Cet article présente une ingénierie didactique pour l’enseignement et l’apprentissage de l’étude de fonctions rationnelles dans les classes de 5e scientifique et technique industrielle. Cette ingénierie fait suite à l’observation de classes et à l’analyse de l’enseignement de l’étude de fonctions rationnelles dans ces classes, que nous avons faites dans certaines écoles de la Ville de Kinshasa. Une approche méthodologique est utilisée au niveau de l’enseignement pour faciliter les apprentissages et favoriser l’acquisition de connaissances afin que les élèves puissent étudier une fonction rationnelle sans trop de difficultés.

Soil fertility is an indicator of good agricultural production and consequently of the agricultural activity of a locality. In the Sahel and in particular in the basin of the Thies region, soils gradually lose their production capacity. Desertification caused by the combined and simultaneous action of climatic and anthropogenic factors continues to progress. However, studies by the National Agency for Statistics and Demography (ANSD) reveal that the extent of farms in the different regions of Senegal is not correlated with the potential of land production. The objective of this study is to determine whether the areas cultivated in the groundnut basin of the Thies region are related to soil fertility. The methodology adopted is based on a physico-chemical soil analysis to determine a possible relationship between soil fertility and the extent of agricultural land. Field studies were also carried out on the adaptation strategies developed by local producers in the face of this decline in soil fertility. The Bernoulli formula was used for the selection of the study sample. The results of the soil physico-chemical analysis reveal that the areas cultivated by farmers are larger in the less fertile lands. Therefore, the control methods undertaken in the face of declining soil fertility have been fruitful.

Introduction: Uterine prolapse is a descent of the uterus into the small pelvis that can be associated with the descent of the vagina, the bladder and the rectum. In this study, our goal was to determine the prevalence and major risk factors for uterine prolapse in Kisangani, and to describe its management. Material and methods: A cross-sectional study with a descriptive and multicentric focus was carried out in 5 main general reference hospitals and university clinics in the town of Kisangani from 1st January 2005 to 1st January 2015. We selected 43 cases of uterine prolapse on 7039 cases of gynecological pathologies. Results: The prevalence of uterine prolapse is 0.61% in Kisangani; 93.02% had consulted for organ removal and 69.76% for abdomino-pelvic pain. 20.93% of these patients were aged 61-70 years, 18.6% were over 70 years of age with Extremes: 18 and 73 years, 76.73% had a parity greater than or equal to 4, 12.05% were obese and 32.53% of patients were HIV positive. The Dolleris-Pellonda was performed in 51.16% and the total hysterectomy at 34.88%. Recurrences were recorded in 16.27% of cases. Conclusion: Uterine prolapse remains a reality in medical practice in our town. If several risk factors are found, it is also appropriate to retain the role played by HIV / AIDS infection in the genesis of this disease.

A number of aggregation operators have been proposed. Traditional approaches do not perform aggregation of criteria with sufficient flexibility and adaptability to the specific contexts of organizations. In this paper we propose a decision making method using linguistic power means operators for hierarchical aggregation process of information. The proposal allows the inclusion of aspects such as the importance of the criteria and simultaneity. To demonstrate the applicability of the proposal, a case study is developed. The paper ends with further work recommendations for extending the method.

Rapid exhaustion of fossil fuels and the increase in environmental concerns have promoted recent attention towards converting various oils into fuels (biofuels) as alternatives to petroleum diesel. Methanol was used to trans esterify waste cooking oil using the molar ratios of 1:3, 1:6, 1:9 and 1:12 (oil to methanol) in the presence of potassium hydroxide (KOH) as catalyst and 650C activation temperature. The physicochemical properties of the resulting methyl ester of standard molar ratio (1:6) and its blends were investigated and the resulting properties were compared with that of fossil fuel. These properties were also compared with standard values of biodiesel using European Standard (EN 14214), United States Standard (ASTM D6751) and South African Standard (SANS 1935). Results from the variation of the molar ratio of oil to methanol i.e. 1:3, 1:6, 1:9 and 1:12 showed that the percentage yield of methyl ester increased as the molar ratio increased until at 1:9 where the percentage yield of methyl ester started to decline which might be as a result of excess methanol present in the reaction. The value of each of the physicochemical properties for biodiesel (B100) was close to that of petroleum diesel (B0) and almost the same as European Standard (EN 14214), United States Standard (ASTM D6751) and South African Standard (SANS 1935) when compared. The study concludes that waste cooking oil methyl ester and its blends compare favorably with fossil diesel in terms of physicochemical properties and the values are within the acceptable standards.

The high energy demand in the industrialized world as well as the pollution problems caused due to the use of fossil fuels make it increasingly necessary to develop a new renewable energy source. This work transesterified waste cooking oil with methanol and investigated combustion characteristics of the resulting methyl ester and its blends in a compression ignition engine. The methyl ester and its blends were combusted in a direct injection single cylinder four-stroke air cooled diesel engine one after the other and the combustion characteristics such as combustion temperature, cylinder pressure, heat release rate and ignition delay were investigated at different loads of 0.0, 20.0, 40.0, 60.0, 80.0 and 100.0% with full throttle speed of the engine. Results obtained showed that the combustion temperature, cylinder pressure and heat release rate increased as the load increased for each blend. And for each load, the combustion temperature, cylinder pressure and heat release rate increased as the percentage of methyl ester in the blends increased. While ignition delay reduced as the load increased but increased as the percentage of methyl ester in the blends increased. The study concludes that waste cooking oil methyl ester and its blends compare favorably with petroleum diesel and possessed combustion characteristics very close to that of fossil diesel in terms of combustion temperature, cylinder pressure, heat release rate and ignition delay when combusted in a compression ignition engine.

The African continent is one of the continents in the world where the proportion of young people is as high as possible. Some of the major challenges facing young people include unemployment and underemployment, among others. In view of this situation, the question of employability and the employability of young graduates remains more than ever a highly sought-after object and a crucial problem facing the developing countries, notably Cameroon. The purpose of this article is to examine the impact of vocational integration programs on the employability of young graduates. It emphasizes the importance of evaluation mechanisms in the direction of programs. The data of this work are the result of a survey carried out in the cities of Yaoundé and Douala on the employability of young graduates. Our sample is made up of 637 young people, including 143 beneficiaries of the various vocational integration programs. Econometric tests show the significant importance of youth employment policies. Indeed, the estimation of the model shows that the selection of the beneficiaries of the different programs does not take into account the temporal dependence of young people on the states that reduce their employability. Moreover, the model refutes the existence of a significant effect on the exit from unemployment in the post-program situation.

The present study aimed to evaluate the protective effects of aqueous extract of Bersama engleriana leaves against cypermethrin-induced oxidative stress and reproductive toxicity. Thus, fifty male guinea pigs were divided into 5 groups (G1, G2, G3, G4 and G5) of 10 animals each. During 90 days, animals of G1 were orally given 1 ml/kg of body weight (bw)/day of distilled water, while the other groups received 137.50 mg/kg bw of cypermethrin. In addition, G3, G4 and G5 received respectively 50, 100 and 200 mg/kg bw of aqueous extract of Bersama engleriana leaves. At the end of the treatment period, the testicular concentration of malondialdehyde and the activities of superoxide dismutase and catalase decreased significantly (P<0.05) in guinea pigs exposed to cypermethrin and aqueous extract of B. engleriana leaves compared to those exposed to cypermethrin only (G2), while the reverse was observed with the activity of peroxidases. The time of reaction of male guinea pig in the presence of females and the percentage of abnormal spermatozoa decreased significantly (P<0.05) in animals treated with the insecticide and the aqueous extract of B. engleriana leaves compared to G2 animals. The weight of testes, serum level of testosterone, sperm count, mobility and percentage of spermatozoa with entire plasma membrane increased significantly (P<0.05) in guinea pigs given extract compared to those submitted to cypermethrin only. Thus, the aqueous extract of Bersama engleriana leaves protected male guinea pigs against cypermethrin toxicity.