Experimental investigation of Taylor-Couette-Poiseuille flow at low Taylor and Reynolds numbers.

Flow patterns of a Taylor-Couette-Poiseuille flow were studied at low axial Reynolds and rotational Taylor numbers (Re ≤ 10.5, Ta ≤ 319). The radius ratio of the inner and outer cylinders was 0.804 and the ratio of the length of the annulus to the gap width was 44.5. Complete map of the studied flow regimes was elaborated. The axial and azimuthal components of the wall shear rate γ were measured at the outer fixed cylinder using a three-segment electrodiffusion probe. The components of the wall shear rate of helices have never been measured in previous investigations. Spatio-temporal description of multiple flow patterns was obtained using flow visualizations and simultaneous measurements of wall shear rate components. The flow structures include Taylor vortices, helices winding in the same direction as the base flow or in the opposite direction, helices that were stagnant or moving in the axial direction, smooth or with superposed azimuthal waves, among others. The influence of different flow structures on the wall shear stress components is discussed with and without axial base flow. It was found that the wall shear stress is a function of Ta but no significant dependence on Re was observed for the studied flow regimes and that the mean wall shear stress increases with the number of azimuthal waves. It was also noted that the ED probes provide a more detailed information about flow patterns than torque measurements and visualizations described in the literature.

Resilience of Key Biological Parameters of the Senegalese Flat Sardinella to Overfishing and Climate Change.

The stock of the Senegalese flat sardinella, Sardinella maderensis, is highly exploited in Senegal, West Africa. Its growth and reproduction parameters are key biological indicators for improving fisheries management. This study reviewed these parameters using landing data from small-scale fisheries in Senegal and literature information dated back more than 25 years. Age was estimated using length-frequency data to calculate growth parameters and assess the growth performance index. With global climate change there has been an increase in the average sea surface temperature along the Senegalese coast but the length-weight parameters, sex ratio, size at first sexual maturity, period of reproduction and condition factor of S. maderensis have not changed significantly. The above parameters of S. maderensis have hardly changed, despite high exploitation and fluctuations in environmental conditions that affect the early development phases of small pelagic fish in West Africa. This lack of plasticity of the species regarding of the biological parameters studied should be considered when planning relevant fishery management plans.

Estimated impact and cost-effectiveness of rotavirus vaccination in Senegal: A country-led analysis.

INTRODUCTION: Rotavirus is the leading cause of acute severe diarrhea among children under 5 globally and one of the leading causes of death attributable to diarrhea. Among African children hospitalized with diarrhea, 38% of the cases are due to rotavirus. In Senegal, rotavirus deaths are estimated to represent 5.4% of all deaths among children under 5. Along with the substantial disease burden, there is a growing awareness of the economic burden created by diarrheal disease. This analysis aims to provide policymakers with more consistent and reliable economic evidence to support the decision-making process about the introduction and maintenance of a rotavirus vaccine program. METHODS: The study was conducted using the processes and tools first established by the Pan American Health Organization's ProVac Initiative in the Latin American region. TRIVAC version 2.0, an Excel-based model, was used to perform the analysis. The costs and health outcomes were calculated for 20 successive birth cohorts (2014-2033). Model inputs were gathered from local, national, and international sources with the guidance of a Senegalese group of experts including local pediatricians, personnel from the Ministry of Health and the World Health Organization, as well as disease-surveillance and laboratory specialists. RESULTS: The cost per disability-adjusted life-year (DALY) averted, discounted at 3%, is US$ 92 from the health care provider perspective and US$ 73 from the societal perspective. For the 20 cohorts, the vaccine is projected to prevent more than 2 million cases of rotavirus and to avert more than 8500 deaths. The proportion of rotavirus deaths averted is estimated to be 42%. For 20 cohorts, the discounted net costs of the program were estimated to be US$ 17.6 million from the healthcare provider perspective and US$ 13.8 million from the societal perspective. CONCLUSION: From both perspectives, introducing the rotavirus vaccine is highly cost-effective compared to no vaccination. The results are consistent with those found in many African countries. The ProVac process and tools contributed to a collaborative, country-led process in Senegal that provides a platform for gathering and reporting evidence for vaccine decision-making.