Physical Sciences and Mathematics Commons^™

The Power Law Distribution Of Agricultural Land Size, Lauren Chamberlain

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

This paper demonstrates that the distribution of county level agricultural land size in the United States is best described by a power-law distribution, a distribution that displays extremely heavy tails. This indicates that the majority of farmland exists in the upper tail. Our analysis indicates that the top 5% of agricultural counties account for about 25% of agricultural land between 1997-2012. The power-law distribution of farm size has important implications for the design of more efficient regional and national agricultural policies as counties close to the mean account for little of the cumulative distribution of total agricultural land. This has …

Humans As Sensors: The Influence Of Extreme Heat Vulnerability Factors On Risk Perceptions Across The Contiguous United States, Forrest Scott Schoessow

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Extreme heat events are the deadliest natural hazard in the United States and will continue to get worse in the coming years due to the effects of climate change. As a result, more people will experience deadly heat conditions. This highlights the need for decision-makers to develop better strategies for preventing future losses. How badly individuals are affected by extreme heat depends on many circumstances, such as how high temperatures actually are, weather conditions, and location. For example, a dry 90 °F day in Phoenix is probably more tolerable than a humid 90 °F day in New Orleans for most …

Factors Influencing The Distribution Of Brown Trout (Salmo Trutta) In A Mountain Stream: Implications For Brown Trout Invasion Success, Christy Meredith

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Brown trout (Salmo trutta), one of the world’s most successful introduced species in river and lake systems, negatively impacts native species through predation, competition, and systemwide effects. Thus, there is a need to understand factors controlling the distribution of brown trout, in order to prioritize and develop conservation and management strategies. Within the context of invasion success, I investigated how the physical characteristics of the Logan River influence the distribution of brown trout, as well as the potential for brown trout predation on a native fish, the mottled sculpin (Cottus bairdi).

In chapter 1, I evaluated …

Individualistic Response Of Piñon And Juniper Tree Species Distributions To Climate Change In North America's Arid Interior West, Jacob R. Gibson

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Piñon and juniper tree species have species-specific climatic requirements, resulting in unique distributions and differential responses to climate change. Piñons and junipers co-dominate the arid woodlands of North America as groups with widespread hybridization. Two piñons, Pinus edulis; P. monophylla, and four junipers, Juniperus deppeana var. deppeana; J. monosperma; J. occidentalis; J. osteosperma, are endemic to the midlatitude interior west and form three groups of hybridizing sister species, P. edulis-P. monophylla; J. deppeana var. deppeana-J. monosperma; J. occidentalis-J. osteosperma. Recent droughts have caused widespread mortality among piñons, but have had less impact on …

The Influence Of Redd Distribution And Microhabitat Availability On The Distribution And Abundance Of Young-Of-The-Year Trout In The Green River, Utah, Michael J. Buntjer

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Redd distribution, redd density, and physical habitat were used to explain the distribution and abundance of young-of-the-year (YOY) brown trout (Salmo trutta) and rainbow trout (Oncorhynchus mykiss) in the Green River, Utah. The importance of variables at both a microhabitat and macrohabitat scale were assessed using stepwise regression analysis. Availability of cover (rock and vegetation) and proximity to spawning sites were the most important variables used to explain the distribution and abundance of YOY brown trout and rainbow trout. In addition, YOY brown trout and rainbow trout occupied specific microhabitats and showed patterns of use for …

Probability Of Discrete Failures, Weibull Distribution, Mary Jo Hansen

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The intent of this research and these is to describe the development of a series of charts and tables that provide the individual and cumulative probabilities of failure applying to the Weibull statistical distribution. The mathematical relationships are developed and the computer programs are described for deterministic and Monte Carlo models that compute and verify the results. Charts and tables reflecting the probabilities of failure for a selected set of parameters of the Weibull distribution functions are provided.

Least Squares Estimation Of The Pareto Type I And Ii Distribution, Ching-Hua Chien

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The estimation of the Pareto distribution can be computationally expensive and the method is badly biased. In this work, an improved Least Squares derivation is used and the estimation will be less biased. Numerical examples and figures are provided so that one may observe the solution more clearly. Furthermore, by varying the different methods of estimation, a comparing of the estimators of the parameters is given. The improved Least Squares derivation is confidently employed for it is economic and efficient.

The Transport And Intracellular Distribution Of Iron In The Basidiomycete, Ustilago Sphaerogena, Charles W. Passavant

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The transport and intracellular distribution of iron in Ustilago sphaerogena via the native siderochrome ferrichrome A has been examined. Evidence is presented which suggests the involvement of deferriferrichrome in iron transport when the metal is supplied to the cell as ferrichrome A. This process requires both oxygen and ATP synthesis and may require a transmembrane electrochemical gradient. Once inside the cell, iron derived from ferrichrome A is rapidly distributed, with a major fraction found in the mitochondria, presumably as heme.

The kinetics of ferrichrome and ferrichrome A uptake have also been investigated. The Km of transport of ferrichrome was …

Extreme Value Distribution In Hydrology, Bill (Tzeng-Lwen) Chen

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The problems encountered when empirical fit is used as the sole criterion for choosing a distribution to represent annual flood data are discussed. Some theoretical direction is needed for this choice. Extreme value theory is established as a viable tool for analyzing annual flood data. Extreme value distributions have been used in previous analyses of flood data. However, no systematic investigation of the theory has previously been applied. Properties of the extreme value distributions are examined. The most appropriate distribution for flood data has not previously been fit to such data. The fit of the chosen extreme value distribution compares …

Model For Predicting Simultaneous Distribution Of Salt And Water In Soils, Satish C. Gupta

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Knowledge of water and salt movement in soils is necessary for development of a management scheme for controlling the quality of irrigation return flow. A computer model was developed to predict the distribution of water and salts in the root zone under varying initial and boundary conditions. The model consists of water flow and salt flow sub-models. The water flow sub-model considers the numerical approximation of the general water flow equation with modification for water loss by evapotranspiration (and thus root extraction). The salt flow sub-model considers the mass flow of salts, chemical exchange, precipitation or dissolution of CaCO_{3 …}