23 research outputs found
Geochemical and Geodynamic Constrain of Tholeiitic Volcanism and Related Intrusions in the Kampti Gold District, Southwest Burkina Faso: Implication for Mineral Exploration
No full textThe Kampti serie is a volcano-plutonic complex in the south-eastern corner of the Houndé belt, closed to the border with Ivory Coast. The stratigraphy comprises initially: a thick sequence of tholeiitic and pillowed basalt followed by pyroclastic projections derivated from bimodal volcanism; and flowing mostly to the south. The volcanic sequence is cross-cut by mafic cumulate body, stocks of gabbro, diorite, subvolcanic dykes and lately intrude by granitoid. It is bordered to the west by the pelitic schist of the Bambela basin with minor intercalation of Tarkwa type sediment. volcanoclastic facies is dominantly plagioclase-phyric (albite +/- oligoclase), zoned plagioclase has a core of anorthoclase. Secondary mineral infilled (quartz, kutnahorite, ripidolite, clinozoisite) of spherulites and oolite highlight a general low grade metamorphism of greenschist facies affecting the complex. Based on trace element chemistry, the tholeiitic rocks present flat REE pattern contrasting with the felsic rocks more enriched in LREE and depleted in HREE. The style of the magmatism in the Kampti serie is compatible with an island arc model, describe elsewhere in the birimian. Gold mineralisation and base metal occurrences associated to the nature of rocks and tectonics highlight a polymetallic district.</jats:p
Historical study on analyses and designs of biaxially loaded RC columns
No full text摘要
鋼筋混凝土雙向柱之分析設計上較為困難，早期多以經驗法或近似法為之，隨著電腦及程式運算不斷的發展，許多基於規範之設計和驗算方法不斷出現。本研究對多年來各方所提出之方法，作一整理與歷史回顧，最後以ACI318-11規範為準，檢核不同方法的結構設計結果，並比較探討之。
研究中所介紹的方法，包括；(1). Bresler’s 近似法(2). Etabs 設計法(3). 準牛頓法(4). 類神經網路法。並將原本為人工計算之Bresler’s近似法，改為計算機程式化來執行。
分析結果顯示，使用準牛頓法以及類神經網路法所得到之結果最為理想，因此建議在工程上分析及設計鋼筋混凝土雙向柱時，應參考此兩種方法來進行模擬及分析。此外，雖然使用Etabs設計法及Bresler’s 近似法所得之結果，比準牛頓法所得較為保守。受到軸力較大彎矩較小的狀況下，使用Etabs 設計法準確性較差；但resler’s 近似法所得之結果，則恰恰相反。使用時必須注意。The analysis and design of reinforced concrete columns under biaxial bending are difficult. Over the years various design and checking methods have been developed. This thesis presents a historical study on different methods for strength estimation of such structural elements according to ACI design code. A comparison of design results according to ACI318-11 via different methods is also made.
Four design methodsstudied includes: (1). Bresler’s Approximation method, (2). Etabs method, (3). Direct iterative method, and (4). Neural network method. The first method is the only one which is applied manually. The author also proposed a handy procedure to make it work in computer environment.
This study revealed that the quasi Newton design and the neural network design methods present closest results. If available, these two methods should be used in engineering practices.
The Etabs design and reciprocal load design method are conservative andunconservative respectively compared to the quasi-Newton method. Moreover for columns with a large nominal axial strength and small bending moment Etabs design method is less accurate. On the other hand the reciprocal load design has good results for that kind of columns and less for columns subject to a low nominal axial strength. The author recommends the use of Etabs design method for columns with low to intermediate axial force and reciprocal load method for columns having a large axial force.Chapter I Introduction 1
Chapter II Reinforced Concrete Columns Subjected to uniaxial and biaxial Bendings 3
2.1 Uniaxial bending 3
2.1.1 Column sectional strength 3
2.1.2 Strength interaction curve 4
2.2 Biaxial bending 4
2.2.1 Column Sectional capacity 4
2.2.2 Strength interaction surface 5
Chap III Biaxial Bending RC Column Analysis and Design methods 7
3-1 Approximative method 7
3.2 Direct calculation methods (iterative methods) 10
3.2.1 A single variable alternating iterative method 10
3.2.2 Quasi-Newton method 11
3.3 Etabs design method 13
3.4 Neural network method 15
Chapter IV Design example according to ACI 318-11by various methods and results comparison 16
4.1 Structure model and design requirements 16
4.1.1 Structure model 16
4.1.2 Design loads 17
4.2 Analysis method and results 19
4.3 Design results and comparisons 20
4.3.1 Etabs design method using ACI 318-11 20
4.3.2 Bresler’s reciprocal load method 21
4.3.3 Quasi Newton design method 21
4.3.4 Neural network method 22
4.3.5 Comparison of the results 22
Chapter V Conclusion 25
References 27
List of Tables and Figures 29-47
Appendix 48-5
Etude géospatiale de l’évolution du site minier artisanal de Bouda, ceinture de Kaya-Goren (Burkina Faso, Craton Ouest Africain)
No full textArtisanal mining is a key sector of Burkina Faso's economy. This activity, which is properly regulated, remains vital for the population, despite the environmental and security problems the country has been experiencing since 2015. Exploring new areas for gold mining under these conditions is difficult, but essential if mining activities are to continue. It is therefore important to find alternatives to continue geological exploration, while providing a solution to the supervision of artisanal mining in Burkina Faso. Our study focused on the Bouda pilot site.A remote sensing based approach was developed to study the structural control of artisanal mining expansion at the Bouda site and to define prospecting corridors. The Minimum Noise Fraction (MNF) is applied to Landsat images (7-ETM+, 5-TM and 8-OLI for the years 2000, 2011 and 2022 respectively) to detect mining sites and perform a spatio-temporal analysis of the expansion of areas affected by gold mining. This process shows that the near-infrared and short-wave infrared bands of Landsat imagery make a significant contribution to the detection of mining areas.A morphological study of the Bouda site over time and a Principal Component Analysis (PCA) on Landsat 8-OLI allowed us to perform a lineament analysis. The expansion of mining activity at the Bouda site is structurally controlled, as evidenced by the correlation between gold occurrences and high lineament densities, particularly in the dominant NE-SW direction. The results of these analyses suggest five high potential prospecting corridors on the Bouda site.This study also used a combination of data to investigate the geological features favourable to mineralisation at the Bouda site and to define prospecting targets. Two main lithological units were identified: metamorphic units (metapelites and amphibolitised basalts) and igneous units (doleritic basalts and gabbros).A supervised classification using the Spectral Angle Mapper (SAM) algorithm was correlated with the magnetic analytical signal (SA), leading to the conclusion that the metamorphic formations at the Bouda site have a high potential for mineralisation. The analysis also revealed the presence of deep structures, in particular faults.A Landsat 8-OLI image was processed to define the relationship between hydrothermal alteration and gold occurrences. Gold at Bouda is associated with a hydrothermal alteration duality consisting of iron minerals and clays/carbonates.Eight prospecting targets have been defined for the discovery of a probable deposit at Bouda, five of which are already being mined by artisanal miners.The study highlights the importance of using advanced satellite imagery, airborne geophysics and field work for rapid, cost-effective exploration that is rich in geological information.At the end of the study, we proposed a framework for monitoring artisanal mining in Burkina Faso, integrating our methodology into the exploration phase. This framework is based on a specific model of community entrepreneurship, where each party emerges as a winner at the end of the process. This will create a climate of trust between mining operators and the state, so that artisanal mining in Burkina Faso can be properly reorganised, with a gradual shift towards small-scale mining.L’exploitation minière artisanale est un secteur clé de l’économie du Burkina Faso. Cette activité, convenablement réglementée, reste essentielle pour la population, malgré les problèmes environnementaux et les problèmes de sécurité que vit le pays depuis 2015. L’exploration de nouvelles zones pour l’exploitation de l’or dans ces conditions est difficile mais essentielle pour la poursuite des activités extractives. Il est donc important de trouver des alternatives à la poursuite de l’exploration géologique tout en apportant une solution à l’encadrement de l’exploitation minière artisanale au Burkina Faso. Le site pilote de Bouda a été l’objet notre étude.Une approche basée sur la télédétection a été élaborée pour étudier le contrôle structural de l’expansion de l’exploitation minière artisanale sur le site de Bouda et définir des corridors de prospection. La fraction de bruit minimal (MNF) est appliquée aux images Landsat (7-ETM+, 5-TM, et 8-OLI respectivement pour les années 2000, 2011 et 2022) pour détecter les sites d’extraction et effectuer une analyse spatio-temporelle de l’expansion des zones affectées par l’extraction de l’or. Il ressort de ce processus que les bandes du proche infrarouge et de l’infrarouge à ondes courtes des images Landsat contribuent de manière significative à la détection des zones d’extraction. Une étude morphologique du site de Bouda dans le temps et une analyse en composantes principales (ACP) sur Landsat 8-OLI nous ont permis de réaliser une analyse linéamentaire. L’expansion de l’activité minière du site de Bouda est structuralement contrôlée, comme le révèle la corrélation entre les occurrences aurifères et les fortes densités linéamentaires, en particulier dans la direction dominante NE-SW. Les résultats de ces analyses suggèrent cinq corridors de prospection à potentialité élevée sur le site de Bouda.Cette étude a également utilisé une combinaison de données pour étudier les caractéristiques géologiques favorables à la minéralisation du site de Bouda et définir des cibles de prospection. Deux principales ensembles lithologiques ont été identifiées : les ensembles métamorphiques (métapélites et basaltes amphibolitisés) et les ensembles magmatiques (basaltes doléritiques et gabbros).Une classification supervisée utilisant l’algorithme Spectral Angle Mapper (SAM) a été mise en corrélation avec le signal analytique magnétique (SA), permettant de conclure que les formations métamorphiques du site de Bouda présentent un fort potentiel de minéralisation. De plus, l’analyse a révélé la présence de structures profondes, notamment des failles.Une image Landsat 8-OLI a été traitée pour définir les relations entre les altérations hydrothermales et les occurrences aurifères. L’or de Bouda est associé à une dualité d’altérations hydrothermales constituée de minéraux ferreux et d’argiles/carbonates. Huit cibles de prospection ont été définies pour la découverte d’un probable gisement à Bouda, dont cinq font déjà l’objet d’exploitation minière artisanale.L’étude souligne l’importance de l’utilisation de traitements avancés d’imagerie satellitaire, de la géophysique aéroportée et des travaux de terrain pour une exploration rapide, économique et riche en informations géologiques. A l’issue de cette étude, nous avons proposé un canevas pour l’encadrement de l’artisanat minier au Burkina Faso où notre méthodologie s’intègre à l’étape de l’exploration. Ce canevas est basé sur un modèle spécifique d’entrepreneuriat communautaire, où chaque partie ressort gagnant à la fin du processus. Cela créera un climat de confiance des exploitants miniers vis-à-vis de l’Etat pour une réorganisation adéquate de l’exploitation minière artisanale au Burkina Faso, en la faisant migrer progressivement vers la petite mine
The integration of creative oral forms and techniques in Fidèle Padwindbé Rouamba's Pouvoir de plume
Get PDFFidèle Padwindbé Rouamba's novel, Pouvoir de plume ("Pen power", 2003) summarises the life of a journalist, Gouma Tansoba, alias Gilbert Torro. The principal narrator is Jean de Dieu, a friend of the journalist. The journalist recorded the narrative on five cassettes, which the heterodiegetic narrator has reconstituted to form a novel. The novel is also a pertinent analysis of the development problems of the democracy in the country and in Africa in general. Particularly striking is the way the author exploits the oral tradition. Thus he makes an effort to use many proverbs drawn from the Moaaga oral tradition. A folktale "Le caïman et l'homme" ("The Caiman and the man") is also included in the narrative. Moreover, in chapter nine, "Le Club" ("The Club"), the author introduces a story to illustrate the jesting alliance between the Bisa and Gourounsi. he therefore exploits, as did the Burkinabè novelists Patrick Ilboudo in Le procès du meut ("The trail of the deaf-mute") and Noaga Kollin Le retour au village ("Back to the village"), the virtues of this traditional practice, firmly established in the ethnic culture of Burkina Faso. I shall endeavour to reveal how the novelist Rouamba exploits the oral tradition in his work, in order to see how all the creative oral forms and techniques borrowed from the oral tradition act as catalysts in the production of a novel.  
Author Correction: Spatial analysis and risk mapping of Crimean-Congo hemorrhagic fever (CCHF) in Sub-Saharan Africa
No full textThe Belahourou granite pluton (Djibo greenstone belt, Burkina Faso): Emplacement mechanism and implication for gold mineralization along a shear zone
No full textIntrusion-related gold mineralization: Inata gold deposit, Bélahourou district, Northern Burkina Faso (West-Africa)
No full textAuthor response: APOL1 renal risk variants have contrasting resistance and susceptibility associations with African trypanosomiasis
No full textAre teachers at higher risk of HIV infection than the general population in Burkina Faso?
No full textIn order to assess the human immunodeficiency virus (HIV) prevalence among teachers in Burkina Faso, we carried out a national survey in 336 primary and secondary schools from urban and rural areas. Among 2088 teachers who agreed to participate, 1498 (71.7%) provided urine for HIV testing. The crude prevalence of HIV among teachers was 2.8% (95% confidence interval [CI]: 2.0-3.6), with no difference between teachers from primary schools (2.9%, 95%CI: 2.1-4.0) and those from secondary schools (2.5%, 95%CI: 0.5-4.5). Age- and area-standardized HIV prevalence was 1.0% (95%CI: 0.4-1.2) in male teachers, 2.5 times lower than among men in the general population (as assessed from a concomitant Demographic Health Survey), and it was 3.5% (95%CI: 2.5-5.2) in female teachers, 1.7 times higher than in Demographic Health Survey women.This finding calls for the implementation of specific HIV prevention programmes in the education sector targeting women more specifically. © The Author(s) 2013
Plasmodium falciparum gametocyte carriage in symptomatic patients shows significant association with genetically diverse infections, anaemia, and asexual stage density
No full textInternational audienceAbstract Background Multi-genotype malaria infections are frequent in endemic area, and people commonly harbour several genetically distinct Plasmodium falciparum variants. The influence of genetic multiplicity and whether some specific genetic variants are more or less likely to invest into gametocyte production is not clearly understood. This study explored host and parasite-related risk factors for gametocyte carriage, and the extent to which some specific P. falciparum genetic variants are associated with gametocyte carriage. Methods Gametocytes and asexual forms were detected by light microscopy on thick smears collected between 2010 and 2012 in Nanoro, Burkina Faso. Merozoite surface protein 1 and 2 were genotyped by nested PCR on clinical samples. Associations between gametocyte carriage and factors, including multiplicity of infection, parasite density, patient age, gender, haemoglobin (Hb) level, and body temperature were assessed. The relationship between the presence of a particular msp1 and msp2 genetic variants and gametocyte carriage was also explored. Results Of the 724 samples positive to P. falciparum and successfully genotyped, gametocytes were found in 48 samples (6.63%). There was no effect of patient gender, age and body temperature on gametocyte carriage. However, the probability of gametocyte carriage significantly increased with increasing values of multiplicity of infection (MOI). Furthermore, there was a negative association between parasite density and gametocyte carriage. MOI decreased with parasite density in gametocyte-negative patients, but increased in gametocyte carriers. The probability of gametocyte carriage decreased with Hb level. Finally, the genetic composition of the infection influenced gametocyte carriage. In particular, the presence of RO33 increased the odds of developing gametocytes by 2 while the other allelic families K1, MAD20, FC27, and 3D7 had no significant impact on the occurrence of gametocytes in infected patients. Conclusion This study provides insight into potential factors influencing gametocyte production in symptomatic patients. The findings contribute to enhance understanding of risk factors associated with gametocyte carriage in humans. Trial registration NCT01232530
