Preliminary design considerations for a commercial launch vehicle upper stage.

Masters Degree. University of KwaZulu- Natal, Durban.The African small satellite industry (micro and nano satellites in particular) continues to grow with developments in the miniaturization of satellite technology. However, the costs and delays involved with the traditional “piggy backing” satellite launch method is unsustainable for small sat developers and has thus created a niche market for dedicated small satellite launch services. Notably, there is no satellite launch capability whatsoever in Africa, meaning all of the continent’s launch requirements are serviced by foreign providers, incurring additional cost. As its primary objective, the University of KwaZulu-Natal’s (UKZN’s) Aerospace Systems Research Group (ASReG) seeks to enable the establishment of an indigenous small satellite launch capability in alignment with the South African Government’s goals. To this end, ASReG is currently developing the LOX/Kerosene SAFFIRE (South African First Integrated Rocket Engine) to propel a hypothetical two-stage orbital launch vehicle, termed Commercial Launch Vehicle 1 (CLV). The upper stage of the launch vehicle will use a vacuum-expanded variant of SAFFIRE called SAFFIRE-V. The upper stage for both cases must meet the design constraints of a 0.85 mass fraction and a 1.2 m outer diameter. CLV has been envisaged to deliver a 75kg payload to 400 km sun synchronous orbit. This thesis presents a high level analysis focusing on the upper stage of CLV, which intends to guide design decisions by comparing design options based on mass, and develop a methodology for upper stage vehicle design. One of the major design decisions is the type of propellant feed system the vehicle should use; in this regard, the analysis compares an electric pump feed system to a pressure fed system. Another is the selection of propellant tank material, given that the propellant tanks constitute most of the mass of a rocket. Stainless steel (301 and Duplex), aluminium alloy (7075), aluminium-lithium (2195), carbon fibre reinforced plastic (T700/Epoxy), as well as combinations of materials were compared. To perform the preliminary mass analysis, each of the major components/systems of the CLV upper stage were independently designed and the various design options available for each of the components/systems were compared based on mass. These systems and components include: fuel and oxidiser propellant tanks, the propellant pressurization system and the reaction control system. After the individual analyses of the variations of each component, the best suited architectures were modelled in SolidWorks CAD software. The components were then assembled, in CAD. The analysis found that, on a preliminary basis, the Lithium ion (Li-Ion) based electric pump fed upper stages did not meet the mass requirements while Lithium polymer (Li-Po) based upper stages achieved the mass requirements. An upper stage employing stainless steel propellant tanks was found to meet the mass requirements, but only for a pressure fed upper stage. Overall, pressure fed upper stages had lower masses compared to electric pump vehicles. The mass reduction of thin walled, low pressurized, propellant tanks (resulting from using electric pumps) was offset by the mass of the battery packs required to power the pumps

Effects of parent material on soil erosion within Mediterranean new vineyard plantations

Parent material can determine specific physical and chemical soil properties and, therefore, soil erosion rates. However, for new vine plantations, there is not enough research on soil erosion assessment on different parent materials which could be helpful for agricultural management plans. The main aim of this research was to quantify soil erosion rates of two recent vineyard plantations under similar climate and land use management conditions, but on different parent materials, namely colluvium (2 years old) and marls (8 years old), located within the Les Alcusses valley vineyards in Eastern Spain. To achieve this goal, the ISUM (improved stock unearthing method) was applied. ISUM involves measurements of vertical distances from a horizontally stretched meter band attached to opposite pair vine plants to the topsoil surface at 5 sampling points along the cross sections of the pair vine rows. The original surface level was determined from the fixed distance of 2 cm of the graft unions from the soil surface. Digital elevation modelling of the vertical measurements was used to infer the erosion rates. Annual total soil erosion rates were 87.7 Mg ha−1 year−1 and 4.35 Mg ha−1 year−1 in the marls and colluvium plots, respectively. For the marls plot, 67% of the depletion occurred in the inter-row areas, whereas for the colluvium plot the inter-row areas registered 4.78 Mg ha−1 year−1 depletion and the row areas showed only a deposition of 0.44 Mg ha−1 year−1. We hypothesised that the inter-row areas registered the highest erosion rates due to the tillage practices. In the row areas, the cover of the vines possibly reduced soil erosion rates and acted as sinks for sediments. This behaviour of the inter-row areas acting as sources and the row areas as sinks for sediments was more evident on the colluvium plot, while most sections on the marls plot showed intense erosion features. It is suggested that more attention should be paid by policymakers and stakeholders to these differences when new plantations are introduced on marls and colluvium vineyards. We claim that initial soil erosion control measures should be applied during the first few years of plantations instead of when the vineyards are much older and soil has already been mobilised

Estimating malaria parasite density: assumed white blood cell count of 10,000/μl of blood is appropriate measure in Central Ghana.

BACKGROUND: White blood cells count (WBCc) is a bedrock in the estimation of malaria parasite density in malaria field trials, interventions and patient management. White blood cells are indirectly and relatively used in microscopy to estimate the density of malaria parasite infections. Due to frequent lack of facilities in some malaria-endemic countries, in order to quantify WBCc of patients, an assumed WBCc of 8.0 X 10(9)/L has been set by the World Health Organization to help in estimating malaria parasite densities. METHODS: This comparative analysis study, in Central Ghana, compiled laboratory data of 5,902 Plasmodium falciparum malaria parasite positive samples. Samples were obtained from consented participants of age groups less than five years. Full blood counts (FBC) of participants' samples were analysed using the ABX Micros 60 Haematology Analyzer. Blood slides were read by two competent microscopists to produce concordant results. All internal and external quality control measures were carried out appropriately. Parasite densities were calculated using participants' absolute WBCc and assumed WBCc of 5,000 to 10,000 per microlitre of blood. RESULTS: From the 5,902 Pf malaria positive samples, the mean (SD) WBCc and geometric mean parasite density were 10.4 (4.6) × 10(9)/L and 7,557/μL (95% CI 7,144/μL to 7,994/μL) respectively. The difference in the geometric mean parasite densities calculated using absolute WBCs and compared to densities with assumed WBCs counts were significantly lower for 5.0 × 10(9)/L; 3,937/μL, 6.0 × 10(9)/L; 4,725/μL and 8.0 × 10(9)/L; 6,300/μL. However, the difference in geometric mean parasite density, 7,874/μL (95 % CI, 7,445/μL to 8,328/μL), with assumed WBCc of 10.0 × 10(9)/L was not significant. CONCLUSION: Using the assumed WBCc of 8.0 X 10(9)/L or lower to estimate malaria parasite densities in Pf infected children less than five years old could result in significant underestimation of parasite burden. Assumed WBCc of 10.0 × 10(9)/L at 95 % CI of geometric mean of parasite density statistically agreed with the parasite densities produce by the absolute WBCc of participants. The study suggests where resources are limited, use of assumed WBCc of 10.0 × 10(9)/L of blood to estimate malaria parasite density in central Ghana. Preferably, absolute WBCc should be used in drug efficacy and vaccine trials

Impacts of Weather Types on Soil Erosion Rates in Vineyards at "Celler Del Roure" Experimental Research in Eastern Spain

[EN] To understand soil erosion processes, it is vital to know how the weather types and atmospheric situations, and their distribution throughout the year, affect the soil erosion rates. This will allow for the development of efficient land management practices to mitigate water-induced soil losses. Vineyards are one of the cultivated areas susceptible to high soil erosion rates. However, there is a lack of studies that link weather types and atmospheric conditions to soil erosion responses in viticultural areas. Thus, the main aim of this research is to assess the impacts of weather types and atmospheric conditions on soil erosion processes in a conventional vineyard with tillage in eastern Spain. To achieve this goal, rainfall events from 2006 to 2017 were monitored and the associated runoff and soil loss were collected from experimental plots. Our results showed that the highest volume of runoff and soil erosion is linked to rainfall associated with the eastern winds that accounted for 59.7% of runoff and 63.9% of soil loss, while cold drops in the atmospheric situation classifications emerged as the highest contributor of 40.9% in runoff and 44.1% in soil loss. This paper provides new insights into the development of soil erosion control measures that help to mitigate the negative impact of extreme rainfall and runoff considering atmospheric conditions.This research was funded by the European Union Seventh Framework Program (FP7/2007-2013) under grant No. 603498 (RECARE Project).Rodrigo-Comino, J.; Senciales-González, JM.; Terol, E.; Mora Navarro, JG.; Gyasi-Agyei, Y.; Cerdà, A. (2020). Impacts of Weather Types on Soil Erosion Rates in Vineyards at "Celler Del Roure" Experimental Research in Eastern Spain. Atmosphere. 11(6):1-14. https://doi.org/10.3390/atmos11060551S114116Panagos, P., Borrelli, P., Meusburger, K., van der Zanden, E. H., Poesen, J., & Alewell, C. (2015). Modelling the effect of support practices (P-factor) on the reduction of soil erosion by water at European scale. Environmental Science & Policy, 51, 23-34. doi:10.1016/j.envsci.2015.03.012Stewart, B. A. (1994). Soil Erosion: A Threat to Mankind. Ecology, 75(4), 1193-1193. doi:10.2307/1939447Ghafari, H., Gorji, M., Arabkhedri, M., Roshani, G. A., Heidari, A., & Akhavan, S. (2017). Identification and prioritization of critical erosion areas based on onsite and offsite effects. CATENA, 156, 1-9. doi:10.1016/j.catena.2017.03.014Chehlafi, A., Kchikach, A., Derradji, A., & Mequedade, N. (2019). Highway cutting slopes with high rainfall erosion in Morocco: Evaluation of soil losses and erosion control using concrete arches. Engineering Geology, 260, 105200. doi:10.1016/j.enggeo.2019.105200Streeter, M. T., & Schilling, K. E. (2019). Assessing and mitigating the effects of agricultural soil erosion on roadside ditches. Journal of Soils and Sediments, 20(1), 524-534. doi:10.1007/s11368-019-02379-3García‐Ruiz, J. M., Beguería, S., Lana‐Renault, N., Nadal‐Romero, E., & Cerdà, A. (2016). Ongoing and Emerging Questions in Water Erosion Studies. Land Degradation & Development, 28(1), 5-21. doi:10.1002/ldr.2641Brevik, E. C., Steffan, J. J., Rodrigo‐Comino, J., Neubert, D., Burgess, L. C., & Cerdà, A. (2019). Connecting the public with soil to improve human health. European Journal of Soil Science, 70(4), 898-910. doi:10.1111/ejss.12764Rubio‐Delgado, J., Schnabel, S., Gómez‐Gutiérrez, Á., & Lavado‐Contador, J. F. (2019). Temporal and spatial variation of soil erosion in wooded rangelands of southwest Spain. Earth Surface Processes and Landforms, 44(11), 2141-2155. doi:10.1002/esp.4636Benda, L., James, C., Miller, D., & Andras, K. (2019). Road Erosion and Delivery Index (READI): A Model for Evaluating Unpaved Road Erosion and Stream Sediment Delivery. JAWRA Journal of the American Water Resources Association, 55(2), 459-484. doi:10.1111/1752-1688.12729García-Ruiz, J. M., Beguería, S., Nadal-Romero, E., González-Hidalgo, J. C., Lana-Renault, N., & Sanjuán, Y. (2015). A meta-analysis of soil erosion rates across the world. Geomorphology, 239, 160-173. doi:10.1016/j.geomorph.2015.03.008Panagos, P., Meusburger, K., Ballabio, C., Borrelli, P., & Alewell, C. (2014). Soil erodibility in Europe: A high-resolution dataset based on LUCAS. Science of The Total Environment, 479-480, 189-200. doi:10.1016/j.scitotenv.2014.02.010Jie, C., Jing-zhang, C., Man-zhi, T., & Zi-tong, G. (2002). Soil degradation: a global problem endangering sustainable development. Journal of Geographical Sciences, 12(2), 243-252. doi:10.1007/bf02837480Ricci, G. F., Jeong, J., De Girolamo, A. M., & Gentile, F. (2020). Effectiveness and feasibility of different management practices to reduce soil erosion in an agricultural watershed. Land Use Policy, 90, 104306. doi:10.1016/j.landusepol.2019.104306Novara, A., Gristina, L., Guaitoli, F., Santoro, A., & Cerdà, A. (2013). Managing soil nitrate with cover crops and buffer strips in Sicilian vineyards. Solid Earth, 4(2), 255-262. doi:10.5194/se-4-255-2013Guadie, M., Molla, E., Mekonnen, M., & Cerdà, A. (2020). Effects of Soil Bund and Stone-Faced Soil Bund on Soil Physicochemical Properties and Crop Yield Under Rain-Fed Conditions of Northwest Ethiopia. Land, 9(1), 13. doi:10.3390/land9010013Chevigny, E., Quiquerez, A., Petit, C., & Curmi, P. (2014). Lithology, landscape structure and management practice changes: Key factors patterning vineyard soil erosion at metre-scale spatial resolution. CATENA, 121, 354-364. doi:10.1016/j.catena.2014.05.022Blavet, D., De Noni, G., Le Bissonnais, Y., Leonard, M., Maillo, L., Laurent, J. Y., … Roose, E. (2009). Effect of land use and management on the early stages of soil water erosion in French Mediterranean vineyards. Soil and Tillage Research, 106(1), 124-136. doi:10.1016/j.still.2009.04.010Nunes, J. P., Seixas, J., & Pacheco, N. R. (2008). Vulnerability of water resources, vegetation productivity and soil erosion to climate change in Mediterranean watersheds. Hydrological Processes, 22(16), 3115-3134. doi:10.1002/hyp.6897Nearing, M. A., Yin, S., Borrelli, P., & Polyakov, V. O. (2017). Rainfall erosivity: An historical review. CATENA, 157, 357-362. doi:10.1016/j.catena.2017.06.004Nadal-Romero, E., Cortesi, N., & González-Hidalgo, J. C. (2013). Weather types, runoff and sediment yield in a Mediterranean mountain landscape. Earth Surface Processes and Landforms, 39(4), 427-437. doi:10.1002/esp.3451Fernández-Raga, M., Palencia, C., Keesstra, S., Jordán, A., Fraile, R., Angulo-Martínez, M., & Cerdà, A. (2017). Splash erosion: A review with unanswered questions. Earth-Science Reviews, 171, 463-477. doi:10.1016/j.earscirev.2017.06.009Marzen, M., Iserloh, T., Casper, M. C., & Ries, J. B. (2015). Quantification of particle detachment by rain splash and wind-driven rain splash. CATENA, 127, 135-141. doi:10.1016/j.catena.2014.12.023Minea, G., Ioana-Toroimac, G., & Moroşanu, G. (2019). The dominant runoff processes on grassland versus bare soil hillslopes in a temperate environment - An experimental study. Journal of Hydrology and Hydromechanics, 67(4), 297-304. doi:10.2478/johh-2019-0018Senciales González, J. M., & Ruiz Sinoga, J. D. (2013). Análisis espacio-temporal de las lluvias torrenciales en la ciudad de Málaga. Boletín de la Asociación de Geógrafos Españoles, (61). doi:10.21138/bage.1533Mineo, C., Ridolfi, E., Moccia, B., Russo, F., & Napolitano, F. (2019). Assessment of Rainfall Kinetic-Energy–Intensity Relationships. Water, 11(10), 1994. doi:10.3390/w11101994Choo, Jo, Yun, & Lee. (2019). A Study on the Improvement of Flood Forecasting Techniques in Urban Areas by Considering Rainfall Intensity and Duration. Water, 11(9), 1883. doi:10.3390/w11091883Bryan, R. B. (2000). Soil erodibility and processes of water erosion on hillslope. Geomorphology, 32(3-4), 385-415. doi:10.1016/s0169-555x(99)00105-1Angulo-Martínez, M., & Beguería, S. (2009). Estimating rainfall erosivity from daily precipitation records: A comparison among methods using data from the Ebro Basin (NE Spain). Journal of Hydrology, 379(1-2), 111-121. doi:10.1016/j.jhydrol.2009.09.051Ruiz Sinoga, J. D., Garcia Marin, R., Martinez Murillo, J. F., & Gabarron Galeote, M. A. (2010). Precipitation dynamics in southern Spain: trends and cycles. International Journal of Climatology, 31(15), 2281-2289. doi:10.1002/joc.2235Gholami, H., Telfer, M. W., Blake, W. H., & Fathabadi, A. (2017). Aeolian sediment fingerprinting using a Bayesian mixing model. Earth Surface Processes and Landforms, 42(14), 2365-2376. doi:10.1002/esp.4189Cerdà, A. (1998). Relationships between climate and soil hydrological and erosional characteristics along climatic gradients in Mediterranean limestone areas. Geomorphology, 25(1-2), 123-134. doi:10.1016/s0169-555x(98)00033-6Peña-Angulo, D., Nadal-Romero, E., González-Hidalgo, J. C., Albaladejo, J., Andreu, V., Bagarello, V., … Bienes, R. (2019). Spatial variability of the relationships of runoff and sediment yield with weather types throughout the Mediterranean basin. Journal of Hydrology, 571, 390-405. doi:10.1016/j.jhydrol.2019.01.059Nadal-Romero, E., González-Hidalgo, J. C., Cortesi, N., Desir, G., Gómez, J. A., Lasanta, T., … Zabaleta, A. (2015). Relationship of runoff, erosion and sediment yield to weather types in the Iberian Peninsula. Geomorphology, 228, 372-381. doi:10.1016/j.geomorph.2014.09.011Gonzalez-Hidalgo, J. C., Batalla, R. J., Cerda, A., & de Luis, M. (2012). A regional analysis of the effects of largest events on soil erosion. CATENA, 95, 85-90. doi:10.1016/j.catena.2012.03.006Martínez-Valderrama, J., Ibáñez, J., Del Barrio, G., Sanjuán, M. E., Alcalá, F. J., Martínez-Vicente, S., … Puigdefábregas, J. (2016). Present and future of desertification in Spain: Implementation of a surveillance system to prevent land degradation. Science of The Total Environment, 563-564, 169-178. doi:10.1016/j.scitotenv.2016.04.065Rodrigo-Comino, J., Senciales, J. M., Sillero-Medina, J. A., Gyasi-Agyei, Y., Ruiz-Sinoga, J. D., & Ries, J. B. (2019). Analysis of Weather-Type-Induced Soil Erosion in Cultivated and Poorly Managed Abandoned Sloping Vineyards in the Axarquía Region (Málaga, Spain). Air, Soil and Water Research, 12, 117862211983940. doi:10.1177/1178622119839403Cerdà, A., Rodrigo-Comino, J., Novara, A., Brevik, E. C., Vaezi, A. R., Pulido, M., … Keesstra, S. D. (2018). Long-term impact of rainfed agricultural land abandonment on soil erosion in the Western Mediterranean basin. Progress in Physical Geography: Earth and Environment, 42(2), 202-219. doi:10.1177/0309133318758521Agata, N., Artemi, C., Carmelo, D., Giuseppe, L. P., Antonino, S., & Luciano, G. (2015). Effectiveness of carbon isotopic signature for estimating soil erosion and deposition rates in Sicilian vineyards. Soil and Tillage Research, 152, 1-7. doi:10.1016/j.still.2015.03.010Rodrigo-Comino, J. (2018). Five decades of soil erosion research in «terroir». The State-of-the-Art. Earth-Science Reviews, 179, 436-447. doi:10.1016/j.earscirev.2018.02.014Rodrigo-Comino, J., Keesstra, S., & Cerdà, A. (2018). Soil Erosion as an Environmental Concern in Vineyards. The Case Study of Celler del Roure, Eastern Spain, by Means of Rainfall Simulation Experiments. Beverages, 4(2), 31. doi:10.3390/beverages4020031Rodrigo-Comino, J., Novara, A., Gyasi-Agyei, Y., Terol, E., & Cerdà, A. (2018). Effects of parent material on soil erosion within Mediterranean new vineyard plantations. Engineering Geology, 246, 255-261. doi:10.1016/j.enggeo.2018.10.006Rodrigo-Comino, J., García-Díaz, A., Brevik, E. C., Keestra, S. D., Pereira, P., Novara, A., … Cerdà, A. (2017). Role of rock fragment cover on runoff generation and sediment yield in tilled vineyards. European Journal of Soil Science, 68(6), 864-872. doi:10.1111/ejss.12483Rodrigo Comino, J., Keesstra, S. D., & Cerdà, A. (2018). Connectivity assessment in Mediterranean vineyards using improved stock unearthing method, LiDAR and soil erosion field surveys. Earth Surface Processes and Landforms, 43(10), 2193-2206. doi:10.1002/esp.4385Haurwitz, B. (1945). INSOLATION IN RELATION TO CLOUDINESS AND CLOUD DENSITY. Journal of Meteorology, 2(3), 154-166. doi:10.1175/1520-0469(1945)0022.0.co;2Haurwitz, B. (1946). INSOLATION IN RELATION TO CLOUD TYPE. Journal of Meteorology, 3(4), 123-124. doi:10.1175/1520-0469(1946)0032.0.co;2Haurwitz, B., & Collaborators. (1945). ADVECTION OF AIR AND THE FORECASTING OF PRESSURE CHANGES. Journal of Meteorology, 2(2), 83-93. doi:10.1175/1520-0469(1945)0022.0.co;2Giambelluca, T., & Nullet, D. (1991). Influence of the trade-wind inversion on the climate of a leeward mountain slope in Hawaii. Climate Research, 1, 207-216. doi:10.3354/cr001207HARRISON, M. S. J. (1993). ELEVATED INVERSIONS OVER SOUTHERN AFRICA: CLIMATOLOGICAL PROPERTIES AND RELATIONSHIPS WITH RAINFALL. South African Geographical Journal, 75(1), 1-8. doi:10.1080/03736245.1993.9713555Li, Z., Zuidema, P., & Zhu, P. (2014). Simulated Convective Invigoration Processes at Trade Wind Cumulus Cold Pool Boundaries. Journal of the Atmospheric Sciences, 71(8), 2823-2841. doi:10.1175/jas-d-13-0184.1Tompkins, A. M. (2001). Organization of Tropical Convection in Low Vertical Wind Shears: The Role of Cold Pools. Journal of the Atmospheric Sciences, 58(13), 1650-1672. doi:10.1175/1520-0469(2001)0582.0.co;2Xoplaki, E., González-Rouco, J. F., Luterbacher, J., & Wanner, H. (2004). Wet season Mediterranean precipitation variability: influence of large-scale dynamics and trends. Climate Dynamics, 23(1), 63-78. doi:10.1007/s00382-004-0422-0Engelbrecht, F. A., McGregor, J. L., & Engelbrecht, C. J. (2009). Dynamics of the Conformal-Cubic Atmospheric Model projected climate-change signal over southern Africa. International Journal of Climatology, 29(7), 1013-1033. doi:10.1002/joc.1742Barros, A. P., & Lettenmaier, D. P. (1994). Dynamic modeling of orographically induced precipitation. Reviews of Geophysics, 32(3), 265. doi:10.1029/94rg00625McCabe Jr., G. J., & Muller, R. A. (1987). SYNOPTIC WEATHER TYPES: AN INDEX OF EVAPORATION IN SOUTHERN LOUISIANA. Physical Geography, 8(2), 99-112. doi:10.1080/02723646.1987.10642314Chu, P.-S., & Chen, H. (2005). Interannual and Interdecadal Rainfall Variations in the Hawaiian Islands*. Journal of Climate, 18(22), 4796-4813. doi:10.1175/jcli3578.1Yeh, H.-C., & Chen, Y.-L. (1998). Characteristics of Rainfall Distributions over Taiwan during the Taiwan Area Mesoscale Experiment (TAMEX). Journal of Applied Meteorology, 37(11), 1457-1469. doi:10.1175/1520-0450(1998)0372.0.co;2Romero, R., Sumner, G., Ramis, C., & Genovés, A. (1999). A classification of the atmospheric circulation patterns producing significant daily rainfall in the Spanish Mediterranean area. International Journal of Climatology, 19(7), 765-785. doi:10.1002/(sici)1097-0088(19990615)19:73.0.co;2-tWallis, T. W. R., & Griffiths, J. F. (1995). An assessment of the weather generator (WXGEN) used in the erosion/productivity impact calculator (EPIC). Agricultural and Forest Meteorology, 73(1-2), 115-133. doi:10.1016/0168-1923(94)02172-gFernández-Raga, M., Fraile, R., Keizer, J. J., Varela Teijeiro, M. E., Castro, A., Palencia, C., … Da Costa Marques, R. L. (2010). The kinetic energy of rain measured with an optical disdrometer: An application to splash erosion. Atmospheric Research, 96(2-3), 225-240. doi:10.1016/j.atmosres.2009.07.013Sadeghi, S. H., Nouri, H., & Faramarzi, M. (2017). Assessing the Spatial Distribution of Rainfall and the Effect of Altitude in Iran (Hamadan Province). Air, Soil and Water Research, 10, 117862211668606. doi:10.1177/1178622116686066Wilby, R. L., Dalgleish, H. Y., & Foster, I. D. L. (1997). The impact of weather patterns on historic and contemporary catchment sediment yields. Earth Surface Processes and Landforms, 22(4), 353-363. doi:10.1002/(sici)1096-9837(199704)22:43.0.co;2-gPattison, I., & Lane, S. N. (2011). The relationship between Lamb weather types and long-term changes in flood frequency, River Eden, UK. International Journal of Climatology, 32(13), 1971-1989. doi:10.1002/joc.2415Jones, P. G., & Thornton, P. K. (2013). Generating downscaled weather data from a suite of climate models for agricultural modelling applications. Agricultural Systems, 114, 1-5. doi:10.1016/j.agsy.2012.08.002McNew, K. P., Mapp, H. P., Duchon, C. E., & Merritt, E. S. (1991). Sources and Uses of Weather Information for Agricultural Decision Makers. Bulletin of the American Meteorological Society, 72(4), 491-498. doi:10.1175/1520-0477(1991)0722.0.co;2Ramos, A. M., Barriopedro, D., & Dutra, E. (2015). Circulation weather types as a tool in atmospheric, climate, and environmental research. Frontiers in Environmental Science, 3. doi:10.3389/fenvs.2015.00044Philipp, A., Bartholy, J., Beck, C., Erpicum, M., Esteban, P., Fettweis, X., … Tymvios, F. S. (2010). Cost733cat – A database of weather and circulation type classifications. Physics and Chemistry of the Earth, Parts A/B/C, 35(9-12), 360-373. doi:10.1016/j.pce.2009.12.010Fleig, A. K., Tallaksen, L. M., Hisdal, H., Stahl, K., & Hannah, D. M. (2010). Inter-comparison of weather and circulation type classifications for hydrological drought development. Physics and Chemistry of the Earth, Parts A/B/C, 35(9-12), 507-515. doi:10.1016/j.pce.2009.11.005Gu, C., Mu, X., Gao, P., Zhao, G., Sun, W., & Tan, X. (2019). Distinguishing the effects of vegetation restoration on runoff and sediment generation on simulated rainfall on the hillslopes of the loess plateau of China. Plant and Soil, 447(1-2), 393-412. doi:10.1007/s11104-019-04392-4Zhang, X., Wu, K., Fullen, M. A., & Wu, B. (2020). Synergistic effects of vegetation layers of maize and potato intercropping on soil erosion on sloping land in Yunnan Province, China. Journal of Mountain Science, 17(2), 423-434. doi:10.1007/s11629-019-5392-0Luo, J., Zhou, X., Rubinato, M., Li, G., Tian, Y., & Zhou, J. (2020). Impact of Multiple Vegetation Covers on Surface Runoff and Sediment Yield in the Small Basin of Nverzhai, Hunan Province, China. Forests, 11(3), 329. doi:10.3390/f11030329Amare, T., Zegeye, A. D., Yitaferu, B., Steenhuis, T. S., Hurni, H., & Zeleke, G. (2014). Combined effect of soil bund with biological soil and water conservation measures in the northwestern Ethiopian highlands. Ecohydrology & Hydrobiology, 14(3), 192-199. doi:10.1016/j.ecohyd.2014.07.00

Prevalence of vulvovaginal candidiasis, bacterial vaginosis and trichomoniasis in pregnant women attending antenatal clinic in the middle belt of Ghana.

BACKGROUND: Vaginal infections usually caused by Candida sp, organisms responsible for bacterial vaginosis and Trichomonas vaginalis are associated with considerable discomfort and adverse outcomes during pregnancy and child birth. The study determined the prevalence of vulvovaginal candidiasis (VVC), bacterial vaginosis (BV) and trichomoniasis (TV) in pregnant women attending antenatal clinic at the Kintampo Municipal Hospital. METHODS: A study adopted a cross sectional design and recruited 589 pregnant women after seeking their informed consent from September, 2014 to March, 2015. Semi-structured questionnaire were administered to participants and vaginal swabs were collected. The samples were analysed using wet mount method and Gram stain (Nugent criteria) for vaginal infection. Univariate and multivariate analysis were used to investigate association of risk factors to vaginal infections. RESULTS: The overall prevalence of at least one vaginal infection was 56.4%. The prevalence of vulvovaginal candidiasis, bacterial vaginosis and trichomoniasis were 36.5, 30.9 and 1.4% respectively. Women with more than four previous pregnancies (OR: 0.27, 95% CI: 0.13-0.58) and those in the third trimester of pregnancy (OR: 0.54, CI: 0.30-0.96) were associated with a lower risk of bacterial vaginosis. Douching and antibiotic use were neither associated with VVC or BV. CONCLUSION: The prevalence of vaginal infections was high among pregnant women in the Kintampo area. There is the need for interventions such as adequate investigations and early treatment of vaginal infections to reduce the disease burden to avoid associated complications

Assessing the performance of only HRP2 and HRP2 with pLDH based rapid diagnostic tests for the diagnosis of malaria in middle Ghana, Africa.

BACKGROUND: Rapid diagnostic test (RDT) kits have been useful tools to screen for the presence of infection with malaria parasites. Despite the improvement, false results from RDTs present a greater challenge. The need for quality test kits is desirable. We evaluated the diagnostic accuracy of three malaria RDTs. METHOD: The team consented and enrolled 754 participants from the two major public hospitals in Kintampo districts of Ghana from June 2014 to August 2014. Venous blood samples were obtained by trained personnel and samples were screened for malaria using CareStart and SD Bioline HRP2 and HRP2 with pLDH based RDTs with blood slides for malaria microscopy as "gold standard". Geometric mean parasite densities were estimated and parasite densities were used to estimate the quantitative limits of the RDTs. The sensitivities, specificities and other performance criteria were calculated using statistical analytical software. RESULT: The median age of participants was 21 (range 5-31) years. There were 28.6% (215/752) were males and 71.4% (537/752) were females. Comparing with microscopy, the sensitivity, specificity, positive predictive value, negative predictive value and the ROC were for CareStart (HRP2), 98.2%, 66.5%, 82.6%, 95.6%, 0.82; for CareStart (HRP2/pLDH) 98.2%, 66.5%, 82.6%, 95.6%, 0.82 and for SD-Bioline (HRP2/pLDH) RDTs 98.2%, 69.2%, 84.2%, 96.0%, 0.84 respectively. The performance for all the kits were acceptable at a cut-off of 25 or more parasites/μl of blood. CONCLUSIONS: The diagnostic performance of the three malaria RDTs was acceptable, according to the World Health Organisation criteria, to detect densities ≥25 parasite/μl of blood. The RDTs with HRP2/pLDH targets were comparable to those with only HRP2 and could successfully substitute current and commonly used HRP2-based RDTs

Bacterial and Fungal Gut Community Dynamics Over the First 5 Years of Life in Predominantly Rural Communities in Ghana.

BACKGROUND: Bacterial and fungal microbiotas are increasingly recognized as important in health and disease starting early in life. However, microbiota composition has not yet been investigated in most rural, low-resource settings, and in such settings, bacterial and fungal microbiotas have not been compared. Thus, we applied 16S and ITS2 amplicon sequencing, respectively, to investigate bacterial and fungal fecal microbiotas in rural Ghanaian children cross-sectionally from birth to 5 years of age. Corresponding maternal fecal and breast milk microbiotas were additionally investigated. RESULTS: While bacterial communities differed systematically across the age spectrum in composition and diversity, the same was not observed for the fungal microbiota. We also identified a novel and dramatic change in the maternal postpartum microbiota. This change included much higher abundance of Escherichia coli and much lower abundance of Prevotella in the first vs. fourth week postpartum. While infants shared more bacterial taxa with their mother's stool and breast milk than with those of unrelated mothers, there were far fewer shared fungal taxa. CONCLUSION: Given the known ability of commensal fungi to influence host health, the distinct pattern of their acquisition likely has important health consequences. Similarly, the dynamics of mothers' bacterial microbiotas around the time of birth may have important consequences for their children's health. Both topics require further study