Physical Sciences and Mathematics Commons^™

A Bayesian Latent Scale Model For Multivariate Longitudinal Data, Kruti Pandya

Dissertations and Theses

In order to understand the entire course of slow progressing diseases like Alzheimer's dementia or multiple sclerosis, it is essential to characterize long term disease dynamics from a healthy stage to a late disease stage. Cohort studies typically recruit subjects at different stages of the disease and then follow them for a relatively short period of time. In this dissertation, we propose a novel Bayesian nonlinear mixed effects model with latent time scale to characterize long term disease dynamics using the observed short term longitudinal data from cohort studies without relying on clinical diagnosis. This model can accommodate noisy longitudinal …

Methodologies For Quantum Circuit And Algorithm Design At Low And High Levels, Edison Tsai

Dissertations and Theses

Although the concept of quantum computing has existed for decades, the technology needed to successfully implement a quantum computing system has not yet reached the level of sophistication, reliability, and scalability necessary for commercial viability until very recently. Significant progress on this front was made in the past few years, with IBM planning to create a 1000-qubit chip by the end of 2023, and Google already claiming to have achieved quantum supremacy. Other major industry players such as Intel and Microsoft have also invested significant amounts of resources into quantum computing research.

Any viable computing system requires both hardware and …

Observation And Control Of Photoemission And Electric Field Enhancement Of Plasmonic Antennas Through Photoemission Electron Microscopy, Christopher M. Scheffler

Dissertations and Theses

Photoemission electron microscopy (PEEM) is an imaging method which uses electrons excited through the photoelectric effect to characterize a sample surface with nanometer-level resolution. In PEEM, a high intensity laser excites electrons from the surface of the material and electron optics are used to form an image from the intensity and spatial distribution of the photoemission from the sample. The goal of this research was to study and maximize light confinement, which was accomplished using plasmonic nanostructures. Surface plasmons represent oscillations in the electron density of a material and can occur along the transition interface between a metal and a …

Data-Driven Analysis Of Drug And Substance Abuse Rates Across The Varying Regions In The United States Of America, Reem Saleh

University Honors Theses

Drugs and substance abuse is one of the leading causes of death for adolescents in the United States. The consequences of using these drugs are profound and can cause both damage to one's physical and psychological health. The rates of drug abuse in the United States continue to increase over the years. This paper analyzes the trends in rates of drug abuse in the four regions in the United States. It looks at the rates in cocaine, cigarettes, marijuana, and tobacco. A preliminary analysis was done to look at the trend in rates followed by an ARIMA time series model …

The Hyperporphyrin Concept: A Contemporary Perspective, Carl C. Wamser, Abhik Ghosh

Chemistry Faculty Publications and Presentations

The Gouterman four-orbital model conceptualizes porphyrin UV–visible spectra as dominated by four frontier molecular orbitals─two nearly degenerate HOMOs and two exactly degenerate LUMOS under D4h symmetry. These are well separated from all the other molecular orbitals, and normal spectra involve transitions among these MOs. Unusual spectra occur when additional orbitals appear in this energy range, typically as a consequence of the central coordinated atom. For example, metals with empty d orbitals in a suitable energy range may lead to charge transfer from porphyrin (ligand) to metal, that is, so-called LMCT transitions. Metals with filled p or d orbitals may …

Ecosystem Connectivity For Livable Cities: A Connectivity Benefits Framework For Urban Planning, Carole Hardy, Catherine De Rivera, Leslie Bliss-Ketchum, Eric P. Butler, Sahan Dissanayake, Dorothy A. Horn, Ben Huffine, Amanda M. Temple, Michael Vermeulen, Hailey Wallace, Jennifer Michelle Karps

Environmental Science and Management Faculty Publications and Presentations

Urbanization disrupts landscapes and ecosystem functions, which poses threats to biodiversity, social systems, and human health, particularly among vulnerable populations. Urban land-use planners are faced with competing demands for housing, safety, transportation, and economic development and often lack tools to integrate these with protecting environmental functions. We identify three major barriers to integrating the benefits that flow with connected, functioning ecosystems into land-use planning. The lack of a shared language among planners and stakeholders poses a barrier to the restoration and preservation of ecological features. Methods of incorporating the benefits from connectivity are not standardized because values are not readily …

Analysis Of Aftershock Parameters For The Alaskan Subduction Zone Tectonic Region, Gabrielle M. Paris

Geology Undergraduate Honors Theses

Forecasting how many earthquakes will occur following a potentially damaging earthquake helps the public and emergency operators stay safe and make informed decisions. The U.S. Geological Survey issues aftershock forecasts following potentially damaging earthquakes, using models to predict the number of earthquakes that should occur within the next day, week, month, and year with 95% confidence to reflect the uncertainty in aftershock behavior. The USGS considers the forecast to be "successful" when the number of earthquakes observed within the forecasted time period is within the 95% confidence interval. For aftershock sequences that occur along the forearc of the Alaskan subduction …

Understanding Ch4 Emissions From Compostables: An Exploration Of Local Ch4 Emissions From Landfilled Compostables And The Efficacy Of Emission Mitigation Via Anaerobic Biogas Digestion, Jordan-Yoosuf Aljbour

University Honors Theses

Methane (CH₄) is the second most abundant anthropogenic greenhouse gas within the atmosphere, comprising ~16% of the total anthropogenic greenhouse gas composition on Earth. It has an ~12-year lifetime relative to its eventual oxidation via reaction with tropospheric hydroxyl radicals (OH), and has a 100-year indirect global warming potential (GWP) approximately ranging between 28-36 [Environmental Protection Agency, 2021]. In recent years, the observed average global concentration of atmospheric CH₄ has increased by ~11.0% from 2020 (~15.3 ppb) to 2021 (~17.0 ppb) [Dlugokencky et al., 1994; National Oceanic and Atmospheric Administration, 2022]. With …

National Climate Data Graphical Plotting Software Review, Melissa Barnes

University Honors Theses

This is a review of an undergraduate Computer Science Capstone project. The paper discusses the development process, what software tools were used, the challenges faced during the development process, and what the software does. The software described in this paper is a python program that utilizes United States county-scoped climate and drought data from the National Climate Data Center to create visualizations and mathematical calculations. The software has an interactive user interface that displays various graphs, heat maps and calculated values. Elevation and population data estimates for populated areas in most counties is also provided. Users may select any set …

Scenario Acceleration Through Automated Modelling: A Method And System For Creating Traceable Quantitative Future Scenarios Based On Fcm System Modeling And Natural Language Processing, Christopher W.H. Davis

Dissertations and Theses

Scenario planning is used extensively in strategic planning because it helps leaders broaden their perspectives and make better decisions by presenting possible futures in story form. Some of the benefits of using scenarios include breaking away from groupthink, creating better products, acceleration of organization learning and reducing bias. Product development teams, particularly for digital products, are gaining more autonomy in organizations and tend to manage risk by undergoing very short development iterations on their products while leaning on their consumers for feedback -- a process known as agile development. This method tends to limit the perspective of the team and …

Development Of The Chemistry Mindset Instrument (Chemi) For Use With Introductory Undergraduate Chemistry Students, Deborah L. Santos, Jack Barbera, Suazette R. Mooring

Chemistry Faculty Publications and Presentations

Chemistry education research has increasingly considered the role of affect when investigating chemistry learning environments over the past decade. Despite its popularity in educational spheres, mindset has been understudied from a chemistry-specific perspective. Mindset encompasses one's beliefs about the ability to change intelligence with effort and has been shown to be a domain-specific construct. For this reason, students’ mindset would be most relevant in chemistry if it were measured as a chemistry-specific construct. To date, no instrument has been developed for use in chemistry learning contexts. Here we present evidence supporting the development process and final product of a mindset …

Transformative Ecoliteracy Development In Postsecondary Education: Cultivating Intentional Relationships Through Garden-Based Learning, Shevawn Armstrong

Dissertations and Theses

Education can play a critical role in empowering learners to address the global, complex, and interconnected sustainability problems humanity currently faces. Ecoliteracy, as an educational aim, may support the cultivation of values, attitudes, and skills required for the development of sustainability solutions and our collective ability to design regenerative ways of living. However, empirical research that explores and supports the development of ecoliteracy in adults is limited. This grounded theory action research study aimed to contribute to this body of knowledge. This study explored how adult ecoliteracy and practical gardening skills may be cultivated through an intentionally designed, holistic, garden-based …

Synthesis Of Diaryl And Alkyl-Aryl Ethers Via Diaryl Iodonium Reagents, Rory Tennessee Gallagher

Dissertations and Theses

Substituted benzenoid rings are a prevalent motif in many industries including high tech, agrochemicals, and pharmaceuticals. As a result, the arylation of chemical compounds is a highly sought-after chemical transformation. There are many literature methods to achieve this chemical transformation, nucleophilic aromatic substitution and transition metal catalysis are both widely used and studied. Diaryliodonium salt mediated chemistry is an attractive alternative to these methods as it does not require the expensive toxic metals and designer ligands of transition metal catalysis and is not restricted to electron deficient aryl rings with specific substitution patterns like nucleophilic aromatic substitution.

Many diaryliodonium salt …

Equidistant Sets In Spaces Of Bounded Curvature, Logan Scott Fox

Dissertations and Theses

Given a metric space (X,d), and two nonempty subsets A,B ⊆ X, we study the properties of the set of points of equal distance to A and B, which we call the equidistant set E(A,B). In general, the structure of the equidistant set is quite unpredictable, so we look for conditions on the ambient space, as well as the given subsets, which lead to some regularity of the properties of the equidistant set. At a minimum, we will always require that X is path connected (so that E( …

Citizen Science Across Two Centuries Reveals Phenological Change Among Plant Species And Functional Groups In The Northeastern Us, Kerissa Battle, Anna Duhon, Conrad R. Vispo, Theresa M. Crimmins, Todd Rosenstiel, Lilas L. Armstrong-Davies, Catherine De Rivera

Environmental Science and Management Faculty Publications and Presentations

1. Understanding the breadth and complexity of changes in phenology is limited by the availability of long-term historical data sets with broad geographic range.
2. We compare a recently discovered historical data set of plant phenology observations collected across the state of New York (1826–1872) to contemporary volunteer-contributed observations (2009–2017) to evaluate changes in plant phenology between time periods. These multi-site, multi-taxa phenology data matched with temperature data uniquely extend historical observations back in time prior to the major atmospheric effects of the Industrial Revolution.
3. The majority of the 36 trees, shrubs and forbs that comprised our analysable data set flowered and …

Advancing Our Understanding Of Green Roofs With Samantha Hartzell, Samantha Hartzell

PDXPLORES Podcast

Green roofs provide a variety of benefits including increasing stormwater retention, lowering cooling costs and mitigating the urban heat island effect. However, the ecosystem services provided by green roofs vary by vegetation choice and environmental conditions.

Assistant Professor Samantha Hartzell is an ecohydrologist whose research focuses on developing technologies to improve green roof designs, inform vegetation selection, and better understand the value of green roofs.

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Geodesic Bicombings On Some Hyperspaces, Logan S. Fox

Mathematics and Statistics Faculty Publications and Presentations

We show that if (X,d)" role="presentation" style="box-sizing: inherit; display: inline; line-height: normal; word-spacing: normal; overflow-wrap: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; padding: 0px; margin: 0px; position: relative;">(X,d)(X,d) is a metric space which admits a consistent convex geodesic bicombing, then we can construct a conical bicombing on CB(X)" role="presentation" style="box-sizing: inherit; display: inline; line-height: normal; word-spacing: normal; overflow-wrap: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; padding: 0px; margin: 0px; position: relative;">CB(X)CB(X), the hyperspace of nonempty, closed, bounded, and …

Orbital Analysis Of Bonding In Diarylhalonium Salts And Relevance To Periodic Trends In Structure And Reactivity, Shubhendu S. Karandikar, Avik Bhattacharjee, Bryan Metze, Nicole Javaly, Edward J. Valente, Theresa M. Mccormick, David R. Stuart

Chemistry Faculty Publications and Presentations

Diarylhalonium compounds provide new opportunities as reagents and catalysts in the field of organic synthesis. The three center, four electron (3c–4e) bond is a center piece of their reactivity, but structural variation among the diarylhaloniums, and in comparison with other λ3-iodanes, indicates that the model needs refinement for broader applicability. We use a combination of Density Functional Theory (DFT), Natural Bond Orbital (NBO) Theory, and X-ray structure data to correlate bonding and structure for a λ3-iodane and a series of diarylchloronium, bromonium, and iodonium salts, and their isoelectronic diarylchalcogen counterparts. This analysis reveals that the s-orbital on the central halogen …

Pre-Eruptive Magma Configurations And Petrogenetic Relationships Of The Rattlesnake Tuff, Oregon–Insights From Spectacularly Banded High-Silica Rhyolite Pumices, Vanessa M. Swenton, Martin J. Streck

Geology Faculty Publications and Presentations

The 7.1Ma Rattlesnake Tuff (RST) of eastern Oregon is a widespread and voluminous (>300 km3) ignimbrite composed of 99% crystal poor (≤1%) high-silica rhyolite (HSR) and

Understanding The Transport And Chemistry Of Indoor Air During Wildfire Smoke Events With Elliott Gall, Elliott T. Gall

PDXPLORES Podcast

Dr. Elliott Gall, Associate Professor in the Mechanical and Materials Engineering Department at Portland State University, studies indoor air quality in order to better understand how to improve building designs to promote health.

Wildfires are increasing in frequency and intensity. So, too, are wildfire smoke events. Smoke from wildfires pose serious health risks. That is why the Environmental Protection Agency recommends individuals remain indoors during smoke events.

In this episode, Professor Gall discusses the importance of understanding the chemistry of wildfire smoke indoors and how smoke is transported into buildings.

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Social Capital And Cross-Boundary Collaboration In Wyoming Wildfire Management Networks, Hannah L. Spencer, Christian Heisler

Student Research Symposium

Wildfire hotspots often intersect jurisdictional boundaries, so protecting human communities and restoring healthy fire regimes will require collaborative, cross-boundary action from fire managers. However, collaboration between fire management groups can have varied outcomes depending on the actors involved, all with different missions, financial obligations, and cultures. One way to conceptualize the interactions between actors is with the idea of social capital. We will investigate the following research question: how does social capital impact cross-boundary collaboration in wildfire management networks? We will survey wildfire managers in northwestern Wyoming about their collaborative actions using a snowball sampling method. Using Social Network Analysis …

Comparison Of Heavy Metals In Spinach Grown On The Roof Ground Location At Portland State University, Tyler A. Robin

Student Research Symposium

As a result of urbanization, fresh, healthy food can be expensive and easily contaminated but space for local farming is limited. Roofs can be underutilized in densely populated cities and can offer a space for local fresh farming. The purpose of this study is to continue a previous study done in 2021, to find if growing leafy vegetables on the roof can limit heavy metal exposure from air pollutants. This study compares spinach grown on the roof in 2021, 2019 and spinach bought from stores around the Portland State University campus and the heavy metals found in these greens. The …

Surface Plasmon Characterization In Ag Nanotriangles For Evaluation Of Fano Resonance Conditions, Nabila Islam

Student Research Symposium

Surface plasmon polariton (SPP) is a collective oscillation of electrons and light at the metal -dielectric interface excited by the incident radiation on metal surface through the momentum matching conditions. The properties of SPPs and the resonance conditions are highly dependent on the confining materials and geometry of the confining nanostructure. The sensitivity of the surface plasmon resonance to the property of the confining materials made Surface plasmon resonance (SPR) sensors a central tool for biosensing. However, the frequency resolution of SPR sensors is typically limited by the broad resonance of the SPR mode. The resolution can be enhanced through …

Growing Reservoir Networks Using The Genetic Algorithm Deep Hyperneat, Nancy L. Mackenzie

Student Research Symposium

Typical Artificial Neural Networks (ANNs) have static architectures. The number of nodes and their organization must be chosen and tuned for each task. Choosing these values, or hyperparameters, is a bit of a guessing game, and optimizing must be repeated for each task. If the model is larger than necessary, this leads to more training time and computational cost. The goal of this project is to evolve networks that grow according to the task at hand. By gradually increasing the size and complexity of the network to the extent that the task requires, we will build networks that are more …

Mapping Ecosystem Service Flows Of Estuary Restoration Projects On The Oregon Coast To Identify Impacted Stakeholders, Shersten Finley

Student Research Symposium

Restoration of largely depleted estuarine systems is increasingly recognized as key to solving a variety of problems coastal communities face currently. Many of these issues will become more acute with climate change and sea level rise. Historic losses of estuary area, and recognition of the ecosystem services provided by functioning estuary ecosystems have resulted in current impetus to pursue estuary restoration. By mapping the flows of ecosystem services using three ecosystem service ‘scorecard’ categories pertaining to coastal resource management: recreation, aesthetics, and cultural/historical/spiritual, we gain a better understanding of the populations impacted by the changes in flows of ecosystem service …

Simple Arenes As Aryne Synthetic Equivalents Via Sulfonium Salt Intermediates, Riley A. Roberts

Student Research Symposium

Arynes are ephemeral molecules that are yet to be fully exploited in synthetic strategy because they are often challenging to access. These reactive intermediates participate in a myriad of reactions that conventional chemistry is incapable of, making them extremely useful for the synthesis of important molecules like pharmaceuticals and agrochemicals. While classical approaches for synthesizing arynes employ cheap starting material, extremely harsh reagents are necessary to generate the aryne. In contrast, methods that do not require harsh reaction conditions do require starting material that is exceedingly difficult to synthesize. To access arynes quickly and efficiently, the work described herein aims …

Using Digital Holographic Microscopy To Characterize Vibrio's Chemotaxis, Jacqueline Acres, Eric Valentino

Student Research Symposium

Vibrio alginolyticus is a marine bacterium that displays distinctive chemotactic behavior. Chemotaxis is the ability to move in response to a concentration gradient, either in the direction of nutrients or away from repellants. Vibrio's single, polar flagellum allows it to form a tight cloud in the presence of a chemoattractant. In this work, we experimentally characterize cloud sizes after both normal culture conditions and simulated microgravity using digital holographic microscopy or DHM. DHM allows visualization of volumetric samples by recording x,y,z and t information in holograms. Plane-by-plane reconstruction retrieves the z-plane information which can then by stitched together into hyperstacks …

The Power Of The Collective: A Multi Agent-Based Modeling Approach To Nuclear Radiation Localization, Benjamin Totten, Christof Teuscher

Student Research Symposium

Gamma radiation is a very high frequency, very dangerous electromagnetic wave that has a chance of being emitted after radioactive decay. Radiation source localization, or locating the previously unknown source of nuclear radiation, in a rapid and efficient manner is critically important, but challenging. We aim to create an architecture for multiple, fully independent agents that cooperate to localize sources faster than existing single-agent architectures, without compromising accuracy. Using Agent-Based Modeling and Deep Reinforcement Learning, agents are enabled to make decisions based on other agents' behaviors while maintaining programmatic autonomy. We hypothesize that radiation sources can be localized faster using …

Research Proposal For An Assessment Of The Potential For The Arbuscular Fungi “Rhizophagus Irregularis” To Aid In Corn Uptake And Availability Of Iron, Caitlin Costello

Student Research Symposium

Global iron deficiency is one factor contributing to malnutrition and varied health conditions. This deficiency accounts for 841,000 deaths and approximately 35,057,000 “disability-adjusted life years lost” (Stoltzfus, R. J. 2003). One way to combat this is to maintain or increase the iron uptake of the globe’s major crops. Research has shown that certain types of mycorrhizal fungi can increase the nutrient uptake of plants. To further this research, we will look at the arbuscular fungi Rhizophagus irregularis and its potential relationship with a short harvest corn variety. This type of mycorrhizal fungi improves plant nutrition including the plant’s ability to …

Houseless Water Insecurity During Covid-19 Pandemic, Alicia N. Gamble

Student Research Symposium

Water security is of the utmost importance for the houseless population. However, little is known about how the houseless population has been resilient to water barriers related to the COVID-19 pandemic. The purpose of this study is to understand houseless individuals' perceptions of public versus grassroots water sources, and the barriers and impacts of these sources. In order to understand these perceptions, individuals experiencing houselessness (e.g. living in tents, vehicles, emergency shelters, couch-surfing, or no roof) that utilize water sources in Portland, Oregon will be interviewed while walking in public areas to gain rich qualitative data, along with GPS data …