807 research outputs found

    Game viewing potential in a multi-use conservation area: a case study of the Great Limpopo Transfrontier Park, Southern Africa

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    A dissertation submitted to the Faculty of Science, University of the Witwatersrand, Johannesburg, in fulfilment of requirements for the degree of Master of Science.Three key objectives of transfrontier conservation are biodiversity conservation, local economic development and the promotion of peace and cooperation across international borders (Ramutsindela, 2004). Transfrontier Conservation Areas (TFCA’s) may incorporate a variety of conservation land uses, and comprise of both consumptive and non-consumptive uses of wildlife (Hanks, 2003). It is critical that this mosaic of land uses is well managed and integrated in order to meet the conservation and socio-economic goals of TFCA’s. One challenge is that different conservation land use areas may have varying effects on wildlife. This study aims to further our understanding of these effects in the Great Limpopo Transfrontier Park of South Africa and Mozambique. The research uses the behavioural responses of wildlife as a way of determining the tolerance of wildlife to potentially disturbing activities. Four different conservation land use areas, namely trophy hunting, communal land, photographic tourism and exclusive photographic tourism were studied and compared in and around the Great Limpopo Transfrontier Park, southern Africa. The aim of this study was to firstly establish the diversity of mammals and the frequency of mammal sightings within each conservation land use area, and secondly, assess the response behaviour of five mammal species to an approaching vehicle. K-means cluster analysis was used on both the mammal sightings data and the response behaviour data in order to determine key influencing variables. Throughout the study period, the mammal diversity and frequency of mammal sightings were the highest in the private ecotourism concession, followed by the national park, and then the trophy hunting reserve and lastly communal land. The behavioural responses displayed by the five study mammals (African elephant, African buffalo, impala, chacma baboon and Burchell’s zebra) also varied considerably between the four conservation land use areas. The lowest response indexes and least number of flight responses occurred in the national park, followed by the private ecotourism concession, and conversely, a higher average initial response index and a greater occurrence of flight responses occurring in the trophy hunting reserve and communal land. According to the findings from the cluster analyses, the type of conservation land use impacts on the sighting potential and sighting quality of mammals, but so do iii topographical differences and seasons. These results can help in the management of each conservation land use area on its own and as an integrated part of a TFCA

    Imaging of a fluid injection process using geophysical data - A didactic example

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    In many subsurface industrial applications, fluids are injected into or withdrawn from a geologic formation. It is of practical interest to quantify precisely where, when, and by how much the injected fluid alters the state of the subsurface. Routine geophysical monitoring of such processes attempts to image the way that geophysical properties, such as seismic velocities or electrical conductivity, change through time and space and to then make qualitative inferences as to where the injected fluid has migrated. The more rigorous formulation of the time-lapse geophysical inverse problem forecasts how the subsurface evolves during the course of a fluid-injection application. Using time-lapse geophysical signals as the data to be matched, the model unknowns to be estimated are the multiphysics forward-modeling parameters controlling the fluid-injection process. Properly reproducing the geophysical signature of the flow process, subsequent simulations can predict the fluid migration and alteration in the subsurface. The dynamic nature of fluid-injection processes renders imaging problems more complex than conventional geophysical imaging for static targets. This work intents to clarify the related hydrogeophysical parameter estimation concepts

    Influence of PWM on the proximity loss in permanent magnet brushless AC machines

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    The winding copper loss can be significantly increased due to skin and proximity eddy current effects. The skin and proximity losses due to fundamental frequency current has been investigated in literature, but the influence of PWM on the skin and proximity losses has not been reported. In this paper, 2-D finite element method is employed to analyze the skin and proximity losses in a permanent magnet brushless AC machine, in which significant proximity loss exists due to high frequency current ripples induced by the PWM, as confirmed by both theoretical calculation and experiment. The analyses should be generally applicable to other machines

    Shared and Distinct Features of Human Milk and Infant Stool Viromes.

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    Infants acquire many of their microbes from their mothers during the birth process. The acquisition of these microbes is believed to be critical in the development of the infant immune system. Bacteria also are transmitted to the infant through breastfeeding, and help to form the microbiome of the infant gastrointestinal (GI) tract; it is unknown whether viruses in human milk serve to establish an infant GI virome. We examined the virome contents of milk and infant stool in a cohort of mother-infant pairs to discern whether milk viruses colonize the infant GI tract. We observed greater viral alpha diversity in milk than in infant stool, similar to the trend we found for bacterial communities from both sites. When comparing beta diversity, viral communities were mostly distinguishable between milk and infant stool, but each was quite distinct from adult stool, urine, and salivary viromes. There were significant differences in viral families in the infant stool (abundant bacteriophages from the family Siphoviridae) compared to milk (abundant bacteriophages from the family Myoviridae), which may reflect significant differences in the bacterial families identified from both sites. Despite the differences in viral taxonomy, we identified a significant number of shared viruses in the milk and stool from all mother-infant pairs. Because of the significant proportion of bacteriophages transmitted in these mother-infant pairs, we believe the transmission of milk phages to the infant GI tract may help to shape the infant GI microbiome

    Largeness and SQ-universality of cyclically presented groups

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    Largeness, SQ-universality, and the existence of free subgroups of rank 2 are measures of the complexity of a finitely presented group. We obtain conditions under which a cyclically presented group possesses one or more of these properties. We apply our results to a class of groups introduced by Prishchepov which contains, amongst others, the various generalizations of Fibonacci groups introduced by Campbell and Robertson

    Fracture of disordered solids in compression as a critical phenomenon: I. Statistical mechanics formalism

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    This is the first of a series of three articles that treats fracture localization as a critical phenomenon. This first article establishes a statistical mechanics based on ensemble averages when fluctuations through time play no role in defining the ensemble. Ensembles are obtained by dividing a huge rock sample into many mesoscopic volumes. Because rocks are a disordered collection of grains in cohesive contact, we expect that once shear strain is applied and cracks begin to arrive in the system, the mesoscopic volumes will have a wide distribution of different crack states. These mesoscopic volumes are the members of our ensembles. We determine the probability of observing a mesoscopic volume to be in a given crack state by maximizing Shannon's measure of the emergent crack disorder subject to constraints coming from the energy-balance of brittle fracture. The laws of thermodynamics, the partition function, and the quantification of temperature are obtained for such cracking systems.Comment: 11 pages, 2 figure
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