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Institution

University of Zimbabwe

EducationHarare, Harare, Zimbabwe
About: University of Zimbabwe is a education organization based out in Harare, Harare, Zimbabwe. It is known for research contribution in the topics: Population & Acquired immunodeficiency syndrome (AIDS). The organization has 4378 authors who have published 6800 publications receiving 160720 citations. The organization is also known as: UZ & University College of Rhodesia and Nyasaland.


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Journal ArticleDOI
TL;DR: Factors influencing behavioural change among smallholder farmers towards adaptation to climate change in transitional climatic zones of Africa, specifically, Hwedza District in Zimbabwe show that the gender of the household head, access to extension services on crop and livestock production, and access to climate information have a positive influence on farmers' attitude towards climate change and variability.

96 citations

Journal ArticleDOI
TL;DR: The results demonstrated the feasibility of broadband multispectral sensors, particularly Sentinel-2 for retrieval of LAI in the saltmarsh ecosystem via inversion of PROSAIL and highlighted the importance of proper parameterisation of radiative transfer models and capacity of Sentinel-1 spectral range and resolution, with impending high-quality global observation aptitude, for retrievalof plant traits at a global scale.
Abstract: The Sentinel satellite fleet of the Copernicus Programme offers new potential to map and monitor plant traits at fine spatial and temporal resolutions. Among these traits, leaf area index (LAI) is a crucial indicator of vegetation growth and an essential variable in biodiversity studies. Numerous studies have shown that the radiative transfer approach has been a successful method to retrieve LAI from remote-sensing data. However, the suitability and adaptability of this approach largely depend on the type of remote-sensing data, vegetation cover and the ecosystem studied. Saltmarshes are important wetland ecosystems threatened by sea level rise among other human- and animal-induced changes. Therefore, monitoring their vegetation status is crucial for their conservation, yet few LAI assessments exist for these ecosystems. In this study, the retrieval of LAI in a saltmarsh ecosystem is examined using Sentinel-2 and RapidEye data through inversion of the PROSAIL radiative transfer model. Field measurements of LAI and some other plant traits were obtained during two succeeding field campaigns in July 2015 and 2016 on the saltmarsh of Schiermonnikoog, a barrier island of the Netherlands. RapidEye (2015) and Sentinel-2 (2016) data were acquired concurrent to the time of the field campaigns. The broadly employed PROSAIL model was inverted using two look-up tables (LUTs) generated in the spectral band’s settings of the two sensors and in which each contained 500,000 records. Different solutions from the LUTs, as well as, different Sentinel-2 spectral subsets were considered to examine the LAI retrieval. Our results showed that generally the LAI retrieved from Sentinel-2 had higher accuracy compared to RapidEye-retrieved LAI. Utilising the mean of the first 10 best solutions from the LUTs resulted in higher R2 (0.51 and 0.59) and lower normalised root means square error (NRMSE) (0.24 and 0.16) for both RapidEye and Sentinel-2 data respectively. Among different Sentinel-2 spectral subsets, the one comprised of the four near-infrared (NIR) and shortwave infrared (SWIR) spectral bands resulted in higher estimation accuracy (R2 = 0.44, NRMSE = 0.21) in comparison to using other studied spectral subsets. The results demonstrated the feasibility of broadband multispectral sensors, particularly Sentinel-2 for retrieval of LAI in the saltmarsh ecosystem via inversion of PROSAIL. Our results highlight the importance of proper parameterisation of radiative transfer models and capacity of Sentinel-2 spectral range and resolution, with impending high-quality global observation aptitude, for retrieval of plant traits at a global scale.

96 citations

Journal ArticleDOI
TL;DR: In this paper, the U-Pb ages of zircons from seven felsic volcanic and plutonic rocks from northern Zimbabwe combined with field data and isotope and geochemical data, constrain the timespan of development of the Harare-Shamva granite-greenstone terrain and establish the relative involvement of juvenile mantle-derived and reworked crustal material.
Abstract: The U-Pb ages of zircons from seven felsic volcanic and plutonic rocks from northern Zimbabwe combined with field data and Pb-Pb and Sm-Nd whole-rock isotope data, constrain the timespan of development of the Harare-Shamva granite-greenstone terrain and establish the relative involvement of juvenile mantle-derived and reworked crustal material. Basement-cover field relationships and isotope and geochemical data demonstrate that the greenstones were deposited onto 3.2–2.8 Ga basement gneisses, in ensialic, continental basins. Geodynamic models for the generation of the areally extensive bimodal magmatic products and growth of the pre-existing crustal nucleus consistent with our interpretations are rift-related: (1) intracontinental rifting related to mantle plume activity or; (2) rifting in a back-arc environment related to a marginal volcanic arc. The data, in conjunction with field evidence, do not indicate the presence and accretion of an older (ca. 2.70 Ga) and a younger (ca. 2.65 Ga) greenstone sequence in the Harare part of the greenstone belt, as was recently postulated on the basis of SHRIMP zircon ages. Zircon ages for basal felsic volcanics (2715±15 Ma) and a subvolcanic porphyry (2672±12 Ma) constrain the initiation and termination of deposition of the greenstone sequence. The timespan of deposition of the Upper Bulawayan part of the greenstone sequence corresponds well with radiometric ages for Upper Bulawayan greenstones in the central and southern part of the craton and supports the concept of craton-wide lithostratigraphic correlations for the late Archaean in Zimbabwe. Zircon ages for a syn-tectonic gneiss (2667±4 Ma) and a late syn-tectonic intrusive granodiorite (2664±15 Ma) pinpoint the age of deformation of the greenstone sequence and compare well with a Pb-Pb age of shear zone related gold mineralization (2659±13 Ma) associated with the latter intrusive phase. The intimate timing relation of greenstone deformation and granitoid emplacement, but also the metamorphic evidence for a thermal effect of the batholiths on the surrounding greenstone belts, and the structural and strain patterns in the greenstone sequence around and adjacent to the batholiths, imply that the intrusion of the granitoids had a significant influence on the tectono-thermal evolution of the greenstone belt. Prolonged magmatic activity is indicated by the zircon ages of small, post-tectonic plutons intrusive into the greenstone belt, with a mineralized granodiorite dated at 2649±6 Ma and an unmineralized tonalite at 2618± 6 Ma. The 2601±14 Ma crystallization age of an “external” Chilimanzi-type granite agrees well with existing radiometric ages for similar granites within the southern part of the craton, demonstrating a craton-wide event and heralding cratonization. The similarity between U-Pb zircon ages and TDM model ages (2.65–2.62 Ga) and the positive ɛNdT values (+3 to +2) for the late syn-tectonic and post-tectonic intrusive plutons within the greenstone belt indicate magmatism was derived directly from the mantle or by anatexis of lower crustal sources, with very short crustal residence times, and minor contamination with older crust. The rather high model μ1 values (8.2–8.6) are unlikely to indicate the involvement of significant amounts of older crust and may be inherited from a high U/Pb mantle source, as was suggested by previous workers for the Archaean mantle beneath Southern Africa. The older TDM ages for the felsic volcanics (3.0–2.8 Ga) and the porphyries (2.8–2.7 Ga) suggest that these felsic magmas were derived by partial melting of a source that was extracted from the mantle ca. 200 Ma prior to volcanism or may indicate interaction between depleted mantle-derived melts and older crustal material.

95 citations

Journal ArticleDOI
TL;DR: In this paper, the authors evaluated and recommended rainwater harvesting techniques that ensure effective capture and utilization of rainfall for sustainable crop production, which was achieved through monitoring residual moisture, after every rainfall shower, in the different tillage treatments.
Abstract: The study was carried out at three sites in Communal Lands of Zimbabwe namely, Mudzi (Natural Region V), Gutu (Natural Region IV) and Chivi (Natural Region V). These areas have marginal rainfall in terms of quantities (below 500 mm per year) and distribution with a normal rainfall year coming once in every five years. Four tillage treatments were experimented on in the three sites. These were tied ridges, infiltration pits, fanya juus and the conventional ploughing on the flat. The tillage treatments were paired at farm level for easy management considering that farmers were participating in the research trials. The conventional tillage technique was used as control. The objective of the study was to evaluate and recommend rainwater harvesting techniques that ensure effective capture and utilization of rainfall for sustainable crop production. This was achieved through monitoring residual moisture, after every rainfall shower, in the different tillage treatments. Monitoring of residual moisture was done, up to a depth of 30 cm, using a θ-probe. Yields of maize from the different tillage treatments were determined. Farmers also carried out their own evaluation of the treatments at mid-season and at the end of the season. In addition the researchers tested dissemination techniques that ensured maximum adoption of rainwater harvesting techniques. Tied ridges were ranked best by both the stakeholders’ evaluation and the theta (θ)-probe in retaining moisture compared to all the other treatments in the season under consideration. The farmers who practiced tied ridges realized yields of about 3 t/ha compared to conventional tillage treatments whose yields were about 1.5 t/ha. Yields were statistically significantly different for the different treatments. The recommendation was for the farmers to adopt the tied ridges in areas that receive marginal rainfall and experience mid-season droughts. Lead farmers should educate others on the advantages of the tillage treatments.

95 citations

Journal ArticleDOI
TL;DR: This study is the most comprehensive characterization of S. haematobium antigens to date and describes novelantigens in all schistosome species.
Abstract: Background Schistosomiasis is a major parasitic disease affecting >200 million people in the developing world, and 400 million people are at risk for infection. This study aimed to identify and compare proteins recognized by serum samples from schistosome-exposed individuals before and after curative praziquantel treatment. Methods Proteins recognized by pooled serum samples from Schistosoma haematobium-exposed Zimbabweans were determined by 2-dimensional Western blotting and identified by mass spectrometry. Results Serum samples recognized 71 spots, which resolved to 26 different characterized proteins. Eleven of these proteins have not previously been shown to be immunogenic in natural human infection or in experimental models of schistosomiasis, making them novel antigens in the parasite. Pretreatment serum samples recognized 59 spots, which resolved to 21 different identified proteins. Posttreatment serum samples recognized an additional 12 spots, which resolved to 8 different identified proteins. Of these 8 proteins, 3 had putative isoforms recognized before treatment, and 5 (calreticulin, tropomyosin 1, tropomyosin 2, paramyosin, and triose phosphate isomerase) did not. Conclusions This study is the most comprehensive characterization of S. haematobium antigens to date and describes novel antigens in all schistosome species. Posttreatment results are consistent with praziquantel treatment inducing quantitative and qualitative changes in schistosome-specific antibody responses.

95 citations


Authors

Showing all 4433 results

NameH-indexPapersCitations
Didier Raoult1733267153016
Roy M. Anderson11652665549
Vikram Patel11665459717
Richard M. Cowling9639230042
Ken E. Giller9255536374
Leif Bertilsson8732123933
Johan Rockström8523657842
Alex Aiken7729520254
Frances M. Cowan7645619984
Robert J. Biggar7323118474
Charles A. Thornton7118217195
David Wilson6961818780
David Katzenstein6928021239
Bruce M. Campbell6722717616
David Sanders6549217119
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Performance
Metrics
No. of papers from the Institution in previous years
YearPapers
202327
202289
2021485
2020393
2019291
2018326