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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
61

Differences in the Susceptibility to Black Band Disease between Two Species of the Genus Diploria on the Reefs of Bermuda

Kuehl, Kristin 01 July 2010 (has links)
On the reefs of Bermuda, the coral Diploria labyrinthiformis is rarely infected with black band disease (BBD) while BBD-infected colonies of D. strigosa are common. This study investigated several possible explanations for the documented difference in BBD prevalence including: 1) temperature and light conditions differentially affect the progression of the disease among these two species; 2) the bacterial communities associated with each species are different and 3) the bacterial composition of BBD in Bermuda is unique from that of other geographical regions where D. labyrinthiformis has been reported with BBD. Results suggest that light and temperature are important variables in determining BBD progression for both species; reef location, rather than coral species dictates the coral associated bacterial diversity; and the BBD bacterial mat in Bermuda is unique compared to other regions of the Caribbean. Many factors are likely responsible for the low occurrence of BBD among D. labyrinthiformis in Bermuda.
62

Crescimento da grama bermuda DiscoveryTM irrigada por gotejamento subsuperficial, sob tensões de água no solo /

Almeida, Amanda Maria de January 2019 (has links)
Orientador: João Carlos Cury Saad / Resumo: O adequado manejo de irrigação aliado ao uso de sistemas de irrigação por gotejamento subsuperficial podem maximizar a eficiência de uso da água como fator de produção em cultivos de gramados esportivos e ornamentais. Objetivou-se avaliar os parâmetros fitotécnicos da grama bermuda DiscoveryTM sob tensões de água no solo em gotejamento subsuperficial a diferentes profundidades. O experimento foi conduzido na Faculdade de Ciências Agronômicas (FCA) da Universidade Estadual Paulista “Júlio de Mesquita Filho” (UNESP) na cidade de Botucatu-SP, no período de 05 de março de 2018 a 01 de junho de 2019. O delineamento experimental adotado foi de blocos em faixas, com quatro repetições, sendo os tratamentos constituídos por quatro tensões de água no solo (30, 40, 50 e 60 kPa) e três profundidades de instalação da linha lateral (0, 5 e 10 cm abaixo do tapete). Foram avaliados nos meses de janeiro a maio de 2019 os parâmetros fitotécnicos: medida indireta de clorofila, altura de folhas, massa de aparas secas, comprimento e massa seca de raízes. Ao final, avaliou-se também se houve obstrução dos emissores. A medida indireta de clorofila, altura de folhas e massa de aparas secas diminuíram com as tensões de água no solo acima de 30 kPa e com o aumento da profundidade de instalação da linha lateral. As maiores expressões do comprimento radicular e da massa seca do gramado foram observadas na tensão de 30 kPa e com a linha lateral posicionada a 10 cm de profundidade. A profundidade de insta... (Resumo completo, clicar acesso eletrônico abaixo) / Mestre
63

Microborings from the deep Atlantic (Bermuda Pedestal ; Blake Plateau) and Gulf of Mexico (Florida Escarpment) : borers and the ecological and diagenetic fate of the microborings

Hook, James Entrican January 1991 (has links)
Thesis (Ph. D.)--Boston University, 1991. / Interest in deep sea microbiota was stimulated by recent discoveries of productive redox communities associated with hydrothermal vents and brine seeps, and based on bacterial chemolithotrophy. This study investigates microbial destruction of mussel shells from a redox community at the base of the Florida Escarpment (3360 m), in comparison with microbial boring in shells of typical, low productivity areas of the ocean floor. An assemblage of eukaryotic and prokaryotic periostracum borers and their boring traces were discovered in shells of Bathymodiolus mussels from the base of the Florida Escarpment, and characterized. Microbial destruction of this protective layer results in colonization of secondary microbial inhabitants inside boreholes, and exposes the underlying mineralized shell to colonization and destruction by microbial endoliths. Microbial consumption of periostracum often proceeds in successive waves. These organisms show different "foraging" behaviors and leave accordingly varied boring patterns. These activities create a labyrinth of pits, holes and tunnels which, in tum, provide sheltered microenvironments for secondary microbial settlers, including primary producers, which all constitute an abundant food source for numerous ciliates and gastropods observed on the shells. This concerted attack on the periostracum eventually leads to the exposure of the mineralized shell. Such exposed areas are characterized by [TRUNCATED]
64

Strategies for Reducing Employee Absenteeism for a Sustainable Future: A Bermuda Perspective

Forte, Allison Nicola Simone 01 January 2017 (has links)
Employee absenteeism results in billions of dollars in revenue losses and lost productivity annually. Given the consequences that organizations could face resulting from high levels of work absences, executives should develop strategies to manage absenteeism to support organizational growth and sustainability. Grounded in the theory of planned behavior, the purpose of the single case study was to explore strategies managers in the private insurance industry used to reduce employee absenteeism. The population consisted of 3 managers located in Bermuda who implemented strategies to decrease employee absenteeism from a Bermuda perspective. Data included semistructured interviews, results of the company's 2016 engagement survey, and annual reports from 2014 to 2016 that highlighted the company's commitment to providing strategies to enhance employees' engagement and dedication to its strategic objectives. Through thematic analysis, 4 themes emerged: employee engagement, managerial communication, employee wellness and health promotion programs, and achieving work-life balance. Business managers could use these findings to understand how specific human resources strategies with a focus towards reducing employee absenteeism minimize work absences. Minimizing work absences could contribute to positive social change through increased economic growth in local communities and higher quality of life for its residents.
65

Evaluation of quickstand bermudagrass fertilized with two rates of nitrogen and grazed by sheep at different stocking rates in a temperate environment

Baker, Scott M. 24 November 2009 (has links)
Two grazing trials and a feedlot trial were conducted with crossbred lambs to evaluate 'Quickstand' bermudagrass (Cynodon dactylon [L.] Pers.) in a cool temperate environment. Four stocking rates and two N fertilization rates (4 x 2 factorial) were replicated three times on .11-ha paddocks. Paddocks were continuously stocked with two, four, six, or eight lambs (light, moderate, heavy, and very heavy stocking rate, respectively) in grazing trial 1. Stocking rates were increased to 4, 8, 12, or 16 lambs per paddock, respectively, in grazing trial 2. In both grazing trials, paddocks were fertilized with 114 (low N) or 340 (high N) kg N ha-1yr-1 in split applications. / Master of Science
66

Influence of iron and cytokinin on Cynodon spp. cultured at chilling temperatures

White, Richard Hampton January 1985 (has links)
Bermudagrass (<i>Cynodon</i> spp.), when cultured at the northern limit of adaptation for semitropical grasses, is exposed seasonally to temperatures low enough to limit growth and turf quality. Research was conducted to investigate the influence of foliar iron and cytokinin applications on bermudagrass growth during fall and spring. The relationship of photosynthesis, respiration, and nonstructural carbohydrate composition to chilling temperatures was also studied. Foliar applications of Fe in late-summer and fall extended bermudagrass performance during low temperature periods of fall. Frequent Fe applications aided the retention of green bermudagrass turf during prolonged exposure to chilling temperatures. Iron applied the previous season stimulated post-dormancy recovery. Benzyladenine (BA) applied alone was not as effective as Fe for promoting green bermudagrass color retention during fall and BA had few effects on spring growth when applied the previous season. Applications of BA in conjunction with Fe were beneficial for retention of green bermudagrass color during late fall when clear plastic covers were used to prevent frost injury. A 6- to 8-week longer bermudagrass growing season occurred when clear plastic covers were used to prevent frost injury. Iron and BA did not significantly affect the total nonstructural carbohydrate (TNC) levels in Midiron bermudagrass rhizomes and stolons at the onset of dormancy in field studies. Midiron bermudagrass had higher photosynthetic and respiration rates than Tifgreen bermudagrass after 4 days exposure to chilling (10/7°C day/night) temperatures in controlled environment studies. Midiron recovered higher photosynthetic rates than Tifgreen when returned to a warm (30°C) environment after exposure to chilling temperatures. The TNC in leaves of Midiron and Tifgreen increased 88 and 160%, respectively, during 5 days at chilling temperatures. The inability to transport carbohydrate from and the subsequent accumulation of high photoassimilate levels in leaves was associated with the inability of bermudagrass to fully recover high photosynthetic rates following chilling. Reduced respiratory activity was apparently responsible for the accumulation of high TNC levels in leaves. In contrast to photosynthesis, respiration was reversibly inhibited by short term exposure of bermudagrass to chilling temperatures. Rapid recovery of high respiratory activity may be important for maintenance of aesthetically pleasing bermudagrass turf following chilling. Foliar applied Fe or BA generally caused darker green Midiron and Tifgreen turf after exposure to chilling temperatures in a controlled environment, although the enhancement of physiological activity differed with chemical applied and cultivar. Iron stimulated recovery of photosynthetic and respiratory activity in both cultivars after exposure to chilling temperatures. However, during chilling Midiron CO₂ exchange was more responsive to Fe applications. Benzyladenine increased photosynthesis in Tifgreen but not in Midiron and did not significantly affect respiration in either cultivar. Neither Fe nor BA had a consistent effect on TNC levels in bermudagrass leaves, rhizomes, or stolons. These investigations indicate that cultivar selection may play a major role in determining turf quality at chilling temperatures. Iron may modify bermudagrass physiology and enhance performance of bermudagrass exposed to chilling temperatures. / Ph. D. / incomplete_metadata
67

Disease management strategies for controlling spring dead spot and frequency of occurrence of the causal organism Ophiosphaerella korrae on 'Tifway' bermudagrass (Cynodon dactylon x C. transvaalensis)

Perry, D. Hunter January 2007 (has links)
Thesis (M.S.)--Mississippi State University. Department of Entomology and Plant Pathology. / Title from title screen. Includes bibliographical references.
68

The use of various soil ameliorants and indigenous grasses, in the rehabilitation of soil from open cast coal mines in Mpumalanga, South Africa.

Webb, Christy Mary Winifred. January 2004 (has links)
A series of pot trials were undertaken to test the growth of indigenous grasses (Themeda triandra and Cynodon dactylon) on mine capping soil, treated with various soil ameliorants. The capping soils were obtained from open cast coal mines (Optimum Mine and Syferfontein Mine) in the Mpumalanga Highveld, south of Witbank. However, because mine soil was not available at the commencement of the project, the initial pot trial used soil from the Umlazi Landfill in Durban. The trials were the Umlazi Landfill Trial, Microbe Trial, Legume Trial and Fly Ash Trial. For the Umlazi Landfill Trial, landfill top and subsoil was used along with fertilizer, sewage sludge, K-humate, lime and microbes. The soil ameliorant treatments for the Microbe trial were Trichoderma harzianum (Eco'T), Bacillus subtilis Strain 69 (B69) and Bacillus subtilis Strain 77 (B77), for the Legume Trial, Medicago sativa, phosphorus and/or potassium were applied. For the Fly Ash Trial, lime and fly ash were introduced. From the Landfill trial it was shown that fertilizer and sewage sludge significantly increased the above ground, below ground and total biomass of T. triandra, further, there were no significant treatment differences between fertilizer and sludge. The lime treatment for this trial, surprisingly, significantly reduced below ground biomass but the application of microbes (B69 and BcoT) alleviated this negative effect. However, in the Microbe Trial the microbes (BcoT, B69 and B77) had a negative or no effect on the biomass of T. triandra and C. dactylon. In the Legume Trial it was shown that the above ground biomass of T. triandra was significantly reduced when grown with M. sativa. The Fly Ash Trial revealed that the lime and fly ash treatments had no effect on the biomass of M. sativa and T. triandra, and they did not maintain a reduction in soil acidity. The results therefore indicated that either organic fertilizer or sewage sludge could be used to significantly improve the growth of T. triandra. It was also suggested that lime not be applied to soils with an acid saturation of approximately 1%, as this could retard plant growth. The application of microbes and the growth of a legume with grass, although both have been recorded to have beneficial effects in aiding plant growth, in the short-term however, the application of T. harzianum, B. subtilis Strain 69 and 77 applied to the soil while growing T.triandra and C. dactylon and the growth of M. sativa with T. triandra is not recommended. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2004.
69

The role of arbuscular mycorrhizal fungi in the biotransformation of coal and application in dump rehabilitation

Mukasa-Mugerwa, Thomas Tendo January 2007 (has links)
Fundamental processes underpinning the biotransformation of coal by fungal biocatalysts have been intensively investigated, however, limited large-scale industrial applications using such systems have been reported. The un-anticipated sporadic growth of Cynodon dactylon on the surface of un-rehabilitated discard coal dumps has been noted and this was found to be coupled with the breakdown of coal into a humic soil-like material in the top 1.5 metres of the dumps. Extensive fungal growth was observed to be associated with the Cynodon dactylon root system and examination of plant roots indicated the presence of mycorrhizal fungi. Analysis of the Cynodon dactylon plant roots around which coal biotransformation was occurring confirmed the presence of arbuscular mycorrhizal colonisation with the species Glomus clarum, Paraglomus occultum, Gigaspora gigantea and Glomus mosseae identified to be associated with the plants. Further molecular characterisation of non-mycorrhizal rhizospheric fungi showed the presence of fungal species with coal-degrading capabilities that most likely played a role in the coal biotransformation observed. The discard coal dump environment was simulated in pot and column studies and coal biotransformation was reproduced, with this process enhanced by the addition of mycorrhizal and non-mycorrhizal rhizospheric fungal inocula to the environment. Mycorrhizal and non-mycorrhizal species in the inoculum were re-isolated from the simulated environment fulfilling a number of Koch’s postulates and indicating a causal role in the biotransformation of coal. An inversion of conventional mycorrhizal colonisation was demonstrated in this system with reduction in extraradicular presence and an increase in intracellular colonisation compared to soil controls. A descriptive model was formulated suggesting a two-part fungal system involving organic carbon and nutrient exchange between the plant, mycorrhizal fungi and non-mycorrhizal coal-degrading rhizospheric fungi ultimately resulting in the biotransformation of coal. The biotransformation observed was comparable to reports of “rock-eating fungi”. Results suggest that the biological degradation of coal in situ with the production of a soil-like substrate could provide a feasible method of discard coal dump rehabilitation as well as provide a humic-rich substrate that can be utilised in further industrial applications.
70

Joyau du patrimoine mondial et tourisme : l'exemple de St-George, Bermudes

Gagnon, Maxime 09 1900 (has links)
Ce mémoire présente l’étude de cas de la ville de St George, ancienne capitale du protectorat britannique des Bermudes. Sa situation géographique particulière et la présence d’un ensemble architectural colonial britannique et d’ouvrages militaires lui ont récemment valu le titre de Site du patrimoine mondial de l’UNESCO, ce qui constitue une reconnaissance de la valeur exceptionnelle universelle de cet ensemble urbain. Cette inscription survient au moment où les autorités locales souhaitaient diversifier l’économie de l’archipel en misant davantage sur le tourisme culturel et patrimonial. L’hypothèse centrale de ce mémoire est que la ville St George se révèle, au sens où l’entendent G.J. Ashworth et J.E. Tunbridge dans leur ouvrage The tourist-historic city, un « joyau du patrimoine », ce dernier étant défini comme une petite collectivité territoriale recelant des ressources historiques exceptionnelles qui en définissent de manière notable la morphologie urbaine et l’identité paysagère et orientent les politiques municipales. La recherche, suite à la présentation d’un cadre théorique sur le patrimoine mondial et le tourisme patrimonial, a par ailleurs permis de montrer que le concept de « cité historico-touristique » développé par les mêmes auteurs s’applique aux Bermudes à la condition qu’un transfert d’échelle soit opéré. En effet, nous ne sommes pas en présence d’un espace touristique constitué de deux secteurs d’une même ville qui contribuent, chacun à sa façon, à la définition de l’attractivité touristique, mais plutôt de deux petites villes voisines – St-George et Hamilton, la capitale – qui constituent le substrat d’une cité historico-touristique éclatée. / This dissertation presents the case study of the town of St. George, historic capital of Bermuda. Its unique geography, the presence of British colonial architecture and of many military forts allowed its inclusion on the UNESCO world heritage List. This nomination in itself constitutes a recognition of the exceptional universal value of this urban entity. This inscription happens at the exact moment where the local authorities wish to diversify the archipelago’s economy by exploiting cultural and heritage tourism. The hypothesis of this dissertation is that the town of St. George is, according to the proposition of G.J Ashworth and J.E Tunbridge in their book The tourist-historic city, a «heritage gem », that is, a small community containing a great number of exceptional historic resources shaping the urban morphology, the landscape identity and local policies. The research, following the introduction of the relevant theoretical framework on world heritage and heritage tourism, demonstrated that the concept of the “tourist-historic city” developed by the same authors can be easily applied to the case of Bermuda if a scale reduction is made. Indeed, we are not presented with a touristic space created by two different sectors of the same city, but by two small neighbouring cities – St. George and Hamilton, the capital – which are the basis of a fragmented tourist-historic city.

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