Caractérisation structurale et magnétique du pluton granitique de Misajé (Nord-Ouest Cameroun)

The objective of this study was to map the Misajé pluton based on the magnetic susceptibility, petrographic, geochemical and structural (classic) data in order to integrate it in the tectonic evolution of the Central African Fold Belt. It appears at the end of this work that, the Misajé granitic pluton, elongated NNE-SSW is located in the westhern domain of the Pan-African Belt in Cameroon. It was emplaced around 569-560 Ma in the ante-Pan-African basement rocks, composed of biotite hornblende migmatite and amphibolites reactivated in the Pan-African. It (Misajé granitic pluton) consists of biotite hornblende granite, biotite granite, granodiorite and leucocratic granite, differenciated by fractional crystallization.The study area has recorded three deformation phases. The D1 phase, characterized by an E-W foliation in the basement rocks, has been progressively transposed by dominant D2 phase, observed in the basement rocks, biotite hornblende granite and biotite granite. This D2 phase, orientated NE-SW to N-S is dated between 569 ± 12 Ma in the biotite hornblende granite and 560 ± 9 Ma in the biotite granite. The D3, dated at 532 ± 35 Ma is observed in the biotite hornblende orthogneiss. It is characterized by dextral strike-slip with a non-coaxial deformation, which permit (1) the development of the N-S structures and dextral shear movement, (2) the emplacement of leucocratic granite. The microstructural study shows that, in the Misajé pluton, the deformation started during the magmatic state and followed up till the mylonitic state.The rocks of the Misajé granitic pluton are dominated by paramagnetic behavior (54 % of stations). The presence of ferromagnetic minerals reveals that the carriers of the susceptibility are mainly dominated by magnetite that can be euhedral or anhedral. The T Jelinek factor shows that the dominant strain ellipsoids are plano-linear, nevertheless, 80 % of stations have P values less than 1.2, suggesting that, the emplacement of the Misajé pluton is dominated by magmatic flowing. This magmatic flow induced a flattening on the edge of the massif. The domiance of the dynamic flow in the emplacement of the Misajé pluton, the presence of flat minerals edging the pluton, the presence of preferred orientation of feldspar megacrysts, the presence of a discrete NE- SW shear zone in biotite granite and the magnetic structures (foliation and lineation) suggest a syn-kinematic dome emplacement in a NNE-SSW. These structures are parallel to the major regional structures described in Mayo Nolti and Godé Gormaya Shear Zone (MNSZ and GGSZ) and folds developed during the extensional collapse of western Gondwana, as described in eastern Nigeria and NE Brazil.L’objectif de cette étude était d’établir à partir des données de susceptibilité magnétique, de pétrographie, de géochimie et de structurale (classique), une cartographie des formations du pluton de Misajé afin de l’intégrer dans l’évolution de la Chaîne Panafricaine d’Afrique Centrale (CPAC). A l’issu de ce travail, nous retiendrons que le pluton de Misajé, allongé NNE-SSW est situé dans le domaine Ouest de la CPAC au Cameroun. Ce pluton s’est mis en place par injections successives autour de 569-560 Ma dans un socle anté panafricain constitué de migmatite à biotite et amphibole et d’amphibolites, réactivé au Pan-Africain. Quatre ensembles pétrographiques mis en place par cristallisation fractionnée le composent : la granodiorite, le granite à biotite et amphibole, le granite à biotite et le granite leucocrate. La région de Misajé est affectée par trois phases de déformations. La phase D1, caractérisée par une foliation E-W, observée dans l’encaissant a été progressivement transposée par la phase D2 simultanément observée dans l’encaissant, dans le granite à biotite et amphibole et dans le granite à biotite. Cette phase D2, orientée NE-SW à N-S est datée entre 569 ± 12 Ma dans le granite à biotite et amphibole et 560 ± 9 Ma Ma dans le granite à biotite. La phase D3, datée à 532 ± 35 Ma est décrite dans les orthogneiss à biotite et amphibole comme étant la phase de mylonitisation du granite à biotite et amphibole qui se transforme en orthogneiss à biotite et amphibole. Elle est caractérisée par un mécanisme de déformation ductile au cours duquel une déformation non-coaxiale a permis (1) le développement des structures N-S et une déformation par cisaillement dextre et (2) la mise en place du granite leucocrate. L’étude microstructurale permet d’envisager pour le pluton de Misajé une déformation continue (du stade magmatique au stade mylonitique) au cours de sa mise en place. Les roches du pluton granitique de Misajé sont à dominance paramagnétique (54 % de stations). La contribution ferromagnétique existante révèle que les minéraux porteurs de la susceptibilité sont dominés par la magnétite qui peut être automorphe ou xénomorphe. Le facteur T de Jelinek montre que les ellipsoïdes de déformation dominants sont plano-linéaires, cependant, 80 % de stations ont des valeurs de P < 1,2 ; indiquant une mise en place dominée par l’écoulement dynamique. Cet écoulement magmatique a induit un aplatissement en bordure du massif. La domination de l’écoulement magmatique dans la mise en place du pluton de Misajé, la présence des minéraux aplatis en bordure du pluton, la présence des mégacristaux de feldspath orientés, la présence d’un couloir de cisaillement discret NE-SW idenfié par la méthode d’ASM dans le granite à biotite et les structures (foliation et linéation) magnétiques, permettent d’envisager pour le massif de Misajé une mise en place syn-cinématique en coupoles ou dômes dans un continuum cinématique NNE-SSW, parallèlement aux grandes structures régionales (Cisaillement de Mayo Nolti et le Cisaillement de Godé-Gormaya) et aux chaînes plissées développées lors de l’assemblage du Gondwana Ouest, telle que décrite à l’Est du Nigéria et au NE du Brésil

Rock magnetic investigation of possible sources of the Bangui magnetic anomaly

International audienceThe Bangui magnetic anomaly (BMA) is the largest lithospheric magnetic field anomaly on Earth at low latitudes. Previous studies investigated its geological source using constraints from satellite and ground magnetic field measurements, as well as from surface magnetic susceptibility measurements on rocks from the Panafrican Mobile Belt Zone (PMBZ). Here we combine magnetic field data modelling and rock magnetic property measurements (susceptibility and natural remanent magnetization, NRM) on many samples from this PMBZ and the surrounding formations. It reveals that NRM is a significant component of the total magnetization (Mt) of the BMA source, which reaches 4.3 A/m with maximum thicknesses of 38 and 54 km beneath the western and eastern parts of the BMA. Only the isolated and relatively thin banded iron formations and some migmatites show such Mt values. Thus we suggest that the thick BMA source may be composed either by overlapped slices of such metamorphic rocks, or by an iron-rich mafic source, or by a combination of these two geological structures

Aphrodisiac property of aqueous and methanolic extracts of Raphia vinifera (Arecaceae) in sexually experienced male rats

Background: Raphia vinifera (Arecaceae) is a medicinal plant commonly used as a sexual enhancer. Objective: To investigate the aphrodisiac potential of aqueous extract (AE) and methanolic extract (ME) of R. vinifera in sexually experienced male rats. Materials and Methods: Thirty male Wistar rats were randomly distributed into six groups (5 rats per group) and administered for 14 days with distilled water (10 ml/kg), sildenafil citrate (1.44 mg/kg), and AE or ME of R. vinifera (100 or 500 mg/kg). The copulatory activity was tested on days 0, 7, and 14 using receptive females. Further, on day 14, rats were sacrificed and biochemical analyses (testosterone, total protein, and acid phosphatase) were performed. Results: Sildenafil citrate significantly decreased the intromission latency (day 14, p = 0.04) and frequency (days 7 and 14, p = 0.03) but increased the mount frequency (day 14, p = 0.04), compared with control. Remarkably, R. vinifera enhanced the sexual activity by significantly decreasing the intromission latency (AE and ME, 500 mg/kg, day 14, p = 0.04) and increasing the mount frequency (AE and ME, 100 mg/kg, day 7, p = 0.02) compared with control. Moreover, R. vinifera improved plasmatic (AE, 100 mg/kg, p = 0.03; AE, 500 mg/kg, p = 0.001; ME, 100 mg/kg, p = 0.01) and testicular (AE, 100 mg/kg, p = 0.001; AE, 500 mg/kg, p = 0.01; ME, 100 mg/kg, p = 0.001; ME, 500 mg/kg, p = 0.01) testosterone levels as well as plasmatic total proteins concentration (ME, 500 mg/kg, p = 0.04). Conclusion: These findings showed that R. vinifera possesses an aphrodisiac property which could further justify its folkloric use in traditional medicine as a sexual enhancer

Enseigner la lecture-écriture par la méthode syllabique : Une expérimentation formative

a présente étude sur l’enseignement/apprentissage de la lectureécriture du français comme langue étrangère en classe d’initiation, a été réalisée suite au constat d’échec de la méthode syllabique dans le système éducatif camerounais. L’étude menée à la lumière des théories d’apprentissage de Nuttin (1971) et de Piaget (1965) vise à vérifier l’efficacité des nouveaux outils pédagogiques mis au point, pour une amélioration des pratiques d’enseignement/apprentissage. Une expérimentation formative fondée sur le modèle d’observation avant-après a ainsi été conduite pendant 9 mois, sur deux groupes expérimentaux et témoins placés en zone semi-urbaine dans la Région de l’Est Cameroun, avec un corpus empirique constitué de 170 sujets âgés de 6 ans. La mise en tension des résultats de l’évaluation sommative des compétences littéraires de base à laquelle ont été soumis les groupes expérimentaux et témoins en fin d’année scolaire 2019/2020 nous a permis d’enregistrer les taux de réussite de 87,66% et 17, 09% respectivement ; ceci nous a permis de confirmer la haute efficacité des nouveaux outils pédagogiques mis au point par rapport aux anciens. &nbsp; This study on the teaching/learning of reading and writing of French as second language in elementary classes was carried out because of the failure of the syllabic method in Cameroon’s education system. The study, enlightened by the learning theories of Nuttin (1971) and Piaget (1965, aims at verifying the effectiveness of the newly designed pedagogic tools with the view to ameliorate the teaching and learning practices. A formative experiment based on the before-after observation model was thus conducted for 9 months, on an experimental and a control group located in semi-urban areas in the Eastern Region of Cameroon, on an empirical corpus of 170 students aged 6. The results scored by the experimental and control groups from the summative evaluation of basic literacy skills at the end of the 2019/2020 school year, allowed us to record success rates of 87.66% and 17.09% respectively. This result allowed us to confirm the high effectiveness of the new teaching/learning tools, compared to the old ones

Suctioning of the upper and lower respiratory tract : Clinical guidebook for nursing students

Experience has shown that respiratory tract suctioning is an important factor in caring for patients with respiratory obstruction, especially while in intensive care units, ear nose and throat unit, surgical unit, and care homes. Nurses while attending to duties often face issues of respiratory difficulties from their patients due to accumulation of mucus in the airways. It is incumbent for nurse to manage the patients’ respiratory problems while they are being treated. The purpose of this project thesis therefore is to produce an easy to understand, evidence-based guidebook for nursing students on how to perform suctioning in the upper and lower respiratory tract. With respect to the objective, the goal is to provide nursing students with instructions by use of a guidebook to boost their knowledge and improve their skills on the implementation of airways suctioning. This project thesis report, therefore, led to the production of an easy-to-understand guidebook for nursing students on how to perform upper and lower respiratory tract suctioning. During project process, authors gained lots of theoretical and teamwork skills which will be beneficial in later part of authors working life. The product is an e- PDF file which contain theoretical knowledge of suctioning and pictures demonstrating each procedure of upper and lower airways suctioning. The Authors decided to make three different guidebooks to keep it short and simple, hence facilitating reading. The authors received feedbacks and improvement were made before the guidebooks were accepted. Authors used the waterfall model of project management in which each step of the thesis project was carefully analysed and completed before going to the next stage. The Waterfall project management model, which the authors utilized, the initial stage, the planning stage, the execution stage, and the concluding and evaluation stage. Information and data in this thesis were achieved from eveidenced based websites, Finnish database, and textbooks written by Finnish authors. intext references and list of references follows the Satakunta Universities of Applied Sciences instructions. This project and guidebook was evaluated by the supervising teacher and other tutors in the nursing department, because of time constrain authors could not produce questioners for the target group

Aspirations professionnelles de jeunes bacheliers au Cameroun : l’influence de la pratique de l’orientation scolaire revisitée

This study questions the causes of unemployment of youth in Cameroon and focused on poor assistance to students in the consolidation of their professional aspirations, guarantee of socio-professional insertion. Data collected from 181 students in Upper Sixth classes of Government Bilingual High School Bafoussam through a random sampling method and analysed by regression ordinal logistic stands out that consulting with a guidance counselor does not influence in a significant way the types of professional aspirations entertained by students. Same goes for fields of study and their openings. Initiation to self-awareness contributes in developing in students more realistic professional aspirations rather than oblique, or utopian than undefined. Information on the realities of the job market and the world of employment contributes to developing in students more realistic professional aspirations rather than oblique, or utopian than undefined. The personal qualities of a guidance counselor also contributes to developing in students more realistic professional aspirations rather than oblique, or utopian

Pertinence des reformes LMD au Cameroun : analyses des qualités personnelles et professionnelles des diplômés employés dans les entreprises formelles

The present contribution deals with the appreciation of the personal and professional qualities of graduate employees in the era of the LMD reforms by their direct supervisors in formal public and private enterprises in Cameroon. Drawing on the fields of intervention of occupational psychosociology and organisations, ten indicators of the personal and professional qualities of an employee was cross-referenced with the graduating institutions (polytechnics and public and private universities). Following multiple imputation of missing values, the test of homogeneity of variances (Box Test) led them to the use of the non-parametric Kruskal-Wallis H test. The results reveal a differentiated assessment of the personal and professional qualities of employed graduates according to the graduating institutions. Direct supervisors find polytechnicians better equipped than academics, as it was already the case before the LMD reforms. As it stands, these results reveal a vagueness that detracts from the political rhetoric on the professionalization of academics in the LMD reform period, on the one hand, and the new world order in education marked by a process of standardization that ignores particularities, on the other

Aspirations professionnelles de jeunes bacheliers au Cameroun : l’influence de la pratique de l’orientation scolaire revisitée

This study questions the causes of unemployment of youth in Cameroon and focused on poor assistance to students in the consolidation of their professional aspirations, guarantee of socio-professional insertion. Data collected from 181 students in Upper Sixth classes of Government Bilingual High School Bafoussam through a random sampling method and analysed by regression ordinal logistic stands out that consulting with a guidance counselor does not influence in a significant way the types of professional aspirations entertained by students. Same goes for fields of study and their openings. Initiation to self-awareness contributes in developing in students more realistic professional aspirations rather than oblique, or utopian than undefined. Information on the realities of the job market and the world of employment contributes to developing in students more realistic professional aspirations rather than oblique, or utopian than undefined. The personal qualities of a guidance counselor also contributes to developing in students more realistic professional aspirations rather than oblique, or utopian