all of the above frequency ranges would be desirable for optimizing channel usage in hydrometeor retrievals depending on the observed situation. Copyright © 2006 Royal Meteorological Society. [source] Karyotype differentiation in Chromaphyosemion killifishes (Cyprinodontiformes, Nothobranchiidae): patterns, mechanisms, and evolutionary implicationsBIOLOGICAL JOURNAL OF THE LINNEAN SOCIETY, Issue 1 2008MARTIN VÖLKER Chromaphyosemion killifishes are a karyotypically highly diverse group of small, sexually dimorphic fishes living in rainforest rivulets in tropical West and Central Africa. In the present study, we used various chromosome banding and staining techniques to analyse the karyotypes of 13 populations representing seven described species (Chromaphyosemion loennbergii, Chromaphyosemion punctulatum, Chromaphyosemion splendopleure, Chromaphyosemion volcanum, Chromaphyosemion malumbresi, Chromaphyosemion melanogaster, Chromaphyosemion bitaeniatum) and two undescribed forms (Chromaphyosemion cf. lugens, Chromaphyosemion sp. Rio Muni GEMHS00/41). Diploid chromosome numbers (2 n) and the number of chromosome arms (NF) ranged from 2 n = 24 in C. malumbresi to 2 n = 40 in C. bitaeniatum and from NF = 40 in C. volcanum and C. cf. lugens to NF = 54 in one population of C. loennbergii. A tentative XX/XY sex chromosome system was revealed in C. loennbergii, C. melanogaster, C. malumbresi, and Chromaphyosemion sp. Rio Muni GEMHS00/41. Mapping cytogenetic data for all described Chromaphyosemion species onto a recently published mitochondrial DNA phylogeny revealed a complex pattern of chromosomal evolution with several independent reductions of 2 n and independent modifications of NF and nucleolus organizer region phenotypes. Together with the results of preliminary crossing and mate choice experiments, the cytogenetic and molecular phylogenetic data suggest that, contrary to previous hypotheses, chromosomal rearrangements are probably not the most important and certainly not the only factor driving speciation in Chromaphyosemion killifishes. © 2008 The Linnean Society of London, Biological Journal of the Linnean Society, 2008, 94, 143,153. [source] Petroleum System of the Sufyan Depression at the Eastern Margin of a Huge Strike-slip Fault Zone in Central AfricaACTA GEOLOGICA SINICA (ENGLISH EDITION), Issue 6 2009ZHANG Yamin Abstract: The present paper mainly studies the petroleum system of the Sufyan Depression in the Muglad Basin of central Africa and analyzes its control of hydrocarbon accumulation. On the basis of comprehensive analysis of effective source rock, reservoir bed types and source,reservoir,seal assemblages, petroleum system theory has been used to classify the petroleum system of the Sufyan Depression. Vertically, the Sufyan Depression consists of two subsystems. One is an Abu Gabra subsystem as a self generating, accumulating and sealing assemblage. The other subsystem is composed of an Abu Gabra source rock, Bentiu channel sandstone reservoir and Darfur group shale seal, which is a prolific assemblage in this area. Laterally, the Sufyan Depression is divided into eastern and western parts with separate hydrocarbon generation centers more than 10 000 m deep. The potential of the petroleum system is tremendous. Recently, there has been a great breakthrough in exploration. The Sufyan C-1 well drilled in the central structural belt obtained high-yielding oil flow exceeding 100 tons per day and controlled geologic reserves of tens of millions of tons. The total resource potential of the Sufyan Depression is considerable. The central structural belt is most favorable as an exploration and development prospect. [source] Occurrence of the Uganda variant of East African cassava mosaic virus (EACMV-Ug) in western Democratic Republic of Congo and the Congo Republic defines the westernmost extent of the CMD pandemic in East/Central AfricaPLANT PATHOLOGY, Issue 3 2002P. Neuenschwander No abstract is available for this article. [source] | ||||||||||||||||||||||||||||||||||||||||