Physical Sciences and Mathematics Commons^™

Experimental Investigation Of Snapover: The Sudden Increase Of Plasma Current Drawn To A Positively Biased Conductor When Surrounded By A Dielectric, Clint D. Thomson

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Snapover is particularly relevant to Earth-orbiting spacecraft powered by high-voltage solar arrays. During snapover, the current collected by a positively biased conductor that is immersed in a plasma suddenly increases when two conditions are met: i) there is an immediately adjacent insulator; ii) the conductor exceeds a positive threshold voltage with respect to the plasma. The enhanced current develops as a consequence of the insulator, either through secondary electron (SE) emission or by material ionization. Experiments were performed to examine snapover onset potential and current collection dependence on conductor and insulator materials, conductor size and shape, sample history, biasing rate, …

Effects Of High Ammonium/Nitrate Ratios On Nitrification And Growth Of Wheat In Hydroponics, Dawn J. Muhlestein

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Nitrogen is the only plant nutrient taken up as both a cation (NH₄⁺) and anion (NO₃^-). Nitrate is considered the "safe" form of N and NH/ is generally thought to be toxic, especially at high levels. High NH₄⁺/NO₃^- ratios are thought to be toxic because they result in a rhizosphere pH low enough to damage root membranes, induced cation deficiencies, and build-up of NH3 caused by delayed NH/ assimilation. These factors can be minimized in hydroponic culture. The objective of these studies was to quantify the effects of high …

Climatology Of Upper Thermospheric Daytime Neutral Winds From Satellite Observations, John T. Emmert

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

We studied the global climatology of mid- and low-latitude F region daytime neutral winds using extensive measurements by the Wind Imaging Interferometer (WINDII) instrument on board the Upper Atmosphere Research Satellite (UARS). Quiet-time winds are mostly poleward and westward during the day, and are generally 5-20 m/s smaller in the longitudinal sector closest to the magnetic pole, compared to longitudinally averaged winds. The pre-noon zonal winds are less westward with increasing solar flux, while the post-noon meridional winds are less poleward. Our quiet-time results are in good agreement with the NCAR Thermosphere-Ionosphere- Electrodynamics General Circulation Model (TIEGCM).

We computed residual …

Effectiveness Of Earthen Escape Ramps In Reducing Big Game Mortality In Utah, Mary L. Hammer

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

One-way escape gates and earthen escape ramps are structures used to enable deer to exit the highway right-of-way along fenced roads. I compared the use of one-way escape gates and earthen escape ramps by mule deer on two highways in Utah to determine if deer exhibited a preference for either structure. Results showed that earthen escape ramps were used by mule deer 8-11 times more frequently than one-way gates. Highway mortality data suggest that the installation of the escape ramps likely reduced mortality of mule deer in both study locations, because we could not attribute reductions in mortality to decreased …

Intensification In A Risky Environment: The Case Of Improving Private Grazing Land For Beef Production In Utah, Louise D. Sainsbury

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Utah ranchers commonly face risks to their livelihoods. The objective of this work was to determine if ranchers could make profitable improvements to private land forage given the combined threat of low beef prices, drought, and possible loss of public grazing.

We used linear programming (LINDO) to identify the most profitable solutions for private land investment with an 11-year simulation. Operations were divided into small, medium, and large size classes. Various forage improvements and public permits were options. Two phases of a beef price cycle (peak and trough) and 2 precipitation patterns (wet and drought) were combined as joint favorable …

Ecology Of Treeline Whitebark Pine (Pinus Albicaulis) Populations In Central Idaho: Successional Status, Recruitment, And Mortality, And A Spring Temperature Reconstruction From Whitebark Pine Tree Rings, Dana Lee Perkins

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

This research investigated the successional status of treeline whitebark pine (Pinus albicaulis) populations on 14 stands in central Idaho and used empirical statistical models to determine the principal factors affecting recruitment and mortality. The longest lived whitebark pines from four additional high-elevation sites were used to develop a tree-ring chronology to reconstruct over 1,000 years of average April-May temperature.

The assessment of stand structures using size-frequency distributions generally provides evidence that treeline whitebark pine populations are currently self-sustaining in areas of low to nonexistent incidence of white pine blister rust (Cronartium ribicola). However the presence of …

Structural And Geochemical Analyses Of Disseminated-Gold Deposits, Bald Mountain-Alligator Ridge District, Nevada: Insights Into Fault-Zone Architecture And Its Effect On Mineralization, K. Jill Hammond

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Structural and geochemical analyses of the Top and Casino deposits, Bald Mountain-Alligator Ridge district, Nevada, were conducted to determine how structures affected gold deposition in Carlin-type deposit s. We also examined how permeability changed over time in a fault that cuts siltstone-dominated sedimentary rocks. The association of gold and related arsenic with faults at the margins of a Jurassic pluton and sedimentary rocks suggests that ore fluids migrated along faults and fracture s. Permeability of the faults changed over time within the Casino deposit, where the ore-controlling fault was a distributed conduit in the early stages of mineralization but a …

The Efficacy Of Plant Residue Degradation Products On Phosphorus, Iron, Iodine, And Fluorine Bioavailability To Plants, Cheryl L. Mackowiak

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Plant and animal wastes degrade in soils to form relatively stable humified compounds, which form ion complexes that affect the bioavailability of elements in the soil solution. Hydroponic studies with wheat and rice were conducted to characterize the effect of humic acid (HA) on phosphorus (P), iron (Fe), fluorine (F), and iodine (I) bioavailability. Ferrihydrite [Fe(OH)₃] precipitation was greater on root surfaces without HA or synthetic chelates. Oxides such as ferrihydrite strongly adsorb P and provide exchange sites for metals. HA reduced this precipitate and increased P and Fe uptake.

Humic acid had no effect on F toxicity …

Structural Analysis And A Kink Band Model For The Formation Of The Gemini Fault Zone, An Exhumed Left-Lateral Strike Slip Fault Zone In The Central Sierra Nevada, California, Matthew A. Pachell

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The structure and regional tectonic setting of an exhumed, 9.3-km long, left-lateral strike-slip fault zone eludicates processes of growth, linkage, and termination for strike-slip fault zones in granitic rocks. The Gemini fault zone is composed of three steeply dipping, southwest-striking, noncoplanar segments that nucleated and grew along preexisting joints. The fault zone has a maximum slip of 131 m and is an example of a segmented, hard-linked fault zone in which geometrical complexities of the faults and compositional variations of protolith and host rock resulted in nonuniform slip orientations, complex interactions at fault segments, and an asymmetric slip-distance profile. Regional …

Rotational Structure Of Extremely Floppy Van Der Waals Complexes: Adiabatic Separation Of Angular And Radial Motion, P. Daniel Ward

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The adiabatic or Born-Oppenheimer approximation is often used in molecular calculations to simplify the solution to the Schrödinger equation. The basis of the approximation is the large difference in the relative motions of the nuclei and electrons in the molecule—the electrons are able to respond almost instantly to the movements of the nuclei. Thus, the nuclei may be regarded as being fixed in a certain position and the Schrödinger equation can then be solved using the potential obtained by solving the electronic problem at fixed nuclear configuration.

A similar argument can be used to decouple the angular and radial motions …

Comparing Nonlinear And Nonparametric Modeling Techniques For Mapping And Stratification In Forest Inventories Of The Interior Western Usa, Gretchen Gengenbach Moisen

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Recent emphasis has been placed on merging regional forest inventory data with satellite-based information both to improve the efficiency of estimates of population totals, and to produce regional maps of forest variables. There are numerous ways in which forest class and structure variables may be modeled as functions of remotely sensed variables, yet surprisingly little work has been directed at surveying modem statistical techniques to determine which tools are best suited to the tasks given multiple objectives and logistical constraints. Here, a series of analyses to compare nonlinear and nonparametric modeling techniques for mapping a variety of forest variables, and …

Positive Solutions Obtained As Local Minima Via Symmetries, For Nonlinear Elliptic Equations, Florin Catrina

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

In this dissertation, we establish existence and multiplicity of positive solutions for semilinear elliptic equations with subcritical and critical nonlinearities. We treat problems invariant under subgroups of the orthogonal group. Roughly speaking, we prove that if enough "mass " is concentrated around special orbits, then among the functions with prescribed symmetry, there is a solution for the original problem.

Our results can be regarded as a further development of the work of Z.-Q. Wang, where existence of local minima in the space of symmetric functions was studied for the Schrödinger equation. We illustrate the general theory with three examples, all …

A New Perspective On Classification, Guohua Zhao

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The idea of voting multiple decision rules was introduced in to statistics by Breiman. He used bootstrap samples to build different decision rules, and then aggregated them by majority voting (bagging). In regression, bagging gives improved predictors by reducing the variance (random variation), while keeping the bias (systematic error) the same. Breiman introduced the idea of bias and variance for classification to explain how bagging works. However, Friedman showed that for the two-class situation, bias and variance influence the classification error in a very different way than they do in the regression case.

In the first part of …

Theoretical Studies Of Penetration Of Magnetospheric Electric Fields To The Ionosphere, Stanislav Sazykin

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Ionospheric disturbance electric fields of magnetospheric origin play an important role in determining the global morphology and dynamics of the ionosphere of the Earth. In this work, we present a number of numerical simulations of the transient electric fields in the middle and inner magnetosphere and the ionosphere equatorward of the auroral zone caused by idealized changes in the magnetospheric driving parameters. For these studies, we use the Rice Convection Model (RCM), a large computer code of the magnetosphere-ionosphere coupling which consistently computes the electric fields, currents, and plasma densities in the magnetosphere and the electric field and currents in …

Studies On The Roles Of Atp In Nitrogenase Catalysis, Wei Wu

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Nitrogenase is the enzyme that catalyzes the reduction of nitrogen to ammonia in a reaction requiring MgATP hydrolysis. Two component proteins of nitrogenase are the iron protein (Fe protein) and the molybdenum-iron protein (MoFe protein).

Nitrogenase contains two nucleotide binding sites. During catalysis, the Fe protein binds two MgATP first. The conformational changes induced upon MgATP binding allow the Fe protein to associate with the MoFe protein. After the formation of the Fe protein-MoFe protein complex, a single electron is transferred from the Fe protein to the MoFe protein, an event that is coupled to MgATP hydrolysis in the Fe …

Responses Of Sphagnum And Carex Peatlands To Ultraviolet-B Radiation, And A Meta-Analysis Of Uv-B Effects On Vascular Plants, Peter S. Searles

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The severity of stratospheric ozone depletion in the temperate and polar latitudes has raised concerns about the sensitivity of terrestrial vegetation and ecosystems to solar ultraviolet (UV-B) radiation. This dissertation examined the responses of plants and microbes to solar UV-B for 3 years in Tierra del Fuego, Argentina (55° S). This region is under the influence of the Antarctic "ozone hole" during the austral spring. Additionally, a quantitative review of the UV-B literature was conducted using a set of statistical techniques known as meta-analysis.

For the field studies in Tierra del Fuego, plots were established in a Sphagnum moss peatland …

Debris-Flow Activity In Canyon Of Lodore, Colorado: Implications For Debris-Fan Formation And Evolution, Jennifer A. Martin

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Large-scale characteristics of Ladore Canyon debris fans are dependent upon the bedrock and lithology of the mainstem and tributary canyons. The largest fans occur in the widest section of the mainstem canyon, which typically correlates with the location of large faults. The steepest fans are found at the mouths of tributaries where cliffs are formed by resistant lithologies. Smaller-scale fan characteristics are dependent upon the magnitude and frequency of events from the respective drainage basin, which is controlled primarily by climate. Three distinct deposit ages (oldest, intermediate, youngest) were distinguished on individual fans and were tentatively correlated throughout the canyon …

Mean-Square Error Bounds And Perfect Sampling For Conditional Coding, Xiangchen Cui

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

In this dissertation, new theoretical results are obtained for bounding convergence and mean-square error in conditional coding. Further new statistical methods for the practical application of conditional coding are developed.

Criteria for the uniform convergence are first examined. Conditional coding Markov chains are aperiodic, π-irreducible, and Harris recurrent. By applying the general theories of uniform ergodicity of Markov chains on general state space, one can conclude that conditional coding Markov chains are uniformly ergodic and further, theoretical convergence rates based on Doeblin's condition can be found.

Conditional coding Markov chains can be also viewed as having finite state space. …

The Sequence Stratigraphy Of The Middle Cambrian Wheeler Formation In The Drum Mountains Of West Central Utah, Loren P. Schneider

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The majority of the Middle Cambrian Wheeler Formation in the Drum Mountains was deposited during a single 3^rd order sequence. Superimposed onto this sequence are three indistinct 4^th order cycles and twenty distinct 5^th order cycles. These higher order cycles were likely deposited within short intervals of geologic time (204 to 405 ky).

The lower sequence boundary zone occurs within the Swasey Formation. The Transgressive Surface is the contact between the Swasey and Wheeler Formations. The Maximum Flooding Surface is located near the top of the lower Wheeler Formation, which also approximates the base of the Ptychagnostus …

Holocene Tephrostratigraphy, Southern Kenai Peninsula, Lower Cook Inlet, Alaska, Kathleen J. Lemke

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

This thesis describes the results of a study of 33 tephra layers found within two peat sections near Anchor Point and Homer, Alaska, on the lower Kenai Peninsula. Numerous lower Cook Inlet volcanoes have been active through the Holocene. Tephra layers found at these two sites provide a partial record of their eruptive activity. The hazards that accompany this activity have increased as populations and commercial activities expand and air traffic over the region increases. The tephras analyzed for this study provide an initial geochemical database for the lower Cook Inlet volcanoes. The database is available in electronic format at …

Late Quaternary Glacier Fluctuations And Vegetation Change In The Northwestern Ahklun Mountains, Southwestern Alaska, Yarrow L. Axford

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

This research examines moraine and lacustrine records of glacier fluctuations, in combination with palynological records of vegetation change, from the previously unstudied northwestern Ahklun Mountains in southwestern Alaska.

Moraine mapping reveals that ice-cap outlet glaciers in the study area extended ca. 60 km from the center of the Ahklun Mountians ice dome during the early Wisconsin (sensu lato), and ca. 40 km during the late Wisconsin. Correlations with well-studied moraines in the southern Ahklun Mountains indicate an asymmetry of glaciation over the range, with ice-cap outlet glaciers more extensive to the south. This asymmetry was more striking during …

Sequence Stratigraphy And Paleoecology Of The Middle Cambrian Spence Shale Member Of The Langston Formation Of Northeastern Utah And Southeastern Idaho, Scott H. Wright

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The Middle Cambrian Spence Shale Member contains meter-scale, shallowing-up cycles (parasequences) and record approximately 360 ky of deposition. These meter-scale cycles are nested within transgressive systems tracts (TST) and highstand systems tracts (HST) which reflect different stages of a lower-order, higher-magnitude sea-level excursion.

Fossil assemblages are located in stratigraphic positions within the Spence Shale Member that can be predicted on the basis of sequence architecture. The cycle architecture, taphonomy, and geochemistry of the Spence parasequences confirm synthetic sections and theoretical models of meter-scale cycles developed in other studies. Delineation of meter-scale cycles, based on taphonomic and sedimentologic criteria, allows high-resolution …

Investigation Of The Determinants Of African Savanna Vegetation Distribution: A Case Study From The Lower Omo Basin, Ethiopia, Catherine A. Schloeder

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The Ethiopian Wildlife Conservation Organization has little information on the extent and ecological determinants of plant species composition and distribution in Omo National Park. Elsewhere, the determinants of African savanna vegetation dynamics have been the focus of numerous investigations, yet our understanding of the hierarchical nature and relative importance of any relationships remains very general. As well, our ability to derive predictions about vegetation responses is limited to extreme generalizations. African savanna landscape ecotones have received even less attention than most landscapes. In this dissertation, I test hypotheses about plant species distribution-determinant relationships in Omo National Park, a park that …

Ultraviolet-B Radiation: Effects On Pollen Of 34 Taxa, And Inheritance Patterns And Carryover Of Radiation Response In Arabidopsis, Javad Torabinejad

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Although considerable research has addressed effects of elevated ultraviolet-B (UV-8) radiation on vegetative plant structures and processes, the reproductive biology and patterns of inheritance of UV-B tolerance have received much less attention. I examined the effects of UV-B radiation on pollen of 34 taxa. I also addressed questions concerning the patterns of inheritance of UV-B tolerance in Arabidopsis thaliana and examined potential cumulative carryover effects of UV-B exposure through multiple generations of this species.

In the first study, a significant reduction in pollen germination occurred in only five species, but pollen tube growth in more than half of the species …

Tertiary Stratigraphy And Structural Geology, Wellsville Mountains To Junction Hills, North-Central Utah, Kathryn M. Goessel

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

This study integrates detailed mapping of Tertiary deposits along the divide between the lower Bear River basin and the Cache Valley basin with several other techniques to generate a depositional model, define extension-related structures, and compile a geologic history for this part of the northeastern Basin and Range province. The study area is situated along the topographic divide between Box Elder and Cache Counties, Utah, from the Wellsville Mountains north almost to Clarkston Mountain. These ranges are cored by folded and thrusted Paleozoic rocks. They are bound on the west by normal faults of the Wasatch fault zone and on …

A Social Analysis Of Grazing Management On National Forest Lands: A Case Study In Catron County, New Mexico, Alexis S. Watts

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The rural west in this country faces increased national pressure concerning the management of natural resources on public lands. Issues regarding natural resource management are becoming more important as they continue to affect rural communities and capture the attention of a variety of interest groups. Natural resource managers are increasingly required to consider social dimensions of resource use and management. Lack of consideration in these areas can lead to dissatisfied, and even hostile, local residents and interest groups. Often land managers face criticism from many groups at once as a result of management decisions.

This study analyzed a particular resource …

The Role Of Iron And Reactive Oxygen Species In Particulate Air Pollution-Dependent Biochemical And Biological Activities, Kevin Richard Smith

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Particulate air pollution is known to exacerbate respiratory diseases, such as asthma and chronic obstructive pulmonary disease, in humans. It has been proposed that transition meta ls from inhaled particles may play a role in this exacerbation by generating radical species leading to damage in the lungs.

The aim of this research was to determine the role that iron from particulate air pollution played in the generation of reactive oxygen species and subsequently the induction of inflammatory mediators in cells in culture. The production of reactive oxygen species by particulate air pollution was found to be dependent on the mobilization …

Vessiot: A Maple Package For Varational And Tensor Calculus In Multiple Coordinate Frames, Charles E. Miller

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The Maple V package Vessiot is an extensive set of procedures for performing computations in variational and tensor calculus. Vessiot is an extension of a previous package, Helmholtz, which was written by Cinnamon Hillyard for performing operations in the calculus of variations. The original set of commands included standard operators on differential forms, Euler-Lagrange operators, the Lie bracket operator, Lie derivatives, and homotopy operators. These capabilities are preserved in Vessiot, and enhanced so as to function in a multiple coordinate frame context. In addition, a substantial number of general tensor operations have been added to the package. These include standard …

Construction And Analysis Of A Family Of Numerical Methods For Hyperbolic Conservation Laws With Stiff Source Terms, Cinnamon Hillyard

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Numerical schemes for the partial differential equations used to characterize stiffly forced conservation laws are constructed and analyzed. Partial differential equations of this form are found in many physical applications including modeling gas dynamics, fluid flow, and combustion. Many difficulties arise when trying to approximate solutions to stiffly forced conservation laws numerically. Some of these numerical difficulties are investigated.

A new class of numerical schemes is developed to overcome some of these problems. The numerical schemes are constructed using an infinite sequence of conservation laws.

Restrictions are given on the schemes that guarantee they maintain a uniform bound and satisfy …

Prediction Of Suburban Encroachment On The Ethan Allen Firing Range And Camp Johnson, Chittenden County, Vermont, John D. Calandrelli

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Suburban encroachment is a growing concern for many National Guard training installations. The Ethan Allen. Firing Range and Camp Johnson, Vermont, are either experiencing or are completely enclosed by urban encroachment. The objective of this study was to analyze the trends of suburban growth within Chittenden County, Vermont, to evaluate growth and explore future training site viability of the Ethan Allen Firing Range and Camp Johnson.

This study focused on historical data, recent real estate transactions, population projections, and county plans for growth. Using historical and contemporary data, I developed a predictive model of suburban encroachment on Camp Johnson and …