4,592 research outputs found

    Abundance and behavioural ecology of bottlenose dolphins (Tursiops truncatus) in the Marlborough Sounds, New Zealand : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science in Conservation Biology at Massey University

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    In order to survive, animals require both food and protection from predators. These ecological factors are major determinants in habitat selection and social interactions. Determining the causes of habitat selection and examining the behavioural ecology of marine mammals is often a difficult task. In the ever-changing marine environment, factors such as shifts in prey availability, turbidity, sea surface temperature, and salinity result in a highly dynamic ecosystem that influences distribution. This research's primary focus was to establish baseline information on the behavioural ecology of bottlenose dolphins, Tursiops truncatus in and around the Marlborough Sounds, New Zealand. Boat based surveys, photo-identification, and group focal follows were used to assess spatial distribution, abundance, home range, and social interactions. Boat based surveys were conducted from 2003 to 2005. Photo-identification data collected from 1997 to 2005 were used in analysis. Uniquely marked individuals (n = 335) were sighted throughout the Marlborough Sounds and long-term site fidelity was observed among members in this large open population. Aggregations of between 3 to 172 individuals were observed with a median group size of 12. Group size was influenced by the presence of calves, with groups tending to be larger when calves were present. Larger groups were found to rest more than smaller groups and resting occurred less in the spring months. Association patterns revealed long- and short-term preferred associations between individuals throughout the Sounds. Distribution and movement patterns of dolphins showed they used all areas within the Marlborough Sounds. The population of bottlenose dolphins observed in the Marlborough Sounds were found to be semi-resident with 211.5 (C.I. = 195 - 232) individuals utilising the Sounds year round while other individuals were found to migrate in and out of the area on an annual basis. The Marlborough Sounds appear to be only a portion of a much larger home range for this population

    Clay minerals and sedimentary basin history

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    Clay minerals in the mud and soil that coat the Earth's surface are part of a clay cycle that breaks down and creates rock in the crust. Clays generated by surface weathering and shallow diagenetic processes are transformed into mature clay mineral assemblages in the mudrocks found in sedimentary basins. During metamorphism, the release of alkali elements and boron from clay minerals generates magmas that are subsequently weathered and recycled, representing the magma-to-mud pathway of the clay cycle. Volcanogenic clay represents an important but hitherto underestimated proportion of recycled clay. Within sedimentary basins, immature clays are transformed to mature and supermature clay assemblages by a series of reactions that generally obey the Ostwald Step Rule. Bedding-parallel microfabric generated by these reactions produce significant changes in the physical properties of deeply buried mudrocks. Clay minerals react to form equilibrium assemblages in 1 x 104 years in some hydrothermal systems, but immature clays may survive for up to 2 x 109 years in mid-continental rift basins. Clay mineral assemblages and the b cell dimension of K-white mica can be used to infer the geotectonic settings of sedimentary basins

    Sir C. Wyville Thomson\u27s letters to staff-commander Thomas H. Tizard, 1877-1881

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    These original letters from Thomson to Tizard are concerned with the publication of the results of the CHALLENGER Expedition, as well as the study of the Faroe Channel and the eventual delineation of the Wyville Thomson Ridge with its diversity of cold and warm area bottom fauna. They also provide evidence of Thomson\u27s indefatigability as well as certain historical sidelights

    SSME turbopump bearing analytical study

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    Three shuttle pump bearings operating under severe overspeed and shut-down conditions are evaluated. The specific parameters investigated include outer race stresses, cage stresses, cage-race drag, bearing heating, and crush loading. A quasi-dynamic version of the BASDAP computer code was utilized which involved the calculation of ball-race forces (inner and outer), contact pressures, contact dimensions, and contact angles as a function of (1) axial load, (2) radial load, and (3) centrifugal load on the bearing. Generally, radial loads on the order of 13,300 N (3000 pounds) per bearing or 26,700 N (6000 pounds) per bearing pair, could be expected to cause severe problems to any of the bearings with a 17,800 N (4000 pounds) axial load. Further, when possible temperature excursions are considered, even a load of 8900 N (2000 pounds) may be excessive. However, high momentary radial loads with a 3800 N (850 pounds) axial load would not be anticipated to cause catastrophic failure of the fuel pump bearing

    A tool for estimating Best Management Practice effectiveness in Arkansas

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    Increased nutrient and sediment losses from expanding agricultural practices and urban development in Arkansas are important environmental concerns. Best Management Practices (BMPs) are being implemented to lessen the effects of these developments on existing water bodies. There is, however, insufficient scientific base as to the effectiveness of these practices. A number of studies have been conducted in recent years to determine BMP effectiveness. Data from these studies can only be reliably used for the individual site from which they were obtained. When considered collectively, these data comprise quantitative effectiveness over a wide range of conditions and can thus be used to provide reliable estimates of BMP effectiveness. This study develops a tool for estimating BMP effectiveness, based on accumulation and analyses of data reported in previous studies, with a focus on site conditions and management interventions in Arkansas. This study incorporates data from a variety of regions in the southeastern U.S., which have site conditions and management similar to those in Arkansas. Developed within Microsoft® Access© from a pre-existing BMP characterization tool, this tool will be made accessible to local and state agencies and will aid rural and urban planners in developing management solutions for nutrients and sediment control. The tool describes individual BMPs in detail and gives site-specific estimates of their long-term effectiveness in sediment and nutrient control

    High pressure oxygen turbopump bearing cage stability analyses

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    The low service life of the high pressure oxygen turbopump (HPOTP) bearings used in the space shuttle main engine was examined by use of the Battelle "BASDAP' bearing computer stability model. The dynamic instability of the bearing cage resulted in excessive wear and eventual failure of the unit. By maintaining a cage/race clearance of no more than 0.25 millimeters (0.010 inches), ball/pocket clearance of no less than 0.54 millimeters (0.025 inches), dynamic balancing of the cages, and maintaining adequate lubricant films between the balls and races, cage instability and subsequent bearing degradation can be reduced
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