Made available in DSpace on 2014-11-10T11:09:40Z (GMT). No. of bitstreams: 0 Previous issue date: 2014-02-07Bitstream added on 2014-11-10T11:58:48Z : No. of bitstreams: 1 000788566.pdf: 21022540 bytes, checksum: d6b25eb7f401d2f54ea65ced1d872cd6 (MD5) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Devido à falta de conhecimento estatístico, muitos pesquisadores utilizam métodos empíricos ou subjetivos para a tomada de decisão, ignorando o processo de casualização e, consequentemente, influenciando seus resultados, nomeadamente no processo de homogeneização de amostras, imprescindível para a randomização em pesquisas que envolvem animais como unidade experimental. esse processo, tem-se o hábito errôneo de fazê-lo de maneira fragmentada ou intencional, utilizando-se de apenas um parâmetro conveniente para classificar o grupo como homogêneo. Fato que, além de resultar numa homogeneização viesada e inadequada, favorece a possibilidade de descartar animais por um simples valor espúrio do que por semelhança ou dessemelhança biológica. Tendo em vista essa problemática, este trabalho sugere um critério estatístico multivariado elaborado com a finalidade de rescindir o paradigma biológico que avalia o animal (unidade experimental) de maneira fragmentada. Nesse critério, considera-se a situação biológica do animal como um todo, já que o organismo reage de maneira conjunta a qualquer intervenção ou tratamento, ou seja, analisam-se conjuntamente todos os parâmetros do animal, pois estes são correlacionados, e a melhor forma de entender o comportamento animal está expressa em um conjunto de informações numéricas que represente suas características biológicas. Esse modelo foi aplicado a um conjunto de dados de animais induzidos à estenose aórtica que possibilitou a identificação de seis espúrios ao grupo. Sua importante contribuição explica-se pelo melho!amento na qualidade de homogeneização e por assegurar com máxima acurácia a inclusão de animais semelhantes e pequena frequência de descartes, motivando maximizar o lote homogêneo para posterior submissão ao delineamento experimental por processo simples de casualização dos tratamentos. / Due to lack of statistical knowledge, many researchers use empirical or subjective methods to make a decision, ignoring the randomization process and thus influencing its results, particularly in the process of samples homogenization, essential for randomization in research involving animals as experimental unit. In this process, researchers have the erroneous habit of doing it in a fragmented or intentional manner, using only one convenient parameter to classify the group as homogeneous. Fact that besides resulting in inadequate homogenization, favors the possibility of discarding animals by simple spurious value than by bialogical similarity or dissimilarity. Considering this problem, this work suggests a multivariate statistical criterion of high accuracy developed in order to rescind the biological paradigm that evaluates the animal (experimental unit) in a fragmented manner. In this criterion, it is considered the animal biological condition as a whole, since the body reacts conjointly to any intervention ar treatment, in other words, all the parameters of the animal are analyzed together, as they are correlated, and the best way to understand animal behavior is expressed in a set of numerical information that faithfully represents its biological characteristics. This model was applied to a data set of animais with aortic stenosis and allowed the identification of six animais spurious to the group. It's remarkable contribution is explained by the improvement in the quality of homogenization and by ensuring with maximum accuracy the inclusion of similar animais and small frequency discards, motivating to maximize the homogeneous batch for subsequent submission to the experimental design by simple randomization process of the treatments. / FAPESP: 12/11976-6

Human performance will be altered by changes in movement speed. The inertial properties of human limbs may play an important role in these alterations. The effects of these changes may be observed with the measurement of joint and segmental mechanics, as well as muscular kinematics, kinetics and muscular activity patterns. In this study, the cycling motion was used to investigate these inertial effects, following the development of a new mechanical model that provided the theoretical basis of coordination changes with movement speed. The alteration of cycling performance with different pedaling speed was examined using: (1) Surface EMG as an indication of the changes in muscular coordination as a function of cadence; (2) Inverse dynamics and decomposition of mechanical parameters to identify the influence of gravitational, inertial, and external factors; and (3) Simulations via a musculoskeletal modeling approach to assess the contributions of individual muscles. As predicted by the theoretical model, an increase in pedaling speed produced greater changes at the hip joint compared to knee and ankle joint in both muscular activities and mechanical measures. The changes in muscular activity were evident in both the activity of the single joint hip extensor and the coordination among the synergistic muscles. The altered muscular activities with increased cadence were accompanied by changes in joint moments, in the order of hip, knee and ankle joint from greatest to smallest. Further, the responses in movement organization were not linearly related to the increased inertial influence as the pedaling speed increased. Finally, the simulation analysis demonstrated a compensatory relation between gastrocnemius and soleus muscular activities with different pedaling speeds, although the combined patterns of the two were consistent.

A dissertation submitted to the Faculty of Science in fulfilment of the requirements for the Master of Science degree. in School of Animal, Plant and Environmental Sciences, University of The Witwatersrand, Johannesburg July 2017. / Fire is known to affect spatial patterns of grazing by altering the amount and quality of forage. Animals select the post-burn green flush that remains palatable until the grass recovers its biomass. How quickly the grass regrows depends on the rainfall and grass growth rates, and also grazing intensity. Theoretically, highly concentrated grazing can maintain short (relatively more palatable) grasslands throughout a growing season. Therefore this study aimed at; i) determining how long different grazer species were attracted to the burn, and whether this increased grazing pressure (as a result of concentrating grazers on a small burnt patch) maintained a short, palatable grass sward throughout the growing season, ii) investigating the long-term impacts of herbivore attraction to small burns on grass community and landscape function in a Highveld grassland. We therefore monitored grazer utilization of an experimentally applied small (5ha) burnt patch using dung counts and camera traps, and also measured the structural changes of the burnt patch over a period of 12 months. To test whether this process of attraction to small burns could have long-term impacts on grass community composition and landscape function we quantified species composition, infiltration rates, soil compaction, soil moisture, and ANPP in another landscape which had received 10+ years of small annual burns (a firebreak). A novel finding was that indeed grazers especially the short-grass specialist stayed on the burn and kept the grass short (<10cm) for the duration of the study post fire: the burn only treatment on the 5ha burn recovered its biomass within 2 months of the first rains. This result was due to the fact that it was a drought year with half the normal rainfall (and lower grass regrowth rates). However, the long-term study indicated that the attractive effect of small fires in this ecosystem alters both community composition and ecosystem properties. The firebreak had more bare ground and less water infiltration than the surrounding grassland – but was more diverse and had higher grass productivity. It also continued to attract the short-grass specialist species (blesbok, wildebeest and hartebeest). This counter-intuitive result indicates that perhaps these grasslands are not as severely degraded as we think. This study therefore, showed that coupling small burns with appropriate grazer species has a great potential for creating palatable grazing “hotspots”, in sourveld grassland without obvious damage to ecosystem function. / LG2018

A research report submitted to the Faculty of Science, University of the Witwatersrand, Johannesburg, in partial fulfilment of the requirements for the degree of Master of Science. Johannesburg, 2017. / The distribution of grazing herbivores is influenced by several factors, including spatial and temporal availability of resources. The Telperion and Ezemvelo Nature Reserves (TENR), located on the border between Gauteng and Mpumalanga Provinces, experienced a declining hartebeest (Alcelaphus buselaphus caama) distribution over the last years. Simultaneously, an increase in the density of plains zebra (Equus quagga) occurred in the reserves. In this study, I investigated the changes in the distribution of four herbivore species, namely red hartebeest, plains zebra, blue wildebeest and black wildebeest in TENR, and the possible influence that biotic and abiotic factors had on the distribution of hartebeest between 2010 and 2016. Data of aerial surveys conducted in the wet season of each year were used to assess the variation in herbivores distribution along the period. Furthermore, the influence of variables known to affect herbivore distribution (e.g. distance to water, slope gradient, spatial distribution of other herbivore species and vegetation greenness) was tested on hartebeest distribution in TENR. The results indicate that blue wildebeest (Connochaetes taurinus) had the highest distribution variation, while plains zebra presented the most spread distribution among the four species, and black wildebeest (Connochaetes gnou) concentrated their distribution almost entirely at the Ezemvelo nature reserve. Hartebeest avoided areas with the highest concentration of plains zebra, but did not show the same avoidance for areas with prevalence of wildebeest species. Further, high quality forage resources influenced the hartebeest distribution in TENR. Thus, competition for forage resources with bulk feeders may have affected the population and distribution of hartebeest between 2010-2016. / LG2018

Mannheimia haemolytica is the principal bacterial agent associated with bovine respiratory disease (BRD). It has a significant economic impact on the beef feedlot industry. The current methods for BRD prevention and treatment have various problems and limitations, especially with reports of increased antimicrobial resistance in M. haemolytica. Bacteriophage therapy presents a novel method to mitigate M. haemolytica. This study aimed to isolate strictly lytic M. haemolytica-specific bacteriophages from bovine nasopharyngeal swabs and feedlot trough water. This was accompanied by an extensive characterization of temperate bacteriophages induced from representative strains of a M. haemolytica collection. Phage morphology, host specificity, genomic diversity, and comparative genomics were determined. Even though temperate bacteriophages are not ideal candidates for phage therapy, they can be engineered or modified to serve this function. Genome sequences of selected temperate bacteriophages also provide a foundation for future studies on the biology of these microorganisms. / viii, 107 leaves : ill. ; 29 cm