Physical Sciences and Mathematics Commons^™

The Coefficient Of Bohm Diffusion In Fully Ionized Plasma And Its Theoretical Proof, Ahmad Talaei, Reza Amrollahi

Graduate Student Presentations

As we know, the classical diffusion can not be able to respond the experimental results of the diffusion in the fully ionized and isothermal plasma. In this article, we purpose to extract the empirical coefficients of the Bohm diffusion and its confinement time, theoretically, in the fully ionized plasma, using the single fluid MHD equations.

Final Technical Report: Integrated Restoration Strategies Towards Weed Control On Western Rangelands, Robert Nowak

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

Invasive species are having severe ecological (Mack et al. 2000) and economic (Pimentel et al. 2005) impacts on ecosystems around the world. Invasive species can alter many ecosystem processes (Crooks 2002, Walker & Smith 1997) including: water and nutrient availability, such as form and amount of N if the soil (Evans et al. 2001, Sperry et al. 2006); primary productivity, through shifts in growth rates or efficiency of resource use; disturbance regimes, including the type, frequency, and severity of disturbances such as fire (D’Antonio 2002); and community dynamics, such as species replacements (Alvarez & Cushman 2002). The economic losses and …

A Linear Modulation Osl Study Of The Unstable Ultrafast Component In Samples From Glacial Lake Hitchcock, Massachusetts, Usa, R. J. Goble, Tammy M. Rittenour

Geosciences Faculty Publications

Optical ages were determined for samples from delta and sand dune deposits associated with Glacial Lake Hitchcock near Amherst, Massachusetts using the single aliquot regenerative-dose (SAR) optically stimulated luminescence (OSL) technique. However, a strong unstable ultrafast component caused initial rejection of data from a large proportion of aliquots. A linearly modulated blue OSL (LM-OSL) study was undertaken on the sample with the strongest ultrafast component, with the data modelled using the equation of Bulur et al. (2000) as 5 fast, medium and slow components, and 1 ultrafast component.

The ultrafast component dominates the LM–OSL, almost completely obscuring the fast component. …

From Herd Diversification To Livelihood Diversification As A Response To Poverty: The Case Of The Waso Boran Of Northern Kenya, D. Layne Coppock, Abdullahi D. Jillo, Abdillahi A. Aboud

Environment and Society Faculty Publications

The Waso Boran of northern Kenya used to have large, mobile, and diverse herds of livestock that exploited equally large and diverse rangelands. Forty years of human population growth, drought, environmental change, and lack of relevant policies have altered this situation, however, with the majority of Waso Boran today being livestock poor and engaged in a variety of non-pastoral activities to diversify their livelihoods. One-third of 540 households we surveyed in Isiolo District now have ten head of cattle or less, and a larger census suggests that only 15 percent of households can currently be categorized as mobile pastoralists. The …

Community Perceptions Concerning Key Ecological Resources At Risk In Baringo District, Kenya, D. Layne Coppock, Mark N. Mutinda, Abdillahi A. Aboud

Environment and Society Faculty Publications

Key ecological resources in arid and semi-arid lands are often characterized by small patches of seasonal grazing and important water points that lend critical support to entire production systems. When key resources are degraded or lost, production systems can be badly compromised. The Baringo District of north-central Kenya is well known for enduring decades of environmental degradation and food relief. As an initial part of an effort to map and characterize key ecological resources at risk in Baringo, we interviewed 136 resident leaders from pastoral and agro-pastoral areas. We asked them to identify and rank their most vulnerable ecological resources, …

Collective Action By Women’S Groups To Combat Drought And Poverty In Northern Kenya, D. Layne Coppock, Solomon Desta, Getachew Gebru, Adan Wako, Ibrahim Aden, Chachu Tadecha, Seyoum Tezera

Environment and Society Faculty Publications

Collective action can be an effective means of local development and risk reduction among rural people, but few examples have been documented in pastoral areas. We conducted extensive interviews for 16 women’s groups residing in northern Kenya. Our objectives were to understand how groups were formed, governed, and sustained and what activities they have pursued. The groups we interviewed were 10 years old, on average. Charter memberships averaged about 24 women, 20 of whom were illiterate. Half of the groups formed after facilitation by a development partner and half formed spontaneously. Groups are governed under detailed constitutional frameworks with elected …

Public Engagement To Prioritize The Pastoral Research Agenda At The Pastoral And Agro-Pastoral Research Center Of Oari In Ethiopia, D. Layne Coppock, Getachew Gebru, Lemma Gizachew, Sintayehu Mesele, Mohammed Hassena, Solomon Desta

Environment and Society Faculty Publications

The Oromia Agricultural Research Institute (OARI) has a mandate to conduct agricultural and livestock research throughout the Regional State of Oromia in Ethiopia. OARI has recently opened a facility near Yabello town on the Borana Plateau called the Pastoral and Agro-Pastoral Research Center. A meeting was held in August 2006 at Yabello that involved representatives from pastoral communities, the private sector, government, and non-governmental organizations. The aim was to engage stakeholders in a process of problem prioritization and set the stage to create new partnerships to better address pressing problems. The final priorities included: addressing a general decline in forage …

Mesospheric Gravity Waves Observed Near Equatorial And Low-Middle Latitude Stations: Wave Characteristics And Reverse Ray Tracing Results, C. M. Wrasse, T. Nakamura, H. Takahshi, A. F. Medeiros, Michael J. Taylor, D. Gobi, C. M. Denardini, J. Fechine, R. A. Buriti, A. Salatun, Suratno, E. Achmad, A. G. Admiranto

All Physics Faculty Publications

Gravity wave signatures were extracted from OH airglow observations using all-sky CCD imagers at four different stations: Cachoeira Paulista (CP) (22.7° S, 45° W) and São João do Cariri (7.4° S, 36.5° W), Brazil; Tanjungsari (TJS) (6.9° S, 107.9° E), Indonesia and Shigaraki (34.9° N, 136° E), Japan. The gravity wave parameters are used as an input in a reverse ray tracing model to study the gravity wave vertical propagation trajectory and to estimate the wave source region. Gravity waves observed near the equator showed a shorter period and a larger phase velocity than those waves observed at low-middle latitudes. …

Changes In Land Cover And Soil Conditions For The Yabelo District Of The Borana Plateau, 1973-2003, D. Layne Coppock, Sintayehu Mesele, Heluf Gebrekidan, Lemma Gizachew

Environment and Society Faculty Publications

It has been proposed that the Borana Plateau has markedly changed in terms of land cover and land use in recent decades, but no hard data have been available to critically assess this claim. In addition, systematic analysis of soil properties has been limited. Research was designed to measure changes in land cover/land use over 30 years in the 400-km2 Yabelo District of southern Ethiopia using three satellite images taken at an average interval of 15 years. Samples were also collected to assess variation in the physical and chemical properties of dominant soils. Results indicated that Yabelo District has indeed …

Moving Object Tracking: Seeking Extensible Solutions, Jeremy Pack

Undergraduate Honors Capstone Projects

Moving object tracking is a difficult field with no "best" solution. The documents contained here detail software that was developed in order to perform tracking of objects that are in the line of sight of multiple cameras. Some of the software developed is already in use by the US Army Dugway Proving Ground. Other software represents prototype or early development code. This software was written by Jeremy Pack, who was the lead programmer, and Luke Andrew at the Space Dynamics Laboratory in Logan, Utah.

Bear River Watershed Historical Digital Collection, Cheryl D. Walters, Stephen C. Strugeon

Library Faculty & Staff Publications

This presentation to the Bear River Water Commission introduced a new digital collection of images and text resources about the Bear River Watershed in Utah and Idaho.

Mercury Exchange Between The Atmosphere And Low Mercury Containing Substrates, Mae Sexauer Gustin, Mark Engle, Jody Ericksen, Seth N. Lyman, Jelena Stamenkovic, Mei Xin

USU Uintah Basin Faculty Publications

Mercury is emitted to the air from Hg-enriched and low Hg-containing (natural background) substrates. Emitted Hg can be geogenic, or can be derived from the re-emission of Hg that was previously deposited to the soil from the atmosphere. Atmospheric Hg can be derived from natural and/or anthropogenic sources and can be deposited by wet or dry processes. It is important to understand the relative magnitude of emission, deposition, and re-emission of Hg associated with terrestrial ecosystems with natural background soil Hg concentrations because these landscapes cover large terrestrial surface areas. This information is also important for developing biogeochemical mass balances, …

Methods For High Resistivity Measurements Related To Spacecraft Charging, Jr Dennison, Jerilyn Brunson, Prasanna Swaminathan, Nelson Green, A Robb Frederickson

Journal Articles

A key parameter in modeling differential spacecraft charging is the resistivity of insulating materials. This parameter determines how charge will accumulate and redistribute across the spacecraft, as well as the time scale for charge transport and dissipation. ASTM constant voltage methods are shown to provide inaccurate resistivity measurements for materials with resistivities greater than ~10¹⁷ Ω-cm or with long polarization decay times such as are found in many polymers. These data have been shown to often be inappropriate for spacecraft charging applications, and have been found to underestimate charging effects by one to four orders of magnitude for many …

Response To Earl Wunderli's Critique Of Alma 36 As An Extended Chiasm, Boyd F. Edwards, W. F. Edwards

All Physics Faculty Publications

No abstract provided.

Tropic And East Fork Irrigation Company, Tropic Ditch Replacement Project, Environmental Assessment, Bureau Of Reclamation, Provo Area Office

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

The purpose of this project is to reduce the amount of salt entering the Paria River and ultimately the Colorado River. One way to reduce the amount of salt reaching the Colorado River is to eliminate seepage from the historic Tropic Ditch. The Bureau of Reclamation, Provo Area Office has proposed funding for the project under the Colorado River Salinity Control Program. In addition to reducing the amount of salt loading, the project would also conserve water lost to evaporation and seepage.

The purpose of this Environmental Assessment (EA) is to analyze the potential environmental consequences of the proposed construction …

Propagation Velocities Of Chemical Reaction Fronts Advected By Poiseuille Flow, Boyd F. Edwards

All Physics Faculty Publications

Poiseuille flow between parallel plates advects chemical reaction fronts, distorting them and altering their propagation velocities. Analytical solutions of the cubic reaction-diffusion-advection equation resolve the chemical concentration for narrow gaps, wide gaps, and small-amplitude flow. Numerical solutions supply a general description for fluid flow in the direction of propagation of the chemical reaction front, and for flow in the opposite direction. Empirical relations for the velocity agree with numerical solutions to within a few percent, and agree exactly with the analytical limits. Applications to nonlinear fingering are discussed.

Methods For Resistivity Measurements Related To Spacecraft Charging, John R. Dennison, Jerilyn Brunson, Prasanna Swaminathan, Nelson Green, A. Robb Frederickson

All Physics Faculty Publications

A key parameter in modeling differential spacecraft-charging is the resistivity of insulating materials. This parameter determines how charge will accumulate and redistribute across the spacecraft, as well as the timescale for charge transport and dissipation. American Society for Testing and Materials constant-voltage methods are shown to provide inaccurate resistivity measurements for materials with resistivities greater than ~10¹⁷ Omegamiddotcm or with long polarization decay times such as are found in many polymers. These data have been shown to often be inappropriate for spacecraft-charging applications and have been found to underestimate charging effects by one to four orders of magnitude for …

Evolution Of The Electron Yield Curves Of Insulators As A Function Of Impinging Electron Fluence And Energy, John R. Dennison, Alec Sim, Clint Thomson

All Physics Faculty Publications

Electron emission and concomitant charge accumulation near the surface of insulators is central to understanding spacecraft charging. A study of changes in electron emission yields as a result of internal charge buildup due to electron dose is presented. Evolution of total, backscattered, and secondary yield results over a broad range of incident energies are presented for two representative insulators, Kapton and Al₂O₃. Reliable yield curves for uncharged insulators are measured, and quantifiable changes in yields are observed due to <100-fC/mm² fluences. Excellent agreement with a phenomenological argument based on insulator charging predicted by the yield curve …

Experimentally Derived Resistivity For Dielectric Samples From The Crres Internal Discharge Monitor, Nelson W. Green, A. Robb Frederickson, John R. Dennison

All Physics Faculty Publications

Resistivity values were experimentally determined using charge-storage methods for six samples remaining from the construction of the internal discharge monitor flown on the Combined Release and Radiation Effects Satellite (CRRES). Three tests were performed over a period of three to five weeks each in a vacuum of ~5times10^-6 torr with an average temperature of ~25degC to simulate a space environment. Samples tested included FR4, polytetrafluoroethylene (PTFE), and alumina with copper electrodes attached to one or more of the sample surfaces. FR4 circuit-board material was found to have a dark-current resistivity of ~1times10¹⁸ Omegamiddotcm and a moderately high polarization …

On The Computation Of Secondary Electron Emission Models, Sebastien Clerc, John R. Dennison, Ryan Hoffmann, Jonathon Abbott

All Physics Faculty Publications

Secondary electron emission is a critical contributor to the charge particle current balance in spacecraft charging. Spacecraft charging simulation codes use a parameterized expression for the secondary electron (SE) yield delta(E_o) as a function of the incident electron energy E_o. Simple three-step physics models of the electron penetration, transport, and emission from a solid are typically expressed in terms of the incident electron penetration depth at normal incidence R(E_o) and the mean free path of the SE lambda. In this paper, the authors recall classical models for the range R(E_o): a power …

Bear River Resource Conservation And Development Council Area Plan, United States Department Of Agriculture, Natural Conservation Service, Bear River Resource Conservation And Development Council

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

This five-year Area Plan is the guiding document for the Bear River RC&D Council, Inc. It identifies needs and opportunities and goals and objectives which lead the RC&D Council in its work.

Does Joseph's Letter To Emma Of 4 November 1838 Show That He Knew About Chiasmus?, Boyd F. Edwards, W. F. Edwards

All Physics Faculty Publications

No abstract provided.

Micro-Structural And Phase Configuration Effects Determining Water Content: Dielectric Relationships Of Aggregated Porous Media, J. M. Blonquist, Jr., Scott B. Jones, I. Lebron, D. A. Robinson

Plants, Soils, and Climate Faculty Publications

Many porous media in which we determine water content are aggregated and characterized by a dual-porosity pore network, composed of interaggregate pores and intra-aggregate pores. This paper reports sample-scale permittivity measurements made in four stable aggregate media with dual porosity. Results indicate two distinct dielectric responses depending on whether the aggregates are surrounded by water or air. We relate transitions in the permittivity response to the water retention characteristic (WRC), showing that after the interaggregate pores have drained, the slope of the water content–permittivity relationship is significantly reduced (permittivity values ranging from 5 to 7). The hydraulic critical water content …

Evaluating The Computational Efficiency Of Xfbat And Fbat For Family Based Studies, Yanwei Ouyang

All Graduate Plan B and other Reports, Spring 1920 to Spring 2023

Family-based study designs are often employed when investigating the genetic causes of complex disease. While the transmission disequilibrium test (TDT) and its extensions were developed to use family data for assessing linkage between a known genetic marker and a disease-causing gene, the so-called FBAT approach proposed by Rabinowitz and Laird (2000) effectively subsumes these family-based procedures as special cases. FBAT is fully conditional, but its implementation in the freely available FBAT software package uses a large-sample distributional approximation to compute p-values. The exact distribution for FBAT can be enumerated, but doing so explicitly is computationally intensive, particularly for relatively larger …

Secondary Electron Production And Transport Mechanisms By Measurement Of Angle-Energy Resolved Cross Sections Of Secondary And Backscattered Electron Emission From Gold, Jason T. Kite

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

This work provides information about interactions that produce emitted electrons from polycrystalline Au. Emission energy- angle- dependent electron spectra from a polycrystalline Au surface have been measured at several incident electron beam energies. The range of incident energies (~100 eV to 2500 eV) extends from below the first crossover energy, through E_maxo, to above the second crossover energy. The conventional distinction between secondary electrons (SE) (<50 eV) is found to be crude for the investigation of electron yields using these energy- angle- resolved measurements. A more realistic boundary occurs at the local minima of the emission spectra; this feature is studied as a function of incident energy and emission angle. In addition, deviations observed in the angular resolved emission spectra from isotropic behavior suggests that residual signatures exist in the emission spectra resulting from the anisotropic SE production mechanisms. Based on the disparity between our observations and recent modeling of the emission spectra, the most recent theory and simulation studies may overestimate the occurrence of randomizing collisions of scattered secondary electrons in the model of the transport mechanism. Finally, description of extensive modification to instrumental and analysis methods are described, and their effectiveness is evaluated.

Minimal Nodal Domains For Strictly Elliptic Partial Differential Equations With Homogeneous Boundary Conditions, Charles E. Miller

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

This work presents a proof of the dependence of the first eigenvalue for uniformly elliptic partial differential equations on the domain in a less abstract setting than that of Ivo Babušhka and Rudolf Výborný in 1965. The proof contained here, under rather mild conditions on the boundary of the domain, ∂Ω, demonstrates that the first eigenvalue of elliptic partial differential equation

{Lu + λu = 0 in Ω

{u = 0 on ∂Ω

depends continuously on the domain in the following sense. If a sequence of domains is such that Ω_i → Ω in …

Lower Paleozoic Sequence Stratigraphy, Deposystems And Paleogeography Of Northwestern Ordos Basin, North China, Benjamin J. Kessel

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The Ordos basin rests upon the North China Block and is one of the largest sedimentary basins in north China, with more than 15 km of Phanerozoic strata. Published estimates suggest that over 2000 m of carbonates and lesser amounts of siliciclastics were deposited on the North China Carbonate Platform (NCCP) from the Lower Can1brian through the Middle Ordovician. However, lower Paleozoic facies successions and deposystems of northwestern Ordos basin remain poorly represented in western literature. This paper constrains depositional environments, lithologies, facies relationships and sea-level history of the northwestern part of the North China block (NCB) in an effort …

Environmental, Chemical, And Genetic Reduction Of Ethylene Sensitivity In Crop Plants, Timothy J. Hudelson

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Ethylene is an endogenously synthesized plant hormone that dissipates quickly in field conditions and seldom exceeds five nmol mol^-1. Ethylene can accumulate to 1000 times this level in closed environments. The best-known effects of ethylene are its impacts on fruit ripening and senescence, yet ethylene influences growth and development throughout the plant life cycle. At low, continuous concentrations (20 to 50 nmol mol^-1), ethylene reduces yield of many plants. Clean-air treatment during critical stages of floral development, silver thiosulfate (STS), and 1-methylcyclopropene (1-MCP) may delay flower senescence and reduce the detrimental effects of ethylene on peas …

Wavelet Techniques In Time Series Analysis With An Application To Space Physics, Agnieszka Jach

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Several wavelet techniques in the analysis of time series are developed and applied to real data sets.

Methods for long-memory models include wavelet-based confidence intervals for the self-similarity parameter in potentially heavy-tailed observations. Empirical coverage probabilities are used to assess the procedures by applying them to Linear Fractional Stable Motion with many choices of parameters. Asymptotic confidence intervals provide empirical coverage often much lower than nominal and it is recommended to use subsampling confidence intervals. A procedure for monitoring the constancy of the self-similarity parameter is proposed and applied to Ethernet data sets.

A test to distinguish a weakly dependent …

The Evolution From Late Miocene West Salton Detachment Faulting To Cross-Cutting Pleistocene Oblique Strike-Slip Faults In The Sw Salton Trough, Southern California, Alexander N. Steely

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Field studies in the southwest Salton Trough between Yaqui Ridge and Borrego Mountain show that the West Salton detachment fault was active during the Pliocene and may have initiated during the latest Miocene. At Yaqui Ridge dominantly east-directed extension is recorded by slickenlines on the NW-striking detachment fault, and shows that the fault is actually a low-angle dextral oblique strike-slip fault. Crustal inheritance is responsible for the position of the fault at Yaqui Ridge, which reactivates a late Cretaceous reverse-sense mylonite zone at map scale.

Late Miocene to Pliocene basin fill deposits at Borrego Mountain display progressive unconformities, contain detritus …