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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.
31

An Agricultural Model for the Central and Sacaba Valleys in Cochabama, Bolivia

Ibañez-Meier, Carlos A. 01 May 1980 (has links)
The purpose of this thesis is to assess the impact of increasing the quantity of water supplied for irrigated agriculture in the Central and Sacaba Valleys. Specifically, this study examines the feasibility of Misicuni multiple-purpose project in Cochabamba, Bolivia. This project involves construction of a reservoir for the purpose of irrigating and the above mentioned areas, supply potable water to the urban areas, and produced electrical power. The Misicuni Survey, Ministerio de Agricultura y Asuntos Campesionos (MACA) bulletins, and information from other institutions were used as a source of data for the formulation of a linear programming model which represents the agricultural sector in that area. Using the model, pseudo data relating different levels of agricultural production were obtained with different levels of input combinations. The problem was solved by maintaining the demand for agricultural products in the area at the levels prevalent in 1976-1977. This data was fitted by linear regression techniques to a translogarithmic production function which defines a continuous functional relationship between the value-added to GNP by the region under study and the input factors of production. The results derived from the estimated production function show that, unless considerable expansion in the demand for agricultural products is induced in this area, the change in the value of output through increases in the quantity of water available for irrigation by the Misicuni Project will be insignificant. If the government constructs the mentioned dam (as designed), there is a high probability of unused excess water resource capacity. This will result in considerable economic loss and a misallocation of the scarce resources of the country.
32

Hydrogeomorphic Factors Influencing Clonal Recruitment of Cottonwoods in Mountain Valleys

Roberts, Michael D. 01 May 1999 (has links)
Riparian cottonwoods (populus spp.) are keystone pioneer species that contribute to critical streamside and in-stream habitats, water quality, and aesthetic and recreational value. Land use and river regulation have caused a widespread reduction in the extent and regeneration of this genus. The majority of research on Populus species' reproduction has examined seedling recruitment that dominates in wide alluvial valleys. In contrast, I evaluated reproductive strategies of Populus angustifoliain mountain valleys. Research was conducted in northern Utah on the Little Bear River, a gravel-bedded stream that flows north out of the Bear River Range onto deposits of Ancient Lake Bonneville. I used allozyme electrophoretic data and vegetation mapping to investigate recruitment mechanisms of cottonwoods at two steep, confined mountain valley sites and two wide, alluvial valley sites. Allozyme electrophoretic analysis on samples from sites one through four revealed 60%, 69%, 86%, and 84% clonal recruitment, respectively. The size of cottonwood clones may be on the order of 200-300 m in this system. Vegetation mapping supported allozyme data and suggested that clonal recruitment dominates the system. I also collected data at four sites containing no cottonwoods to compare hydrogeomorphic influences at non-cottonwood (NC) sites and cottonwood recruitment (CR) sites. CR sites possess a distinctive geomorphic template relative to NC sites and this template may facilitate root disturbance resulting in clonal recruitment. A high frequency of woody debris and mid-channel islands characterizes CR sites. Channels at CR sites are less entrenched, more sinuous, and exhibit larger bankfull channel width and width to depth ratios, and finer grain sizes than channels at NC sites. At CR sites, estimates of bankfull average boundary shear stress and unit stream power are less compared to those at NC sites. Cottonwood recruitment models that typically describe seedling reproduction in alluvial valley environments do not apply in narrow, steep-gradient environments. I found clonal recruitment of cottonwoods to correlate spatially and temporally with channel and root disturbance associated with rain on snow events on the order of the 25-30-yr flood event.
33

Observed circulation and inferred sediment transport in Hudson Submarine Canyon /

Hotchkiss, Frances Luellen Stephenson. January 1982 (has links)
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Earth and Planetary Science, 1982. / Supervised by Erik Mollo-Christensen. Vita. Includes bibliographical references (leaves 217-223).
34

Observed circulation and inferred sediment transport in Hudson Submarine Canyon /

Hotchkiss, Frances Luellen Stephenson. January 1900 (has links)
Thesis (Ph. D.)--Massachusetts Institute of Technology and the Woods Hole Oceanographic Institution, 1982. / Vita. Includes bibliographical references (p. 217-223).
35

Characterisation of microbial communities associated with hypolithic environments in Antarctic Dry Valley soils.

Khan, Nuraan. January 2008 (has links)
<p>The Eastern Antarctic Dry Valley region is a polar desert, where conditions of extreme aridity, high temperature fluctuations and high irradiation levels make it one of the most extreme environments on earth. Despite the harsh environment, the soils in this region yield a wide range of bacterial and eukaryotic phylotypes in greater abundance than previously believed. In the Dry Valleys, highly localized niche communities colonise the underside of translucent quartz rocks and present macroscopic growth.</p>
36

The Study of the Variation Trend for Diastolic Pressure of the Surgical Patients utilizing Non-Invasive Plethysmography Signal

Chen, Ching-Hsiu 04 August 2004 (has links)
The purpose of this research is the estimation for the trend of diastolic pressure of surgical patients utilizing non-invasive photo-plethysmography (PPG) signal. There are two major ways to measure blood pressure during medical treatment : invasive and non-invasive methods. Both them have advantages and disadvantages. For invasive method, it is used for surgical operations. Although it can response the true situation of arterial blood pressure, the damage and uncomfortable are the most disadvantages for itself. And for non-invasive method, it is convenient to use but the measurement results have lower accuracy. In this research, we try to estimate the continuous trend of diastolic pressure utilizing PPG signal. And calculate the accuracy of the results.
37

Comparative analysis of microbial community composition throughout three perennially ice-covered lake systems in the McMurdo Dry Valleys, Antarctica and its relationship with lake geochemistry

Foo, Wilson L. January 2009 (has links)
Thesis (Ph. D.)--University of California, Riverside, 2009. / Includes abstract. Available via ProQuest Digital Dissertations. Title from first page of PDF file (viewed March 16, 2010). Includes bibliographical references. Also issued in print.
38

Characterisation of microbial communities associated with hypolithic environments in Antarctic Dry Valley soils.

Khan, Nuraan. January 2008 (has links)
<p>The Eastern Antarctic Dry Valley region is a polar desert, where conditions of extreme aridity, high temperature fluctuations and high irradiation levels make it one of the most extreme environments on earth. Despite the harsh environment, the soils in this region yield a wide range of bacterial and eukaryotic phylotypes in greater abundance than previously believed. In the Dry Valleys, highly localized niche communities colonise the underside of translucent quartz rocks and present macroscopic growth.</p>
39

Paleoenvironmental Interpretations of the Lower Taylor Group, Olympus Range area, southern Victoria Land, Antarctica

Gilmer, Greer Jessie January 2008 (has links)
The Devonian Taylor Group, in the Olympus Range area, southern Victoria Land (SVL), Antarctica, is separated from the basement by a regional nonconformity (Kukri Erosion Surface). A second localized unconformity within the Taylor Group called the Heimdall Erosion Surface separates the New Mountain Sandstone and older units from the younger Altar Mountain Formation. The depositional environment of the New Mountain Sandstone has long been under contention. The New Mountain Sandstone Formation is a predominantly quartzose cross-bedded sandstone. Its newly defined Mt Jason Member is a coarse arkosic small scale cross-bedded pebbly sandstone that grades up section into the rest of the quartzose New Mountain Sandstone with large scale cross beds. The New Mountain Sandstone has been divided into five lithofacies including the Basal Conglomerate Lithofacies, Pebbly Sandstone Lithofacies, Granule Cross-bedded Lithofacies, Pinstripe Cross-bedded Lithofacies and Cross-bedded Sandstone Lithofacies. Deposition was in a shoreface environment with minor coastal aeolian deposition. The environment changed from upper shoreface to lower shoreface up section, forming transgressive to highstand systems tracts. The Heimdall Erosion Surface truncates the Cross-bedded Sandstone Lithofacies and the Pinstripe Cross-bedded Lithofacies and was formed due to relative sea level fall leading to exposure and erosion of underlying sedimentary and basement rocks. It forms a type 1 sequence boundary. The New Mountain Sandstone was partially or totally lithified before erosion as shown by the jagged morphology of the eroded cross beds on the surface. It is not known when cementation of the NMS took place or how much of the formation has been eroded. The Heimdall Erosion Surface and Kukri Erosion Surface converge locally due to erosion on the Heimdall Erosion Surface and relief on the Kukri Erosion Surface. The Heimdall Erosion Surface became a shore platform and the site of deposition as relative sea level rose. The Altar Mountain Formation with its Odin Member is a cross-bedded, massive and bedded feldspathic and quartzose sandstone that fines up section and is deposited on the erosion surface. The Altar Mountain Formation is divided into four lithofacies including the Conglomerate Lithofacies, Trough Cross-bedded Lithofacies, Cross-bedded Bioturbated Lithofacies and Bedded Fine Lithofacies. Deposition was in a shoreface environment, changing up section to an inner shelf environment with minor estuarine/tidal influence near the top of the section forming transgressive to highstand to regressive system tracts. The sedimentary rocks are derived mainly from the Granite Harbour Intrusives and Koettlitz Group, which underlie the sandstones, but were exposed elsewhere in SVL. The sandstone clasts within the Conglomerate Lithofacies could be derived from underlying older Taylor Group rocks or exotic sources from outside the field area. Correlation with data from adjacent areas suggests deposition of the New Mountain Sandstone occurred in a shallow sea that existed from the Olympus Range, southwards into the Asgard Range and included Vashka Crag. The area around Sponsors Peak and to the north was exposed and supplying feldspathic and quartzose sediment and pebbles into the depositional basin. As relative sea level fell due to either tectonic uplift or eustatic processes a large area of southern Victoria Land was exposed including the Olympus and Asgard Ranges and Bull Pass-St Johns Range area. This lead to erosion of the New Mountain Formation and basement rocks. Deposition of the New Mountain Sandstone continued further south shown by the gradational contact between it and the overlying Altar Mountain Formation. Relative sea level rise led to deposition of the Altar Mountain Formation. Shallow seas once more dominated the southern Victoria Land with deltas in the east (in the Bull Pass-St Johns Range area) feeding feldspathic sediment into the depositional basin (Odin Member). Further sea level rise drowned the delta region and a shallow marine to inner shelf environment led to deposition of the rest of the Altar Mountain Formation.
40

Rossby adjustment over canyons

Chen, Xiaoyang. January 1996 (has links)
Thesis (Ph. D.)--University of British Columbia, 1996. / Includes bibliographical references (leaves 260-262).

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