Digital Commons Network^™

Hopf Bifurcation In A Parabolic Free Boundary Problem, Yoon-Mee Lee

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

We deal with a free boundary problem for a nonlinear parabolic equation, which includes a parameter in the free boundary condition. This type of system has been used in models of ecological systems, in chemical reactor theory and other kinds of propagation phenomena involving reactions and diffusion.

The main purpose of this dissertation is to show the global existence, uniqueness of solutions and that a Hopf bifurcation occurs at a critical value of the parameter r. The existence and uniqueness of the solution for this problem are shown by finding an equivalent regular free boundary problem to which existence …

Effects Of Rumen Protein Degradability On Rumen Characteristics, Milk Production And Reproductive Performance In Holstein Dairy Cows, Mario Raul Figueroa

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Three non-lactating Holstein cows fitted with rumen cannula were used to determine crude protein and dry matter rate of disappearance of two protein supplements: 1) soybean meal and 2) bypass protein blend by using the in situ bag technique. Rate disappearance (%/hr) was higher for soybean meal. Two collection periods were completed using 6 cows with a minimum of 21 d adaptation to the treatment top dressed on to the total mixed ration. Ruminal concentration of ammonia N, blood ammonia, and urea did not differ between treatments. Total concentration of volatile fatty acids was higher for bypass protein blend-fed cattle …

Responses Of Canada Thistle To Defoliation And To Damage From A Stem-Mining Weevil In Utah, Wendy Sue Halsey

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The responses of Canada thistle stems to damage by two types of herbivores were investigated to determine the potential role of these herbivores as biological control agents. Canada thistle stems at a cattle exclosure in Rich County, Utah were cut at one to two centimeters aboveground in June, 1991, to mimic grazing by cattle. Neighboring stems within 30 centimeters were also cut in some treatments to investigate the effects of physiologically connected ramets on the growth and reproductive responses of individual focal stems. I measured plant height, stem diameter, and number of flowerheads for each of the focal stems during …

Sedimentology And Community Structure Of Reefs Of The Yucatan Peninsula, Mexico, Matthew J. Novak

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Holocene carbonate sediments from Mexican reefs in the Caribbean and Gulf of Mexico display variations in constituent composition, texture and mineralogy which are related to their locations on the reefs. Samples were collected at barrier reef environments at Akumal and Chemuyil, on the northeast coast of the Yucatan Peninsula; at the oceanic atoll of Chinchorro, off the southeast coast of the peninsula; and at the shelf atoll of Alacranes, in the Gulf of Mexico. Samples were collected through a depth range of 0-40 m, which encompasses back reef, shallow fore reef, and deeper fore reef environments.

Constituent-particle analysis of reef …

Effects Of Polyacrylamide On Rangeland Soils And Plants, Saud Leily R. Al-Rowaily

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The objectives of this study were to determine the effects of two forms of polyacrylamide (PAM) conditioners (Cross-linked and Non-cross-linked PAM) on evaporation, saturated hydraulic conductivity, water retention, crust and crack formation of soils, seed germination, and seedling and tubeling growth.

The two PAM conditioners, 0.2% concentration by weight, were mixed with seven soils of different textures (sandy loam, silt, silty clay loam, silt loam, fine sand, medium sand, and coarse sand) to investigate the effects on evaporation, saturated hydraulic conductivity, and water retention. Soil samples of different textures were brought to field capacity and placed in a growth chamber …

Optimization Of Ranch Management Alternatives In Utah, Scott G. Evans

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The purpose of this study was to determine the optimum combination of various cattle production, range forage, and crop harvesting alternatives available to ranch owners and managers in Utah. While many promising alternatives are available, determining which alternatives to implement is difficult because the total ranch operation must be considered.

Linear programming (LP) is a tool available to ranch managers which allows the profit maximizing combination of improvements to be easily determined. LP allows ranchers to examine the entire ranch operation and to reduce the amount of risk and uncertainty involved in the decision making process.

The typical Utah ranch …

The Behavioral Responses Of Utah Prairie Dogs (Cynomys Parvidens) To Translocation, Steven H. Ackers

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

In cases where refuge acquisition or captive breeding programs are not practical or justifiable, wild caught animals are frequently translocated into areas of suitable habitat. Such management programs seldom are designed to account for the behavioral responses of translocated animals to an unfamiliar habitat, breakup of social units, and/or interactions with existing social units in the new habitat. Ongoing efforts to translocate threatened Utah prairie dogs (Cynomys parvidens) from areas where conflicts with other land uses are occurring to public land sites have met with limited success. This could be due, in part, to behavioral responses associated with …

Marten Use Of Subnivean Access Points In Yellowstone National Park, Wyoming, Stuart Scott Sherburne

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Subnivean prey appeared to be the primary reason for subnivean access point use by martens. A logistic regression was used to create a predictive model for differential access point use. Prey biomass in grams and percent ground cover of coarse woody debris (CWD) were used as variables in the model. Goodness of fit of the multivariate model was 0.216; biomass was significant al p = 0.0003, CWD was significant at p = 0.0718. Mean values for prey biomass at used and unused access points were 174.2 g and 81 g, respectively, while mean values of CWD were 24.7% and 18.5%, …

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 …

Dynamic Multi-Species Animal Habitat Modeling With Forest Succession Models, Stephen A. Compton

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

This research determines and demonstrates the ability to simulate dynamic multi-species animal habitat suitability with forest succession models. A literature review of dynamic animal habitat models is presented. The structure of an existing forest simulation model (MASS10) was modified from a basal area-based model to a volume-based model (DYNAM10). The forest model was calibrated using data from permanent-plot growth and vegetation samples collected by USDA Forest Service Forest Survey procedures. The theoretical growth parameters used to simulate stand development were validated. Predictions of DBH and height growth, as well as stand-level behavior, were verified. A subroutine, VEGDYN, was added to …

Soil Heterogeneity And Its Exploitation By Plants, Robert B. Jackson

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

In this dissertation I first examine the ability of individual plants in the field to garner localized soil nutrients. I then measure actual soil variability around perennial plants and use various statistics to quantify the scale and degree of that variability.

Soil patches on opposite sides of Pseudoroegneria spicata tussocks were treated with distilled water or a nutrient solution containing N, P, or K in three field experiments. When P was augmented in the enriched soil patches, rates of P uptake increased significantly for roots from enriched patches compared with roots in control patches. Rates of ammonium and potassium uptake …

Characterization Of Pigments Responsible For Red Or Pink Discoloration In Cooked Pork, Viswasrao M. Ghorpade

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The pigments responsible for pink or red discoloration in cooked vacuum-packaged meat products {bratwurst (pork and beef), ground pork, and pork roasts} were investigated. In bratwurst, this study attempted to characterize the red pigment that appears upon refrigerated storage, and to determine the effect of pH, cooking and storage temperature, and sodium lactate on incidence of red discoloration. Myoglobin was identified in the exudate of samples with red discoloration. Myoglobin levels of cooked products were significantly lower in samples of low initial pH (5.5) or cooked to higher than normal internal temperature (74°C). Red discoloration was associated with microbial growth. …

Effects Of Potassium Lactate, Encapsulated Citric Acid And Storage Temperature On Microbial Growth And Shelf Life Of Pork Sticks, Yen-Kan Su

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

A new product, pork sticks, was developed. Optimum shelf life and safety were major concerns associated with this product. Potassium lactate (3%) or citric acid (0.5%, 0.56%, 0.60% or 0.66%) was added to pork sticks to determine their effects on microbial growth, sensory evaluation, and shelf life when stored frozen (-20°C), refrigerated (2°C), or at room temperature (22°C). Two raw materials, pork blade meat (shoulder meat; 91% lean, 9% fat) and regular 80:20 pork trim (80% lean, 20% fat) were used. The consumer panel preferred lean pork sticks made from blade meat over high-fat pork sticks made from regular 80:20 …

Genetics And Applications Of Nisin Production In Lactococcus Lactis Subsp. Lactis And Conjugal Exchange Of This Trait, Jeffery R. Broadbent

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Chapter I reviews current literature on gene transfer systems in lactic acid bacteria, how genetically altered microorganisms for food are presently regulated, and how nisin is used as a food preservative.

Chapter II investigates previous reports which linked genes for nisin biosynthesis and sucrose utilization (Nip⁺Suc⁺) to plasmid DNA in two well characterized L. lactis subsp. lactis strains. Plasmid curing studies, conjugations, and DNA-DNA hybridizations indicated that these genes were encoded by chromosomal loci in all Nip⁺Suc⁺ strains examined. Similar results were noted in nisin-sucrose transconjugants of L. lactis subsp. cremoris and S. …

Estimation Of Selected Milk Protein Genetic Variants By Multi-Component Analysis Of Amino Acid Profiles, Carol M. Hollar

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Cation-exchange fast protein liquid chromatography separated whole casein into β-casein A², A¹, and B, K-casein, α_s1-casein, and α_s2-casein fractions as well as γ-caseins and several unidentified peaks using a urea-acetate buffer at pH 5 and a NaCl gradient. The whole casein fractions eluted in the following order: breakdown products of β-casein and unidentified peaks; β-casein A², A^l, and B; additional breakdown products of β-casein and unidentified peaks; K-casein; α_s1-casein; and α_s2-casein. The calculated composition of the four major caseins correlated well with values obtained …

The Efficacy Of Multidisciplinary Treatment Programs For Chronic Low-Back Pain: A Meta-Analysis, Jane E. Curtis

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Chronic low-back pain is a prevalent and costly problem for many adults in the United States. Currently, multidisciplinary treatment approaches are the treatment of choice for this problem. A meta-analysis was conducted on 43 published studies to describe the nature of these programs, the patients involved in them, treatment efficacy at discharge and follow-up, and possible relationships between these characteristics and outcome.

Results show that these programs were often in university medical settings, with an emphasis on active patient participation. Common treatment approaches included physical therapy, skills training, medication management, supportive therapy, and behavior modification. Patients involved in these programs …

Comparison Of Optimization Methodologies For Sustained-Yield Groundwater Pumping Planning In East Shore Area, Utah, Shu Takahashi

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Combined simulation and optimization models, which are helpful for long-term groundwater planning of complex nonlinear aquifer systems, are developed using alternative modelling approaches. The models incorporate a representation of steady-state, quasi-three-dimensional head response to pumping within an optimization. An embedding model which describes exactly the nonlinear flow of an unconfined aquifer is presented. In contrast with the embedding models presented in the Utah State University Ground Water Model, it directly achieves the optimal solution without a "cycling." To address the nonlinearity of the flow system, response matrix models couple superposition with the cycling procedure. Their linear influence coefficients are generated …

Interactions Between Populations Of Intermediate Wheatgrass And Western Wheatgrass As Influenced By Short-Duration Grazing And Moisture Availability, Gerrit B. Bartels

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The effects of grazing and moisture availability on the competitive interactions of intermediate wheatgrass (Thinopyrum intermedium (Host) Barkw. & D.R. Dewey) and western wheatgrass (Pascopyrum smithii (Rhydb.) A. Love) were examined under a short-duration grazing system in central Utah. The fate of tiller cohorts was observed at approximately monthly intervals at the interface between patches of these two rhizomatous grasses and in monospecific stands. The effects of short-duration grazing, clipping of western wheatgrass following grazing to achieve levels of utilization equivalent to that of intermediate wheatgrass, irrigation, and removal of the competitor were assessed in terms of the …

Effects Of Knowledge Of Accountability In Mastery Learning Programs On Academic Achievement, Goal Setting Characteristics, And Locus-Of-Control Orientation, Donn C. Ritchie

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

During the past quarter century, over 1000 articles have documented changes in student behaviors related to participation in mastery learning programs. Although the results have been generally positive, a debate continues as to the cause for increased student performance: Are results due to changes in how students attend to the information, or simply due to increased study time as a result of remediation?

In this study, a videodisc-based program in fractions was used with fifth-grade students. The videodisc-based instruction was chosen to help minimize differences in instructional materials, instructional time, and instructional delivery. A pretest-posttest, control-group design was used to …

Wheat Kernel Hormone Levels During Development And Their Relevance To Zygotic And Somatic Embryogenesis, J. Richard Hess

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Wheat (Triticum aestivum L.) zygotic embryogenesis occurs in a dynamically regulated ovular environment, and in ovulo hormones regulate embryogenic processes. Levels of ABA, IAA, and the cytokinins Z, ZR, DHZ, DHZR, iP, and iPA were studied in developing wheat kernels from anthesis to maturity. High cytokinin and low IAA and ABA levels were associated with the early stage of embryo formation and active tissue histodifferentiation. Following histodifferentiation, cytokinin levels declined while IAA accumulated throughout the stage of active grain growth and then declined with grain maturity. ABA levels increased at the soft-dough developmental stage and through to grain maturity. …

Effect Of Various Growth-Promoting Factors On Preimplantation Bovine Embryo Development In Vitro, Mark Randall Flood

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The purpose of this research was to define the effects of various growth-promoting factors on in vitro embryonic development of in vitro matured and in vitro fertilized bovine embryos. The control medium was a chemically defined medium which improves the possibility of closely determining the in vivo conditions the embryo is actually exposed to. The growth-promoting factors tested in this experiment included transferrin, IGF-I (insulin-like growth factor-one), IGF-II (insulin-like growth factor-two), TGF-𝛼 (transforming growth factor-alpha), TGF-𝛽1 (transforming growth factor-beta1), PDGF (platelet derived growth factor), EGF (epidermal growth factor), NGF (nerve growth factor), and bFGF (basic fibroblast growth factor). Transferrin was …

Use Of The Polymerase Chain Reaction In The Detection Of Bovine Leukosis, Emma Jane Kelly

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

A diagnostic test for bovine leukosis was developed using the polymerase chain reaction (PCR) to amplify a 375 base pair region in the gag gene of the proviral genome.

Blood samples were collected from 3 adult Holstein cows shown to be infected with bovine leukosis virus (BLV) by the agar-gel immunodiffusion (AGID) technique. The 3 samples were mixed and the composite blood was used to inoculate 10 cows. Five of the cows were inoculated with 0.1 ml of blood, and the other cows were inoculated with 1 ml of blood. Five of the cows were negative for BLV by AGID …

Circulating Antibodies To Thymic Antigens In Autism And Alzheimer's Disease, Chih-Li Chen

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Abnormal T lymphocyte reactions in both autism and Alzheimer's disease (AD) have been reported. This research investigated the possibility that these abnormalities may involve circulating antithymic antibodies. Plasma samples from autistic patients, AD patients, and normal-matched controls were tested for reactivity against murine thymocytes.

In the first of 3 studies results of the enzyme-linked immunosorbent assay (ELISA) were statistically significant for binding (P < 0.001) between antithymic antibodies in plasmas of AD patients and murine thymocytes. Binding (P < 0.05) in low dilutions (1/2.5 and 1/5} of autistic patient plasmas was also observed. In the second study, plasmas of neither autistic nor AD patients significantly inhibited DNA synthesis of thymic cells in the presence of interleukin-1 (IL-l} and phytohemagglutinin (PHA). In the third study, no significant increases (P > 0.05) in cytotoxic activities were detected using AD patient plasmas and both untreated and heat-treated autistic patient plasmas. After further testing, these heat-treated plasmas diluted 1/64 and 1/128 had increased cytotoxicities (P < 0.05) when rabbit complement was added, an indication that cytotoxicity of antithymic antibodies is complement dependent.

Therefore, circulating antithymic antibodies may …

Immunological Effects Of Amphotericin B Desoxycholate And Liposomal Amphotericin B On Splenocytes From Immune-Normal And Immune-Compromised Mice, Jay Jenson Schindler

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Because of the increasing number of serious risk factors which predispose a normally immune competent host to infection, the incidence of systemic fungal infections is steadily increasing. This epidemiological rise has especially become apparent since the onset of the AIDS epidemic. Amphotericin B is the drug of choice for these life-threatening mycotic infections. Complications due to drug toxicity, however, severely limit amphotericin B's clinical usefulness. The major complication associated with the administration of amphotericin B is renal toxicity. Research has indicated, however, that besides its antifungal activities, amphotericin B may act as an immune stimulant of both humoral and cellular …

Physical And Functional Events Involved In Conjugal Transfer Of Lactose Utilization In Lactococcus Lactis Subsp. Lactis, Hua Wang

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The nature of the cell surface components involved in donor cell clumping (Clu⁺) and the relationship of Clu⁺ to high frequency conjugal transfer of lactose utilization (Lac) in Lactococcus lactis subsp. lactis ML3 was examined. Lactose positive (Lac⁺), Clu⁺ transconjugants, containing a novel 104 kilobase Lac plasmid, were obtained by mating ML3 with LM2301. When used as Lac+ donors in second round matings, these transconjugants transferred Lac at high frequencies ranging from 10^-2 to 10^-4 transconjugants per donor CFU. Treatment of donor cells with EDTA and EGTA containing solutions or proteolytic enzymes …

The Influence Of Dietary Factors On The Risk Of Urinary Stone Formation, A. Hesse, R. Siener, H. Heynck, A. Jahnen

Scanning Microscopy

The action of various beverages and foods on the composition of the urine in the circadian rhythm and in the 24-hour urine has been investigated under standardized conditions. Orange juice leads to a significant increase of urinary pH and citric acid excretion. Black tea leads to a raised excretion of oxalic acid by only 7.9%. In the short term, beer increases diuresis, but afterwards leads to a compensatory antidiuresis with increased risk of stone formation. Depending on their composition, mineral waters have very different effects on the urinary constituents. Milk as well as cocoa beverage significantly increase calcium excretion; moreover, …

Particle Induced X-Ray Emission Microanalysis Of Root Samples From Beech (Fagus Sylvatica), M. Hult, B. Bengtsson, N. P. -O. Larsson, C. Yang

Scanning Microscopy

Beech seedlings (Fagus Sylvatica) were grown in a nutrient solution to which AlCl₃ had been added. The experiments were designed to evaluate the effect of aluminum on the localization of elements in plant root tissue. Cross-sections of roots were analyzed with micro-PIXE (particle induced X-ray emission) and Rutherford backscattering (RBS) simultaneously. A proton beam of either 30x30 μm² or 5x5 μm² was scanned over the samples, and quantitative elemental maps were created. Aluminum was found to accumulate in high concentrations (percent levels) in the epidermis and the outer layer of the cortex, when the nutrient …

Relationship Between Villous Shape And Mural Structure In Neutron Irradiated Small Intestine, K. E. Carr, J. S. Mccullough, A. C. Nelson, S. P. Hume, S. Nunn, H. H. M. Kamel

Scanning Microscopy

Previous work on irradiation of mouse small intestine has assessed the changes produced by counting crypts/microcolonies, scoring villous shape or examining morphological changes in specific parts of the wall.

This paper used scanning and transmission electron microscopy to study the effects of whole body irradiation with 5 Gy neutrons on the surface and internal features of the intestinal wall of CFLP mice, 1 day, 3 days and 7 days after treatment.

Empirical scores from the ultrastructural findings were inserted into a Morphological Index display calculated from analytical data based on cell counts and area measurements obtained from resin histology sections. …

An Improved Method For Preparing Microvascular Corrosion Casts Of Rat Embryos, S. Yoshida, J. Chiba

Scanning Microscopy

This paper presents an improved method for preparing microvascular corrosion casts of rat embryos (day 16.5-21.5). Special attention was paid on the viscosity of the casting material, the method of mechanical restraint, and the subsequent drying of the casts. The embryos were perfused with Mercox resin diluted with 25% methyl methacrylate monomer followed by undiluted Mercox resin to avoid outflow of resin from the vasculature after perfusion. The specimens were mounted on a stainless steel plate with self-curing resin to prevent flotation, mechanical damage, and collapse of the cast specimens following preparation. After digestion and washing, the cast specimens were …

Scanning Electron Microscopy And Energy-Dispersive X-Ray Microanalysis Studies Of Early Dental Calculus On Resin Plates Exposed To Human Oral Cavities, T. Kodaka, Y. Ohohara, K. Debari

Scanning Microscopy

Dental calculus formed after 10 days on resin plates, applied to the lingual sides of the mandibular gingival regions in eight human subjects, was investigated by means of scanning electron microscopy (SEM) and energy-dispersive X-ray microanalysis (EDX). The mineral deposits were mainly divided into three types: A, B, and C. The type A deposits showing an average Ca/P molar ratio of 1.42 were densely packed with fine needle-shaped crystals formed by the intra- and extracellular calcification. The type A deposits, probably composed of Ca-deficient apatites and the transitional forms between apatite and octacalcium phosphate (OCP), were observed in all subjects. …