Physical Sciences and Mathematics Commons^™

Controlling Water Exchange Kinetics And Improving Paracest Imaging, Jacqueline R. Slack

Dissertations and Theses

Generating MR image contrast from exogenous contrast media through chemical exchange saturation transfer (CEST) offers several exciting new possibilities, such as multicolored imaging, the interleaving of pre- and post-contrast images, and the potential to perform ratiometric metabolic imaging. The major limitation of the deployment of CEST imaging is the comparatively high detection limits of exogenous agents and particularly at the low B_¹ power levels required to meet SAR requirements. The large chemical shifts afforded by paramagnetic (paraCEST) agents permit more rapid exchange kinetics and therefore potentially more effective contrast agents. Despite comparatively large chemical shifts, many Ln³⁺ DOTA-tetraamide …

Improved Scoring Models For Semantic Image Retrieval Using Scene Graphs, Erik Timothy Conser

Dissertations and Theses

Image retrieval via a structured query is explored in Johnson, et al. [7]. The query is structured as a scene graph and a graphical model is generated from the scene graph's object, attribute, and relationship structure. Inference is performed on the graphical model with candidate images and the energy results are used to rank the best matches. In [7], scene graph objects that are not in the set of recognized objects are not represented in the graphical model. This work proposes and tests two approaches for modeling the unrecognized objects in order to leverage the attribute and relationship models to …

Refining Bounding-Box Regression For Object Localization, Naomi Lynn Dickerson

Dissertations and Theses

For the last several years, convolutional neural network (CNN) based object detection systems have used a regression technique to predict improved object bounding boxes based on an initial proposal using low-level image features extracted from the CNN. In spite of its prevalence, there is little critical analysis of bounding-box regression or in-depth performance evaluation. This thesis surveys an array of techniques and parameter settings in order to further optimize bounding-box regression and provide guidance for its implementation. I refute a claim regarding training procedure, and demonstrate the effectiveness of using principal component analysis to handle unwieldy numbers of features produced …

The Influence Of Recurrent Modes Of Climate Variability On The Occurrence Of Monthly Temperature Extremes Over South America, Paul C. Loikith, Judah Detzer, Carlos R. Mechoso, Huikyo Lee, Armineh Barkhordarian

Geography Faculty Publications and Presentations

The associations between extreme temperature months and four prominent modes of recurrent climate variability are examined over South America. Associations are computed as the percent of extreme temperature months concurrent with the upper and lower quartiles of the El Niño–Southern Oscillation (ENSO), the Atlantic Niño, the Pacific Decadal Oscillation (PDO), and the Southern Annular Mode (SAM) index distributions, stratified by season. The relationship is strongest for ENSO, with nearly every extreme temperature month concurrent with the upper or lower quartiles of its distribution in portions of northwestern South America during some seasons. The likelihood of extreme warm temperatures is enhanced …

Toxicant Formation In Dabbing: The Terpene Story, Jiries Meehan-Attrash, Wentai Luo, Robert M. Strongin

Chemistry Faculty Publications and Presentations

Inhalable, noncombustible cannabis products are playing a central role in the expansion of the medical and recreational use of cannabis. In particular, the practice of “dabbing” with butane hash oil has emerged with great popularity in states that have legalized cannabis. Despite their growing popularity, the degradation product profiles of these new products have not been extensively investigated. The study herein focuses on the chemistry of myrcene and other common terpenes found in cannabis extracts. Methacrolein, benzene, and several other products of concern to human health were formed under the conditions that simulated realworld dabbing. The terpene degradation products observed …

Turbidity Dynamics During High-Flow Storm Events In The Clackamas River, Oregon 2006-2012, Micelis Clyde Doyle

Dissertations and Theses

Turbidity is a useful parameter that can be utilized to help understand the water quality in a river and is an expression of the optical properties of a liquid that cause light rays to be scattered and absorbed rather than transmitted in straight lines. A total of 41 storm events occurring during water years 2006-2012 were analyzed for this study. A hysteresis index (HI) was used to assess the difference in turbidity on the rising and falling limbs of a storm-hydrograph. The upstream Carter Bridge site exhibited a clockwise (C) hysteresis in 38 of 41 storm events and counter-clockwise (CC) …

Filtered Subspace Iteration For Selfadjoint Operators, Jay Gopalakrishnan, Luka Grubišić, Jeffrey S. Ovall

Portland Institute for Computational Science Publications

We consider the problem of computing a cluster of eigenvalues (and its associated eigenspace) of a (possibly unbounded) selfadjoint operator in a Hilbert space. A rational function of the operator is constructed such that the eigenspace of interest is its dominant eigenspace, and a subspace iteration procedure is used to approximate this eigenspace. The computed space is then used to obtain approximations of the eigenvalues of interest. An eigenvalue and eigenspace convergence analysis that considers both iteration error and dis- cretization error is provided. A realization of the proposed approach for a model second-order elliptic operator is based on a …

Investigations Of Electronic Cigarette Chemistry: 1. Formation Pathways For Degradation Products Using Isotopic Labeling; And 2. Gas/Particle Partitioning Of Nicotine And Flavor Related Chemicals In Electronic Cigarette Fluids, Kilsun Kim

Dissertations and Theses

Use of electronic cigarettes (e-cigarettes) is rapidly growing around the world. E-cigarettes are commonly used as an alternative nicotine delivery system, and have been advocated as generating lower levels of harmful chemicals compared to conventional cigarettes. Cigarette smoke-like aerosols are generated when e-cigarettes heat e-liquids. The main components of e-cigarette liquids are propylene glycol (PG) and glycerol (GL) in a varying ratio, plus nicotine and flavor chemicals. Both PG and GL are considered safe to ingest in foods and beverages, but the toxicity of these chemicals in aerosols is unknown. Current studies of e-cigarettes have mainly focused on dehydration and …

Compositional And Physical Gradients In The Magmas Of The Devine Canyon Tuff, Eastern Oregon: Constraints For Evolution Models Of Voluminous High-Silica Rhyolites, Shelby Lee Isom

Dissertations and Theses

Large-volume silicic ignimbrites erupt from reservoirs that vary in composition, temperature, volatile content and crystallinity. The 9.7 Ma Devine Canyon Tuff (DCT) of eastern Oregon is a large-volume (>250 km³), compositionally zoned and variably welded ignimbrite. The ignimbrite exhibits heterogeneous trace element compositions, variable volatile content and crystallinity. These observations were utilized in the investigation into the generation, accumulation and evolution of the magmas composing the DCT. Building off previous research, pumices were selected from the range of trace element compositions and analyzed with respect to crystallinity, mineral abundances and assemblages. The DCT displays a gradational trace …

Invertebrate Community Composition Across Inundation Regimes And Its Potential To Reduce Plant Stress, Inez Ilicia Lawson

Dissertations and Theses

Appreciation of the ecological and economic values associated with healthy salt marshes has led to a recent rise in the number of marshes that are being targeted for restoration by dike removal. The success of restoration is often measured by the return of marsh plants, though this overlooks a key component of salt marshes, that of the invertebrate community within marsh sediments. To evaluate the short-term recovery of these invertebrates, sediment cores were collected across an elevational gradient in a recent dike removal marsh, one and two years post removal, and a nearby reference marsh. Abundance, richness and diversity as …

Constraining The Holocene Extent Of The Northwest Meers Fault, Oklahoma Using High-Resolution Topography And Paleoseismic Trenching, Kristofer Tyler Hornsby

Dissertations and Theses

The Meers Fault (Oklahoma) is one of few seismogenic structures with Holocene surface expression in the stable continental region of North America. Only the ~37 km-long southeastern section of the ~55 km long Meers Fault is interpreted to be Holocene-active. The ~17 km-long northwestern section is considered to be Quaternary-active (pre-Holocene); however, its low-relief geomorphic expression and anthropogenic alteration have presented difficulties in evaluating the fault length and style of Holocene deformation. We reevaluate surface expression and earthquake timing of the northwestern portion of the Meers Fault to improve fault characterization, earthquake rupture models, and seismic hazard evaluations based on …

Detecting Change In Rainstorm Properties From 1977-2016 And Associated Future Flood Risks In Portland, Oregon, Alexis Kirsten Cooley

Dissertations and Theses

In response to increased greenhouse gases and global temperatures, changes to the hydrologic cycle are projected to occur and new precipitation characteristics are expected to emerge. The study of these characteristics is facilitated by common indices to measure precipitation and temperature developed by the Expert Team on Climate Change Detection and Indices (ETCCDI). These indices can be used to describe the likely consequences of climate change such as increased daily precipitation intensity (SDII) and heavier rainfall events (R95p). This study calculates a subset of these indices from observed and modelled precipitation data in Portland, Oregon. Five rainfall gages from a …

Melting In The Mantle Wedge: Quantifying The Effects Of Crustal Morphology And Viscous Decoupling On Melt Production With Application To The Cascadia Subduction Zone, Jiaming Yang

Dissertations and Theses

Arc magmatism is sustained by the complex interactions between the subducting slab, the overriding plate, and the mantle wedge. Partial melting of mantle peridotite is achieved by fluid-induced flux melting and decompression melting due to upward flow. The distribution of melting is sensitive to temperature, the pattern of flow, and the pressure in the mantle wedge. The arc front is the surface manifestation of partial melting in the mantle wedge and is characterized by a narrow chain of active volcanoes that migrate in time. The conventional interpretation is that changes in slab dip angle lead to changes in the arc …

Southern Annular Mode Drives Multicentury Wildfire Activity In Southern South America, Andrés Holz, Juan Paritsis, Ignacio A. Mundo, Thomas T. Veblen, Thomas Kitzberger, Grant J. Williamson, Ezequiel Aráoz, Carlos Bustos-Schindler, Mauro E. González, H. Ricardo Grau, Juan M. Quezada

Geography Faculty Publications and Presentations

The Southern Annular Mode (SAM) is the main driver of climate variability at mid to high latitudes in the Southern Hemisphere, affecting wildfire activity, which in turn pollutes the air and contributes to human health problems and mortality, and potentially provides strong feedback to the climate system through emissions and land cover changes. Here we report the largest Southern Hemisphere network of annually resolved tree ring fire histories, consisting of 1,767 fire-scarred trees from 97 sites (from 22 °S to 54 °S) in southern South America (SAS), to quantify the coupling of SAM and regional wildfire variability using recently created …

Field Mapping Investigation And Geochemical Analysis Of Volcanic Units Within The Dinner Creek Tuff Eruptive Center, Malheur County, Eastern Oregon, Matthew Cruz

Dissertations and Theses

The Dinner Creek Tuff is a mid-Miocene rhyolitic to dacitic ignimbrite, consisting of four cooling units with ⁴⁰Ar/³⁹Ar ages 16--15 Ma. Previous geologists have suspected that the source of the tuff is located in northwestern Malheur County, eastern Oregon. This broad area is called the Dinner Creek Tuff Eruptive Center.

This thesis summarizes field work, XRF/ICP-MS geochemistry, thin section petrography, and SEM feldspar analysis from the summers of 2015 and 2016. The main purpose of this study is to identify sources for the Dinner Creek Tuff units within the Dinner Creek Tuff Eruptive Center. The secondary purpose …

Green Leasing Internship: Final Presentation, 2017, Emily Quinton

Campus Sustainability Office Publications, Reports and Presentations

Presentation slides from summer 2017 Green Leasing Internship, Portland State University

How To Be A Successful Organic Chemist, Alexander H. Sandtorv

PDXOpen: Open Educational Resources

How to be a successful organic chemist is meant as an introductory text for undergraduates taking organic chemistry teaching labs. The text is a clear and practical introduction to safety, chemical handling, organic chemistry techniques, and lab reports.

Adopt/Adapt
If you are an instructor adopting or adapting this PDXOpen textbook, please help us understand your use by filling out this form

An Spm Stage Driven By 3 Stepper Motors, Jianghua Bai, Andres H. La Rosa

Physics Faculty Publications and Presentations

A Scanning Probe Microscope (SPM) stage controlled by 3 stepper motors is designed in this project. The SPM stage controlled by 3 steppers is more versatile than a stage controlled by one motor, but the control of the system is more complicated. In this project, we build the stage actions in an Arduino microcontroller. A finite state machine (FSM) is also built in Arduino to communicate with a PC and an RF controller. A special displaying scheme which has 5 states, is also employed to indicate the operation of the stage. Finally, the SPM stage is fully tested and has …

Prozac In The Water: Chronic Fluoxetine Exposure And Predation Risk Interact To Shape Behaviors In An Estuarine Crab, Joseph R. Peters, Elise F. Granek, Catherine E. De Rivera, Matthew Rollins

Environmental Science and Management Faculty Publications and Presentations

Predators exert considerable top-down pressure on ecosystems by directly consuming prey or indirectly influencing their foraging behaviors and habitat use. Prey is, therefore, forced to balance predation risk with resource reward. A growing list of anthropogenic stressors such as rising temperatures and ocean acidification has been shown to influence prey risk behaviors and subsequently alter important ecosystem processes. Yet, limited attention has been paid to the effects of chronic pharmaceutical exposure on risk behavior or as an ecological stressor, despite widespread detection and persistence of these contaminants in aquatic environments. In the laboratory, we simulated estuarine conditions of the shore …

Lyapunov Exponents And The Belousov-Zhabotinsky Oscillator: An Interactive Computational Approach, Matthew W. Eskew, Reuben H. Simoyi

Chemistry Faculty Publications and Presentations

The Belousov-Zhabotinsky (BZ) chemical oscillator is the most studied oscillator. It has been modelled on the basis of single-step mechanisms which have been continuously refined since the seminal manuscript by Field, Koros and Noyes in 1972. This manuscript reports on a unique way of modelling the global dynamics of the oscillator by assuming that the BZ oscillator has shown chaotic behaviour. The unique mathematical definition of chaos is very stringent, and, in this manuscript, we attempt to trace this unique exotic behaviour by the use of ‘onto’ maps of the interval onto itself which are known to exhaustively show a …

Formaldehyde Hemiacetal Sampling, Recovery, And Quantification From Electronic Cigarette Aerosols, James C. Salamanca, Ian Munhenzva, Jorge O. Escodedo, R. Paul Jensen, Angela Shaw, Robert Campbell, Wentai Luo, David H. Peyton, Robert Strongin

Chemistry Faculty Publications and Presentations

The electronic cigarette solvents propylene glycol and glycerol are known to produce toxic byproducts such as formaldehyde, acetaldehyde and acrolein. However, the aerosol toxin yield depends upon a variety of chemical and physical variables. The formaldehyde hemiacetals derived from these solvents were reported as major electronic cigarette aerosol components by us in 2015. In the study described herein, the formaldehyde hemiacetals were found at higher levels than those of free formaldehyde via an orthogonal sample collection protocol. In addition, the common aldehyde collection methods for electronic cigarettes, such as impingers and sorbent tubes containing DNPH, significantly underestimate the levels of …

A Weighted Möbius Function, Derek Garton

Mathematics and Statistics Faculty Publications and Presentations

Fix an odd prime ℓ and let G be the poset of isomorphism classes of finite abelian ℓ-groups, ordered by inclusion. If ξ:G→R^≥0 is a discrete probability distribution on G and A ∈ G, define the Ath moment of ξ to be . The question of determining conditions that ensure ξ is completely determined by its moments has been of recent interest in many problems of Cohen–Lenstra type. Furthermore, recovering ξ from its moments requires a new Möbius-type inversion formula on G. In this paper, we define this function, relate it to the classical Möbius …

Coastal Eolian Sand-Ramp Development Related To Paleo-Sea-Level Changes During The Latest Pleistocene And Holocene (21–0 Ka) In San Miguel Island, California, U.S.A., Curt D. Peterson, Jon M. Erlandson, Errol Stock, Steve W. Hostetler, David M. Price

Geology Faculty Publications and Presentations

Coastal eolian sand ramps (5–130 m elevation) on the northern slope (windward) side of the small San Miguel Island (13 km in W-E length) range in age from late Pleistocene to modern time, though a major hiatus in sand-ramp growth occurred during the early Holocene marine transgression (16–9 ka). The Holocene sand ramps (1–5 m measured thicknesses) currently lack large dune forms, thereby representing deflated erosional remnants, locally covering thicker late Pleistocene sand-ramp deposits. The ramp sand was initially supplied from the adjacent island-shelf platform, extending about 20 km north of the present coastline. The sand-ramp deposits and interbedded loess …

Life’S Late Digital Revolution And Why It Matters For The Study Of The Origins Of Life, David A. Baum, Niles Lehman

Chemistry Faculty Publications and Presentations

The information contained in life exists in two forms, analog and digital. Analog information is manifest mainly in the differing concentrations of chemicals that get passed from generation to generation and can vary from cell to cell. Digital information is encoded in linear polymers such as DNA and RNA, whose side chains come in discrete chemical forms. Here, we argue that the analog form of information preceded the digital. Acceptance of this dichotomy, and this progression, can help direct future studies on how life originated and initially complexified on the primordial Earth, as well as expected trajectories for other, independent …

Development Of Physics Curriculum For Pre-Health Students, Elliot Eckman Mylott

Dissertations and Theses

Many pre-health students are required to take introductory physics as undergraduates, though they often struggle to see the relationship between medicine and what they learn in these courses. In order to help students make that connection, reformed curriculum was adopted that teaches physics through the context of biomedicine. This dissertation will discuss the development, implementation, and assessment of the reformed curriculum for the introductory and intermediate level physics courses that targets the needs of pre-health students.

The curriculum created during this project include laboratory activities, multimedia content, and other instructional materials all of which present physics in biomedical contexts. The …

The Tension Between Technocratic And Social Values In Environmental Decision-Making: An'yang Stream Restoration In South Korea, Chang-Yu Hong

Dissertations and Theses

This dissertation examined the extent to which interests and values of diverse stakeholders were considered through participation-oriented decision-making. It covered the An' Yang Stream restoration case in South Korea, which has been judged a successful stream management endeavor led by public-private partnership governance.

This research utilized a mixed methods approach, combining qualitative and quantitative methods. It addressed the extent to which the collaborative and participatory decision-making processes incorporated diverse stakeholder values and visions. The relevant data on stream restoration was collected through nominal group technique (NGT), analytic hierarchy process (AHP), semi-structured interviews, observations at collaborative stakeholder meetings and workshops, and …

Assessing A Fluorescence Spectroscopy Method For In-Situ Microbial Drinking Water Quality, Taylor Jeffery Sharpe

Dissertations and Theses

Waterborne disease is a significant contributor to the global burden of disease, in particular among high-risk populations in developing nations. State-of-the-art methods for the enumeration of microbial pathogens in drinking water sources have important limitations, including high initial cost, 24-48 hour delays in results, high staffing and facility requirements, and training requirements which all become especially problematic in the developing nation context.

A number of alternative approaches to microbial water quality testing have been proposed, with the goal of decreasing the required testing time, decreasing overall costs, leveraging appropriate technology approaches, or improving sensitivity or specificity of the water quality …

Soputan Volcano, Indonesia: Petrological Systematics Of Volatiles And Magmas And Their Bearing On Explosive Eruptions Of A Basalt Volcano, Syegi Lenarahmi Kunrat

Dissertations and Theses

Soputan volcano is one of the few basaltic volcanoes among 127 active volcanoes in Indonesia. It is part of the Sempu-Soputan volcanic complex located south of Tondano Caldera, North Sulawesi and commonly produces both explosive eruptions with VEI 2-3 and effusive lava dome and flow eruptions. Over the last two decades, Soputan had thirteen eruptions, the most recent in 2016. Most eruptions started explosively, followed by dome growth and in some cases pyroclastic flows. Our study focuses on understanding the magmatic system of Soputan and what processes are responsible for its highly explosive eruptions, which are typically uncommon for a …

Anthropogenic Effects On The Fouling Community: Impacts Of Biological Invasions And Anthropogenic Structures On Community Structure, Whitney Elizabeth Mcclees

Dissertations and Theses

Coastal anthropogenic infrastructure has significantly modified nearshore environments. Because these structures often have a strong association with shipping as would be found in ports and harbors, they have been identified as invasion hotspots. Due to propagule pressure from shipping and recreational boating and suitable uncolonized substrate that provides a refuge from native predators, a greater number of non-native species have been found on these structures compared to nearby natural substrate. The mechanisms that limit the spread of non-native species from anthropogenic structures to natural substrate have been explored for several taxa at a species-specific level, but less so from an …

The Discovery And Development Of Metal-Free Arylation Reactions With Unsymmetrical Diaryliodonium Salts, Sunil Kumar Sundalam

Dissertations and Theses

Functionalizing arenes and heteroarenes has been an active area of research since the 19th century, due to the presence of these molecular structures in many industrially important sectors. A tremendous amount of research has been published in achieving these chemical transformations using stoichiometric reagents and transition metal-catalyzed reactions. However, challenges still remain. An alternative and comparable methodology to metal-catalyzed reactions to overcome the drawbacks will advance this particular area of research is desirable.

Hypervalent iodine compounds offer a promising approach to metal-free arylation reactions. These mild, air and moisture stable compounds have showed significant success as non-toxic and metal-free reagents …