Digital Commons Network^™

Mechanical And Physical Properties Of Spider Silk Films Made From Organic And Water-Based Dopes, Chauncey Lewis Tucker

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Spider silk has become a popular material due to its exceptional mechanical and biocompatibility properties. The project team has developed methods of producing and improving the properties of synthetic spider silk films. Other groups have been able to produce similar films having less than impressive mechanical properties using a toxic solvent. The spider silk team here at Utah State University has developed a new way of processing these films to more than triple their mechanical properties and has created a novel form of spider silk films produced from a water-based liquid, making it less expensive, more environmentally friendly, and more …

Global Evaluation Of Biofuel Potential From Microalgae, Jeffrey W. Moody

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The objective of the proposed work is to determine the productivity potential of microalgae around the world based on the current large uncertainty of the productivity
potential found in literature. To achieve this objective, a validated thermal and biological growth model was utilized coupled with weather data files from weather stations around the world. This enabled a realistic assessment of the productivity potential based on actual climatic variables. Sensitivity of microalgae lipid productivity to biomass production, temperature, and variability was performed illustrating the importance of biological and temporal resolution. Results from modeling work were leveraged for a scalability assessment based …

A Comparison Of Antlions, Bees, Darkling Beetles And Velvet Ants Across Sand Dune And Non-Sand Dune Habitats At Ash Meadows National Wildlife Refuge, Nicole F. Boehme

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Ash Meadows National Wildlife Refuge (AMNWR) supports nearly 30 organisms found nowhere else in the world. Most of these species are aquatic, dwelling in more than 50 seeps and springs within the over 24,000 acres of the refuge. Much of the research at AMNWR has centered on these unique and abundant springfed pools across the desert landscape. Many of the terrestrial habitats and species at the refuge have not been as well studied. In 2008, Bio-West, Inc. in Logan, Utah was contracted to inventory the terrestrial organisms present on the refuge. To investigate the terrestrial invertebrate fauna, with special interest …

Modeling To Improve Vegetation-Based Wetland Biological Assessment, Robin C. Jones

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

To meet the requirements of the Clean Water Act (1972), natural resource managers need to be able to detect biological degradation in wetland ecosystems. Biological indices are commonly used by managers to assess wetland biological condition. The accuracy and precision of wetland condition assessments are directly related to the performance of these indices, and biological index performance is thought to be related to how well an index controls for the effects of environmental attributes on biological assemblages. Many plant-based biological indices control for environmental and biological variation through the use of classification schemes that are based on geographic location and …

Ecomorphological And Genetic Investigations Into The Utah Lake, Ut Sucker Complex With Comparisons To The Jackson Lake, Wy Sucker Complex, David D. Cole

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Natural selection within the sucker family of fishes has produced populations including typical benthic (bottom-feeding) suckers (Catostomus) and lakesuckers (Chasmistes), mid-water plankton eaters, in several large western North American lakes. Suckers of intermediate morphology (shape) exist in a continuum of head, mouth, and body characteristics between these two extremes. All current lakesuckers are listed Endangered, and population declines have been attributed in part to hybridization with their Catostomus neighbors.

Chapter 2 describes the investigation of the relationship between morphology and genetics of June sucker, a lakesucker, and Utah sucker, a benthic sucker, in Utah Lake, Utah. …

Control Of Grid-Connected Photovoltaic Systems Using Fractional Order Operators, Hadi Malek

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

This work presents a new peak seeking strategy for maximum power point operation using fractional order operators in the three-phase grid-connected photovoltaic systems. Moreover, fractional order controllers have been implemented in the voltage and current control loops. The simulation results and theoretical analysis indicate that the proposed fractional order control strategy improves the efficiency of the system by reducing the total harmonic distortion of the injected current to the grid and increases the robustness of the system against uncertainties. Additionally, the proposed maximum power point tracking algorithms provide more robustness and faster convergence speed under environmental variations than other maximum …

A Qualitative Study Of Women High School Principals' Career Life Histories, Jan Bradshaw Hansen

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Gender inequalities in the workplace continue to plague aspiring career-directed women. In public education, it is established that there are fewer women high school principals than there are men. In a profession predominantly employing women, the question remains, “Where are the women high school administrators”? This study examines the sociopolitical genders systems and psychological dynamics that perpetuate gender inequality. It then discusses the encumbered or constrained choices women make that are burdened or made more complicated by gendered sociopolitical or psychological dynamics. This study explored the unintentional career journeys of seven women high school principals and analyzed their career life …

Gravitational Wave Astrophysics With Compact Binary Systems, Eric Addison

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Gravitational waves are ripples in the fabric of spacetime that convey information about changing gravitational fields. Large-scale detection projects are currently in operation, and more advanced detectors are being designed and built. Though we have yet to make a direct detection of a gravitational wave signal, upgrades to current detectors are expected to bring the first detections within the next year or two.

Gravitational waves will bring us information about astrophysical phenomena that is complementary to the information gained from photon-based observations (e.g., telescopes and radio receivers). One of the primary sources of gravitational waves are binary systems: two massive …

The Functional Role Of Cd36 Involved In Fatty Acid Transduction, Han Xu

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

As one of the most epidemic health concerns in the world, obesity has become a widespread health issue especially for the developed world. It is related to various health conditions including heart disease, type 2 diabetes and certain types of cancer. It is also quite costly. In United States alone, the medical cost of obesity in 2008 was estimated to be $147 billion. Many underlying mechanisms of obesity have been studied in the past few decades. However, the most prevalent cause appears to be simply an imbalance of energy intake and expenditure, resulting in the accumulation of body fat. On …

The Role Of Trpm5 In Dietary Fat Preference, Intake, And Body Composition, Dulce M. Minaya

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

We recently showed a critical role of Trpm5 in the transduction pathway for long chain polyunsaturated fatty acids. In the present study, I have begun to investigate dietary fat preference and the propensity to develop dietary-induced obesity in Trpm5^-/- mice. My preliminary data shows that in male mice placed on a high fat diet, Trpm5^-/- mice did not enhance their caloric intake as observed in wild type mice. Most surprisingly, however, was that I did not observe the same differences in between female mice, which posits a potential gender effect of this pathway on dietary fat intake. Also, …

Assessing Changes In Waterfowl Population And Community Dynamics, Beth E. Ross

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Studying long-term ecological studies can help ecologists understand what causes populations and communities of wildlife to change. Understanding these causes can help guide conservation efforts. Additionally, results from long-term datasets allow ecologists to predict how populations may shift with global change. Ecologists can then determine necessary management action to maintain sustainable populations in the future. However, there can be a large amount of “noise” in a long-term dataset. If ecologists fail to account for this noise, they may make incorrect management decisions. For example, samples taken in two nearby locations will likely be more similar than samples taken from two …

An Evaluation Of The Food Web Dynamics And Predator Prey Interactions In Scofield Reservoir, Lisa K. Winters

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Reservoirs are artificial, dynamic, and highly manipulated systems, where the appearance of either intentionally or unintentionally introduced species may disrupt interactions within an already complex food web. In some situations, a top predator fish may be stocked as a biological control agent, if these fish-eating predators monopolize on the nuisance and unwelcome prey. Scofield Reservoir, Utah has historically been an extremely popular blue-ribbon fishery. However, a recent decrease in rainbow trout catch and increase in the minnow, Utah chub, have made it difficult to find a balance between providing the public with a trophy sport fishery and maintaining an ecologically …

Parental Perceptions Of The Influence Of Digital Media And Technology On Children's Reading Habits At Home, Kurt W. Johnson

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

This study explored how parents from six participating families in Northern Utah felt about the influence of technology and media on their children’s reading at home. Each family was interviewed about their feelings, filled out a survey about the amount of technology devices in the home, and took photographs of the areas in the home where their children read or used technology. Additionally, each family kept a journal recording the technology and reading activities their children participated in over a 1-week period

Parents talked about how their childhood experiences influenced them to create rules for technology and as well as …

Quantum Mechanical Study Of Weak Molecular Interactions, Upendra Adhikari

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Molecular interactions play key role in the existence of biomolecules like proteins and nucleic acids, and various materials. Molecular interactions are weak forces that hold different molecules or different fragments of the same molecule together, and are often referred to as noncovalent interactions. Due to the complexity in biomolecules, these interactions are still poorly understood. This dissertation presents results from quantum mechanical simulations of various types of noncovalent interactions, which are extremely important for the structure and functions of biomolecules and materials.

A new sort of noncovalent interaction is identified. This new sort of interaction originates from a direct interaction …

Three Essays On The Economics Of Controlling Invasive Species, Yanxu Liu

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Invasive species have caused notable economic damages in agriculture, fisheries, forestry, and other industries over the past several decades. Invasive species control must therefore be designed to prevent the both the introduction and spread of invasive species. This dissertation examines the efficiency and efficacy of tariffs and inspections as a joint control mechanism at a home (i.e., importing) country's border. I find that a traditional tariff can be optimal in the short run when the invasive species level is directly related to a foreign (i.e., exporting) country's shipment size. However, in the long run a traditional tariff results in a …

Excimer-Monomer Switching Molecular Beacon: The Study On Synthetic Cryptosporidium Dna Detection, Thermodynamics, And Magnesium Effects, Michael L. Davis

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The purpose of this study is to quantify and determine the binding of a molecular DNA probe or molecular beacon used in the detection of a known waterborne pathogen Cryptosporidium parvum. The objectives of this study are to determine the stability, sensitivity, and selectivity of the molecular beacon in detecting synthesized Cryptosporidium DNA sequences. The designed probe is based on a two-fluorophore system that is different than similar molecular beacons that utilize a fluorophore and quencher detection method. A comparative study between the two probes was also performed to demonstrate enhanced selectivity of the fluorophore based molecular beacon. Magnesium …

Macroinvertebrate-Driven Nutrient Recycling In Four Large Rivers, Matt A. Schroer

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The cycling of nutrients is a fundamental process in streams and rivers, and scientists are increasingly recognizing the importance of animal communities to nutrient dynamics in these ecosystems. Despite growing evidence that animal excretion (i.e. urine) can supply limiting nutrients to primary producers in small streams, the importance of excretion is uncertain in large rivers. Accordingly, I used three estimation approaches based on past and new excretion rate data to determine nitrogen (N) and phosphorus (P) excretion inputs from insect communities in four large rivers (discharge > 10 cubic meters per second) in North America, and I compared these rates to …

Are Experimentally Derived Estimates Of Thermal Tolerance Useful In Interpreting Species Distribution Models, Iva Sokolovska

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Species distribution models are frequently used in ecology to predict the spatial and temporal occurrence of organisms. Direct interpretation of these models assumes that the relationships between the organisms and their environment are manifestations of causal mechanisms. However, in general, the mechanisms producing these associations have not been experimentally validated, which questions our confidence in their interpretation and application. Temperature is one of the most important factors influencing the fitness and distribution of aquatic organisms, and studying the thermal physiology of aquatic invertebrates could provide a useful approach for validating predictions of the species distribution models.

Experimental thermal tolerance studies, …

The Ecosystem Role Of Fishes In Lotic Environments, Christopher C. Wheeler

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

It is important for humans to understand how ecosystems work because we depend on them for a variety of products and services. For example, rivers and streams provide fisheries, improved water quality, and recreational opportunities to many individuals. In rivers, interactions among fishes, other stream plants and animals, and the physical river environment can influence continued provision of these valuable services. However, the role played by many freshwater fishes in the provision of these services remains unknown. Additionally, it is important to identify different factors that affect the outcome of interactions involving riverine fishes. To address these issues, I evaluated …

Barriers To Curricular Change In General Education Mathematics At A Large Public Institution, Marcus Jorgensen

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

This qualitative study looked for barriers to curricular change in general education mathematics at a large public university (LPU) in the Western United States. The literature showed that a number of national organizations dealing in math education have recommended alternatives to the traditional algebra-intensive curriculum. LPU still relies predominantly on traditional College Algebra as its quantitative literacy (QL) course. With such an algebra-heavy emphasis, students may be missing more relevant and useful mathematics. In addition, the College Algebra course has a low success rate, which becomes a barrier to student retention and graduation. Interviews were conducted with 14 participants who …

A Quantitative Approach To The Development Of Ecological Sites And State-And-Transition Models, Matthew W. Van Scoyoc

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Changes in land-use and climate can trigger changes in ecosystem conditions and may be driving ecosystems toward undesired “states” that provide inadequate ecosystem services. If these changes are drastic enough, energy intensive restoration programs are necessary to restore ecosystems to previous states. Landscape classification systems based on “ecological potential” offer a robust framework to evaluate and manage ecosystems. The ecological site concept is one such landscape classification system that has been developed by the USDA Natural Resources Conservation Service (NRCS) and describes ecosystems and ecosystem dynamics relative to “reference conditions” and response to disturbance. Ecological sites have gained popularity with …

Weir-Baffled Culvert Hydrodynamics Evaluation For Fish Passage Using Particle Image Velocimetry And Computational Fluid Dynamic Techniques, Mohanad A. Khodier

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Due to a recent increase in environmental awareness regarding fish passage through hydraulic structures, including culverts, an evaluation of passage of wild brown trout through a weir-baffled, prototype-scale culvert, was conducted under a variety of culvert slopes and discharge conditions. The influence of the fish sample population and the lengths of the individual fish on passage rates were investigated. The data showed that the fish sample size of 25 per test was sufficiently large to minimize sample size dependency. Fish behavior, including resting/staging zone locations, while traversing the culvert was observed and reported. Two preferable resting zones for the fish …

Prediction Of Climate Change Effects On Streamflow Regime Important To Stream Ecology, Sulochan Dhungel

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Streamflow is expected to change with climate change, but a general understanding of how climate change will affect the characteristics of streamflow important to stream ecosystems is lacking. This thesis focused on specific characteristics of streamflow, or the streamflow regime, that are important to stream ecosystems. The need to evaluate the potential impacts of climate change on stream ecosystems makes it important to study how streamflow regime may change. This work has identified 16 characteristics of daily streamflow time series that quantify the patterns and span the aspects of streamflow regimes important for stream ecosystems. Principal component analysis objectively identified …

The Effects Of Laser Etching On Biocompatability And Mechanical Properties Of Polyetheretherketone, Andrew I. Deceuster

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Polyetheretherketone (PEEK) is a Federal and Drug Administration (FDA) approved biomaterial that has been used as an orthopedic implant material due to its inherent properties. Laser etching has become a popular means to create identification markers on the individual implants as required by the FDA. The interaction of laser energy with polymeric materials could potentially cause changes in the material's biocompatibility and mechanical properties. The objective of this study was to determine the effect of laser energy on the biocompatibility and mechanical properties of implantable PEEK by measuring contact angle, micro-tensile testing, nite-element modeling (FEM), and biocompatibility testing according to …

The Impact Of Social Support, Psychosocial Characteristics, And Contextual Factors On Racial Disparities In Hypertension, E. Miranda Reiter

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Hypertension is a serious medical condition. Although men and women of all racial groups in the US suffer from high blood pressure, black women have the highest rates of hypertension. For instance, the age-adjusted prevalence of hypertension among black women ages 20 and over is 44.3, compared to 28.1 among white women, 40.5 among black men, and 31.1 among white men.

Past research has focused on SES and behavioral factors as potential explanations for blood pressure disparities between black and white women. But, even after controlling for such factors, considerable disparities remain. The goal of this research is to examine …

Structure And Multi-Center Bonding: From Atomic Clusters To Solid Phase Materials, Timur R. Galeev

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The work presented in this dissertation has been focused on structure, stability, and chemical bonding of atomic clusters and solid-state compounds. The common thread was development of theoretical models and methods capable of interpreting bonding and hence, structures of these species. A major part of this work presents joint experimental and theoretical studies of a large series of doped boron clusters. The dissertation introduces a new theoretical tool for interpretation of bonding of solid phase materials in chemically intuitive terms of localized and multi-center bonds. Understanding how interactions between atoms in sub-nano clusters and solid-state compounds determine their structures, physical …

Computational Models Of Intracellular And Intercellular Processes In Developmental Biology, Ahmadreza Ghaffarizadeh

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Systems biology takes a holistic approach to biological questions as it applies mathematical modeling to link and understand the interaction of components in complex biological systems. Multiscale modeling is the only method that can fully accomplish this aim. Mutliscale models consider processes at different levels that are coupled within the modeling framework. A first requirement in creating such models is a clear understanding of processes that operate at each level. This research focuses on modeling aspects of biological development as a complex process that occurs at many scales. Two of these scales were considered in this work: cellular differentiation, the …

Expert Vs. Novice: Problem Decomposition/Recomposition In Engineering Design, Ting Song

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The purpose of this research was to investigate the design behavior. A commonly used design strategy called “problem decomposition and recomposition” was the focus of the study. Dyads of engineering experts, dyads of engineering seniors, and dyads of engineering freshmen completed an engineering design challenge within an hour. The entire design process was video and audio recorded. After the design session, participants participated in a group interview.

The conversation and behavior from the design were transcribed, segmented, and coded. Two coding systems including the FBS ontology and “levels of the problem” were used in this study. A series of statistical …

Bridging The Nano- And Macro-Worlds: Thermal Property Measurement Using Thermal Microscopy And Photothermal Radiometry – Application To Particle-Irradiation Damage Profile In Zirconium Carbide, Colby Bruce Jensen

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Multiscaled experimental investigations of heat transfer from nanoscales to macroscales are requisite to progress in energy technologies. In nuclear applications, material properties can undergo significant alteration due to destructive interaction with irradiating particles at microstructural levels that affect bulk properties. This study expands the current knowledge base regarding thermal transport in ion-irradiated materials through the use of a multiscaled experimental approach using four complementary thermal wave methods. For the first time, the in-depth thermal conductivity profile of an ion-irradiated sample is measured directly.

Restoring The Lost Fishery: An Environmental History Of Northern Nevada's Pyramid Lake And Lower Truckee River Fishery, David Bolingbroke

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

This thesis focuses on fisheries managers’ efforts to restore native cutthroats to northern Nevada’s Pyramid Lake for recreation, and the Paiutes’ battle to preserve them as a means of livelihood. Their efforts to reconstruct the fishery revealed the implausibility of environmental restoration, but more importantly underlined the motivations necessary to attempt it.

Chapter 2 describes how the Pyramid Lake Lahontan cutthroat— historically an important subsistence resource for Northern Paiutes— were initially exploited for profit in the late 1800s and early 1900s, and gradually destroyed as agricultural interests diverted the Truckee River’s water and industrial pollution contaminated the trout’s aquatic habitat. …