Digital Commons Network^™

Synthesis And Characterization Of Highly Stable Fisetin Encapsulated In Lecithin-Chitosan-Savie Nanoparticles, Hart Monyatovsky, Travis Anderson, Jay Nadeau

Physics Faculty Publications and Presentations

Senolytic drugs, of the class of polyphenolic flavonoids, have attracted attention for a wide variety of medical applications for which they may be delivered topically, orally, and/or intravenously. However, due to their hydrophobicity and sensitivity to light and oxygen, they have been proven difficult to package and deliver. Here we report a synthesis method for encapsulated fisetin using lecithin-chitosan ionic gelation with a recently reported surfactant that is an alternative to polyethylene glycol (PEG)-containing compounds. Called “Savie” for a contraction of its components, sarcosine-Vitamin E, this surfactant allows for production of sub-100 nm nanoparticles that are bench stable for at …

Framework And Methodology For Risk-Based Bridge And Tunnel Asset Management: Risk-Based Asset Ranking And Corridor Prioritization, David Y. Yang, Arash Khosravifar, Diane Moug, Avinash Unnikrishnan

Civil and Environmental Engineering Faculty Publications and Presentations

This report presents the results of Phase II of the project, "Framework and Methodology for Risk-based Bridge and Tunnel Asset Management". The research was carried out at Portland State University in collaboration with engineers and officials at the Oregon Department of Transportation (ODOT) and Federal Highway Administration (FHWA). Using the framework and methodology developed in Phase I of the project, the primary goal of Phase II is to showcase the practical application in risk-based asset management. In particular, the report includes the following two case studies: Case Study I — Weighted hazard scenarios for seismic risk assessment of Oregon Highway …

A Generalized Lehmer Conjecture For The Trace Of T ₃, Liubomir Chiriac, Erin Williams

Mathematics and Statistics Faculty Publications and Presentations

The expectation that Ramanujan’s tau function does not vanish, commonly known as Lehmer’s Conjecture, has inspired several extensions to broader settings. In this paper, we focus on one such direction, proposed by Rouse, concerning the non-vanishing of traces of Hecke operators Tn. We refine an algorithm originally introduced by Rouse to resolve the case n = 2, and, together with tools from our earlier work on the case n = 3 in level one, we settle the conjecture for T₃ in full generality. We also discuss an implication of our result for the non-vanishing of all coefficients of the …

Guided Modes Of Helical Waveguides, Jay Gopalakrishnan, Michael Neunteufel

Mathematics and Statistics Faculty Publications and Presentations

This paper studies guided transverse scalar modes propagating through helically coiled waveguides. Modeling the modes as solutions of the Helmholtz equation within the three-dimensional (3D) waveguide geometry, a propagation ansatz transforms the mode-finding problem into a 3D quadratic eigenproblem. Through an untwisting map, the problem is shown to be equivalent to a 3D quadratic eigenproblem on a straightened configuration. Next, exploiting the constant torsion and curvature of the Frenet frame of a circular helix, the 3D eigenproblem is further reduced to a two-dimensional (2D) eigenproblem on the waveguide cross section. All three eigenproblems are numerically treated. As expected, significant computational …

Wind Farm Dynamics Over A Diurnal Cycle: Analysis Of A Comprehensive Large-Eddy Simulation, Web-Services Accessible Dataset, Shuolin Xiao, Xiaowei Zhu, Ghanesh Narasimhan, Dennice F. Gayme, Charles Meneveau

Mechanical and Materials Engineering Faculty Publications and Presentations

The atmospheric boundary layer undergoes significant changes throughout a diurnal cycle, affecting wind turbine performance and wakes in wind farms. Wind farm large-eddy simulations (LES) under such conditions provide rich datasets to study the underlying dynamics and identify important trends. Here, we describe a comprehensive open dataset generated using LES of an eight-turbine wind farm consisting of four rows of two turbines. To avoid specifying either prescribed surface temperature or heat flux, a local one-dimensional soil heat conduction model is used with time-periodic solar surface heating, coupled to LES. After several days of low-resolution LES, an approximately time-periodic behavior is …

Climatic Controls On Soil Production, Transport And Chemical Erosion: Insights From Modelling Topography, Soils And Cosmogenic Nuclides At Little Lake, Oregon, Miles M. Reed, Ken L. Ferrier, Jill A. Marshall, Josh J. Roering, J. Taylor Perron

Geology Faculty Publications and Presentations

Predicting physical and chemical erosion rate responses to climate change are an ongoing challenge in geomorphology. A promising approach for investigating this is by measuring transient variations in physical and chemical erosion rates during climatically variable time periods, which can be accomplished by measuring cosmogenic nuclide concentrations and chemical depletion in sedimentary deposits. Interpreting such measurements warrants applying landscape evolution models that track variations in topography, cosmogenic nuclide concentrations and chemical depletion in soils. We applied a recently developed model that tracks these quantities at Little Lake, Oregon. Previous studies documented variations in cosmogenic nuclide concentrations and chemical depletion in …

Coupling The Parflow Integrated Hydrology Model Within The Nasa Land Information System: A Case Study Over The Upper Colorado River Basin, P.Eyman Abbaszadeh, Fadji Zaouna Maina, Chen Yang, Dan Rosen, Sujay Kumar, Matthew Rodell, Reed Maxwell

Civil and Environmental Engineering Faculty Publications and Presentations

Understanding, observing, and simulating Earth's water cycle is imperative for effective water resource management in the face of a changing climate. While NASA's Land Information System (LIS)/Noah-MP is widely used for land surface modeling, its ability to represent groundwater processes is limited. In contrast, the ParFlow hydrologic model explicitly simulates subsurface water movement. This study explores the effectiveness and usefulness of the newly coupled modeling framework, ParFlow-LIS/Noah-MP (PF-LIS/Noah-MP) over the Upper Colorado River Basin (UCRB). The framework integrates the strengths of both models to provide a physically based representation of surface and subsurface processes and their interactions. Unlike standalone LIS/Noah-MP, …

Understanding The Role Of Sentiment And Emotion For Predicting Forced Displacement, Helge Marahrens, Ameeta Agrawal, Ali Arab, Katharine Donato, Yaguang Liu, Nathan Wycoff, Mohamed Ahmed, Colin Hwang, Lina Laghzaoui, Kate Liggio, Multiple Additional Authors

Computer Science Faculty Publications and Presentations

Digital trace data play an important role determining where and when people will move during migration crises because of their detailed temporal and spatial granularity. Yet, identifying variables that reliably serve as early indicators of movement remains a challenging task. Within this context, we conduct an in-depth analysis of two types of variables that can be constructed from social media data – sentiment and emotion. Sentiment is conceptually broad and easier to detect from social media posts, while emotion is conceptually nuanced and more difficult to determine. We investigate the potential of both sentiment and emotion of Twitter/X posts as …

Rare, Threatened And Endangered Zoology Species Of Oregon (2025), Jesse Laney, Eleanor P. Gaines, Lindsey K. Wise, Misty Nelson

Institute for Natural Resources Publications

This publication provides a 2025 update to the rare, threatened, and endangered zoology species of Oregon. Species lists are also provided in Excel format.

The Oregon Biodiversity Information Center (ORBIC) is part of the Institute for Natural Resources (INR) located at Portland State University (PSU). ORBIC maintains extensive databases of Oregon biodiversity, concentrating on rare and endangered plants, animals and ecosystems. Since its creation in 1979 as the Oregon Natural Heritage Program, ORBIC has been part of the Natural Heritage network. ORBIC is a constituent member of NatureServe, a non-profit organization with a mission to provide the scientific basis for …

A Case Study On The Effectiveness Of Llms In Verification With Proof Assistants, Barış Bayazıt, Yao Li, Xujie Si

Computer Science Faculty Publications and Presentations

Large language models (LLMs) can potentially help with verification using proof assistants by automating proofs. However, it is unclear how effective LLMs are in this task. In this paper, we perform a case study based on two mature Rocq projects: the hs-to-coq tool and Verdi. We evaluate the effectiveness of LLMs in generating proofs by both quantitative and qualitative analysis. Our study finds that: (1) external dependencies and context in the same source file can significantly help proof generation; (2) LLMs perform great on small proofs but can also generate large proofs; (3) LLMs perform differently on different verification projects; …

Digging Deeper With Deep Ram Networks, Andrew J. Wagner

Dissertations and Theses

While Deep Neural Networks (DNNs) have driven major breakthroughs in artificial intelligence, their internal complexity often makes their behavior hard to explain, resulting in the well-known “black box” dilemma. This thesis addresses the challenge of interpretability in DNNs and deep reinforcement learning (DRL) through two main contributions.

In Part I, we revisit and extend the use of Deep RAM Networks (DRNs) within the Arcade Learning Environment (ALE), showing that, with modern architectures and careful hyperparameter tuning, RAM-based agents can achieve performance competitive with established pixel-based baselines on Atari 2600 games, while offering additional advantages for research and analysis. We also …

Characterizing Meteorological Patterns For Oregon's Winter Elevated Pm2.5 Concentrations From 2000-2023, Arielle Golda Sherbak

Dissertations and Theses

Valleys and basins are uniquely susceptible to the buildup of air pollution during the wintertime due to cool, dense air pooling under favorable meteorological conditions, a common occurrence in the Intermountain West. In Oregon, wintertime anthropogenic air pollution is primarily from woodburning stoves and heaters and although efforts have been made to reduce wintertime pollution, stagnation events continue to result in decreased air quality. This analysis aims to understand the relationship between air pollution in six Oregon counties and the associated meteorology in the cool season (November-March) using a 2000-2023 climatology.

This is completed through a composite analysis using key …

Modeling Effective Shade For Oregon Streams Using Satellite Derived Vegetation Structure Metrics, Ella Wagner

Environmental Science and Management Professional Master's Project Reports

In the Pacific Northwest, rising stream temperatures threaten the survival of cold-water species, such as salmonids. The Oregon Department of Environmental Quality (DEQ) regulates stream temperature statewide through Total Maximum Daily Loads (TMDLs). To do this, the DEQ uses stream shade as a surrogate measurement for heat, as stream shade and stream temperature have a well-known strong relationship. This project focused on developing effective shade modeling and monitoring methods that increase the pace and scale of temperature TMDL implementation and tracking in Oregon. Stream shade can be measured in the field and modeled with computer models such as HeatSource, which …

Data-Driven Optimization And Parameter Estimation For A Metric Graph Epidemic Model With Applications To Covid-19 Spread In Poland: A Real-World Example Of Optimization For A Challenging Rosenbrock-Type Objective Function, Hannah Kravitz, Christina Duron, Brittani Nieves, Moysey Brio

Mathematics and Statistics Faculty Publications and Presentations

In this paper, we apply data-driven optimization to estimate key parameters in a metric graph-based epidemiological model, with the aim of analyzing the effect of road networks on the geographic spread of epidemics. As a case study, we fit our model to data from the COVID-19 pandemic in Poland during 2021. Our dataset integrates county-level daily case reports, national census information, and traffic flow studies. This framework allows us to examine the relative contribution of specific travel routes over time and infer unobserved transmission patterns in the presence of incomplete or unreliable case reporting. The optimization problem that arises from …

The Fate Of Recycled Water In Restored Wetlands, Punyotoya Paul

Environmental Science and Management Professional Master's Project Reports

This research investigates the hydrological fate of treated wastewater or "recycled water" used for irrigation at a restored wetland site (Thomas Dairy) near Tigard, Oregon, that is managed by Clean Water Services (CWS). CWS is interested in understanding how treated wastewater moves through plants and soil in ecosystems that might be targeted for recycled water applications. Using a water balance approach, we evaluated irrigation inputs, soil infiltration dynamics, and hydraulic conductivity measurements across three soil types with different textures and other properties. Field measurements were collected using advanced sensors (TEROS and ATMOS devices) and laboratory tools (KSAT) to quantify soil …

The Effect Of Mesoscale Frontal Waves On Landfalling Atmospheric Rivers And Their Associated Precipitation Over The Green River Watershed, Washington, Joseph Michael Riedl

Dissertations and Theses

In this study, the effect of mesoscale frontal waves (MFWs) on extreme precipitation (EP) in the Upper Green River Watershed (UGRW), Washington is investigated. 205 EP days (>95th percentile) are identified in the UGRW between the years 1980 and 2021. To characterize the range of large-scale meteorological conditions associated with EP days, the self-organizing map (SOM) approach is used to cluster daily integrated water vapor transport (IVT) on EP days. To further diagnose the meteorological drivers, composites of several other diagnostic fields are constructed for each SOM node and the preceding days. Together, these results illustrate common orientations of …

Orphan Basalts: Understanding The Origins Of Unassigned Eastern Oregon Basalts, Angela Rae Stetson

Dissertations and Theses

For more than a century, scientists have studied the geologic stratigraphy of eastern Oregon, which chronicles a rich history of volcanic activity spanning millions of years. Recent and ongoing geologic mapping of the northeastern Harney Basin -- along a corridor east of Highway 395 between the towns of Burns and John Day -- provides a more detailed understanding of an area originally mapped only in reconnaissance during the 1960s. At that time, geologic units were poorly delineated, often with entire quadrangles mapped as a single unit. For example, over 90% of the Calamity Butte quadrangle was previously mapped as 'Tba' …

Industries, Self-Rated Health, And Status Characteristics: An Exploration Of Health In Industries At The Intersection Of Race/Ethnicity, Gender, And Disability, Emmanuel Legarreta

Dissertations and Theses

While industries, occupations, and health outcomes have been widely studied, research has neglected self-rated health (SRH) and the intersectionality of different status characteristics in various industries. Using an IPUMS version of the Current Population Survey, this study explores the possible relationships between industries and SRH. More specifically, it seeks to find if workers' disability status, racial minority status, or gender moderates (i.e., differentiates) the relationship between their industry and SRH. Findings show that certain industries are significant predictors of SRH, and that women with disabilities working in Mining and Construction, and Business and Repair Service have significantly worse SRH than …

Edge Percolation Centrality: A New Measure To Quantify The Influence Of Edges During Percolation In Networks, Christina Durón, Hannah Kravitz, Moysey Brio

Mathematics and Statistics Faculty Publications and Presentations

Numerous centrality measures exist to quantify the influence of edges within a network, with edge betweenness being one of the more well-known measures. However, such measures are inadequate in network percolation scenarios (e.g., the transmission of a disease over a transportation network of highways) as they fail to consider the changing percolation states of edges over time. This paper addresses this limitation by extending percolation centrality, a measure originally developed to evaluate the influence of vertices during a percolation process (i.e., a dynamic spread of a contagion) in the network, to the edge level. The proposed measure, edge percolation centrality, …

Probabilistic Intervals Around Population Forecasts: A New Approach With A Subnational Example Using Washington State Counties, David A. Swanson, Jeff Tayman

Publications, Reports and Presentations

Population forecasts produced by governments at all levels are used in the public sector, the private sector, and by researchers. They have been primarily produced using deterministic methods. This paper shows how a method for producing measures of uncertainty can be applied to existing subnational population forecasts while meeting several important criteria, including the concept of utility. The paper includes an assessment of the efficacy of the method by: (1) examining the change in uncertainty intervals it produces by population size and population growth rate; and (2) comparing the width and temporal change of the uncertainty intervals it produces to …

Exploring Underrepresented Stem Undergraduates' Stem Identity Development: The Role Of Social Partners, Sandy Cerda-Lezama

Dissertations and Theses

This dissertation employs a three-study qualitative design to investigate the role of mentorship and social interaction in the identity development of racial minority undergraduate students in STEM disciplines. Grounded in Communities of Practice theory, this research amplifies student narratives to elucidate the relational and contextual factors that inform science identity, belonging, competence, and persistence in higher education. Study One draws upon interview data from fifteen participants in the BUILD program to analyze the role of recognition, particularly from expert scientists--in students' science identity development. This study aims to understand how racial and ethnic identity intersections influence the processes and impact …

Dilemmas Encountered While Planning Social And/Or Political Elementary Mathematics Tasks, Amanda Sugimoto, Simon Byeonguk Han, Courtney Koestler, Eva Thanheiser, Mathew Felton-Koestler, Molly Robinson

Mathematics and Statistics Faculty Publications and Presentations

A mathematical task rooted in social and/or political contexts has the potential to engage students in exploring their own real-ities and learning about the realities of others while building their mathematical knowledge. While there are planning and in-structional practices recommended for these types of tasks, no single practice can fully capture the nuances and challenges thatteachers might encounter. Therefore, this study identified dilemmas encountered by a team of mathematics education research-ers while planning a mathematical task rooted in social and/or political contexts. Using qualitative analysis, the researchersidentified three planning dilemmas: (a) what social and/or political goal to establish, (b) how …

Synoptic-Scale Meteorological Patterns Associated With Extreme Precipitation Over The Contiguous United States And Concomitant Seasonal And Regional Variability, Amy M. Johnson

Dissertations and Theses

Seasonal and spatial variations of synoptic-scale weather patterns concurrent to extreme precipitation days, defined as days above the seasonal 95th percentile of the daily precipitation distribution, are characterized over a 44-year period (1980-2023) for the Contiguous United States (CONUS). Using atmospheric reanalysis data and a grid-cell centered approach, we construct seasonal anomaly composite patterns for sea level-pressure (SLP), integrated water vapor transport, 500 hPa geopotential height (Z500), and 300 hPa wind speed. Atmospheric variables known to be important for extreme precipitation. By interpolating composites for each grid cell onto the same polar coordinate grid relative to the grid cell we …

Improved Fpt Approximation For Sum Of Radii Clustering With Mergeable Constraints, Sayan Bandyapadhyay, Tainzhi Chen

Computer Science Faculty Publications and Presentations

In this work, we study k-min-sum-of-radii (k-MSR) clustering under mergeable constraints. k-MSR seeks to group data points using a set of up to k balls, such that the sum of the radii of the balls is minimized. A clustering constraint is called mergeable if merging two clusters satisfying the constraint, results in a cluster that also satisfies the constraint. Many popularly studied constraints are mergeable, including fairness constraints and lower bound constraints. In our work, we design a (4 + ϵ)-approximation for k-MSR under any given mergeable constraint with runtime 2 O( k ϵ ·log2 k ϵ )n 4 , …

(De)Centralized Water Futures: Key Dimensions Of Infrastructure, Governance, And Operations, Alicia Dailey Cooperman, Jenny Linder Rempel, Ellis Adjei Adams, Alida Cantor, Manuela Muñoz Fuerte, Jeremiah Osborne-Gowey, Nicole J. Wilson, Cassandra L. Workman, Melissa Beresford, Leila M. Harris, Multiple Additional Authors

Geography Faculty Publications and Presentations

Water system centralization and decentralization have variously been promoted as key to achieving household water security and Sustainable Development Goal 6.1. We argue that the lack of specificity with which scholars and practitioners use the terms centralization and decentralization limits our understanding of different water system configurations and their impacts. In this Primer, we provide a framework for thinking about levels of (de)centralization across three linked system dimensions: infrastructure, governance, and operations and maintenance. We encourage those analyzing water systems to characterize (de)centralization with respect to these multiple dimensions, as well as the system's broader political-economic and hydro-climatic contexts. Emphasizing …

Aphasia In South Asian Languages (Asal) Project: A Protocol Of Connected Speech Tasks For Investigating Cross-Linguistic Grammatical Profiles In Aphasia For South Asian Languages, Arpita Bose, Sakshi Bhatia, Lakshmi Venkatesh, Sayantani Banerjee, Gurujegan Murugesan, Sunila John, Sakshi Upadhyay, Manaswita Dutta, Mythili Menon, Danielle Fahey, Multiple Additional Authors

Speech and Hearing Sciences Faculty Publications and Presentations

Background

Languages vary in their syntactic (e.g. word order in sentences), lexical (e.g. presence of specific word classes), and morphological (e.g. inflectional or derivational forms of words) properties. This cross-linguistic variation in language typology influences the manifestation of agrammatic symptoms. However, most theoretical models of agrammatism are based on English and a few European languages, limiting their generalizability. This narrow focus neglects the rich syntactic, lexical and morphological variations available in languages globally. Clinically, the lack of language-specific characteristics of agrammatic impairments limits translational potential for precise and improved diagnosis. The Aphasia in South Asian Languages (ASAL) project addresses this …

From Model To Behavior: Methodological Challenges In Using Fuzzy Cognitive Maps To Represent Mental Models, Catherine Elizabeth Moore

Dissertations and Theses

This dissertation examines the use of Fuzzy cognitive maps (FCMs) as representations of mental models and how these representations connect to individual behavior. Fuzzy cognitive maps (FCMs) are semi-quantitative models that encode cause-and-effect structures as directed graphs. They are frequently used to represent individuals' knowledge structures/mental models and should in theory correlate to actions and decisions of individuals; however, this correlation has yet to be explored in a systematic manner. This dissertation represents the first step in experimental research on the connection between FCMs and individual behavior. It examines two theories of how humans use mental models, one based on …

Mechanistic Rationale For Toxic Aerosol Formation From Vaping And Dabbing With A Focus On Ketene Formation From Semi-Synthetic Cannabinoids, Kaelas Ryan Munger

Dissertations and Theses

Cannabis vaping is a relatively new route of administration that is increasingly common among youth and young adults. Cannabis vaping has been associated with cases of acute lung injury, especially among youth, and most often involves the heating and aerosolization of high-potency products having cannabinoid concentrations of ~ 50 % - 98 % w/w. Proponents argue that vaping is safer than smoking due to the characteristically lower temperatures and fewer plant materials. However, the extreme cannabinoid concentrations, along with non-natural formulations having undisclosed additives, require studies of the health effects of these products. Despite the popularity of cannabis concentrate vaping, …

Impact Of Black Shale Weathering On Stream Water And Sediment Quality In Eastern Kentucky, Brett Hopt

Dissertations and Theses

Black shales contain high concentrations of trace elements in addition to their elevated organic carbon content. Once exposed at the surface, weathering processes release these elements into the environment, including many (e.g., As, Cu, Cd, Cr, U, Zn) that could pose threats to human and environmental health. Previous studies have focused on how these metals are incorporated into the soil column and their effects on crop nutrition. However, few studies have focused on the impact of natural weathering of black shales on local stream water chemistry and the transport and subsequent partitioning of these geogenic contaminants into stream environments.

This …

Fathers' Racial Differences In Perceived Workplace-Induced Stereotype Threat: Impacts On Sense Of Belonging, Job Satisfaction, And Turnover, Frances Evalyne Kealiimahiaiokalani Hampton

Dissertations and Theses

Black fathers (BFs) face unique workplace challenges due to racialized and gendered stereotypes that undermine their legitimacy as men, workers, and parents. Drawing on Stereotype Threat Theory (STT) and Stereotype Embodiment Theory (SET), this study examined how workplace-induced stereotype threat (WIST) affects BFs' job attitudes and turnover intentions (TIs). I hypothesized that BFs would report higher WIST than White fathers (WFs), and that WIST would mediate the effects of race-related perceptions on job satisfaction (JS), sense of belonging (SOB), and TIs. In addition, perceived organizational support (POS) was tested as a moderator on the relationships between WIST and these job-related …