The contrarian model assumes that inferior (superior) past performance can be used as a good indicator of future superior (inferior) performance. In this regard, recent research has integrated the relevance of business magazine cover stories as a possible indicator of this performance, serving as a signal to investors to adopt a particular contrarian investment strategy. This research study replicates with extension a United States-based study that examined whether cover stories acted as effective contrarian indicators. Cover stories from the Financial Mail were collected for a ten-year period to determine whether the nature of the content (classified as either negative, positive or neutral) can act as a useful predictor of future investment performance. The event study method was used to establish whether this future performance was contrarian or momentum in nature, by adjusting the featured company holding-period returns with three benchmark measures: the FTSE-JSE All Share index; a sector-specific index; and an industry-size-matched (ISM) peer company. Statistical tests suggested that while positive stories provided evidence of momentum holding-period return (HPR) performance, negative stories showed weak evidence of contrarian performance for a two-year period. However, when HPR was adjusted for sector or ISM index, most of the abnormal returns dissipated, with only weak evidence of contrarian performance for positive stories and momentum performance for negative stories. The results validated those of the United States-based study, that suggested that magazine cover stories do not function as suitable indicators of either momentum or contrarian performance. Copyright / Dissertation (MBA)--University of Pretoria, 2010. / Gordon Institute of Business Science (GIBS) / unrestricted

Ice regime plays a significant role in River hydraulics and morphology in Northern hemisphere countries such as Canada. The formation, propagation and recession of ice cover introduce a dynamic boundary layer to the top of the stream. Ice cover affects the water velocity magnitude and distribution, water level and consequently conveyance capacity. A stable ice cover also tends to reduce bed shear and associated sediment transport, but bank scour and ice jamming events can increase sediment entrainment. These effects are even more intense during the ice cover break-up period when extreme conditions such as ice-jamming and release and mechanical ice cover break-up can locally accelerate the flow, and ice can mechanically scour the river bed and banks. The presence of ice has some important implications for hydro-electrical power generation operations too. The ice cover changes the channel conveyance capacity (and therefore increases the flood risk), may increase sediment transport and causes scouring, and is likely to block water intakes and turbines. The rate of water release should, therefore, be adjusted in the presence of the ice cover to avoid unwanted consequences on the dam structure and equipments as well as on the downstream channel and the environment. Even though the influence of ice cover on rivers is widely recognized, large gaps still exist in our understanding of ice cover processes in rivers. Two main reasons for such a shortage are the difficulty and danger involved in collecting hydraulic and sediment transport data under ice cover, especially during the unstable periods of freeze-up and break-up. In the absence of sufficient data, the applicability of available formulae and theories on hydraulic processes in ice-covered rivers cannot be extensively tested and improved. The purpose of this research mainly is a) to perform a continuous, in-situ monitoring of water velocity profiles, sediment loads and ice-cover condition during several years through winter field campaigns at a section of the Lower Nelson River, Manitoba, Canada.The Lower Nelson River is a regulated river (Manitoba Hydro). It receives augmented flow from the Churchill River Diversion, and is subject to operation of many hydro-electricity facilities, one of which is currently under construction, while others are planned to be constructed in the future. Due to the geographical location of the study reach, it is covered by ice and experiences severe ice condition for several months during the year. b) Analysis of the collected data in order to study the impact of ice cover on the hydraulic properties and sediment conveyance capacity at the study reach and c) using the insight gained from the field data analysis to improve a river ice simulation model to apply in the study of Lower Nelson River ice regime. The selection of the Lower Nelson river is motivated by intention of Manitoba Hydro (MH) ,as the industrial partner in this research, to study the winter flow regime at the Lower Nelson River. Manitoba Hydro operates several dams on the Lower Nelson River and is considering more hydropower developments in the future. This study is composed of six steps as are described in the following main steps. Step 1: Selection of potential study sites and data collection techniques: The particular study site for this research is located immediately upstream of Jackfish Island, between Limestone generating station and Gillam Island in Lower Nelson River, Manitoba, Canada. River width at the study site location is about 1km. Water depth at the deployment site varies between 10-12 meters depending on both the time of year and the time of day due to hydropeaking fluctuations. Given the low accessibility to the field during winter time and considering the type of the required data, acoustic techniques were selected as the main approach for the field measurements. Two types of acoustic instruments, Acoustic Doppler Current Profiler (ADCP) and Shallow Water Ice Profiling Sonar (SWIPS) are selected for field investigations in this study. Both of them were planned to be deployed in the river for an extended period of time in order to record necessary data during the ice cover and open water periods. Step 2: Data acquisition. After the site selection and defining the appropriate techniques, data acquisition has been started through a series of annual field measurement campaigns starting from winter 2012. Measured data mainly consist of water velocity and sediment suspension during various ice cover stages, including river ice break-up. The velocity profiles are analyzed to determine dynamic changes in boundary shear stress and hydraulic resistance and stresses in the flow during the both open water and ice cover periods. Step 3: Data analysis and development/testing of roughness and sediment transport formulas. Several aspects of river-ice interactions are covered in the recorded data including ice cover condition and cover thickness variation, river hydraulic characteristics such as depth and velocity and finally information about the concentration of suspended particles. These data are analyzed to define the behavior of the ice cover and river during different ice stages. Ice effect on river conveyance capacity is also evaluated . The accuracy of common assumptions in composite roughness calculations in rivers is estimated and a new approach is developed and validated using the field observations and measurements. Ice cover influence on suspended sediment concentration is also studied as the other part of this research. Considering the type of the river sediment load (mostly bed load) available methods for sediment transport simulation are studied and applied for estimation of the sediment transport under ice cover condition. According to the results, the most suitable methods were planned to be a part of the river ice numerical simulation model, developed in this study. Turbulent characteristics in ice covered flows are also studied through two years of data recordings. Acoustic Doppler Current Profiler employed in this study is programmed for appropriate recording of the water velocity for this purpose. Results are analyzed and turbulent structures in the river are studied in this research as well. Step 4: Testing of Hatch-MH’s river ice simulation model. A numerical model has been selected in order to simulate the river ice process at the study site (LNR). ICESIM, a steady state, one-dimensional river ice process model originally developed in 1973 by Acres International Limited (now Hatch), is selected for this study.ICESIM is originally developed in FORTRAN and is capable of predicting the progression and stabilization of river ice cover. Step 5: Improvement of Hatch-MH’s river ice simulation model: ICESIM model is converted to Matlab as the first step of the model improvements. A Graphical User Interface (GUI) is designed for the program which facilitates the assessment of model performance during the simulation leads to a more user-friendly model to operate. The new model, ICESIMAT is calibrated and evaluated based on the conducted field studies. Simulation capabilities of ICESIMAT are improved in the form of extended or additional subroutines to enhance its capabilities in the simulation of river ice processes and sediment transport. The current version of ICESIMAT is a steady state model, capable of simulating river ice , river hydrodynamic characteristics and sediment transport along the study reach. Though the model is restricted in the terms of the dimensions of the simulation (only one dimensional) its lower computational cost, permits a longer study reach to be simulated (in the scale of hundred kilometers instead of couple hundred meters in three dimensional simulation). ICESIM model is unable to simulate the break-up period which reduces the model capability in the simulation of the complete cycle of river ice. New subroutines are designed and added to extend the model capability to include simulation of ice processes during the ice cover break-up and finally to calculate the sediment transport under the ice cover. Step 6: As the final step, the new subroutines are adjusted and linked to the main improved code, providing a new framework for dynamic ice cover simulation, more prepared for further future improvements both in terms of conceptual and programming aspects of the river ice modeling . The new Matlab basis of the code facilitates upgrading the model to include more complicated processes like river ice jam simulations. As the general result of this thesis, we have a better understanding of hydraulics and sediment transport processes in ice covered rivers ( direct and indirect measurements of river hydraulics characteristics), improved formulas for these processes (including more involving parameters) and a better version of the river ice simulation model (capable of simulating the complete river ice processes) for the contributors to this study in the industry.

The Bearded Vulture, Gypaetus barbatus, was previously distributed across southern and western South Africa, as far south as Cape Town. Today, the entire population in southern Africa is restricted to the Lesotho highlands and the Drakensberg escarpment and nearby mountains in South Africa, where the population continues to decline. Research has shown that territorial abandonment is apparently associated with the density of human settlements within 10km of a territory. This pattern was assumed to be linked to the increased risk of unnatural mortalities in areas with higher human presence. However, habitat use and habitat selection, especially whether the species actively avoids human settlements has not yet been explored and could contribute to this pattern. In this study, we used data from nine adult Bearded Vultures fitted with Global Positioning System (GPS) satellite tags to determine which habitat is being selected. We modelled habitat selection in relation to various topographic and habitat variables, including information on built-up areas (i.e., areas with a high density of buildings). We predicted that birds would select areas of grassland and avoid areas with high building density and adjoining areas. We found that Bearded Vultures selected areas closer to their nest sites and supplementary feeding sites, with steeper slopes, and highly rugged terrain. In terms of habitat, they selected areas with grassland and avoided areas with forest, while cropland was neither selected nor avoided. As predicted Bearded Vultures avoided built-up areas and their vicinity. These results suggest that the Bearded Vulture may be sensitive to the negative impacts of a changing landscape in its distribution range. These results can help conservation managers in guiding development (e.g., human settlement expansion and afforestation) and protecting priority habitats (e.g., grassland) within the breeding range of adult Bearded Vultures.

Let G = (V, E) be a nontrivial connected graph. For a subset S ⊆ V, the geodesic closure (S) of S is the set of all vertices on geodesics (shortest paths) between two vertices of S. We study the geodetic achievement and avoidance games defined by Buckley and Harary (Geodetic games for graphs, Quaestiones Math. 8 (1986), 321–334) as follows. The first player A chooses a vertex v1 of G. The second player B then selects v2 ≠ v1 and determines the geodetic closure (S 2) for S 2 = {v 1 , v 2 }. If (S 2) = V, then the second player wins the achievement game, but loses the avoidance game. If (S 2) = V, then A picks v 3 ∉ S 2 and determines (S 3) for S 3 = {v 1 , v 2 , v 3 }. In general, A and B alternatively select a new vertex in this manner. The first player who selects a vertex v k such that (S k) = V wins the achievement game; in the avoidance game he is the loser. We solve these games for several families of graphs, including trees and complete multipartite graphs, by determining which player is the winner.

Maximum sustained and peak gust winds from eighteen European windstorms over the last 25 years were analyzed previously to develop surface-level wind predictions across a large and topographically varied landscape based on an anisotropic kriging interpolation methodology for meteorological station data. Results suggested that coastal and mountainous areas experience the highest wind speeds and highest variability over short distances, resulting in the highest errors across concurrent interpolated surfaces. This study utilizes covariates in conjunction with cokriging to investigate the use of cokriging as a method of improvement through the interpolation of five windstorms that impacted both the Alps region and the topographically-varied coastal regions of Western Europe. Results show that cokriging improves isotach interpolation for windstorms in 8 out of 10 models by reducing root mean square error and the total number of high-error stations, primarily in coastal and mountainous areas. Land cover alone contributed to the greatest model improvement in a majority of the models, while aspect and elevation (singularly and collectively) also improved models when compared to original kriging models. Improved surface interpolation is critical for improved understanding of macro-scale windstorm patterns and resulting damage, thus improving risk and vulnerability estimates.

Given a configuration of pebbles on the vertices of a graph, a pebbling move is defined by removing two pebbles from some vertex and placing one pebble on an adjacent vertex. The cover pebbling number of a graph, γ (G), is the smallest number of pebbles such that through a sequence of pebbling moves, a pebble can eventually be placed on every vertex simultaneously, no matter how the pebbles are initially distributed. We determine Bose-Einstein and Maxwell-Boltzmann cover pebbling thresholds for the complete graph. Also, we show that the cover pebbling decision problem is NP-complete.

We obtain first-order cover pebbling thresholds of the complete graph for Maxwell Boltzmann and Bose Einstein configurations.

>Magister Scientiae - MSc / The climate variability and climate change-induced events experienced worldwide have caused a significant decrease in the rainfall volume. South Africa is considered to be one of the driest countries in the world, as it receives an average annual rainfall that is lower than the global annual average. To sustain and grow the agricultural sector, South Africa supplements the low rainfall with its freshwater resources, for irrigation purposes. This action is necessary, especially for meeting the high water requirements of the South African fruit industry, as it is one of the major exporters of fruit in the world. Research has been conducted in an attempt to accurately quantify the water requirements of various fruits, which will assist farmers to save water, to increase their productivity and to managing their irrigation water. However, a knowledge of the water use, actual water consumption rates and the factors that drive them, is minimal and inadequate, and this has had a detrimental effect on the effective management of irrigation water and water allocation by the responsible stakeholders.

The Miombo woodland vegetation of southern Africa has been subjected to anthropogenic pressures in recent years, resulting in a change in its cover and floristic-structural composition, and the population status of important tree species. The recent land use land cover changes (LULCC) is of concern due to the negative impacts on the Miombo woodland ecological functions. Understanding the overall dynamics of the vegetation that include LULCC, forest cover change, tree species composition, and diversity, population structure (PS) in relation to forest degradation, loss of endangered/rare species, is pivotal in influencing policy and sustainable woodland management. The Malawi Government instituted policies that allowed for improved forest management. However, the impact of forest management regimes on forest cover, tree species diversity, and structure is not well established. The study aimed to determine LULCC and forest cover changes and the associated drivers and how co-management (CM) and government-management (GM) impact on the florist-structural composition, diversity and the population structure of the important tree species in Malawian Miombo landscape. Firstly, the study analysed LULCC and the comparative impact of CM and GM on the forest cover in Malawi, for the period 1999-2018. CM involves a contractual agreement between communities (with a forest management plan who have been empowered to manage forest resources) and the Forest Department (representing the Government) in managing forest reserves. GM is the protection of forest resources by the government through the Forest Department. Since the introduction of participatory forest management (PFM), such as CM, its impact has not been established. Google Earth images (Landsat mosaics) for 1999 and 2018 for Malawi were acquired, registered, and pre-processed in Environment for Visualizing Images (ENVI 4.7) Harris Geospatial Solutions. LULCC estimation using the Inter-Governmental Panel on Climate Change (IPCC) classes was determined using the differences in error-adjusted areas between 1999 and 2018. Overall accuracies were >90%. Woodland net losses of 8.4% were to Plantation, Grassland, and Agriculture transition intensities. Agriculture net gains of 9.6% were from Grassland, Settlement, and Woodland transitions for Malawi. Forest cover within CM and GM indicated losses. Participatory land use plans and monitoring for diversified management in Malawian Miombo woodlands are required to mitigate anticipated irreversible impacts in the landscape. The second study investigated the factors that influence changes in CM and GM forest reserves between 1999 and 2018. CM and GM regimes in Miombo woodlands are possible interventions to mitigate forest degradation and deforestation in southern Africa. However, few studies have investigated the direct and indirect drivers of LULCC using socioeconomic characteristics and Remote sensing data in CM and GM regimes. The drivers of LULCC in forest reserves, and management challenges were identified using participatory assessments in both management regimes. The changes in woodland were observed with varying extent. Communities' perceptions in the factors contributing to changes in CM and GM forest reserves were similar and mostly due to the conversion of woodlands to agriculture while extraction of woody products led to forest degradation. In both management strategies, population pressure, youthful age, poverty, and poor education were associated with forest-based livelihood activities and therefore the woodland changes. The overall woodland cover loss to grassland is attributed to its importance as a source of energy. There is thus a need to harmonize policies for sustainable use and management of woodlands in order to address local, national, and regional ecosystem services. Future studies will need to link Remote sensing and socioeconomic data as part of a monitoring tool that could assist to sustainably adapt to changes in the woodlands and surrounding communities. The third study compared the Miombo Tree species composition and diversity between CM and GM regimes in Malawi. Tree species composition and diversity information is limited between CM and GM regimes. Two CM and two GM forest reserves were purposively selected to act as representatives of management regimes in the northern and southern regions of Malawi. Forest inventory data from 80 randomly selected nested circular plots were used. Two plot sizes: a large plot (0.16 ha; radius 22.6 m) to record stems ≥30 cm DBH, and the main plot (0.04 ha; radius 11.28 m) to record stems 5.0-29.9 cm DBH and species names. In total, 109 tree species belonging to 38 families, 87 species in GM FRs (Kaning’ina 58, Thambani 52), and 69 in CM FRs (Perekezi 45, Liwonde 43) were recorded. The largest families (number of species between brackets) were Fabaceae (34, with 3 subfamilies, Caesalpinioideae (17), Papilionoideae (12), and Mimosoideae (5), an indication of their adaptive potential in the area. Other important families were Combretaceae (7), Rubiaceae (7), and Clusiaceae (4). Species similarity between management regimes was low and was attributed to site factors, species characteristics and intensity of disturbances. TWINSPAN classification results were related to differences in site conditions and disturbances caused by historical and current resource use in management regimes. The eigenvalues ≥0.3 across CM and GM sub-communities indicated high stability. Brachystegia and Julbernardia species were highly important in CM and GM sub-communities. Uapaca species were highly important in agriculture and settlement abandoned areas in GM forest reserve. The study recommends selective harvesting to allow for dominant (Brachystegia and Julbernardia) and associated Miombo species to regenerate. Species richness and evenness (diversity) was high in more disturbed CM and GM sub-communities compared to intact areas. The high diversity was related to tree species high abundances of smaller stems with few scattered big trees. These results call for a Forest policy review to allow planned harvesting in GM forest reserves. Law enforcement is also required in both management regimes to mitigate unsustainable harvesting in sensitive areas. Future studies should include zonation to improve differentiation between site factors and wood extraction in stand development stages in management regimes. The fourth study compared the Miombo population structure (PS) between CM and GM regimes. Such information is limited in CM and GM regimes since the introduction of PFM in Malawi. The size class distribution (SCD) of sub-canopy/canopy species showed a reversed J-shaped profile in CM and GM forest reserves (South), when compared to CM and GM, in northern Malawi. These findings may reflect differences in the historical woodland utilization in the two regions. The bell-shaped SCDs in CM sub-communities with high stem density of Brachystegia and Julbernardia species suggest strong demand for light for successful recruitment from regeneration to adult trees and could be related to wood utilization. The reversed J-shape SCDs in northern GM sub-communities with high regeneration stem density of Pittosporum viridiflorum suggest an increase in shade-tolerant evergreen tree species under a low-level disturbance. Timber species showed interrupted SCDs with few to no stems, indicating challenges in regeneration. Pioneer species were associated with disturbances under CM indicating woodland recovery. The patterns in SCD showed similarities and differences between CM and GM sub-communities between the two management strategies. In Community 2, there were significant differences (p = 0.002) between management strategies with low canopy densities in CM, which could be attributed to unsustainable harvesting. Furthermore, saplings showed significant differences with a higher stems ha-1 in CM compared to GM. Trees and regeneration SCDs suggest a thorough analysis of the PS of varied species associations to guide sustainable resource use. An adaptive management approach that uses silvicultural systems to promote sustainable forest management is recommended. Additionally, selective harvesting in recovery stages would reduce intense competition in the dense, even-aged stands. However, there is need for instituting enabling policies and to monitor changes in both management regimes to promote biodiversity conservation, resource use, and diverse ecosystem services at all levels. / Thesis (PhD (Forest Science))--University of Pretoria, 2020. / Malawi Government Scholarship Program and the African Forest Forum / Plant Production and Soil Science / PhD (Forest Science) / Unrestricted

Land cover and climate change with their associated impacts on runoff are among the pressing areas of research within the western United States. In the first paper of this dissertation, we identified a total of 39 watersheds draining to U.S. Geological Survey (USGS) streamflow gauges, chosen either from the USGS Hydroclimatic Climatic Data Network of gauges that are minimally impacted by anthropogenic alterations, or because they have long, relatively continuous streamflow records and are representative of large areas within the study region in Utah. In each of these watersheds we examined trends in precipitation, temperature, snow, streamflow and runoff ratio as well as land use and land cover information. In addition, we developed a water balance model to quantify the sensitivity of runoff to changes in vegetation based on differences in evapotranspiration from different land cover types. The second paper addressed runoff sensitivity to land cover changes in a spatially explicit way by performing detailed simulations using a Regional Hydro Ecological Simulation System (RHESSys) model applied to the Weber River near Oakley watershed (USGS gauge # 10128500). Our runoff sensitivity results suggest that during winter reduced Leaf Area Index (LAI) decreases canopy interception, which tends to increase snow accumulations, and hence snow available for runoff during the early spring melt season. Increased LAI during spring melt season tends to delay the snow melting process due to reduced radiation beneath high LAI surfaces relative to low LAI surfaces. The last paper examined the sensitivity of the Great Salt Lake level to changes in streamflow input or changes in climate that manifest as changes in air temperatures over the lake. We quantified this sensitivity by examining an elasticity measure defined as the ratio of the variability of streamflow, precipitation, evaporation, area and salinity to the variability in historic volume changes. We also developed a mass balance model to simulate lake level and volume driven by stochastic precipitation, streamflow and climate inputs. We showed that fluctuation in streamflow is the dominant factor in lake level fluctuations, but that fluctuations in lake area, which modulates evaporation and precipitation directly on the lake, are also important.