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Capacity development for health research in Africa : experiences managing the African Doctoral Dissertation Research Fellowship Program

2010-01-01T00:00:00Z

Title: Capacity development for health research in Africa : experiences managing the African Doctoral Dissertation Research Fellowship Program Authors: Kabiru, Caroline W.; Izugbara, Chimaraoke O.; Wambugu, Susan W.; Ezeh, Alex C. Abstract: Africa's progress depends on her capacity to generate, adapt, and use scientific knowledge to meet regional health and development needs. Yet, Africa's higher education institutions that are mandated to foster this capacity lack adequate resources to generate and apply knowledge, raising the need for innovative approaches to enhance research capacity. In this paper, we describe a newly-developed program to support PhD research in health and population sciences at African universities, the African Doctoral Dissertation Research Fellowship (ADDRF) Program. We also share our experiences implementing the program. As health research capacity-strengthening in Africa continues to attract attention and as the need for such programs to be African-led is emphasized, our experiences in developing and implementing the ADDRF offer invaluable lessons to other institutions undertaking similar initiatives.

Transferencia de nitrógeno de ecosistemas agrícolas recientemente intensificados a acuíferos: efecto de la variación en las precipitaciones

2012-01-01T00:00:00Z

Title: Transferencia de nitrógeno de ecosistemas agrícolas recientemente intensificados a acuíferos: efecto de la variación en las precipitaciones Authors: Portela, Silvina Isabel Abstract: A partir del monitoreo a campo de cultivos, suelo y agua subterránea, modelos de simulación y un experimento en lisímetros se estudió el intercambio de nitrógeno (N) inorgánico entre cultivos y el agua subterránea en sistemas agrícolas recientemente intensificados con suelos ricos en materia orgánica (MO). El monitoreo (1998-2010) en tres posiciones del paisaje de la Pampa Ondulada permitió captar períodos plurianuales húmedos y secos (1506-444 mm año-1) disparadores de cambios intensos en las profundidades freáticas (<1 a >6 m) que afectaron la función del agua subterránea y de los cultivos como moduladores de los flujos de agua y N. Con niveles freáticos superficiales, se redujo la capacidad de almacenaje del agua drenada hacia la zona no saturada, produciéndose un flujo lateral subsuperficial que redistribuyó el N lixiviado desde posiciones altas hacia los bajos y contribuyó a la recarga del acuífero aguas abajo. Este flujo, favorecido por fuertes gradientes hidráulicos, y la concentración local de solutos disparada por el consumo de agua subterránea por los cultivos en la posición de pie de loma, produjeron picos de concentración de cloruro (>500 mg Clֿ l-1) y nitrato (>45 mg N-NO3ֿ l-1) en el agua freática superficial. Durante períodos normales a secos los drenajes de diferentes eventos de lluvia se alojan en la zona no saturada, disipando y retrasando la respuesta del nivel freático a eventos individuales. El agua de lluvia fluye verticalmente arrastrando N del suelo hacia una superficie freática profunda (con mayor desfasaje temporal entre la concentración de nitrato del drenaje y la del agua freática a medida que el nivel se profundiza) y luego descarga en el arroyo. La aplicación de un fertilizante enriquecido con 15N a un cultivo de maíz en lisímetros permitió demostrar que la fertilización representa un aporte insignificante (1%) al flujo de N lixiviado y que el N derivado de la mineralización de la MO del suelo constituye una fuente importante de N lixiviable durante períodos con balance hídrico positivo y/o baja demanda de los cultivos. A partir de los resultados obtenidos se propone un modelo conceptual de los flujos hidrológicos y de N en paisajes ondulados de uso agrícola para situaciones climáticas contrastantes.; We combined field monitoring of crops, soils and groundwater with the use of simulation models and an experiment in lysimeters, to study inorganic nitrogen (N) exchange between terrestrial ecosystems and groundwater under recently intensified cropping schemes of rich organic matter soils. More than ten years of monitoring (1998- 2010) at three landscape positions of the Rolling Pampas allowed to capture plurianual periods of highly variable precipitation (1506 to 444 mm yr-1) that triggered large changes in water table depths (<1 to >6 m), which altered the role of groundwater and crops as modulators of water and N fluxes. Shallow water tables reduced drainage water storage capacity in the unsaturated zone and promoted sub-horizontal water flow enhancing N transport towards the lower landscape positions and contributing to lowland aquifer recharge. This flow, favored by strong lateral hydraulic gradients, and local concentration of solutes by groundwater consumption by crops in the toe slope position, triggered a striking increase of chloride (>500 mg Clֿ l-1) and nitrate (>45 mg N-NO3ֿ l-1) concentrations in phreatic groundwater. During normal to dry periods, drainage fronts from different rainfall events were mixed within the unsaturated zone, delaying water table level response to individual events. Rain water flowed vertically flushing soil N towards a deep water table (with increasing time lags between nitrate concentration in percolating water and phreatic water as the water table deepened) and was ultimately discharged to the stream. The use of a 15N labelled fertilizer applied to corn in field lysimeters allowed to demonstrate that N fertilization represents a minor contribution (1%) to nitrate leaching and that N derived from soil organic matter mineralization constitutes a key source of leachable N during periods of excess water and/or low crop demand. Our results were used to state a conceptual model that explains water and N fluxes in a smoothly undulating agricultural landscape under contrasting climatic scenarios. Description: Abstract and keywords provided in English; Fecha de defensa de la tesis: 29 de agosto de 2012

Water and nitrate exchange between cultivated ecosystems and groundwater in the Rolling Pampas

2009-01-01T00:00:00Z

Title: Water and nitrate exchange between cultivated ecosystems and groundwater in the Rolling Pampas Authors: Portela, Silvina I; Andriulo, Adrian E; Jobbagy, Esteban G; Sasal, Maria C Abstract: Understanding nitrogen (N) exchange between cultivated ecosystems and groundwater becomes crucial in the Rolling Pampas where high and variable water table levels are accompanied by increasing N-fertilization rates. Field monitoring of crops, soils and groundwater was combined with modeling to evaluate bidirectional flows (from terrestrial ecosystems to aquifers and vice versa) of water and N throughout a 10-year period (1998–2007) of highly variable precipitation (760–1506 mm year 1) and water table depths (6.5 to <1 m). Piezometers at three topographic positions (upland: UP, mid slope: MS, and toe slope: TS; 1740 and 510 m apart) were used to monitor water table depth and phreatic (<14 m), intermediate (35 m) and bottom of the aquifer (45 m) water chemistry. Crop production and soil water and nitrate content were monitored in two agricultural plots (wheat/soybean–corn rotation) where MS and TS piezometers were located. Nitrate concentration in phreatic groundwater was relatively stable and low at UP and MS (<10 mg l 1) but increased sharply at TS (>45 mg l 1) during periods of high water table levels (<3 m deep). Groundwater chloride concentrations increased with depth in piezometers at UP and MS, but showed the opposite trend at TS during periods of high water table levels, suggesting evaporative discharge at this position. The lateral hydraulic gradient (moving energy) between MS and TS ranged from 0.1 to 0.4% and was negatively correlated with water table depth at TS (R2 = 0.23, p < 0.001, n = 79) indicating that groundwater flow towards TS increased as the water table level rose. A capillary transportmodel (UPFLOW) suggested that at TS groundwater supplied an important amount of water and solutes to crops with corn obtaining approximately half of its water needs (228–413 mm) and one fourth of its N requirement (38–76 kg ha 1) from groundwater. Water and N supply from groundwater may have explained the higher biomass and grain yield in the lower positions of each plot with regard to the rest of the area. Our results suggest that the Rolling Pampas landscapes can switch from a typical recharge behavior to a recharge–discharge one following extended rainy periods that rise water table levels and hydraulic gradients, favoring water and solute transport towards the lower positions of the landscape and local concentration of solutes by groundwater consumption, simultaneously affecting groundwater quality.

Evaluation of IDRC Projects: Building Peace and Security Research Capacity in Eastern Africa and UPEACE - IDRC PhD Fellowships/UPEACE-IDRC Doctoral Research Awards (I and II) : final report

2011-01-01T00:00:00Z

Title: Evaluation of IDRC Projects: Building Peace and Security Research Capacity in Eastern Africa and UPEACE - IDRC PhD Fellowships/UPEACE-IDRC Doctoral Research Awards (I and II) : final report Authors: Onyejekwe, Okey Abstract: The objective of this study is to evaluate two projects funded by IDRC and implemented by the Africa Program of the University for Peace (UPEACE). These are the projects: "Building Peace and Security Research in Eastern Africa," funded by the Peace, Conflict and Development Program (PCD), and two phases of an awards project supporting "Doctoral Research Awardees and PhD Fellows in Peace, Conflict, Security and Development" funded by the Fellowships and Awards (F&A) Program. The two programs collaborated to synergize their activities towards a mutual goal of supporting UPEACE undertaking to build and enhance research capacity for peace and security in Africa...