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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.
141

Acoustic monitoring of earthquakes along the Blanco Transform Fault Zone and Gorda plate and their tectonic implications

Dziak, Robert P. 02 June 1997 (has links)
Hydroacoustic tertiary (T-) waves are seismically generated acoustic waves that propagate over great distances in the ocean sound channel with little loss in signal strength. Hydrophone recorded T-waves can provide a lower earthquake detection threshold and an improved epicenter location accuracy for oceanic earthquakes than land-based seismic networks. Thus detection and location of NE Pacific ocean earthquakes along the Blanco Transform Fault (BTFZ) and Gorda plate using the U.S. Navy's SOSUS (SOund SUrveillance System) hydrophone arrays afford greater insight into the current state of stress and crustal deformation mechanics than previously available. Acoustic earthquake information combined with bathymetry, submersible observations, earthquake source-parameter estimates, petrologic samples, and water-column chemistry renders a new tectonic view of the southern Juan de Fuca plate boundaries. Chapter 2 discusses development of seismo-acoustic analysis techniques using the well-documented April 1992 Cape Mendocino earthquake sequence. Findings include a hydrophone detection threshold estimate (M~2.4), and T-wave propagation path modeling to approximate earthquake acoustic source energy. Empirical analyses indicate that acoustic energy provides a reasonable magnitude and seismic moment estimate of oceanic earthquakes not detected by seismic networks. Chapters 3 documents a probable volcanogenic T-wave event swarm along a pull-apart basin within the western BTFZ during January 1994. Response efforts yielded evidence of anomalous water-column ��He concentrations, pillow-lava volcanism, and the first discovery of active hydrothermal vents along an oceanic fracture zone. Chapter 4 discusses the detection of a NE-SW trending microearthquake band along the mid-Gorda plate which was active from initiation of SOSUS recording in August 1991 through July 1992, then abruptly ceased. It is proposed that eventual termination of the Gorda plate seismicity band is due to strain reduction associated with the Cape Mendocino earthquake sequence. Chapter 5 combines bathymetric, hydro-acoustic, seismic, submersible, and gravity data to investigate the active tectonics of the transform parallel Blanco Ridge (BR), along the eastern BTFZ. The BR formation mechanism preferred here is uplift through strike-slip motion (with a normal component) followed by formation and intrusion of mantle-derived serpentinized-peridotite into the shallow ocean crust. The conclusion considers a potential link between the deformation patterns observed along the BTFZ and Gorda plate regions. / Graduation date: 1998
142

Genetic variability for kernel hardness in two soft winter wheat (Triticum aestivum L.) cultivators

Albahouh, Muhammed S. 15 April 1992 (has links)
To remain competitive in the international marketplace, soft white wheat cultivars grown in the Pacific Northwest must have consistent and predictable flour properties including kernel texture. As a consequence, there is a need to develop wheat cultivars for specific end uses. Wheat cultivars with very soft kernels are used largely for making cookies and cakes. Harder soft white wheats are more suitable for noodles and flat breads. Numerous studies have been made to determine the inheritance of kernel texture between hard and soft wheat; however, very little information is available concerning the amount of genetic variability within soft white wheat. Reciprocal crosses were made between a very soft (TJB/MON"S") and a soft (Yamhill) white winter wheat genotype. Data were collected on an individual plant basis for kernel texture, protein content, and eight selected agronomic traits. Kernel hardness and protein content were determined using the near-infrared reflectance spectroscopy (NIR). Genetic differences for kernel texture and the other nine traits were found between the two parents and the resulting F1 progenies. It would appear that kernel texture is qualitatively inherited with one or more genes reflecting additive and nonadditive gene action. However, a large component of non-genetic variation was also detected. Of particular interest was the apparent reciprocal differences found between Fl populations for most of the traits measured and particularly kernel texture. However, for kernel texture, such differences were not due to a dosage effect of the 3n endosperm. Kernel texture was not found to be associated with protein content. A negative association of kernel texture with heading date would suggest a compromise may be necessary when selecting these traits. Positive associations were found between kernel hardness with number of tillers, total biological yield, grain yield, and number of kernels per spike. / Graduation date: 1992
143

Systematic and reproductive studies of Mimulus (Scrophulariaceae) in the Pacific Northwest : implications for conservation biology

Meinke, Robert James 08 May 1992 (has links)
The Mimulus washingtonensis complex is a group of morphologically similar species centered in the Pacific Northwest. All are rare, and most are under consideration for listing as endangered. Morphometric and pollination data were used in developing a revised taxonomy for the group. Five species and two varieties are recognized. Mimulus pulsiferae Gray is the most widespread, occurring from southern Washington to northern California. Mimulus hymenophyllus Meinke and M. jungermannioides Suksd. are cliff species endemic to river drainages in northern Oregon. Mimulus washingtonensis Gand. occurs in east-central Oregon and western Idaho, represented by the var. washingtonensis and var. ampliatus (Grant) Meinke comb. et stat. nov., respectively. Mimulus patulus Pennell is resurrected from synonymy and differentiated from M. washingtonensis on the basis of morphology, distribution, and pollination biology. This autogamous species includes var. patulus, occurring in the Snake River drainage, and var. montanus Meinke var. nov., primarily from the northern Rocky Mountains. Mimulus evanescens Meinke sp. nov. is described from an extant population in Lassen County, California, and historic collections from widely scattered stations in Oregon and Idaho. The new species is morphologically intermediate between M. breviflorus Piper and M. latidens (Gray) Greene. Calyx and leaf morphology also suggest an affinity to M. grayi Grant, M. inconspicuus Gray, and M. acutidens Greene, of cismontane California. Mimulus evanescens should be considered critically endangered, because of its limited numbers and habitat degradation. Mimulus washingtonensis is pollinated by small native bees, primarily two species of Dialictus (Halictidae). These bees were specific to Mimulus flowers but did not distinguish between flowers of M. washingtonensis and M. guttatus DC., a related species that increases with habitat disturbance. Experiments showed that mixed pollen loads diminish seed set in M. washingtonensis, since the thigmotropic stigma of that species closes permanently after any amount of conspecific pollen is applied. Although M. washingtonensis has a low pollen/ovule ratio (29.9), it is considered facultatively xenogamous based on floral morphology, stigma sensitivity, and autogamous seed set levels. Populations occurred in small, edaphically restricted patches, and they exhibited seed set reductions related to outcrossing distance. Substrate disturbance may limit reproduction in M. washingtonensis by changing population structure, threatening pollinators, and increasing competition for pollination by promoting growth and flowering of M. guttatus. / Graduation date: 1992
144

A comparative analysis of stream response to disturbance in the Pacific Northwest

Hodgins-Carlson, Terry Anne 12 January 1993 (has links)
Published literature about six Pacific Northwest stream systems was contrasted to provide a regional perspective on channel response to disturbance. This investigation was prompted by a combination of recent environmental legislation, mounting social pressures to plan projects at a drainage basin scale, and the difficulty in defining and predicting the response and recovery of a stream channel to land-use management or storm events. Detailed studies of Redwood Creek, CA; the San Lorenzo River, CA; the South Fork Salmon River, ID; the Upper Middle Fork of the Willamette River, OR; the Alsea River System, OR; and Carnation Creek, B.C. were reviewed and contrasted. Differences in channel response to disturbance appear to be the result of the sequence of storms, the interactions between storms and land-use, the processes that deliver sediment to the channel, the available stream power, and the bank stability. Basins with low debris avalanche and earthflow potential, high stream power, and stable stream banks experience only localized and short-lived response to disturbance. On the other hand, basins with frequent debris avalanches or high earthflow potential and unstable banks experience widespread and persistent response. This study concludes that there must be realization and acceptance of the random nature of channel response and recovery following disturbance. Field evaluation, professional judgement, risk assessment, and adaptive management are the most powerful tools available in the prediction of channel response. / Graduation date: 1993
145

Response to Hypoxia in the staghorn sculpin, (Leptocottus armatus)

Wagner, Sara Anne 02 November 1990 (has links)
Long-term subae lal survival has been anecdotally noted in the staghorn sculpin, Leptocottus armatus. In this study, I quantified this phenomenon physiologically by examining the following parameters: standard metabolic rate and indications of reduced standard metabolic rate during subaerial exposure; capacity for and mechanism(s) of oxygen consumption in air; capacity for anaerobic production of lactate and/or ethanol; and blood pH. The staghorn sculpin appears well-suited for the subaerial exposure it experiences in nature. Mean subaerial survival time was 6 hours which would enable fish to survive intertidal stranding. Staghorns breathe air through well-supported gills and supplement depressed rates of subaerial aerobiosis by anaerobic production of lactic acid. Most remarkably, the staghorn sculpin may also substantially reduce minimal energy expenditure requirements during periods of hypoxia by reducing resting metabolic rate. / Graduation date: 1991
146

Trophic feedback and carrying capacity of Pacific salmon (Oncorhynchus spp.) on the high seas of the Gulf of Alaska /

Aydin, Kerim Yunus. January 2000 (has links)
Thesis (Ph. D.)--University of Washington, 2000. / Vita. Includes bibliographical references (leaves 364-378).
147

The effect of drought stress on the chemical composition and distribution in Russet Burbank and AO82260-8 potatoes

Zhang, Peifang 07 July 1989 (has links)
The effects of early season and late season drought stress on various carbohydrates, calcium and/or nitrogen content at apical, central and basal tuber locations were studied for Russet Burbank and A082260-8 potatoes. Drought stress which occurred early in the stage of tuber development appeared to have more detrimental effect than later season stress. Interactions between treatment and sampling date and variety x position x date were significant during early season stress. Generally, percent total solids increased during potato development for both varieties. The central portion of tuber had the lowest total solids. Total reducing sugar content generally decreased during potato development for both varieties with significant (P<.05) differences at early season stress due to the interaction effects of treatment x date and variety x position. No significant difference in reducing sugar at later season stress was found regardless of treatment. Variety difference in reducing sugar content occurred at the apical end. Russet Burbank had more reducing sugars than A082260-8 at this end. The exploration of fructose, glucose and sucrose individually showed the same developing pattern as total reducing sugar. Sucrose made up over 50% of the total sugars with glucose and fructose the next in order of importance. The apical end had more sucrose and glucose than the basal end. The interaction of variety and position for both nitrogen and dietary fiber may be a result of growth pattern differences in the two treatments. Total dietary fiber content was generally the highest at the basal portion for both varieties. Russet Burbank appeared to have higher total dietary fiber than A082260-8 at this end. The level of calcium in Russet Burbank was significantly higher than that in A082260-8. Basal and apical portions had higher calcium content than the central portion. / Graduation date: 1990
148

Radiolarian microfauna in the northern California current system : spatial and temporal variability and implications for paleoceanographic reconstructions

Welling, Leigh A. 19 November 1990 (has links)
Graduation date: 1991
149

Millennial-scale surface and deep water oscillations in the N.E. Pacific : implications for late pleistocene climate change

Lund, David Charles 30 October 1997 (has links)
Graduation date: 1998
150

Seamount paleomagnetism and Pacific plate tectonics

Sager, W. W (William W.) January 1983 (has links)
Typescript. / Thesis (Ph. D.)--University of Hawaii at Manoa, 1983. / Bibliography: leaves 441-472. / Microfiche. / xvii, 472 leaves, bound ill., maps 29 cm

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