Physical Sciences and Mathematics Commons^™

Intrinsic Loss In Infrared Optical Fibers, Prapassorn Tantiphanwadi

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Recently, in communication system, fiber optics has become a most interesting development tool as a transmission medium. It first appeared as a feasible transmission medium in 1970. The reason for the development in fiber optics comes from the overwhelming advantage in technology and economy compared to wires and coaxial links. For technology progress, typically, optical fiber has a wide transmission band-width (0.1-1000 GHz), lower loss per unit length (0.15 – 5 dB km^-1[1]), and does not allow electromagnetic interference. For example, signal transmitted over commercial silica-based fiber must be reamplified every 10 to 50 kilometers, whereas signals transmitted …

Mapping Instream Habitat On The San Juan River Using Airborne Videography, Michael J. Pucherelli, William P. Goettlicher, Bureau Of Reclamation, U.S Department Of The Interior

All U.S. Government Documents (Utah Regional Depository)

Concerns have been raised over the potential impacts of the Animas/LaPlata project and the regulation of Navajo Dam. Flow depletions in the San Juan River may adversely affect the remnant population of the native fish, particularly the endangered Colorado squawfish and the razorback sucker. A multiyear research program is currently being conducted on the San Juan River as a result of a Jeopardy Opinion delivered by the U.S. Fish and Wildlife Service on Animas/LaPlata and the subsequent Reasonable and Prudent Alternative that was accepted. A mulidisciplinary research team composed of representatives from the affected agencies is currently investigating the relationship …

Exact Enumeration And Scaling For Fragmentation Of Percolation Clusters, Boyd F. Edwards, M. F. Gyure, M. V. Ferer

All Physics Faculty Publications

The fragmentation properties of percolation clusters yield information about their structure. Monte Carlo simulations and exact cluster enumeration for a square bond lattice and exact calculations for the Bethe lattice are used to study the fragmentation probability a_s(p) of clusters of mass s at an occupation probability p and the likelihood b_s′s(p) that fragmentation of an s cluster will result in a daughter cluster of mass s′. Evidence is presented to support the scaling laws a_s(p_c)∼s and b_s′s(p_c)=s^-φg(s′/s), with φ=2-σ given by the standard cluster-number scaling …

Hydrodynamic Instability Of Chemical Waves, D. A. Vasquez, J. W. Wilder, Boyd F. Edwards

All Physics Faculty Publications

We present a theory for the transition to convection for flat chemical wave fronts propagating upward. The theory is based on the hydrodynamic equations and the one‐variable reaction‐diffusion equation that describes the chemical front for the iodate–arsenous acid reaction. The reaction term involves the reaction rate constants and the chemical composition of the mixture. This allows the discussion of the effects of the different chemical variables on the transition to convection. We have studied perturbations of different wavelengths on an unbounded flat chemical front and found that for wavelengths larger than a critical wavelength (λ≳λ_c) the perturbations grow …

Ultrahigh Vacuum Chamber For Synchrotron X-Ray Diffraction From Films Adsorbed On Single-Crystal Surfaces, John R. Dennison, S. K. Wang, P. Dai, T. Angot, H. Taub, S. N. Ehrlich

All Physics Faculty Publications

An ultrahigh vacuum chamber has been developed for structural analysis of adsorbed films and single‐crystal surfaces using synchrotron x‐ray diffraction. It is particularly well suited for investigations of physisorbed and other weakly bound films. The chamber is small enough to transport and mount directly on a standard four‐axis diffractometer and can also be used independently of the x‐ray diffractometer. A low‐current, pulse‐counting, low‐energy electron diffraction/Auger spectroscopy system with a position‐sensitive detector enables in situ characterization of the film and substrate while the sample is located at the x‐ray scattering position. A closed‐cycle He refrigerator and electron bombardment heater provide controlled …

Electron Mean-Free Paths In The Alkali Metals, G. K. Wertheim, D. Mark Riffe, N. V. Smith, P. H. Citrin

All Physics Faculty Publications

Photoemission data in which the signal from the first atomic layer is well resolved from that of the bulk are used to determine accurately the kinetic-energy dependence of the inelastic-electron mean free path in the alkali metals. At the higher kinetic energies, the data are in very good agreement with the theory of Penn. Below about 10 eV, the mean free path in the heavier alkali metals drops markedly below the theoretical values. This is attributed to electron decay processes involving the unoccupied d bands.

Convective Instability Of Autocatalytic Reaction Fronts In Vertical Cylinders, D. A. Vasquez, J. W. Wilder, Boyd F. Edwards

All Physics Faculty Publications

Linear stability analysis predicts that the onset of convection for an ascending autocatalytic reaction front in a vertical cylinder corresponds to a nonaxisymmetric mode. This mode consists of a single convective roll confined to the region near the reaction front, with fluid rising in half of the cylinder and falling in the other half. Experiments show a flat front below the onset of convection and an axisymmetric front well above the onset of convection. New experiments are called for to closely examine the onset of convection in order to test this prediction.

Final Environmental Impact Statement For Rangeland Ecosystem Management On He Uinta National Forest, Provo, Utah, Usda Forest Service

All U.S. Government Documents (Utah Regional Depository)

This Final Environmental Impact Statement describes alternatives, including a "No Action" alternative for management of National Forest Rangeland Resources on the Uinta National Forest. Alternatives range from no change from past management practices, which in some instances have resulted in less than favorable ecological conditions on National Forest Rangelands and riparian resources, to managing these resources to achieve the "Potential Natural Community" in terms of vegetative cover types and condition. The environmental consequences of all alternatives considered in detail are displayed. The alternatives selected for implementation will become an amendment to the Uinta National Forest Land and Resource Management Plan. …

New Syntheses Of Diaryl Ethers, Tyrosinols, B-Hydroxytyrosinols, L,L-Isodityrosinol And L,L-Isodityrosine-Derived Agents Via The Diels-Alder Reaction, Xianqi Feng

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Syntheses of diaryl ethers were approached by use of a Diels-Alder reaction employing a new type of diene attached with an aryloxy group. Thus, 2-methyl-3-phenoxybutadiene (90b ), 2- methoxy-3-phenoxybutadiene (92b) and (4S)-3-(t- butyloxycarbony1)-2 ,2-dimethyl-4-( 4-(3-methoxy-1,3 -butadienyl-2- oxy )phenylmethyl]oxazolidine (93b) were synthesized in ~65% yields by methylenation of the carbonyl function in the corresponding 2- substituted acrylate aryl ester using Tebbe's reagent. The 1,3- bis[(trimethylsilyl)oxy ]-2-phenoxybutadiene (105) was made from 1-phenoxy-2-propanone (101) by a sequence of formylation and enolsilylation. Methyl propiolate (107) and dimethyl acetylenedicarboxylate (113) were heated at reflux with diene 9 0 b and 92b in toluene to provide …

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 …

A Maple Package For The Variational Calculus, Cinnamon Hillyard

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The HELMHOLTZ package, written in Maple V, is a collection of commands to support research in the variational calculus. These commands include the standard operators on differential forms, Euler-Lagrange operators, homotopy operators, Lie bracket, Lie derivatives, and the prolongation of a vector field. We give a brief introduction to the variational calculus. We describe each of the commands in the HELMHOLTZ package completely along with numerous examples of each. Applications of the package include verification of symmetry groups for differential equations, solving the inverse problem of the calculus of variations, computing generalized symmetries, and finding variational integrating factors. A complete …

A Comparison Of Two Linear Nonparametric Regression Techniques, Sylvain Sardy

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

This thesis presented a useful tool in regression. Nonparametric linear regression techniques were described in the general context of regression. A comparison of two of these techniques, kernel regression and iterative regression, showed various aspects of nonparametric linear regressors.

Disconjugacy And Oscillation Theory Of Linear Differential And Difference Equations, Yuhua Xu

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

This dissertation is both a literature survey and a presentation of new and independent results.

The survey gives an overview of disconjugacy and oscillation theory for linear differential and difference equations with an emphasis on comparing the theory of difference equations to the theory of differential equations. Second order scalar equations, higher order scalar equations, matrix equations (systems) and Hamiltonian systems are discussed. A chapter on three-term recurrences of systems is also included. Both similarities and differences between differential and difference equations are described.

The new and independent results are for Hamiltonian systems of difference equations. Those results include the …

Desert Bighorn Sheep And Riverboat Interactions In Cataract Canyon, Utah, Mark C. Stanger

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

I studied desert bighorn sheep (Ovis canadensis nelsoni) behavior and habitat use in response to boating activities during 1985. The percent of total observed time in attention behavior before the boating season, during the boating season, and while riverboats were< 0.8 km from bighorn sheep groups was 1, 1.4, and 12.2, respectively. Estimated energy expenditure did not significantly differ for high riverboat pressures (2 > 0.2) or seasonal comparisons (2 > 0.1). Habitat use significantly differed for proximity to the river, which was probably related to the summer use of the river for drinking. Moderate, minor, and no responses to passing riverboats were observed 3, 39, and 58%, respectively. Responses to riverboats did not significantly differ according to time of day (2 > 0.15) or …

Inverse Problem In Porous Medium Using Homogenization, Helen Alkes

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The problem under consideration is that of obtaining a representation of the permeability of a porous medium which is heterogeneous and anisotropic from limited information. To solve this inverse problem we propose the use of two different pieces that work together. A simulated annealing algorithm is presented and coupled with an homogenization technique; together these solve the problem which was posed. Further, numerical simulation results are presented illustrating the use of the simulated annealing algorithm as well as a coupling with the homoginization technique. This study illustrates that the performance of the annealing algorithm is enhanced with usage of homogenization.

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 …

Mobilization Of Iron Enhances The Iron-Dependent Biochemical Reactivity Of Asbestos In Vitro And Contributes To The Cytotoxicity Of Asbestos In Cultured Cells, Loren Glen Lund

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Asbestos related research began approximately 60 years ago, yet, the mechanism(s) by which asbestos exerts its biological effects is not well understood. The hypothesis upon which this dissertation is based is that mobilization of iron from asbestos enhances the iron-dependent biochemical reactivity of asbestos in vitro and contributes to asbestos-dependent cytotoxicity. The specific aims for this hypothesis were, 1) to determine whether iron was responsible for the biochemical reactivity of asbestos in vitro and asbestos-induced cytotoxicity in cultured cells, and 2) to determine whether mobilization of iron from asbestos enhanced the reactions catalyzed by asbestos in vitro and contributes to …

Spatial And Temporal Variations Of The Pilot Valley Playa Interpreted From Remotely Sensed Images, Llyn Doremus

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

In the Basin and Range Province, the geologic regime of the Pilot Valley, linear trending block faults have isolated many valleys both topographically and hydrologically. Discharge from these arid, closed basins occurs only as evaporation. Minerals dissolved in discharging fluid are precipitated at the valley floor as the liquid evaporates. The resulting salt flats and high density brines are known as playas.

The Pilot Valley Playa surface was sampled concurrently with the recording of a Thematic Mapper remotely sensed image to define the surface conditions that correspond to image data. An association was found between the band 7 (infrared wavelength …

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 …

The Paleoecology And Geomorphology Of Holocene Deposits Of The Southern Malad River, Box Elder County, Utah, Ann Schaffer Elder

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Widespread Lake Bonneville sediments have been modified by river aggradation and degradation associated with Holocene fluctuations in the Great Salt Lake. Exposures of exceptionally abundant and well-preserved molluscan deposits in the Bear River Valley, Utah, allow detailed paleoenvironmental reconstruction of Holocene environments. The exposed basal unit consists of largely unfossiliferous deltaic silts and clays deposited during Lake Bonneville time (roughly 11,000 - 13,000 yr B. P.). An unconformity representing at least 2000 yr separates the deltaic material from overlying highly fossiliferous stream sands. Eight species of molluscs, comprising a single community, occupied this low energy stream environment at 7690 ± …

An Embedded Ring Approach To The Vibrational Dynamics Of Disordered Two-Dimensional Materials, Timothy Edwin Doyle

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

A theoretical approach was developed to model the vibrational dynamics of amorphous, two-dimensional materials. The materials were modeled as continuous random networks (CRN's) comprising an assemblage of planar rings of diverse size. In-plane vibrational modes for symmetric 4-, 5-, 6-, 7-, and 8-membered rings were examined. Vibrational states of isolated rings were modified by coupling the rings to a continuous network to represent rings embedded in a CRN. An effective force constant was used to couple the ring vibrations to the network's collective motions. Potentials were approximated with the use of a central force model (bond-stretching force constant) and a …

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 …

Quaternary Geology And Neotectonics Of Southern Star Valley And The Southwest Flank Of The Salt River Range, Western Wyoming, Gregory A. Warren

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Southern Star Valley is a structural and physiographic basin bounded on the east by the southern Star Valley fault, an active normal fault associated with Basin and Range extension. The southern Star Valley fault separates southern Star Valley from the Salt River Range and forms a dramatic north-south trending topographic escarpment. Statistical analysis of relative-age dating (RD) parameters taken from glacial deposits in the Salt River Range defined distinctive age groups for the deposits, and comparison of RD data allowed correlations with late Pleistocene and Holocene glacial deposits elsewhere in the Rocky Mountains. However, the sedimentary lithologies in the glacial …

Idaho River Systems Management Study Wetlands Report, United States Department Of The Interior, Bureau Of Reclamations

Natural Resources-Planning, Management, and Conservation

The Bureau of Reclamation is cooperating with the Idaho Department of Water Resources and others in the formulation of a comprehensive water plan for the conservation, development, management, and use of waters within the state's river basins. The impact that wetlands may have on the use of water in the state is a major consideration.

This report identifies opportunities that exist for private citizens, corporations, government agencies, and others to work together to slow the rate of wetland loss and to improve the quality of remaining wetlands. To work together effectively, these groups must reach an understanding of what comprises …

Bulk And Surface Singularity Indices In The Alkali Metals, G. K. Wertheim, D. Mark Riffe, P. H. Citrin

All Physics Faculty Publications

Photoemission data from (110) films of Li, Na, and Rb, in which the signal from the first atomic layer is well resolved, show that the core-hole-screening singularity index is ∼40% larger at the surface than in the bulk for all three metals. This result, which is indicative of the more atomiclike character of metal surface atoms, in general, is particularly large for the alkali metals because their conduction-electron screening is mainly s-like. In addition to quantifying the difference in screening at the surface, the data provide bulk singularity indices of 0.22, 0.16, and 0.14 for Li, Na, and Rb, respectively. …

Ion Composition Of The Topside Equatorial Ionosphere During Solar Minimum, S. A. Gonzales, Bela G. Fejer, R. A. Heelis, W. B. Hanson

Bela G. Fejer

We have used observations from both the Bennett ion mass spectrometer and the retarding potential analyzer on board the Atmosphere Explorer E satellite to study the longitudinally averaged O+, H+, and He+ concentrations from 150 to 1100 km in the equatorial ionosphere during the 1975–1976 solar minimum. Our results suggest that the ion mass spectrometer measurements need to be increased by a factor of 2.15 to agree with the densities from the retarding potential analyzer and with ground-based measurements. The peak H+ concentrations are about 2.5×104 cm−3 during the day and 104 cm−3 at night and vary little with season. …

Thermal And Surface Core-Electron Binding-Energy Shifts In Metals, D. Mark Riffe, G. K. Wertheim, D. N. E. Buchanan, P. H. Citrin

All Physics Faculty Publications

High-resolution photoemission spectra from the shallow core levels of alkali metals and of In have been obtained between 78 K and room temperature. The data yield values for the alkali-metal surface-atom core-level shift and show thermal shifts of comparable size for bulk and surface. The positive surface shifts are due to the spill-out of conduction-electron charge, which is responsible for the surface dipole layer. The surface shifts are in good agreement with values obtained from a Born-Haber cycle expressed in terms of surface energies. The thermal shifts are proportional to the lattice expansion, and arise from both initial-state and final-state …

Calculation Of Barriers To Proton Transfer Using Variations Of Multiconfiguration Self‐Consistent‐Field Methods. Ii. Configuration Interaction, K. Luth, Steve Scheiner

Chemistry and Biochemistry Faculty Publications

Various means are tested of including additional electron correlation into multiconfiguration self‐consistent‐field (MCSCF) methods for computing proton transfer potentials in HF₂⁻, H₇N₂⁺, H₃O₂⁻, and H₅O₂⁺. Configuration interaction allowing single excitations (CIS) and configuration interaction with single + double excitations (CISD) calculations are performed following MCSCF expansion of the wave function using various different MCSCF reference wave functions. The CISD results are excellent, being fairly independent of choice of reference space although it is important that the occupied orbitals be balanced between the …