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Hydropower plants are among the most efficient and reliable renewable energy systems in the world as far as electricity production is concerned. Run-of-river hydropower plants seem more attractive than conventional hydroelectric plants since they can be a cheaper and environmentally friendly alternative. However, their expected energy production pattern heavily depends on several construction variables that need an appropriate design using specific models. This paper analyzes several existing models used for the calculation of the diameter and thickness of a penstock, the optimal selection and implantation (admissible suction head) of a turbine, to estimate the energy produced and expected cost of small hydropower projects for grid-connected and off-grid/micro-grid applications. This review particularly brings out the specificities of each of the models to suggest the most appropriate model according to the context of study and proposes methods to use them more efficiently. This review can be used as a guide in the design and simulation of run-of-river hydropower plants, thus helping in the assessment of the economic feasibility of projects that usually requires a high level of experience and expertise.

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Objectives: Our study aimed to determine the relationship between the initial total prostate-specific antigen (PSA), PSA density, and aggressiveness of prostate cancer (PCa) based on the new Gleason grade group in the two specialized urology centers in Cameroon. Method: A seven-year retrospective study was conducted from January 2012 to December 2019. The study concerned all men diagnosed with PCa graded using the novel Gleason grade group. Data were analyzed descriptively and analytically using Statistical Package for Social Sciences (SPSS) version 20.0. Bivariate analysis was done to identify independent associations. Results: A total of 253 files were reviewed; fulfilling the inclusion criteria. The mean age of our study population was 66.62±8.288 years with the most affected age being those aged between 59-69 years. The commonest finding on DRE was a hard-craggy prostate (46.0%). The mean initial total PSA was 98.78 ng/dL ± 300.17 ng/mL, while the mean PSA density was 1.73 ± 5.94ng/mL². Gleason grade group 2 was the commonest grade (30.6%). There was a positive correlation between initial total PSA and Gleason grade group (r = 0.314 (p-value 0.000)), and between PSA density and Gleason grade group (r = 0.919 (p-value 0.000)). Initial total PSA and the Gleason grade groups were independently associated with the radiological tumour stage (p-value 0.000 and p-value 0.03 respectively). Conclusion: There is a positive correlation between initial total PSA, PSA density, and novel Gleason grade group. We, therefore, recommend that more attention should be placed on PSA density in pre-biopsy decisionmaking. This study enhances the stratification of therapeutic protocols for the management of PCa in Cameroon as well as across African Union member states.