A shallow water numerical method for assessing impacts of hydrodynamics and nutrient transport processes on water quality values of Lake Victoria.

Lake Victoria is the world's largest tropical lake and the third-largest water body, providing significant water resources for surrounding environments including the cultural, societal, and livelihood needs of people in its basin and along the White Nile. The aim of this study was to use decade-long time series of measured lake flow in the lake system and phosphorus deposition to develop a suitable numerical model based on shallow water equations (SWE) for assessing water quality in Lake Victoria, an increasingly important tool under climate variation. Different techniques were combined to identify a numerical model that included: i) a high-resolution SWE model to establish raindrop diffusion to trace pollutants; ii) a two-dimensional (2D) vertically integrated SWE model to establish lake surface flow and vertically transported wind speed flow acting on lake surface water by wind stress; and iii) a site-specific phosphorus deposition sub-model to calculate atmospheric deposition in the lake. A smooth (non-oscillatory) solution was obtained by applying a high-resolution scheme for a raindrop diffusion model. Analysis with the vertically integrated SWE model generated depth averages for flow velocity and associated changes in water level profile in the lake system and showed unidirectional whole lake wind blowing from the southwest to northeast. The atmospheric phosphorous deposition model enabled water value assessment for mass balances with different magnitudes of both inflows and outflows demonstrating annual total phosphorus at 13,500 tons concentrating at mid-lake western and eastern parts. The model developed here is simple and suitable for use in assessing flow changes and lake level changes and can serve as a tool in studies of lake bathymetry and nutrient and pollution transport processes. Our study opens towards refining models of complex shallow-water systems.

Mammals, wildlife trade, and the next global pandemic.

Most new infectious diseases emerge when pathogens transfer from animals to humans.1,2 The suspected origin of the COVID pandemic in a wildlife wet market has resurfaced debates on the role of wildlife trade as a potential source of emerging zoonotic diseases.3-5 Yet there are no studies quantitatively assessing zoonotic disease risk associated with wildlife trade. Combining data on mammal species hosting zoonotic viruses and mammals known to be in current and future wildlife trade,6 we found that one-quarter (26.5%) of the mammals in wildlife trade harbor 75% of known zoonotic viruses, a level much higher than domesticated and non-traded mammals. The traded mammals also harbor distinct compositions of zoonotic viruses and different host reservoirs from non-traded and domesticated mammals. Furthermore, we highlight that primates, ungulates, carnivores, and bats represent significant zoonotic disease risks as they host 132 (58%) of 226 known zoonotic viruses in present wildlife trade, whereas species of bats, rodents, and marsupials represent significant zoonotic disease risks in future wildlife trade. Thus, the risk of carrying zoonotic diseases is not equal for all mammal species in wildlife trade. Overall, our findings strengthen the evidence that wildlife trade and zoonotic disease risks are strongly associated, and that mitigation measures should prioritize species with the highest risk of carrying zoonotic viruses. Curbing the sales of wildlife products and developing principles that support the sustainable and healthy trade of wildlife could be cost-effective investments given the potential risk and consequences of zoonotic outbreaks.

Six percent hetastarch versus lactated Ringer's solution - for preloading before spinal anesthesia for cesarean section.

BACKGROUND: Regional anesthesia has been the choice of preference for elective cesarean sections. This study was designed to determine whether preoperative administration of 6% hetastarch decreases the incidence of hypotension. MATERIALS AND METHODS: This study was conducted on 50 nonlaboring American Society of Anesthesiologists class I and II women undergoing elective cesarean section. Patients were randomly divided into two groups and were preloaded either with 1000 ml Ringer's lactate (RL) or 500 ml of 6% hetastarch 30 min prior to the surgery. Spinal anesthesia was performed with patients in the left lateral position and 2 cc (10 mg) of 0.5% of bupivacaine injected into subarachnoid space. Hemodynamic variables (heart rate, noninvasive blood pressure, and SpO2) were recorded from prior to preloading until the recovery from the subarachnoid blockade. RESULTS: Our study showed the incidence of hypotension to be 28% in the hetastarch group and 80% in the RL group. Rescue ephedrine requirements for the treatment of hypotension were significantly less in patients who were preloaded with 6% hetastarch prior to cesarean section. The neonatal outcome, as determined by Apgar scores was good and similar in both groups. CONCLUSION: Hence, we conclude that 6% hydroxyl ethyl starch is more effective than lactated Ringers solution and that its routine use for preloading prior to spinal anesthesia should be considered.