Physical Sciences and Mathematics Commons^™

On The Model Selection In A Frailty Setting, Jill F. Lundell

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

When analyzing data in a survival setting, whether of people or objects, one of the assumptions made is that the population is homogeneous. This is not true in reality and certain adjustments can be made in the model to account for heterogeneity. Frailty is one method of dealing with some of this heterogeneity. It is not possible to measure frailty directly and hence it can be very difficult to determine which frailty model is appropriate for the data in interest. This thesis investigates three model selection methods in their effectiveness at determining which frailty distribution best describes a given set …

Perceived Fairness And Effectiveness Of Rangeland Collaborative Processes, Kimberly J. Richardson

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Involvement in collaborative partnerships in natural resource management has become a popular method for natural resource management agencies to collect public input, cope with conflicts, and develop ecosystem management plans. This thesis evaluates various collaborative processes, emphasizing multiple-owner partnerships. Qualitative interviews of 46 landowners in Utah were conducted to reveal concerns and suggestions regarding multiple-owner landscape-level collaborative partnerships. Landowners were concerned about private property rights infringement and losing control of their private land. Landowners were primarily concerned about the fairness and effectiveness of any partnership in which they were involved.

However, they were willing to consider participating if certain procedural …

Quaternary Amino Acid Geochronology Of The Lahontan Basin, Nevada, And The Chewaucan Basin, Oregon, Jeffrey Bigelow

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Amino acid geochronology based on fossil molluscs provides a useful approach to determining the Quaternary history of Great Basin lakes. The Lahontan basin, Nevada, and the Chewaucan basin, Oregon, in the northwest corner of the Great Basin, both contained lakes during the Quaternary. The aim of this study is to improve the Quaternary geochronology in these two basins by measuring time-dependent changes in amino acids preserved in fossil molluscan shells. The abundance of D-alloisoleucine relative to Lisoleucine (All) characterizes the extent of racemization, which increases with age and Ul forms the basis of relative and correlated ages. An age-calibration curve …

All-Sky Measurements Of The Mesospheric "Frontal Events" From Bear Lake Observatory, Utah, Seon-Hee Seo

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Studies of internal gravity waves in the earth's upper atmosphere are of considerable interest. These waves play a very important role in the dynamics of the mesosphere and lower thermosphere (ML T) region where they can transfer large amounts of energy and momentum from the lower atmosphere via wave saturation and dissipation. In particular, small-scale short-period ( < 1 hour) waves of the type regularly recorded by all-sky nightglow imagers operated by Utah State University (USU) are known to be very important contributors. In this thesis attention is focused on a subset of small-scale wave phenomena recently discovered using such image data, the so called "frontal events." Frontal events have distinguishable characteristics from usual short-period ( < 1 hour) gravity waves. The principal characteristics are a well defined leading "front, " which exhibits a sharp change in intensity followed by a coherent wave trail (often extending from horizon to horizon) and relatively high phase speeds ( > 50ms^-1) Another unusual characteristic of "frontal events" is an apparent reversal in contrast of the wave structures as imaged in the hydroxyl (OH) emission (peak altitude - 87 km) when compared with the oxygen (OJ) "green line" (557.7 nm) emission (peak …

The Role Of An Invasive Exotic Plant On The Structure Of Aquatic Invertebrate Assemblages: Tamarix In The Southwest United States, Bert Lewis

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Over the past 100 years, riparian vegetation communities throughout the Southwest United States have been extensively invaded by Tamarix spp. (saltcedar). Saltcedar derives its common name from its physiological adaptation to excrete salts. The production of Tamarix detritus with associated secondary chemicals may affect the quality of aquatic invertebrate food and habitat resources. An alteration in food and habitat quality may affect the composition and structure of aquatic invertebrate assemblages.

A series of experiments was conducted contrasting aquatic invertebrate assemblage densities, colonization rates, and growth rates associated with Tamarix versus native vegetation, Populus fremontii (cottonwood) and Salix exigua (willow), to …

Characterization Of Dielectric Properties Of Earth Materials At Low Frequencies, Tarrah Dawn Henrie

Undergraduate Honors Capstone Projects

Sharma and de Lima (1992) have proposed a model based on Fixman's theoretical development of charged macromolecules in external fields (1980). There are three types of charges considered: the fixed surface charges that are covalently bonded, the layer of bound counterions, and the diffuse layer (Fixman, 1980, Lyklema, 1983 ). Figure (1) shows these different layers. Other common theories, such as Schurr's only consider the bound counterions and the diffuse layer. Schurr assumes that the diffuse layer ions can exchange with the electrolyte. A consequence of this assumption is the lack of polarization of the diffuse layer. This leads to …

Utilization Of Spatially Distributed Soil Resources By Several Species Common To The Great Basin, Sarah Duke

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Heterogeneous spatial and temporal distributions of soil resources important to plant growth have been documented in the sagebrush steppe ecosystem. There can exist as much variability in soil resources within the root zone of individual plants as exists across an entire field. The objective of this dissertation research was to evaluate how plants respond to, utilize and influence the spatial heterogeneity of soil resources. The three specific sets of questions addressed are outlined in the three main chapters of this dissertation.

My first study addressed how the number and concentration of phosphorus (P) patches in the root zone of an …

Statistical Characterization Of Fluvial-Deltaic Reservoirs With Archetypes, Laura L. Watkins

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Optimizing the extraction of oil and other hydrocarbon products from existing sites is important. One source of hydrocarbon products is reservoirs found within sedimentary rock formations. Understanding fluid behavior within such formations can be quite useful in optimizing oil production. Fluid behavior within sedimentary formations is influenced by the bedform structure and permeabilities within the formation. Thus, we are concerned with developing a physically and statistically valid method of characterizing sedimentary rock formations. The use of archetypal analysis to generate synthetic bedforms, as well as the use of Kriging to assign permeabilities within a bedform, was explored. With these tools, …

Dynamic And Chemical Aspects Of The Mesospheric Na ‘Wall’ Event On 9 October 1993 During The Aloha Campaign, G. R. Swenson, J. Qian, J. M.C. Plane, P. J. Espy, Michael J. Taylor, D. N. Turnbull, R. P. Lowe

All Physics Faculty Publications

On October 9, 1993, observations were made from the National Center for Atmospheric Research Electra aircraft during a flight from Maui, Hawaii, toward a low-pressure system NW of the island, a flight of 7 hours in total. The leading edge (wall) of a bright airglow layer was observed 900 km NW of Maui at 0815 UT, which was traveling at 75 m s−1 toward the SE, reaching Haleakala, Maui, about 3.25 hours later [see Swenson and Espy, 1995]. An intriguing feature associated with the event was the large increase in the mesospheric Na column density at the wall (∼180%). The …

Application Of Tomographic Inversion In Studying Airglow In The Mesopause Region, T. Nygren, Michael J. Taylor, M. S. Lehtinen, M. Markkanen

All Physics Faculty Publications

It is pointed out that observations of periodic nightglow structures give excellent information on atmospheric gravity waves in the mesosphere and lower thermosphere. The periods, the horizontal wavelengths and the phase speeds of the waves can be determined from airglow images and, using several cameras, the approximate altitude of the luminous layer can also be determined by triangulation. In this paper the possibility of applying tomographic methods for reconstructing the airglow structures is investigated using numerical simulations. A ground-based chain of cameras is assumed, two-dimensional airglow models in the vertical plane above the chain are constructed, and simulated data are …

Epa Superfund Record Of Decision: Murray Smelter Murray City, Ut, Epa

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

The Murray Smelter Site ("the Site") is located in the city of Murray, Utah, in Salt Lake County as illustrated on Figure 1. The Site includes the former operational areas of the Murray Smelter and adjacent Germania Smelter which are referred to as the "on-facility" area., as well as surrounding residential and commercial areas where airborne emissions from the smelters impacted the environment or where contamination in shallow ground water may be transported in the future. These surrounding areas are referred to as the "off-facility" area. The on-facility area is approximately 142 acres. Its boundaries are 5300 South Street to …

Environmental Assessment For The Designation Of The Continental Divide National Scenic Trail, United States Department Of The Interior, Bureau Of Land Management

Environmental Assessments (WY)

On October 2, 1968, Congress passed the National Trails System Act. This Act called for the establishment of a system of national scenic trails "which will be extended trails so located as to provide for maximum outdoor recreation potential and for the conservation and enjoyment of the nationally significant scenic, historic, natural, or cultural qualities of the areas through which such trails may pass." As a result of 1978 amendment to this Act, Congress designated the Continental Divide National Scenic Trail (CDNST) as part of the National Scenic Trail system. The CDNST is a trail route traversing the length of …

Observational Limits For Lidar, Radar And Airglow Imager Measurements Of Gravity Wave Parameters, C. S. Gardner, Michael J. Taylor

All Physics Faculty Publications

By examining the observational limits and biases for lidar, radar, and airglow imager measurements of middle atmosphere gravity waves, we provide plausible explanations for the characteristics of the monochromatic wave parameters that have been reported during the past decade. The systematic dependencies of vertical and horizontal wavelength on wave period, reported in many lidar and some radar studies, are associated with diffusive damping. The prominent waves with the largest amplitudes, most often observed by lidars and radars, are those with vertical phase speeds near the diffusive damping limit. The narrow range of horizontal phase velocities of the waves seen by …

Full-Wave Modeling Of Small-Scale Gravity Waves Using Airborne Lidar And Observations Of The Hawaiian Airglow (Aloha-93) O(1s) Images & Coincident Na Wind/Temperature Lidar Measurements, M. P. Hickey, Michael J. Taylor, C. S. Gardner, C. R. Gibbons

All Physics Faculty Publications

Measurements were made of mesospheric gravity waves in the OI (5577 Å) nightglow observed from Maui, Hawaii, during the Airborne Lidar and Observations of Hawaiian Airglow (ALOHA-93) campaign. Clear, monochromatic gravity waves were observed on several nights. By using a full-wave model that realistically includes the major physical processes in this region, we have simulated the propagation of four waves through the mesopause region and calculated the O(1 S) nightglow response to the waves. Mean winds derived from Na wind/temperature lidar observations were employed in the computations. Wave amplitudes were calculated based on the requirement that the observed and simulated …

Games To Teach Mathematical Modelling, James A. Powell, Jim S. Cangelosi, Ann M. Harris

Mathematics and Statistics Faculty Publications

We discuss the use of in-class games to create realistic situations for mathematical modelling. Two games are presented which are appropriate for use in post-calculus settings. The first game reproduces predator-prey oscillations and the second game simulates disease propagation in a mixing population. When used creatively these games encourage students to model realistic data and apply mathematical concepts to understanding the data.

Climate Change And Utah, United States Environmental Protection Agency

Elusive Documents

No abstract provided.

The Uses Of Existing Information In The Process Of Setting Social Standards For Proposed Wilderness Areas Of Zion National Park, Mark E. Vande Kamp

Elusive Documents

No abstract provided.

Climate Of Salt Lake City, Utah, William J. Alder, Laurence S. Nierenberg, Sean T. Buchanan, William Cope, James A. Cisco, Craig C. Schmidt, Alexander R. Smith, Wilbur E. Figgins

Elusive Documents

No abstract provided.

Adding Nutrients To Enhance The Growth Of Endangered Sockeye Salmon: Trophic Transfer In An Oligotrophic Lake, Phaedra E. Budy, Chris Luecke, Wayne A. Wurtsbaugh

Watershed Sciences Faculty Publications

Snake River sockeye salmon Oncorhynchus nerka, listed under U.S. law as endangered in 1991 in response to a decline in anadromous adult numbers, spend their first 1–2 years in Redfish Lake, Idaho, before migrating to the sea. To determine how nutrient enhancement might influence phytoplankton, zooplankton, and fish production, we performed fertilization experiments in large enclosures in this oligotrophic lake using juvenile kokanee (lacustrine O. nerka) as analogues for endangered sockeye salmon. Fertilization of the metalimnion substantially increased chlorophyll a (150%), phytoplankton biovolume (75%), primary productivity (250%), and zooplankton biomass (200%), and moderately increased fish growth (12%) over our control …

The Role Of Anadromous Sockeye Salmon (Oncorhynchus Nerka) In The Nutrient Loading And Productivity Of The Sawtooth Valley Lakes, Idaho, H. P. Gross, Wayne A. Wurtsbaugh, Chris Luecke

Watershed Sciences Faculty Publications

We constructed a simulation model for Redfish Lake, Idaho, using water budget and nutrient loading measurements, to predict the dependence of lake production on nutrients from the watershed, precipitation, lake fertilization, and marine-derived nutrients from sockeye salmon Oncorhynchus nerka, which historically have reared in the lake. We also used the model to simulate different management scenarios to help restore the endangered Snake River sockeye salmon. The model and other empirical evidence indicated that even before hydropower dams were present in the migration corridor, marine-derived nutrients were not of major importance to lake production, contributing only about 3% of the annual …

Utah State University Ground-Based Test Facility For Study Ofelectronic Properties Of Spacecraft Materials, W. Y. Chang, John R. Dennison, Neal Nickles, R. E. Davies

All Physics Faculty Publications

No abstract provided.

A Compact Rotating-Mirror Autocorrelator Design For Femtosecond And Picosecond Laserpulses, D. Mark Riffe, A. J. Sabbah

All Physics Faculty Publications

An interferometric rapid-scanning autocorrelator employing two antiparallel rotating mirrors in a variable arm is optimized for maximum optical path difference as a function of the separation of the two rotating mirrors. A very compact design (mirror separation≈mirror diameter) is possible without a reduction in the maximum pulse width that can be measured.

Interdisciplinary Scientists Gather For Plasma Structure Workshop, Jan Josef Sojka

All Physics Faculty Publications

Two of the most exciting papers presented at the Third Peaceful Valley Workshop were on the nature of plasma structure found in the nighttime midlatitude E and F regions. The first was from a coordinated rocket campaign called Sporadic E Experiment over Kyushu (SEEK) dedicated to the understanding of puzzling quasi-periodic radar echoes that have been detected in association with sporadic E layers. In-situ probes on two rockets measured localized electric fields as large as 20 mV/m, confirming theoretical predictions of strong polarization processes that may result from wavelike distortions imposed on normally stratified sporadic E layers. An unexpected result …

Dynamical Effects Of Ionospheric Conductivity On The Formation Of Polar Cap Arcs, L. Zhu, Jan Josef Sojka, Robert W. Schunk, D. J. Crain

All Physics Faculty Publications

By using a magnetosphere-ionosphere (M-I) coupling model of polar cap arcs [Zhu et al., 1993], a systematic model study of the effects of ionospheric background conductivity on the formation of polar cap arcs has been conducted. The variations of the ionospheric background conductivity in the model study cover typical ionospheric conditions, including solar minimum, solar maximum, winter, and summer. The simulation results clearly indicate that the ionospheric background conductivity can dynamically affect the mesoscale features of polar cap arcs through a nonlinear M-I coupling process associated with the arcs.

Intercomparison Of Physical Models And Observations Of The Ionosphere, D. N. Anderson, M. J. Buonsanto, M. Codrescu, D. Decker, C. G. Fesen, T. J. Fuller-Rowell, B. W. Reinisch, P. G. Richards, R. G. Roble, Robert W. Schunk, Jan Josef Sojka

All Physics Faculty Publications

Five physical models of the ionosphere were compared with each other and with data obtained at the Millstone Hill Observatory. Two of the models were self-consistent ionosphere-thermosphere models, while for the other ionospheric models the thermospheric parameters were provided by empirical inputs. The comparisons were restricted to midlatitudes and low geomagnetic activity, but four geophysical cases were considered that covered both the summer and winter solstices at solar maximum and minimum. The original motivation of the study was to determine why several physical models consistently underestimated the F region peak electron density, by up to a factor of 2, in …

Spruce Ecosystem Recovery Project Final Environmental Impact Statement, United States Forest Service

Final environmental Impact Statements (UT)

This Final Environmental Impact Statement documents the analysis of the Proposed Action, two action alternatives, and the No Action alternative developed for the Spruce Ecosystem Recovery Project (SERP) area. The Proposed Action and action alternatives considered in detail are consistent with current management direction. Each alternative responds differently to the issues associated with the Proposed Action.

Co Physisorbed On Ionic Crystals: An Extended Beg Spin-Lattice Model Of Absorbed Dipolar Molecules, T. E. Burns, John R. Dennison

All Physics Faculty Publications

The 2D dielectric phases and phase transitions of adsorbed dipolar molecules are studied using a dilute spin-one Ising model. The spin-one formulation assigns a spin S_i=±1 to a (up/down) dipole occupying a lattice site I adsorbed perpendicular to the substrate surface and S_i=0 to unoccupied sites. We relate the mean field expression for the spin-model interaction energy to a more detailed microscopic model involving dipolar, quadrupolar and repulsive interactions beyond nearest neighbor. Analytic solutions in the mean field approximation are discussed for dipole-orientation order–disorder transitions and ferroelectric-to-antiferroelectric transitions as a function of temperature and coverage. The …

Observed Coupling Of The Mesosphere Inversion Layer To The Thermal Tidal Structure, J W. Meriwether, X Gao, Vincent B. Wickwar, T D. Wilkerson, K C. Beissner, S C. Collins, M E. Hagan

All Physics Faculty Publications

Rayleigh lidar observations of mesosphere temperature profiles obtained from 40 to ∼100 km from Logan, Utah (41.7, 111.8 W, altitude, 1.9 km) over 10 nights in late February, 1995, revealed an interesting development between 60 to 75 km of a winter mesosphere inversion layer with an amplitude of ∼20–30 K and a downward phase progression of ∼1 km/hr. The data also showed two altitude regions exhibiting significant cooling of 10–30 K in extent. These were located below and above the peak of the inversion layer, respectively, at altitudes of ∼50–55 km and ∼70–80 km. When these results were compared with …

Secondary Electron Emission And Spacecraft Charging, Neal Nickles, John R. Dennison

All Physics Faculty Publications

Spacecraft charging due to the natural plasma environment found in all orbits is known to produce many of the observed spacecraft anomalies and failures. A primary factor in adverse spacecraft charging is the secondary electron emission of differing materials on the spacecraft. Precipitating electrons and ions from the plasma to spacecraft surfaces can result in varying amounts of charge being released, depending on the secondary electron yield of the materials; this can lead to arcing between surfaces. NASA's Space and Environments Effects (SEE) program has recognized the need to improve their current materials database for modeling spacecraft charging and have …

Gradient Drift Instability Growth Rates From Global-Scale Modeling Of The Polar Ionosphere, Jan Josef Sojka, M. V. Subramanium, L. Zhu, Robert W. Schunk

All Physics Faculty Publications

The winter polar ionosphere, under southward interplanetary magnetic field (IMF) conditions, experiences irregularity development leading to consequences such as scintillation on transionospheric communication links. These irregularities are associated with antisunward convecting polar ionospheric patches. The gradient drift instability (GDI) has been considered a primary candidate for the generation of these irregularities, or at least the long-wavelength energy source of the irregularity-wave cascade process. The Utah State University time-dependent ionospheric model (TDIM) enables the polar cap ionosphere and its patches to be modeled on a large scale in a time-evolving manner. Hence, at each point in space and time, the TDIM …