Digital Commons Network^™

Microbes On The Mountain: Plant-Microbe Associations And Interactions On Mount St. Helens, Emily Rose Wolfe

Dissertations and Theses

Plant-microbe associations and interactions provide critical context to studies in both community and ecosystem ecology, especially in systems that are relatively new and still undergoing early successional processes. Microbes can colonize the surfaces and interiors of all plant tissues, and these assemblages vary in composition both spatially and temporally, even within the same plant. Endophytes are bacteria or fungi that spend most of their lifecycles living within plant tissues asymptomatically--typically, "endophyte" refers specifically to aboveground tissues such as leaves and stems, and therefore may have direct influences on defenses against herbivory, pathogen or pest tolerance, and even afterlife effects on …

A Multiplicity Of Journeys: Stem Education Ecosystems As Sources Of Cultural Sustenance, Christopher Louis Beauprey Cardiel

Dissertations and Theses

In this document, I outline the context and significance of a research problem faced by both formal and informal science, technology, engineering, and math (STEM) educators in the Portland metro area--specifically, the need for greater understanding of the individual and cultural motivations, needs, and agentic behavior of learners, as well as the ways in which these factors intersect with learners' experiences of cultural sustenance within their holistic STEM education ecosystems. I base the significance of this problem on the racial and gender inequities evident in the STEM fields and the social and cultural dynamics that discourage members of these groups …

Proximal Policy Optimization For Radiation Source Search, Philippe Erol Proctor

Dissertations and Theses

Rapid localization and search for lost nuclear sources in a given area of interest is an important task for the safety of society and the reduction of human harm. Detection, localization and identification are based upon the measured gamma radiation spectrum from a radiation detector. The nonlinear relationship of electromagnetic wave propagation paired with the probabilistic nature of gamma ray emission and background radiation from the environment leads to ambiguity in the estimation of a source's location. In the case of a single mobile detector, there are numerous challenges to overcome such as weak source activity, multiple sources, or the …

Information Security Maturity Model For Healthcare Organizations In The United States, Bridget Joan Barnes Page

Dissertations and Theses

This research provides a maturity model for information security for healthcare organizations in the United States. Healthcare organizations are faced with increasing threats to the security of their information systems. The maturity model identifies specific performance metrics, with relative importance measures, that can be used to enhance information security at healthcare organizations allowing them to focus scarce resources on mitigating the most important information security threat vectors. This generalizable, hierarchical decision model uses both qualitative and quantitative metrics based on objective goals. This model may be used as a baseline by which to measure individual organizational performance, to measure performance …

Experiences Of Undergraduates And Graduate Teaching Assistants In Biology Course-Based Undergraduate Research Experiences, Emma Crystal Goodwin

Dissertations and Theses

Evidence of positive student outcomes from course-based undergraduate research experiences (CUREs) has sparked implementation of CUREs in introductory biology laboratory courses, as one approach to boosting student engagement in research. In a CURE, students collaborate with other students and instructors on a research project, where they conduct novel scientific research that has relevance to a local or scientific community. However, previous research rarely considers that graduate teaching assistants (GTAs) often teach introductory labs. The classroom role of GTAs expands in a CURE--they no longer need to simply teach a lab class, but also to serve as research mentors. GTAs, who …

"Like I Was An Actual Researcher": Participation And Identity Trajectories Of Underrepresented Minority And First-Generation Stem Students In Research Training Communities Of Practice, Jennifer Lynn Lindwall

Dissertations and Theses

Although calls for a more diverse workforce in biomedical fields have been widespread, racial and ethnic gaps in biomedical degree attainment remain. Contextualist perspectives seek to understand persistent STEM inequities by examining person-in-context experiences and how systemic factors filter into students' proximal contexts shaping their participation and science identity trajectories. Research training communities of practice aim to offer underrepresented minority and first-generation students support, guidance, and opportunities to learn the practices of science and construct their science identity. However, many students still choose to leave these programs. There is limited research on these students' science identity construction process and their …

Mechanisms Of Connexin-46 And -50 Intercellular Channel Function And Stability By Molecular Dynamics Simulations, Bassam George Haddad

Dissertations and Theses

Gap junctions make up a class of intercellular channels that characteristically connect the cytoplasm of directly apposed cells through large assemblies, or plaques, constituted by a multitude of intercellular channels. Gap junction mediated intercellular communication is critical for a variety of physiological functions, from coordinating electrical impulses in the heart and brain to maintaining homeostasis in most tissues. There are 21 isoforms of connexins, the constituent subunit of the gap junction, expressed in a tissue dependent manner. Gap junctions formed from different isoforms exhibit distinct biophysical properties, such as gating kinetics and sensitivity, as well as unique permeability and selectivity …

Opportunities And Challenges In The Collection And Use Of Socio-Spatial Data In National Forest Planning, Diane Trechsel Besser

Dissertations and Theses

Understanding human-environment connections to places is an important component of land-use management. Tools for collecting geographically referenced public values-based data (defined as socio-spatial data) for use in natural resource planning have been reported in academic journals for decades. The utility of socio-spatial data is in making public values tangible and potentially actionable in land-use analyses and decision processes. However, there is a lack of comprehensive documentation on the ways in which socio-spatial data is perceived, collected, interpreted and applied at a practical level. A better understanding of these factors allows planners to mitigate barriers and leverage opportunities to more …

Affecting Absenteeism Through School-Based Health Services Delivery: A Configurational Comparative Methods Study Of Oregon's Public Secondary Schools, Kelly Elizabeth Coates

Dissertations and Theses

A student's ability to attend school regularly can be profoundly affected by poor health-related behaviors, illnesses, and chronic diseases that are left unaddressed and unattended. The delivery of health services in the school environment is uniquely positioned to interrupt the effects these health barriers to learning (HBLs) can have on subsequent diminished educational and health outcomes. The literature widely acknowledges the intersectionality between health and education, but no comprehensive overview exists of how different structures and processes within a school work (or do not work) together to lead to higher or lower student absenteeism. This research sought to fill that …

Does Experiencing Spousal Support And Strain Impact The Quality Of Family-Based Support That Supervisors Provide To Employees?, Joseph Alvin Sherwood

Dissertations and Theses

Relying on previously collected data from the Work, Family and Health Study (WFHS), and drawing from a sample of 75 supervisors working in the extended healthcare industry, this research investigation empirically tested propositions of the Work-Home Resources Model to explore antecedents of family-supportive supervisor behaviors (FSSB). To explore these relationships a longitudinal, multi-level structural equation model (MSEM) was used to examine how supervisor contextual resources (spousal support) and demands (spousal strain) in the home domain impacted employee perceptions of these supervisors' FSSB through gains in personal resources (psychological distress) across three time points. Results from the MSEM model confirmed one …

Exploring Linkages Between Landscape Patterns And Freshwater And Estuarine Bivalves In The Coast Range Of Oregon, Kaegan Michael Scully-Engelmeyer

Dissertations and Theses

Spatial configurations of landscape variables (biotic, abiotic, and socio-ecological) affect and are affected by ecological processes and species in watersheds. This dissertation explores relationships among landscape patterns, ecosystem processes and bivalve species dynamics in coastal watersheds in Oregon, USA. I approached this broad topic through two primary avenues of research: investigating cross-ecosystem threats from pesticide use in forestland management to downstream aquatic environments, and the landscape ecology of an at-risk freshwater mussel species.

Terrestrial land use activities present cross-ecosystem threats to riverine and marine species and processes. Specifically, pesticide runoff can disrupt hormonal, reproductive, and developmental processes in aquatic organisms, …

An Exploratory Study Of Adjunct Faculty Professional Growth Experiences, Bethany Ann Potts

Dissertations and Theses

Part-time non-tenure track faculty, also referred to as adjunct faculty, are the fastest growing instructional group in higher education, but they are provided minimal professional support from their employing institution(s). This lack of support is a problem because working conditions shape instructors' investment and efficacy of performance in their professional practice. Well established in the literature are inquiries into adjunct faculty working conditions that prioritize analysis of the organization over the lived experiences of the faculty. However, the lived experiences of adjunct faculty offer a unique and important lens from which to interrogate the impact of institutional policies and practices …

Regional Characteristics And Variability Of Extreme Precipitation And Atmospheric Rivers In Past, Present, And Future Climates Over The Contiguous United States, Emily Anne Slinskey

Dissertations and Theses

This dissertation examines the regional and seasonal variability of extreme precipitation and atmospheric rivers (ARs) across the contiguous United States (CONUS) in past, present, and future climates. An extreme precipitation categorization scheme, designed to monitor and track the multi-scale variability of extreme precipitation, is applied to a range of precipitation measurement products as an assessment of observational uncertainty. To investigate the importance of ARs across the CONUS, an objective AR identification algorithm is applied to global reanalysis to identify and characterize AR characteristics regionally over the observational record. Projected change in AR day frequency, geometry, intensity, and associated precipitation is …

'There Are No Bathrooms Available!': How Older Adults Experiencing Houselessness Manage Their Daily Activities, Ellis Jourdan Hews

Dissertations and Theses

Older adults living unhoused encounter limitations and challenges that drastically decrease their wellbeing and quality of life. The purpose of my study was to understand how experiencing houselessness impacted older adults' ability to conduct their activities of daily living (ADLs) and instrumental activities of daily living (IADLs) within their communities. I conducted phone interviews with older adults aged 50 and older who experienced houselessness in the Portland metro area. The participants described the persons and places that shaped their community life when they were living unhoused, and they described how those entities intervened to alleviate barriers to daily activities. The …

Climate Model Evaluation Of Atmospheric Rivers Over The Contiguous United States, Ilan González-Hirshfeld

Dissertations and Theses

Atmospheric rivers (ARs)--long corridors of intense atmospheric water vapor transport--significantly influence the hydrologic cycle and regional hydrometeorological extremes across the contiguous United States (CONUS). Ongoing and future climate change may alter AR characteristics and impacts, making confident climate model projections of future change, especially at regional scales, of critical importance. In order to better constrain uncertainty in such projections of future change, we perform a comprehensive climate model evaluation of AR climatology over the CONUS. Using an established AR detection algorithm, we evaluate the representation of ARs in historical simulations (1984-2013) from a suite of models participating in the sixth …

Relationship Between Image Spectroscopy Spatial Resolution And Crown Level Tree Species Classification Accuracy, Andrew Richard Fritter

Dissertations and Theses

Hyperspectral imagery has become a common remote sensing data type used in tree species classifications because of its rich spectral signals that allow the detection of the variations in canopy reflectance. While high spatial resolution hyperspectral imagery provides fine spatial resolution for discerning surface objects, it has the inherent drawbacks of expensive acquisition costs, large data sizes, and can be computationally taxing to use. This study attempts to determine a relationship between crown level tree species classification accuracy and hyperspectral spatial resolution. Future tree species classification projects can make use of this relationship by targeting a spatial resolution that best …

Nesting Habits Of Cavity Nesting Bees And Wasps In Portland, Oregon, Stefanie Kay Steele

Dissertations and Theses

Native bees are threatened by habitat loss through urbanization, however, there is increasing interest in creating bee nesting habitat in urban areas. Few studies have determined what species are present in the region, or examined the role of nest height or cavity size in attracting the approximate one-third of native bees that nest in cavities. To determine what species were present, and whether they showed preferences for nesting at a certain height or cavity width, we set up artificial wooden cavity nest blocks across fourteen locations in the greater Portland, OR area. Wooden posts were erected with nest blocks at …

Drug Conviction And Employment Restriction: Experiences Of Employees With Drug-Related Criminal Histories, Liana Bernard

Dissertations and Theses

It has been established that there are numerous barriers to obtaining and maintaining employment following a criminal conviction, including background checks, which occur as part of most selection processes. Barriers to obtaining and maintaining employment may be higher for individuals with drug-related criminal histories as they may face particularly severe negative stereotypes. This study examines the experiences of individuals with drug-related criminal histories' integration into the workplace and society. Additionally, because stereotypes about individuals with drug-related criminal histories are contradictory to those of individuals with stable employment, I examine how these individuals are impacted by reductions in the stigma that …

The Development And Application Of Instrumental Methods For The Identification Of Materials And Processes Used In The Manufacture Of Orotone, Hand-Colored Orotone, And Silvertone Photographs, Ivanny Jeannette Jácome-Valladares

Dissertations and Theses

Orotone photographs are positive photographic images on glass with a gold-colored metallic coating or backing. Although the materials and process used in the production of orotones have been previously documented, there is limited published scientific research on the subject. This study focused on expanding those published works by analyzing a greater number of photographs, including eleven orotones, four hand-colored orotones, two silvertones, and one uncoated orotone. The photographs, dating from the early to mid-20^th century, were from the University of Washington (UW) Libraries' collection, except for one orotone that was from the Portland Art Museum.

X-ray Fluorescence (XRF) spectroscopy, …

An Analysis Of Capillary Flow In Finite Length Interior Corners, Samuel Shaw Mohler

Dissertations and Theses

We analyze the mathematical robustness of slow massively parallel interior corner flows in low gravity environments. An interior corner provides a preferential orientation in low gravity environments. This is a luxury usually only found on earth. It also provides a passive pumping mechanism due to geometry of a conduit. The driving force for this flow is a pressure difference due to local surface curvature gradients. An alternative reasoning is that due to the geometrical constraints the interior corner surface energy is unbounded below. This results in the liquid wicking into corners indefinitely. Interior corner flow's main quantity of interest is …

A Ground-Based Assessment Framework For Validating Diesel Particulate Emission Models And Applicability In Portland, Or, Kirsten Marie Sarle

Dissertations and Theses

Exposure to diesel emissions causes a range of health effects throughout the body, impairing; respiratory, cardiovascular, central nervous, renal, and cognitive systems. Diesel particulate matter (DPM) in Portland, Oregon is prevalent due to the layout of highly trafficked roadways, rail lines, and marine ports exposing a dense population to high levels of exhaust pollution. These high concentrations of ambient diesel emissions disproportionately impact minority and low-income populations.

Ground-based monitoring and modeling are two ways to assess ambient DPM. However, there are uncertainties in modeled DPM due to knowledge gaps in emissions inventories as well as lack of model validation against …

Projections Of Large-Scale Atmospheric Circulation Patterns And Associated Temperature And Precipitation Over The Pacific Northwest Using Cmip6 Models, Graham Patrick Taylor

Dissertations and Theses

Projections of 500 hPa geopotential height (Z500) patterns over the Pacific Northwest of North America and their associated surface temperature, precipitation, and frequency of occurrence are assessed using models from the 6th phase of the Coupled Model Intercomparison Project (CMIP6). The self-organizing maps approach is applied to reanalysis data from the Modern-Era Retrospective Analysis for Research and Applications, version-2 (MERRA-2) to cluster daily Z500 anomalies into 12 representative patterns that span the range of historical circulation patterns. CMIP6 data for daily Z500 anomalies are mapped to each node for historical and end of century global warming experiments, and the resulting …

Kinematic Demands On Pile-Supported Wharves Due To Liquefaction-Induced Lateral Ground Deformations, Thomas John Torkelson Ii

Dissertations and Theses

Kinematic demands from lateral soil deformations can be a major cause of damage to maritime and highway transportation structures such as wharves, ports, and bridges. Data from five centrifuge tests on pile-supported wharves were used to evaluate the accuracy of Newmark Sliding Block Analysis in estimating the kinematic demands on piles. The piles in the centrifuge tests were subjected to varying degrees of liquefaction-induced lateral ground deformations. Pile-pinning effects were included in the analysis by incorporating the lateral pile resistance in the limit-equilibrium slope stability analysis. The results of the analysis have shown that the median Newmark displacements better estimated …

Field Trials And Long-Term Monitoring Of Microbially-Induced Desaturation For The Treatment Of Liquefiable Silty Soils, Kayla Rae Sorenson

Dissertations and Theses

Earthquake liquefaction hazards in silty soils are a critical problem in Portland, Oregon, and other areas around the world. This is a particular problem for existing facilities founded on liquefiable soils, for which there exists no cost-effective liquefaction mitigation solution at the present time. It is essential from both a seismic safety and a seismic resilience perspective to be able to mitigate potentially liquefiable soils underneath existing structures, and to do so in a cost-effective manner. Recent studies suggest that liquefaction mitigation using microbially-induced desaturation (MID) may provide this capability.

The objective of MID is to reduce earthquake-induced excess pore …

New Perspectives On Prolific And Voluminous Rhyolite Volcanism Of The Mahogany Mountain--Three Fingers Rhyolite Field, Eastern Oregon, Robert Andrew Jackson

Dissertations and Theses

Voluminous silicic volcanism of the Mahogany Mountain--Three Fingers rhyolite field (MM--TFrf) is spatially and temporally associated with mid-Miocene flood basalts of the Columbia River Basalt province. Early studies of the area advocated for a two-caldera model consisting of the Mahogany Mountain and the slightly younger Three Fingers caldera with pre- and post-caldera effusive rhyolite eruptions. Although close in time, the calderas were thought to be spatially offset producing the tuff of Leslie Gulch and the tuff of Spring Creek. Finding that the tuff of Spring Creek, that is exposed in Leslie Gulch, is an altered product of the tuff of …

Using Quantitative Stereology On High Resolution Sem Images To Estimate Diatom Percentages, Ariadna Covarrubias Ornelas

Dissertations and Theses

Diatoms are single-celled organisms of various shapes and sizes typically found in aquatic environments. When diatoms die, the organic material decomposes, and the outer skeletons (i.e., frustules) settle and accumulate as sedimentary deposits. These soils, called diatomaceous soils, exhibit nontraditional behavior since the diatom particles are typically hollow skeletons composed of amorphous silica with intricately patterned and abrasive surfaces. Recent studies have shown that diatomaceous soils are challenging geomaterials since even a small percentage of diatom particles will notably affect engineering behavior. Furthermore, laboratory studies on diatomaceous soil mixtures have demonstrated that many engineering soil properties depend on the percentage …

Modeling Cyanotoxin Production, Fate And Transport In Surface Waterbodies, Bernadel Rose Hintz Garstecki

Dissertations and Theses

Cyanobacteria exist throughout the world and are frequently associated with forming toxic blooms. The toxins produced by cyanobacteria, cyanotoxins, are harmful to both humans and animals. Rising temperatures due to global climate change, increased nutrient loading, and other anthropogenic impacts on waterbodies are expected to increase the prevalence of cyanobacteria. It is vital that we protect our drinking water supplies and natural water resources. Modeling the production and movement of these toxins is an important step in limiting exposure to them and evaluating management strategies to mitigate their impact. Cyanotoxins are diverse and the conditions under which they are formed …

Marijuana-Related Crime In Oregon Following Legalization Of Recreational Use, Ana Alicia Soto

Dissertations and Theses

In this decade we are seeing the legalization of recreational marijuana occurring across the nation, with new legislation being passed every year. This necessitates research into what works within the regulatory framework of states where MJ has been legalized. This study sets out to look at Oregon's implementation of recreational marijuana and its impact on marijuana-related offenses. Using NIBRS, we examine marijuana-related offenses across 13 counties with crime data from 41 agencies in Oregon from pre-legalization to post-legalization (2010 to 2019). This study uses elements of legalization, licenses, and production to analyze the association between these aspects and offenses that …

Anti-Muslim Bias: Investigating Individual Differences, Threat Perceptions, And Emotions In Islamophobic Policy Support, Aeleah M. Granger

Dissertations and Theses

Following the terrorist attacks of 9/11, Muslims in the United States were victims of increased surveillance by law enforcement on the basis of their religious identity, often resulting in mistreatment and unjustified imprisonment. These biases against Muslims and subsequent policy shifts have been pervasive and have had negative impacts on the growing number of Muslims in the United States. The current study focuses on individual differences that predict Islamophobia, including Social Dominance Orientation (SDO), Right-wing Authoritarianism (RWA), and Nationalism, as well as the specific types of intergroup threat perceptions (i.e., realistic, symbolic, terroristic) and subsequent emotional reactions (e.g., anger, fear) …

Battle Rock: Anatomy Of A Massacre, Adam R. Fitzhugh

Dissertations and Theses

On June 9, 1851, nine men under the direction of a steamboat captain and land speculator named William Tichenor landed on the southern coast of the Oregon Territory at present-day Port Orford with the intention of establishing a permanent settlement. Tichenor's plan was to establish a commercial port that would supply gold mining endeavors in the interior. The landing party's instructions were to survey the townsite while Tichenor traveled to San Francisco to gather more men and supplies. Before departing, he promised the group he would return in exactly two weeks. He also assured them that the local Quatomah Indians, …