https://commons.ru.ac.za/vital/access/manager/Index en-us 5 https://commons.ru.ac.za/vital/access/manager/Repository/vital:30807 Wed 17 Jan 2024 13:06:29 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:30809 Wed 13 Mar 2024 10:54:08 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:32357 Wed 13 Mar 2024 10:12:28 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:30403 Wed 13 Mar 2024 09:09:33 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:30415 Wed 12 May 2021 23:24:20 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:28543 Wed 12 May 2021 23:16:16 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:33920 Wed 12 May 2021 23:03:58 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:33890 Wed 12 May 2021 22:18:17 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:31011 Wed 12 May 2021 20:21:27 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:31828 Wed 12 May 2021 20:00:19 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:30542 Wed 12 May 2021 19:54:48 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:33385 Wed 12 May 2021 19:31:26 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:28477 Wed 12 May 2021 19:31:26 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:30802 Wed 12 May 2021 19:16:44 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:31853 Wed 12 May 2021 19:12:52 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:29964 Wed 12 May 2021 19:12:50 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:29972 Wed 12 May 2021 18:49:49 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:33769 Wed 12 May 2021 18:41:41 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:30468 Wed 12 May 2021 18:25:47 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:30640 Wed 12 May 2021 18:21:41 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:29531 Wed 12 May 2021 18:21:22 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:28902 Wed 12 May 2021 17:54:31 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:33029 10 and TPI between -1 and 1. Landslides are less pronounced on slope zones where slope gradient is <15˚ and >45˚, profile curvature <0, TWI <8 and >18, SPI <10 and TPI >1. Deep soil profiles ranging between 2.5 and 7 meters are a major characteristic of the study area. Soils are characterized by clay pans at a depth ranging between 0.75 and 3 meters within the profiles. The study area is dominated by clay texture, except for the uppermost surface horizons, which are loamy sand. All surface horizons analysed had the percentage of sand, silt and clay ranging from 33 to 55%, 22 to 40% and 10 to 30% respectively. In the deeper horizons, sand was observed to reduce drastically to less than 23%, while clay increased to greater than 50%. The clay content is very high in the deeper horizons exceeding 35%. By implication, such soils with a very high clay content and plasticity index are considered as Vertisols, with a profound influence in the occurrence of landslides. The top soil predominantly contains more quartz, while subsurface horizons have considerable amounts of illite/muscovite as the dominant clay minerals, ranging from 43% to 47 %. The liquid limit, plasticity index, computed weighted plasticity index (PIw), expansiveness (ɛex) and dispersion ranging from 50, 22, 17, 10 and 23 to 66, 44,34,54 and 64, respectively also have strong implications for landslide occurrence. Landslides are not normally experienced during or immediately after extreme rainfall events but occur later in the rainfall season. By implication, this time lag in landslide occurrence and rainfall distribution, is due to the initial infiltration through quartz dominated upper soil layers, before illite/muscovite clays in the lower soil horizons get saturated. Whereas forest cover reduced from 40 % in 1985 to 8% in 2015, cultivated land and settlements increased from 16% and 11% to 52% and 25% respectively during the same period. The distribution of cultivated land decreased in lower slope sections within gradient group < 15˚ by 59%. It however increased in upper sections within gradient cluster 25˚ to 35˚ by over 85% during the study period. There is a shift of cultivated land to the steeper sensitive upper slope elements associated with landslides in the study area. More than 50% of the landslides are occurring on cultivated land, 20% on settlements while less than 15 % and 10% are occurring on grassland and forests with degraded areas respectively. Landslides in Kigezi highlands are triggered by a complex interaction of multiple- factors, including dynamic triggers and ground condition variables. Topographic hollows are convergence zones within the landscape where all the parameters interact to cause landslides. Topographic hollows are therefore potential and actual landslide sites in the study area. Characterized by deep soil horizons with high clay content dominated by illite/muscovite minerals in the sub soils and profile concave forms with moderately steep slopes, topographic hollows are the most vulnerable slope elements to landslide occurrence. The spatial temporal patterns of landslide occurrence in the study area has changed due to increased cultivation of steep middle and upper slopes. Characterized by deep soil horizons with high clay content dominated by illite/muscovite minerals in the sub soils and profile concave forms with moderately steep slopes, topographic hollows are the most vulnerable slope elements to landslide occurrence. The spatial-temporal patterns of landslide occurrence in the study area has changed due to increased cultivation of steep middle and upper slopes. A close spatial and temporal correlation between land use/cover changes and landslide occurrence is discernible. The understanding of these topographical, pedological and land use/cover parameters and their influence on landslide occurrence is important in land management. It is now possible to identify and predict actual and potential landslide zones, and also demarcate safer zones for community activities. The information generated about the area’s topographic, pedological and land cover characteristics should help in vulnerability mitigation and enhance community resilience to landslide hazards in this fragile highland ecosystem. This can be done through designating zones for community activities while avoiding potential landslide zones. It is also recommended that, tree cover restoration be done in the highlands and the farmers encouraged to re-establish terrace farming while avoiding cultivation of sensitive steep middle and upper slope sections.]]> Wed 12 May 2021 17:50:51 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:39686 Wed 12 May 2021 17:48:16 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:28353 Wed 12 May 2021 17:41:57 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:29866 Wed 12 May 2021 17:40:54 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:30799 Wed 12 May 2021 17:07:55 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:30596 Wed 12 May 2021 17:07:32 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:32397 Wed 12 May 2021 16:36:39 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:30414 Wed 12 May 2021 16:34:19 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:32479 Wed 12 May 2021 16:31:53 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:30825 Wed 12 May 2021 16:10:54 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:42050 Wed 12 May 2021 15:09:56 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:41295 Wed 12 May 2021 15:09:32 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:41363 Wed 12 May 2021 14:25:59 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:42048 Wed 12 May 2021 13:59:14 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:30786 Thu 13 May 2021 13:38:18 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:28455 Thu 13 May 2021 09:54:13 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:31495 Thu 13 May 2021 08:56:34 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:32513 Thu 13 May 2021 08:52:29 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:32396 80 mm) showed a greater component of invertebrates in previously unexplored habitats, which proves their omnivorous diet related to ontogenetic niche use. Knowledge of fine-scale habitat use by fishes is essential for conservation planning as exclusion zones can be optimised to limit anthropogenic influence on nursery use patterns in fishes. The availability of shallow water habitats (<60 cm) was assessed as an additional driver to explain the species diversity and richness of juvenile fishes within the lower reaches. These habitats are known as important nursery habitats providing numerous marine and estuarine spawned fishes with adequate refuge and food supply. This shallow water volume was measured by means of a two-man kayak using both the spring high and low tides in the lower reaches of these systems to assess juvenile assemblages. It was clear from the results that aquatic vegetation significantly adds to the volume of these areas and as a result, much greater fish density and species richness were observed. Generalized additive models showed that marine spawned species were particularly reliant on the availability of this shallow water along with submerged vegetation and additional environmental variables. The presence of structurally submerged vegetation typically characterized within shallow estuarine waters is commonly believed to reduce predation risk resulting in elevated densities of biota. Based on the current stock status and percentage of pristine breeding stock, five fish species classified as collapsed/overexploited was consistently found within these systems with an additional 14 species currently classified as exploited/vulnerable. Based on the current species richness and diversity, available habitat cover and knowledge regarding important recreational species, priority areas that require some form of legal protection in order to meet potential biodiversity targets, could be identified. It is a legal requirement in South Africa that all estuaries require management plans that should be based on good knowledge of priority habitats for fauna and flora. The identification of estuarine protected areas is seen as a mechanism for protecting a representative sample of the biodiversity accompanied by a complete range of environmental gradients and habitat types at a reasonable scale in order to maximize the protection of estuarine species.]]> Thu 13 May 2021 08:20:19 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:30432 Thu 13 May 2021 06:47:35 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:39714 Thu 13 May 2021 06:27:44 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:33630 Thu 13 May 2021 06:26:49 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:30854 Thu 13 May 2021 06:20:56 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:30585 Thu 13 May 2021 05:45:06 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:30581 Thu 13 May 2021 05:38:41 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:31374 Thu 13 May 2021 05:35:24 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:30579 Thu 13 May 2021 05:34:31 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:32669 Thu 13 May 2021 05:24:44 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:31640 Thu 13 May 2021 05:23:01 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:30146 Thu 13 May 2021 05:21:06 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:33442 Thu 13 May 2021 05:11:34 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:33379 Thu 13 May 2021 05:00:45 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:30537 B ± 0.1ᵒ and (111) ± 0.1ᵒ] using similar growth conditions yielded a higher dot density on the (100) substrate compared to the (111) substrate. This was attributed to the presence of terraces/atomic steps induced by the misorientation on the (100) substrate, which invariably gives rise to increased adsorption and an enhanced sticking coefficient of adatoms. Studies on the influence of a buffer layer on the morphology of uncapped dots showed that the shape and size of the dots are sensitive to the thickness of the buffer layer. In some case a corrugated buffer surface resulted, which introduced order in the arrangement of the dots, which formed preferentially inside the troughs. An increase in the V/III ratio from 1.0 to 3.0 was found to reduce the areal density of the QDs, while an analysis of the diameter histograms showed a narrowing of the size distribution with an increase in V/III ratio. The larger size distribution at low V/III was ascribed to the increase in indium species and the increased indium adatom migration length. This leads to increased dot density and nucleation sites, and thus triggers an increase in the conversion of tiny QDs into thermodynamically more suitable larger dots via coalescence. However, as the V/III ratio increased, the number of indium adatoms available for growth on the surface reduced, which automatically led to a decrease in the migration length of indium species which is unfavourable for the production of nucleation sites and to a decrease in dot density. Low growth rates were found to be beneficial for the growth of a high density (~5×1010cm-2) of QDs. Photoluminescence (PL) analysis of the capped samples at low temperature (~10 K), using an excitation power of 2 mW, showed a PL peak at ∼732 meV. Upon an increase in laser power to 120 mW, a blue shift of ∼ 8 meV was noticed. This emission typically persisted up to 60–70 K. An increase in the number of InSb QD-layers, was observed to cause an increase in the luminescence spectral line width and a long-wavelength shift of the PL lines, together with an enhancement in the strength of the PL emission. However, high resolution transmission electron microscopy (HRTEM) of the capped dots revealed the formation of an InGaSb quantum well-like structure, ∼10 nm thick, which was responsible for the PL signal mentioned above. The absence of QDs in the capped sample was attributed to inter-diffusion of Ga and In during the deposition of the cap layer, giving rise to a quantum well (QW) instead of the intended QDs. The presence of threading dislocations and stacking faults were also observed in the TEM micrographs of the samples containing multilayers, which can account for the fast quenching of the PL emission with increasing temperature from these samples. Theoretical simulations of the band alignment, wave functions and energy levels were in good agreement with the data collected from the PL spectra of the samples.]]> Thu 13 May 2021 04:56:31 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:33939 Thu 13 May 2021 04:32:53 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:33941 Thu 13 May 2021 04:07:46 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:30944 Thu 13 May 2021 03:58:25 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:29989 Thu 13 May 2021 03:41:22 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:33771 Thu 13 May 2021 03:27:28 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:31235 Thu 13 May 2021 02:19:18 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:36128 Thu 13 May 2021 02:02:22 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:30826 Thu 13 May 2021 01:54:40 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:30087 Thu 13 May 2021 01:29:01 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:30588 Thu 13 May 2021 01:18:44 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:33609 Thu 13 May 2021 00:55:08 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:34047 Thu 13 May 2021 00:29:28 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:32795 Thu 13 May 2021 00:27:37 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:30958 Thu 13 May 2021 00:22:00 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:30642 Thu 13 May 2021 00:17:25 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:33371 Fri 15 Mar 2024 09:15:47 SAST ]]>