Digital Commons Network^™

Dependence Comparisons Of Order Statistics In The Proportional Hazards Model, Subhash C. Kochar

Mathematics and Statistics Faculty Publications and Presentations

Let X₁,…,X_n be mutually independent exponential random variables with distinct hazard rates λ₁,…,λ_n > 0 and let Y₁,…,Y_n be a random sample from the exponential distribution with hazard rate $\bar \lmd = \sum_{i=1}^n \lmd_i/n$. Also let X_1:n < ⋯ < X_n:n and Y_1:n < ⋯ < Y_n:n be their associated order statistics. It is shown that for 1 ≤ i < j ≤ n, the generalized spacing X_j:n - X _i:n is more dispersed than Y_j:n− Y_i:n according to dispersive ordering. This result is used to solve a long standing open problem …

Effects Of Pore-Forming Peptides (Melittin And Magainin 2) On The Phospholipid Bilayer Interior, Elmukhtar Ehmed Alhatmi

Dissertations and Theses

Antimicrobial peptides (AMPs) are one of the most promising solutions to drug-resistant bacteria. Melittin and magainin 2 are two of the most representative and extensively studied AMPs. In this research, I investigated the interaction of these two AMPs with three models of cell membranes: 80% POPC 20% POPG, 40%POPC 40% POPE and 20% POPG, and 80%POPC 20%POPG plus 30% mole fraction of cholesterol. Time-resolved fluorescence emission and fluorescence anisotropy decays of the fluorescent probe 1,6-diphenyl-1,3,5-hexatriene (DPH) were analyzed to determine the effects of AMPs on the bilayer headgroup packing and changes in the interior of the phospholipid bilayer during the …

Modeling Cyanobacteria Vertical Migration, Corina Christina Mae Overman, Scott A. Wells

Civil and Environmental Engineering Faculty Publications and Presentations

Cyanobacteria often cause harmful algal blooms and release toxic substances that can harm humans and animals. Accurately modeling these phytoplankton is a step towards predicting, preventing, and controlling such blooms. Certain cyanobacteria species are known to migrate vertically in the water column on a daily cycle. Capturing this behavior is one aspect of modeling their dynamics. Previous studies on modeling cyanobacterial vertical migration are reviewed and summarized. Several models of cyanobacteria vertical movement are tested using data from field studies. These models are applied using both continuum and particle-tracking frameworks. Models range in complexity from simple functions of time to …

Working Paper No. 58, Auro Ex Oleum: Departing The American Gold Standard*, Zakhary L. Roth

Working Papers in Economics

This inquiry seeks to establish that the character of the United States dollar fundamentally changed over the course of the 20th century as it moved away from its being rooted in the gold standard. As the global economy transitioned into the 20th century and the United States began establishing itself as a cornerstone of global trade, the dollar evolved into the standard currency of the world economy, changing significantly along the way as it moved from a gold-backed standard to the reserve currency of the international petroleum trade. These changes are reflected in U.S. foreign and monetary policy throughout this …

Fenchel-Rockafellar Theorem In Infinite Dimensions Via Generalized Relative Interiors, Dang Van Cuong, Mau Nam Nguyen, B. S. Mordukhovich, G. Sandine

Mathematics and Statistics Faculty Publications and Presentations

In this paper we provide further studies of the Fenchel duality theory in the general framework of locally convex topological vector (LCTV) spaces. We prove the validity of the Fenchel strong duality under some qualification conditions via generalized relative interiors imposed on the epigraphs and the domains of the functions involved. Our results directly generalize the classical Fenchel-Rockafellar theorem on strong duality from finite dimensions to LCTV spaces.

Quantification Of Reynolds Shear Stress Wave-Phase Dependence In Fixed-Bottom Offshore Wind Turbine Via Quadrant Analysis, Cerrina Mouchref

University Honors Theses

As the need for a reliable renewable energy supply is increasing, many have looked to offshore wind because they hold more potential for power production than onshore wind. Interests in expanding offshore wind energy has brought along many challenges when it comes to understanding the complex dynamics experienced offshore, including the relationship between the wind-turbine generated wakes and ocean waves. This experimental study characterizes the relationship between Reynolds shear stress and the phase of surface waves above the air-sea interface in the wind-turbine wake region. The experimental setup combines a wave tank, wind tunnel, and a fixed-bottom wind turbine. Particle …

Using Intrinsically-Typed Definitional Interpreters To Verify Compiler Optimizations In A Monadic Intermediate Language, Dani Barrack

Dissertations and Theses

Compiler optimizations are critical to the efficiency of modern functional programs. At the same time, optimizations that unintentionally change the semantics of programs can systematically introduce errors into programs that pass through them. The question of how to best verify that optimizations and other program transformations preserve semantics is an important one, given the potential for error introduction. Dependent types allow us to prove that properties about our programs are correct, as well as to design data types and interpreters in such a way that they are correct-by-construction. In this thesis, we explore the use of dependent types and intrinsically-typed …

Coming To Know The Local Environment: Children's Experiences In Rautamai Gaunpalika, Nepal, Elsie Nicole Love

Dissertations and Theses

This qualitative research, conducted over three months from late monsoon season into early fall of 2018 with twenty-six children and thirteen adults, explores how children in the hills of Rautamai Gaunpalika, Province 1, Nepal come to know their local environment. Semi-structured interviews with children, their family members, and teachers, and participant observation with children as they worked and played in forests, fields, and streams, suggest that outside of school, children come to know their local environment in the following ways: through participation in and application of knowledge to subsistence practices; through collaborative learning and teaching in mixed-age groups; through relationships …

Can The Concepts Of Energy And Psychological Energy Enrich Our Understanding Of Psychosocial Adaptation To Traumatic Experiences, Chronic Illnesses And Disabilities?, Hanoch Livneh

Counselor Education Faculty Publications and Presentations

The aim of this paper is to familiarize the reader with the concept of psychological energy (PE), and the role it plays in deepening our understanding of psychosocial adaptation to traumatic life events and, more pointedly, the onset of chronic illness and disability (CID). In order to implement this aim, the following steps were undertaken: First, a brief historical review of the nature of energy, force and action, as traditionally conceived in the field of physics, is provided. Second, an overview of PE is presented, with a shared emphasis on both its historical underpinnings and its present conceptualizations in the …

Cetacean Strandings In The Us Pacific Northwest 2000–2019 Reveal Potential Linkages To Oceanographic Variability, Amanda J. Warlick, Jessica L. Huggins, Dyanna M. Lambourn, Deborah A. Duffield, Dalin Nichole D'Alessandro, James M. Rice, John Calambokidis, M. Bradley Hanson, Joseph K. Gaydos, Multiple Additional Authors

Biology Faculty Publications and Presentations

Studying patterns in marine mammal stranding cases can provide insight into changes in population health, abundance, and distribution. Cetaceans along the United States West coast strand for a wide variety of reasons, including disease, injury, and poor nutritional status, all of which may be caused by both natural and anthropogenic factors. Examining the potential drivers of these stranding cases can reveal how populations respond to changes in their habitat, notably oceanographic variability and anthropogenic activities. In this study, we aim to synthesize recent patterns in 1,819 cetacean strandings across 26 species in the Pacific Northwest from 2000 to 2019 to …

Classifying Dead Code In Software Development, Arman Alavizadeh

University Honors Theses

Dead code pervades as an issue in the world of software development as a source of many famous software disasters such as the ARIANE 5 rocket failure and chemical bank withdrawal error. Defining dead code on narrow levels of granularity has not been fully explored, yet is crucial to better our understanding of dead code. Here we will be starting a discussion on how to approach classifying dead code via comparing dead code research specific to an industry segment. Research will be compared primarily by methodology and limitations. Dead code subtype classifications are gleaned from research comparisons and can serve …

An Introduction To Number Theory, J. J. P. Veerman

PDXOpen: Open Educational Resources

These notes are a preliminary text intended for a graduate course in Number Theory. A thoroughly improved, revised, and expanded version of this book will be published in 2026 through Springer under the title Numbers from All Angles.

Chapters 1-14 of this preliminary text represent almost 3 trimesters of the course. No prior familiarity with number theory is assumed. The current content represents courses the author taught in the academic years 2020-2021 and 2021-2022.

Continuum Dynamics And Statistical Correction Of Compositional Heterogeneity In Multivalent Idp Oligomers Resolved By Single-Particle Em, Barmak Mostofian, Russell Mcfarland, Aiden Estelle, Jesse Howe, Elisar J. Barbar, Steve L. Reichow, Daniel M. Zuckerman

Chemistry Faculty Publications and Presentations

Multivalent intrinsically disordered protein (IDP) complexes are prevalent in biology and act in regulation of diverse processes, including transcription, signaling events, and the assembly and disassembly of complex macromolecular architectures. These systems pose significant challenges to structural investigation, due to continuum dynamics imparted by the IDP and compositional heterogeneity resulting from characteristic low-affinity interactions. Here, we developed a modular pipeline for automated single-particle electron microscopy (EM) distribution analysis of common but relatively understudied semi-ordered systems: 'beads-on-a-string' assemblies, composed of IDPs bound at multivalent sites to the ubiquitous ∼20kDacross-linking hub protein LC8. This approach quantifies conformational geometries and compositional heterogeneity on …

Effects Of Long Duration Earthquakes On The Interaction Of Inertial And Liquefaction-Induced Kinematic Demands On Pile-Supported Wharves, Milad Souri, Arash Khosravifar, Stephen E. Dickenson, Nason Mccullough, Scott Schlechter

Civil and Environmental Engineering Faculty Publications and Presentations

Nonlinear dynamic analyses were performed to evaluate the effects of ground motion duration on the dynamic response of a pile-supported wharf subjected to liquefaction-induced lateral ground deformations. The numerical model was first calibrated using recorded data from a well-instrumented centrifuge test, after which incremental dynamic analyses were conducted using a suite of spectrally matched motions with different durations. The nonlinear dynamic analyses were performed to evaluated three loading scenarios: combined effects of inertial loads from the wharf deck and kinematic loads from ground deformations, deck inertial loads only in the absence of liquefaction (with minimal kinematic loads), and kinematic loads …

An Algorithm For Identifying Eigenvectors Exhibiting Strong Spatial Localization, Jeffrey S. Ovall, Robyn Reid

Mathematics and Statistics Faculty Publications and Presentations

We introduce an approach for exploring eigenvector localization phenomena for a class of (unbounded) selfadjoint operators. More specifically, given a target region and a tolerance, the algorithm identifies candidate eigenpairs for which the eigenvector is expected to be localized in the target region to within that tolerance. Theoretical results, together with detailed numerical illustrations of them, are provided that support our algorithm. A partial realization of the algorithm is described and tested, providing a proof of concept for the approach.

Does Restoration Of Urban Riparian Zones Impact Stream Water Quality In Portland, Oregon, Ash Ivanov

University Honors Theses

Riparian zones influence urban stream quality through factors such as shading the stream, adding nutrients through leaf litter, stabilizing the stream banks to reduce turbidity, and filtering toxins out of the water. Riparian restoration often involves changing plant assemblage to be more diverse and include primarily native species instead of non-native, improving connection to the stream through changing stream morphology, improving species habitat, and reducing pollution. The goal of this study was to determine if urban riparian restoration projects in the region were successful, and if not, why that may be the case. The study was performed in the Portland, …

Minimality Of Integer Bar Visibility Graphs, Emily Dehoff

University Honors Theses

A visibility representation is an association between the set of vertices in a graph and a set of objects in the plane such that two objects have an unobstructed, positive-width line of sight between them if and only if their two associated vertices are adjacent. In this paper, we focus on integer bar visibility graphs (IBVGs), which use horizontal line segments with integer endpoints to represent the vertices of a given graph. We present results on the exact widths of IBVGs of paths, cycles, and stars, and lower bounds on trees and general graphs. In our main results, we find …

Co-Seismic And Post-Seismic Deformation For The 1995 Colima–Jalisco And 2003 Tecoman Thrust Earthquakes, Mexico Subduction Zone, ́ From Modelling Of Gps Data, Beatriz Cosenza-Muralles, Charles Demets, O. Sanchez, Enrique Cabral-Cano, J. Stock, B. Márquez-Azúa, Robert Mccaffrey

Geology Faculty Publications and Presentations

We invert ∼25 yr of campaign and continuous Global Positioning System daily positions at 62 sites in southwestern Mexico to estimate co-seismic and post-seismic afterslip solutions for the 1995 M_w = 8.0 Colima–Jalisco and the 2003 M_w = 7.5 Tecomán earthquakes, and the long-term velocity of each GPS site. Estimates of the viscoelastic effects of both earthquakes from a 3-D model with an elastic crust and subducting slab, and linear Maxwell viscoelastic mantle are used to correct the GPS position time-series prior to our time-dependent inversions. The preferred model, which optimizes the fit to data from several years …

Efficient Capture Of Co2 And Its Selective Reduction To Formic Acid Using Tin-Based Nanomaterials, Emmanuel Oluwaseun Abdul

Dissertations and Theses

CO₂ emissions from the combustion of fossil fuels and other anthropogenic sources have become the main contributing factors to global warming. Chemical methods of absorbing/capturing CO₂ from combustion flue gases have made it a sought-after approach in engineering emission solutions because of its simplistic and convenient operation and high absorption efficiency. The conversion of CO₂ into renewable fuels and high energy density chemicals by clean and economic processes has drawn scientists' attention over the decades. The electrocatalytic conversion of CO₂ using Sn-based materials has been demonstrated to be a promising method for producing formate, an important …

Stratigraphic And Geochemical Evaluation Of Distal Flows Of The Columbia River Flood Basalts In The Greater Vale Area, Southeastern Oregon, Lena Marie Fox

Dissertations and Theses

Exposures of Columbia River Basalt Group (CRBG) in southeastern Oregon are dominated by the four main phase CRBG units: Steens Basalt, Imnaha Basalt, Grande Ronde Basalt (GRB), and Picture Gorge Basalt (PGB). These units are best seen in stratigraphic sequence along the Malheur Gorge corridor of southeastern Oregon, between the towns of Vale and Juntura, with flows of Steens Basalt from the south overlain by flows of Imnaha and GRB from the north. Recently, PGB flows were found to be part of the eastern Malheur Gorge stratigraphy as well.

In Malheur Gorge, local units of Birch and Hunter Creek Basalt …

Visualizing Connectivity For Wildlife In A World Without Roads, Catherine De Rivera, Leslie Bliss-Ketchum, Martin Lafrenz, A. V. Hanson, L. E. Mckinney-Wise, A. H. Rodriguez, J. Schultz, Alana Simmons, D. Taylor Rodriguez, Multiple Additional Authors

Environmental Science and Management Faculty Publications and Presentations

Roads are not the only determining factor for wildlife movement across the landscape, but due to the extensive distribution of the road network their impact can be dramatic. Although it has been well documented that roads decrease habitat connectivity for wildlife due to animal-vehicle collisions, habitat fragmentation, and avoidance behavior, approaches for identifying connectivity across the landscape often do not fully examine the barrier effect of roads. Here, we explored the extent of the impact of roadways on wildlife connectivity by using Omniscape to model connectivity including and without the barrier effect of roads, then evaluating the difference between these …

Variability Of Potential Soil Nitrogen Cycling Rates In Stormwater Bioretention Facilities, Erin N. Rivers, Jennifer L. Morse

Environmental Science and Management Faculty Publications and Presentations

Low-impact development (LID) is a common management practice used to infiltrate and filter stormwater through vegetated soil systems. The pollutant reduction potential of these systems is often characterized by a single pollutant removal rate; however, the biophysical properties of soils that regulate the removal of pollutants can be highly variable depending on environmental conditions. The goal of this study was to characterize the variability of soil properties and nitrogen (N) cycling rates in bioretention facilities (BRFs). Soil properties and potential N cycling processes were measured in nine curbside bioretention facilities (BRFs) in Portland, OR during summer and winter seasons, and …

Maximum Entropy And Constraints In Composite Systems, John D. Ramshaw

Physics Faculty Publications and Presentations

The principle of maximum entropy (PME), as expounded by Jaynes, is based on the maximization of the Boltzmann-Gibbs-Shannon (BGS) entropy subject to linear constraints. The resulting probability distributions are of canonical (exponential) form. However, the rationale for linear constraints is nebulous, and probability distributions are not always canonical. Here we show that the correct noncanonical distribution for a system in equilibrium with a finite heat bath is implied by the unconstrained maximization of the total BGS entropy of the system and bath together. This procedure is shown to be equivalent to maximizing the BGS entropy of the system alone subject …

Speciation Of Diaryliodonium Salts In Solution And Their Reactivity Towards N-Nucleophiles (Phthalimide And Amines) And O-Nucleophiles (Phenols And Phenoxide), Souradeep Basu

Dissertations and Theses

Benzenoid rings are prevalent in pharmaceutical drug molecules, agrochemical molecules and even in some polymers used in electronic device. Aryl rings are often installed using metal catalysis, however, metal free arylations are known but limited. Diaryliodonium salts are novel electrophilic arylating agents. Herein, metal free N-arylation of phthalimide and diarylether formation using aryl(TMP)iodonium salts is described.

The structure of diaryliodonium salts has been primarily studied in either the solid state or in-silico. The structure and speciation of diaryliodonium salts in solution is not well explored. In this work evidence of dimer formation of aryl(Mes)iodonium salts in chloroform using …

Exploring Student Perceptions Of Behavioral, Cognitive, And Emotional Engagement At The Activity Level In General Chemistry, Nicole Naibert, Elizabeth Vaughan, Kylee M. Brevick, Jack Barbera

Chemistry Faculty Publications and Presentations

Although active learning strategies are being incorporated into many higher-education STEM courses, not all students benefit from these activities to the same extent. As these types of activities are designed to engage students in their learning, differences in student engagement may explain some of the differences in learning outcomes. However, before student engagement in active learning activities can be meaningfully measured using a self-report survey, it is important to evaluate if students perceive engagement similarly to the literature definitions on which these measures are based. Therefore, this study sought to explore students’ perceptions of the behavioral, cognitive, and emotional dimensions …

Development And Evaluation Of A Survey To Measure Student Engagement At The Activity Level In General Chemistry, Nicole Naibert, Jack Barbera

Chemistry Faculty Publications and Presentations

Student engagement is an important consideration when incorporating active learning activities into a classroom. To facilitate the large-scale assessment of students’ engagement in activities, a survey measure must first be developed and evaluated. Therefore, the goal of this study was to create a self-report measure of student engagement for use with active learning activities in general chemistry classes. The Activity Engagement Survey (AcES) was modified from an existing survey of engagement of middle and high school science students that contained behavioral, cognitive, emotional, and social engagement items. Multiple rounds of response process interviews and factor analyses were used to modify …

The Castle Rock And Ironside Mountain Calderas, Eastern Oregon, Usa: Adjacent Venting Sites Of Two Dinner Creek Tuff Units—The Most Widespread Tuffs Associated With Columbia River Flood Basalt Volcanism, Matthew Cruz, Martin J. Streck

Geology Faculty Publications and Presentations

The Dinner Creek Tuff is an important unit of mid-Miocene rhyolite volcanism contemporaneous to flood basalts of the Columbia River magmatic province. Field mapping along with analytical data of tuff samples identify two calderas, the Castle Rock and Ironside Mountain calderas, as the venting sites of two widespread ignimbrites of the Dinner Creek Tuff. Both calderas lie within the area of the proposed general storage sites of main-phase Columbia River Basalt magmas. The Castle Rock caldera formed during the eruption of the 16.16 Ma Dinner Creek Tuff unit 1. The northwestern boundary of the caldera is roughly defined by the …

Can We Do Better Next Time? Italians’ Response To The Covid-19 Emergency Through A Heuristics And Biases Lens, Raffaella Misuraca, Ursina Teuscher, Costanza Scaffidi Abbate, Francesco Ceresia, Michelle Roccella, Lucia Parisi, Luigi Vetri, Silvana Miceli

Psychology Faculty Publications and Presentations

During the outbreak of COVID-19 in Italy, people often failed to adopt behaviors that could have stopped, or at least slowed down, the spread of this deadly disease. We offer cognitive explanations for these decisions, based on some of the most common heuristics and biases that are known to influence human judgment and decision-making, especially under conditions of high uncertainty. Our analysis concludes with the following recommendations: policymakers can and should take advantage of this established science, in order to communicate more effectively and increase the likelihood that people choose responsible actions in a public health crisis.

A New Agent-Based Model Offers Insight Into Population-Wide Adoption Of Prosocial Common-Pool Behavior, Garry Sotnik, Thaddeus Shannon, Wayne Wakeland

Complex Systems Faculty Publications and Presentations

New theoretical agent-based model of population-wide adoption of prosocial common-pool behavior with four parameters (initial percent of adopters, pressure to change behavior, synergy from behavior, and population density); dynamics in behavior, movement, freeriding, and group composition and size; and emergence of multilevel group selection. Theoretical analysis of model’s dynamics identified six regions in model’s parameter space, in which pressure-synergy combinations lead to different outcomes: extinction, persistence, and full adoption. Simulation results verified the theoretical analysis and demonstrated that increases in density reduce number of pressure-synergy combinations leading to population-wide adoption; initial percent of contributors affects underlying behavior and final outcomes, …

New Opportunities And Untapped Scientific Potential In The Abyssal Ocean, Jeffrey J. Marlowe, Rika E. Anderson, Anna-Louise Reysenbach, Jeffrey S. Seewald, Timothy M. Shank, Andreas P. Teske, V. Dorsey Wanless, S. Adam Soule

Biology Faculty Publications and Presentations

The abyssal ocean covers more than half of the Earth’s surface, yet remains understudied and underappreciated. In this Perspectives article, we mark the occasion of the Deep Submergence Vehicle Alvin’s increased depth range (from 4500 to 6500 m) to highlight the scientific potential of the abyssal seafloor. From a geologic perspective, ultra-slow spreading mid-ocean ridges, Petit Spot volcanism, transform faults, and subduction zones put the full life cycle of oceanic crust on display in the abyss, revealing constructive and destructive forces over wide ranges in time and space. Geochemically, the abyssal pressure regime influences the solubility of constituents such as …