Examining the early distribution of the artemisinin-resistant Plasmodium falciparum kelch13 R561H mutation in areas of higher transmission in Rwanda

BACKGROUND: Artemisinin resistance mutations in Plasmodium falciparum kelch13 (Pfk13) have begun to emerge in Africa, with Pfk13-R561H being the first reported in Rwanda in 2014, but limited sampling left questions about its early distribution and origin. METHODS: We genotyped P. falciparum positive dried blood spot (DBS) samples from a nationally representative 2014-2015 Rwanda Demographic Health Surveys (DHS) HIV study. DBS were subsampled from DHS sampling clusters with >15% P. falciparum prevalence, as determined by rapid testing or microscopy done during the DHS study (n clusters = 67, n samples = 1873). RESULTS: We detected 476 parasitemias among 1873 residual blood spots from a 2014-2015 Rwanda Demographic Health Survey. We sequenced 351 samples: 341/351 were wild-type (97.03% weighted), and 4 samples (1.34% weighted) harbored R561H that were significantly spatially clustered. Other nonsynonymous mutations found were V555A (3), C532W (1), and G533A (1). CONCLUSIONS: Our study better defines the early distribution of R561H in Rwanda. Previous studies only observed the mutation in Masaka as of 2014, but our study indicates its presence in higher-transmission regions in the southeast of the country at that time

The Pioneer anomaly in the context of the braneworld scenario

We examine the Pioneer anomaly - a reported anomalous acceleration affecting the Pioneer 10/11, Galileo and Ulysses spacecrafts - in the context of a braneworld scenario. We show that effects due to the radion field cannot account for the anomaly, but that a scalar field with an appropriate potential is able to explain the phenomena. Implications and features of our solution are analyzed.Comment: Final version to appear at Classical & Quantum Gravity. Plainlatex 19 page

Role of Sterile Neutrino Warm Dark Matter in Rhenium and Tritium Beta Decays

Sterile neutrinos with mass in the range of one to a few keV are important as extensions of the Standard Model of particle physics and are serious dark matter (DM) candidates. This DM mass scale (warm DM) is in agreement with both cosmological and galactic observations. We study the role of a keV sterile neutrino through its mixing with a light active neutrino in Rhenium 187 and Tritium beta decays. We pinpoint the energy spectrum of the beta particle, 0 < T_e < (Q_{beta} - m_s), as the region where a sterile neutrino could be detected and where its mass m_s could be measured. This energy region is at least 1 keV away rom the region suitable to measure the mass of the light active neutrino, located near the endpoint Q_{beta} . The emission of a keV sterile neutrino in a beta decay could show up as a small kink in the spectrum of the emitted beta particle. With this in view, we perform a careful calculation of the Rhenium and Tritium beta spectra and estimate the size of this perturbation by means of the dimensionless ratio R of the sterile neutrino to the active neutrino contributions. We comment on the possibility of searching for sterile neutrino signatures in two experiments which are currently running at present, MARE and KATRIN, focused on the Rhenium 187 and Tritium beta decays respectively.Comment: 16 pages, 10 figures. Version to appear in Nucl. Phys. B. Results and conclusions unchange

A Head-to-Head Comparison of Four Artemisinin-Based Combinations for Treating Uncomplicated Malaria in African Children: A Randomized Trial

BackgroundArtemisinin-based combination therapies (ACTs) are the mainstay for the management of uncomplicated malaria cases. However, up-to-date data able to assist sub-Saharan African countries formulating appropriate antimalarial drug policies are scarce.Methods and findingsBetween 9 July 2007 and 19 June 2009, a randomized, non-inferiority (10% difference threshold in efficacy at day 28) clinical trial was carried out at 12 sites in seven sub-Saharan African countries. Each site compared three of four ACTs, namely amodiaquine-artesunate (ASAQ), dihydroartemisinin-piperaquine (DHAPQ), artemether-lumefantrine (AL), or chlorproguanil-dapsone-artesunate (CD+A). Overall, 4,116 children 6-59 mo old with uncomplicated Plasmodium falciparum malaria were treated (1,226 with AL, 1,002 with ASAQ, 413 with CD+A, and 1,475 with DHAPQ), actively followed up until day 28, and then passively followed up for the next 6 mo. At day 28, for the PCR-adjusted efficacy, non-inferiority was established for three pair-wise comparisons: DHAPQ (97.3%) versus AL (95.5%) (odds ratio [OR]: 0.59, 95% CI: 0.37-0.94); DHAPQ (97.6%) versus ASAQ (96.8%) (OR: 0.74, 95% CI: 0.41-1.34), and ASAQ (97.1%) versus AL (94.4%) (OR: 0.50, 95% CI: 0.28-0.92). For the PCR-unadjusted efficacy, AL was significantly less efficacious than DHAPQ (72.7% versus 89.5%) (OR: 0.27, 95% CI: 0.21-0.34) and ASAQ (66.2% versus 80.4%) (OR: 0.40, 95% CI: 0.30-0.53), while DHAPQ (92.2%) had higher efficacy than ASAQ (80.8%) but non-inferiority could not be excluded (OR: 0.35, 95% CI: 0.26-0.48). CD+A was significantly less efficacious than the other three treatments. Day 63 results were similar to those observed at day 28.ConclusionsThis large head-to-head comparison of most currently available ACTs in sub-Saharan Africa showed that AL, ASAQ, and DHAPQ had excellent efficacy, up to day 63 post-treatment. The risk of recurrent infections was significantly lower for DHAPQ, followed by ASAQ and then AL, supporting the recent recommendation of considering DHAPQ as a valid option for the treatment of uncomplicated P. falciparum malaria.Trial registrationClinicalTrials.gov NCT00393679; Pan African Clinical Trials Registry PACTR200901000091175

Space-time variation of hydrological processes and water resources in Rwanda : focus on the Migina catchment; Dissertation, UNESCO-IHE Institute for Water Education, Delft.

This book presents the hydrological research carried out in the Migina catchment (260 km2), Southern Rwanda. The main objective of the research is to explore the hydrological trends and climate linkages for catchments in Rwanda (26,338 km2), and to contribute to the understanding of dominant hydrological process interactions. Different hydro-meteorological instrumentations have been installed in the Migina catchment during April 2009 to July 2009 and measurements have been carried out and are still ongoing. The trend analysis is based on Mann-Kendall (MK) test and Pettitt test on times series data varying from 30 to 56 years before 2000. The hydrometric data and modern tracer methods are used for hydrograph separation and show that subsurface runoff is dominating the total discharge even during rainy seasons of May 2010 and 2011 at Cyihene-Kansi and Migina sub-catchments, respectively. Further, a semi-distributed conceptual hydrological model HEC-HMS is applied for assessing the spatio-temporal variation of water resources in the Migina catchment. The model results are compared with tracer based hydrograph separation results in terms of the runoff components. The model performed reasonably well in simulating the total flow volume, peak flow and timing as well as the portion of direct runoff and baseflow

Space-time variation of hydrological processes and water resources in Rwanda: Focus on the Migina catchment

This book presents the hydrological research carried out in the Migina catchment (260 km2), Southern Rwanda. The main objective of the research is to explore the hydrological trends and climate linkages for catchments in Rwanda (26,338 km2), and to contribute to the understanding of dominant hydrological process interactions. Different hydro-meteorological instrumentations have been installed in the Migina catchment during April 2009 to July 2009 and measurements have been carried out and are still ongoing. The trend analysis is based on Mann-Kendall (MK) test and Pettitt test on times series data varying from 30 to 56 years before 2000. The hydrometric data and modern tracer methods are used for hydrograph separation and show that subsurface runoff is dominating the total discharge even during rainy seasons of May 2010 and 2011 at Cyihene-Kansi and Migina sub-catchments, respectively. Further, a semi-distributed conceptual hydrological model HEC-HMS is applied for assessing the spatio-temporal variation of water resources in the Migina catchment. The model results are compared with tracer based hydrograph separation results in terms of the runoff components. The model performed reasonably well in simulating the total flow volume, peak flow and timing as well as the portion of direct runoff and baseflow.Water ManagementCivil Engineering and Geoscience

Identification of runoff generation processes using hydrometric and tracer methods in a meso-scale catchment in Rwanda

Understanding of dominant runoff generation processes in the meso-scale Migina catchment (257.4 km2) in southern Rwanda was improved using analysis of hydrometric data and tracer methods. The paper examines the use of hydrochemical and isotope parameters for separating streamflow into different runoff components by investigating two flood events which occurred during the rainy season "Itumba" (March–May) over a period of 2 yr at two gauging stations. Dissolved silica (SiO2), electrical conductivity (EC), deuterium (2H), oxygen-18 (18O), major anions (Cl− and SO2−4) and major cations (Na+, K+, Mg2+ and Ca2+) were analyzed during the events. 2H, 18O, Cl− and SiO2 were finally selected to assess the different contributing sources using mass balance equations and end member mixing analysis for two- and three-component hydrograph separation models. The results obtained by applying two-component hydrograph separations using dissolved silica and chloride as tracers are generally in line with the results of three-component separations using dissolved silica and deuterium. Subsurface runoff is dominating the total discharge during flood events. More than 80% of the discharge was generated by subsurface runoff for both events. This is supported by observations of shallow groundwater responses in the catchment (depth 0.2–2 m), which show fast infiltration of rainfall water during events. Consequently, shallow groundwater contributes to subsurface stormflow and baseflow generation. This dominance of subsurface contributions is also in line with the observed low runoff coefficient values (16.7 and 44.5%) for both events. Groundwater recharge during the wet seasons leads to a perennial river system. These results are essential for better water resources planning and management in the region, which is characterized by very highly competing demands (domestic vs. agricultural vs. industrial uses)

Identification of runoff generation processes using hydrometric and tracer methods in a meso-scale catchment in Rwanda

Understanding of dominant runoff generation processes in the meso-scale Migina catchment (257.4 km2) in southern Rwanda was improved using analysis of hydrometric data and tracer methods. The paper examines the use of hydrochemical and isotope parameters for separating streamflow into different runoff components by investigating two flood events which occurred during the rainy season "Itumba" (March–May) over a period of 2 yr at two gauging stations. Dissolved silica (SiO2), electrical conductivity (EC), deuterium (2H), oxygen-18 (18O), major anions (Cl? and SO2?4) and major cations (Na+, K+, Mg2+ and Ca2+) were analyzed during the events. 2H, 18O, Cl? and SiO2 were finally selected to assess the different contributing sources using mass balance equations and end member mixing analysis for two- and three-component hydrograph separation models. The results obtained by applying two-component hydrograph separations using dissolved silica and chloride as tracers are generally in line with the results of three-component separations using dissolved silica and deuterium. Subsurface runoff is dominating the total discharge during flood events. More than 80% of the discharge was generated by subsurface runoff for both events. This is supported by observations of shallow groundwater responses in the catchment (depth 0.2–2 m), which show fast infiltration of rainfall water during events. Consequently, shallow groundwater contributes to subsurface stormflow and baseflow generation. This dominance of subsurface contributions is also in line with the observed low runoff coefficient values (16.7 and 44.5%) for both events. Groundwater recharge during the wet seasons leads to a perennial river system. These results are essential for better water resources planning and management in the region, which is characterized by very highly competing demands (domestic vs. agricultural vs. industrial uses).Water ManagementCivil Engineering and Geoscience