Physical Sciences and Mathematics Commons^™

Glacial Meltwater Modeling To Simulate Streamflow And Lake Levels In Taylor Valley, Antarctica, Julian M. Cross, Andrew G. Fountain

Student Research Symposium

The McMurdo Dry Valleys (MDV) are the largest ice-free region (4,500 km²) in Antarctica. The MDV are a polar desert with an average annual temperature of -18˚C and minimal precipitation, < 50 mm w.e. a^-1. In Taylor Valley (77°35’ S, 163°00’ E), a closed-basin, perennially ice-covered lakes occupy the valley floor. Ephemeral streams transfer glacier meltwater for ~10 weeks each summer. Glacial meltwater accounts for nearly the total inflow to these streams and lakes, groundwater is essentially non-existent. A microbially-dominated ecosystem in Taylor Valley depends on glacier runoff and thus is highly sensitive to changes to the hydroclimatic regime. A model …

Exploring And Expanding The One-Pixel Attack, Umairullah Khan, Walt Woods, Christof Teuscher

Student Research Symposium

In machine learning research, adversarial examples are normal inputs to a classifier that have been specifically perturbed to cause the model to misclassify the input. These perturbations rarely affect the human readability of an input, even though the model’s output is drastically different. Recent work has demonstrated that image-classifying deep neural networks (DNNs) can be reliably fooled with the modification of a single pixel in the input image, without knowledge of a DNN’s internal parameters. This “one-pixel attack” utilizes an iterative evolutionary optimizer known as differential evolution (DE) to find the most effective pixel to perturb, via the evaluation of …

Arbuscular Mycorrhizal Fungi Associations Across Multiple Saltmarsh Plant Species Mitigating The Impacts Of Sea-Level Rise, Rayna Koberstein, Catherine E. De Rivera

Student Research Symposium

Sea level rise caused by climate change will detrimentally impact saltmarsh habitats by increasing the elevation and rate of terrestrial salt water inundation, thereby reducing effective functionality of ecosystem services provided by saltmarshes. Facilitation is key to community structuring and function in habitats characterized by abiotic stress, such as salt marshes. Halophytic plants within salt marshes can benefit from symbiotic arbuscular mycorrhizal fungi (AMF) facilitations through increased inundation tolerance, greater nutrient availability and uptake, alleviation from drought stress and relief from saline stress.

Through this research, land managers developing sea-level rise mitigation plans will have data supporting which plants will …

Cluster Chondrite Accretion Temperatures Determined With Electron Backscatter Diffraction, Secana Goudy, Alexander Ruzicka

Student Research Symposium

We studied ordinary chondrites with cluster chondrite lithologies using electron backscatter diffraction to measure the temperatures of their olivine grains during deformation. Samples analyzed with the technique are shock classified as S1 and are type 3, so the deformation analyzed is inferred to represent the temperatures of the chondrules during accretional deformation. It was found that the studied samples are of a mixture of chondrules at mostly hot temperatures (>850°C) and some at cold.

Effects Of Wavelength Variation On Localized Photoemission In Triangular Gold Antennas, Christopher M. Scheffler, Robert Campbell Word, Rolf Könenkamp

Student Research Symposium

Exposing metal-dielectric structures to light can result in surface plasmon excitation and propagation along the transition interface, creating a surface plasmon polariton (SPP) response. Photoemission electron microscopy (PEEM) has been used to image nanometer scale plasmonic responses in micron-sized plasmonic devices. With PEEM, optical responses can be characterized in detail, aiding in the development of new types of plasmonic structures and their applications. In thin, triangular gold platelets SPPs can be excited and concentrated within specific regions of the material. In this regard, the platelets act as receiver antennas by converting the incident light into localized excitations in specific regions …

Crystal Structures Of Dotma Chelates From Ce³+ To Yb³+ : Evidence For A Continuum Of Metal Ion Hydration States, Mark Woods, Katherine M. Payne, Edward J. Valente, Benjamin E. Kucera, Victor G. Young

Chemistry Faculty Publications and Presentations

The crystal structures of chelates formed between each stable paramagnetic lanthanide ion and DOTMA are described. A total of 23 individual chelates structures were obtained, in each chelate the coordination geometry around the metal ion is best described as a twisted square antiprism (torsion angle -25.0° – - 31.4°). Despite the uniformity of the general coordination geometry provided by the DOTMA ligand, there is a considerable variation in the hydration state of each chelate. The early Ln3⁺ chelates are associated with a single inner sphere water molecule, the Ln-OH₂ interaction is remarkable for being very long. After a …

Spontaneous Advent Of Genetic Diversity In Rna Populations Through Multiple Recombination Mechanisms, Benedict A. Smail, Bryce E. Clifton, Ryo Mizuuchi, Niles Lehman

Chemistry Faculty Publications and Presentations

There are several plausible abiotic synthetic routes from prebiotic chemical materials to ribonucleotides and even short RNA oligomers. However, for refinement of the RNA World hypothesis to help explain the origins of life on the Earth, there needs to be a manner by which such oligomers can increase their length and expand their sequence diversity. Oligomers longer than at least 10-20 nucleotides would be needed for raw material for subsequent natural selection. Here, we explore spontaneous RNA-RNA recombination as a facile means by which such length and diversity enhancement could have been realized. Motivated by the discovery that RNA oligomers …

Quantifying Increased Ground Water Demand From Prolonged Drought In The East African Rift Valley, Evan A. Thomas, Joseph A. Needoba, Doris Kaberia, John Butterworth, Emily C. Adams, Phoebe Oduor, Denis Macharia, Multiple Additional Authors

OHSU-PSU School of Public Health Faculty Publications and Presentations

Millions of people in the arid regions of Kenya and Ethiopia face water scarcity and frequent drought. Water resource forecasting and reliable operation of groundwater distribution systems may improve drought resilience. In this study, we examined three remote sensing data sets against in-situ sensor-collected groundwater extraction data from 221 water points serving over 1.34 million people across northern Kenya and Afar, Ethiopia between January 1, 2017 and August 31, 2018. In models containing rainfall as a binary variable, we observed an overall 23% increase in borehole runtime following weeks with no rainfall compared to weeks preceded by some rainfall. Further, …

A Characterization Of Structures Across The Hurricane Ridge Fault In The Southeastern Olympic Peninsula, Wa, Hamma Hamma River Transect, Veronica Catherine Biesiada

Dissertations and Theses

The Olympic Mountains in northwestern Washington, USA are defined by the arcuate shape of the basaltic Crescent Formation (Fm.) that wraps a faulted and folded meta-sedimentary core. This area was developed through accretion and exhumation by subduction-related processes, but how this relates to the deformational history of the area is not fully understood. The region has been mapped geologically, however little focus has been placed on interpreting meso-scale structures. This study investigates structures along a transect where the Hamma Hamma River crosses the Hurricane Ridge Fault, which juxtaposes the meta-sedimentary core (west) and the basaltic Crescent Fm. (east). In the …

Performance Of Genetic Distance Metrics In Gravity And General Mixed Effects Models, Nathan B. Alexander, Crysta Gantz, Jane L. Remfert, Melanie A. Murphy

Environmental Science and Management Faculty Publications and Presentations

There are many causes for the genetic patterns that arise among populations across a landscape. Effective population size, natal site preference, geographic distance, or barriers to gene flow associated with landscape composition may work in opposition or in concert resulting in varying degrees of population differentiation. Here, we simulate 40 populations under 3 different ecological hypotheses of individual dispersal with random mating for 1500 generations, with scenarios: 1) dispersal and mating is dependent on habitat between populations, 2) dispersal and mating is dependent on individuals finding habitat similar to their natal habitat, and 3) dispersal and mating is dependent on …

A Mixed-Methods Approach To Determine How Conservation Management Programs And Techniques Have Affected Herbicide Use And Distribution In The Environment Over Time, Melanie Malone, Eugene Foster

Environmental Science and Management Faculty Publications and Presentations

No-till agriculture has the ability to reduce fuel consumption, increase soil moisture, reduce soil erosion and increase organic matter. However, it remains unclear whether it increases herbicide use overall in the long term for communities that use no-till as their primary source of conservation agriculture. The preponderance of literature suggests that no-till has increased herbicide use, but it is difficult to quantify how much herbicide has increased in a given location and to directly correlate changes in herbicide use to changes in soil and water quality. This paper provides several methods to determine how herbicide use has changed over time …

Monitoring Lesser Known Harmful Algal Blooms On The Oregon Coast, Taylor Dodrill, Tawnya D. Peterson, Matthew Hunter, Micah Rogers

OHSU-PSU School of Public Health Annual Conference

Ocean warming has expanded the niche of harmful algal blooms (HABs), including HABs previously believed to pose little risk of shellfish contamination in the Pacific Northwest. Monitoring efforts in Washington and California have demonstrated that Dinophysis spp. is a HAB of emerging concern and has been linked to diarrhetic shellfish poisoning events. However, quantitative monitoring for Dinophysis spp. on the Oregon Coast has been limited. This analysis provides a preliminary characterization of risk that Dinophysis spp. poses to shellfish consumers in Oregon. Furthermore, we assess the predator-prey interaction between Dinophysis spp. and its prey, Mesodinium rubrum, to determine whether …

Analysis Of Toxic Pollutant Sources And Characteristics Contributing To Water Quality Impairments In The Willamette River Basin, Melinda Borgens

Environmental Science and Management Professional Master's Project Reports

Point and nonpoint sources contribute toxic pollutants to surface waters, degrading water quality and impairing aquatic and human life. As of 2012, 51 stream segments totaling approximately 6,000 kilometers (3,750 miles) in Oregon’s Willamette River Basin (the Basin) were listed as impaired on the Clean Water Act's (CWA) Section 303(d) list with 48 toxic pollutants. These toxic pollutants exceed the Oregon Department of Environmental Quality's (DEQ) state water quality standards, requiring Total Maximum Daily Loads (TMDLs) to restore water quality and protect beneficial uses. Identifying toxic pollutant point and nonpoint sources, and the total loads a waterbody receives, are critical …

Traffic Signal Consensus Control, Gerardo Lafferriere

TREC Final Reports

We introduce a model for traffic signal management based on network consensus control principles. The underlying principle in a consensus approach is that traffic signal cycles are adjusted in a distributed way so as to achieve desirable ratios of queue lengths throughout the street network. This approach tends to reduce traffic congestion due to queue saturation at any particular city block and it appears less susceptible to congestion due to unexpected traffic loads on the street grid. We developed simulation tools based on the MATLAB computing environment to analyze the use of the mathematical consensus approach to manage the signal …

A Decentralized Network Consensus Control Approach For Urban Traffic Signal Optimization, Gerardo Lafferriere

TREC Project Briefs

Automobile traffic congestion in urban areas is a worsening problem that comes with significant economic and social costs. This report offers a new approach to urban congestion management through traffic signal control.

Mountain Lakes: Eyes On Global Environmental Change, Katrina A. Moser, Jill S. Baron, Janice Brahney, Isabella A. Olesky, Jasmine E. Saros, Elizabeth J. Hundey, Steven A. Sadro, Jiri Kopácek, Ruben Sommaruga, Martin J. Kainz, Angela L. Strecker, Sudeep Chandra, David M. Walters, Daniel L. Preston, Neal Michelutti, Fabio Lepori, Sarah A. Spaulding, Kyle R. Christianson, John M. Melack, J. P. Smol

Environmental Science and Management Faculty Publications and Presentations

Mountain lakes are often situated in protected natural areas, a feature that leads to their role as sentinels of global environmental change. Despite variations in latitude, mountain lakes share many features, including their location in catchments with steep topographic gradients, cold temperatures, high incident solar and ultraviolet radiation (UVR), and prolonged ice and snow cover. These characteristics, in turn, affect mountain lake ecosystem structure, diversity, and productivity. The lakes themselves are mostly small and shallow, and up until recently, have been characterized as oligotrophic. This paper provides a review and update of the growing body of research that shows that …

Process-Based Modeling Of The Dairy Mckay Watershed To Inform Monitoring For Agricultural Best Management Practices, Brittany Saeman

Environmental Science and Management Professional Master's Project Reports

The project described in this paper specifically looks at the influence of land management practices on water quality, specifically total phosphorus (TP) loads in the Dairy McKay Watershed (DMW). The project is being used to inform a water quality monitoring plan for the Oregon DEQ via outputs from a SWAT model. The DMW is known to have high TP levels that are linked to low dissolved oxygen levels in the Tualatin River. There is a total maximum daily load (TMDL) for the Tualatin River that specifies target TP levels coming out of the DMW, if these targets are met, the …

Contrasting Local And Long-Range-Transported Warm Ice-Nucleating Particles During An Atmospheric River In Coastal California, Usa, Andrew C. Martin, Gavin Cornwell, Charlotte M. Beall, Forest Cannon, Sean Reilly, Bas Schapp, Dolan Lucero, Jessie Creamean, F. Martin Ralph, Hari T. Mix, Kimberly Prather

Geography Faculty Publications and Presentations

Ice-nucleating particles (INPs) have been found to influence the amount, phase and efficiency of precipitation from winter storms, including atmospheric rivers. Warm INPs, those that initiate freezing at temperatures warmer than −10ºC, are thought to be particularly impactful because they can create primary ice in mixed-phase clouds, enhancing precipitation efficiency. The dominant sources of warm INPs during atmospheric rivers, the role of meteorology in modulating transport and injection of warm INPs into atmospheric river clouds, and the impact of warm INPs on mixed-phase cloud properties are not well-understood. In this case study, time-resolved precipitation samples were collected during an atmospheric …

Leveraging Variation Of Historical Number Systems To Build Understanding Of The Base-Ten Place-Value System, Eva Thanheiser, Kathleen Melhuish

Mathematics and Statistics Faculty Publications and Presentations

Prospective elementary school teachers (PTs) come to their mathematics courses fluent in using procedures for adding and subtracting multidigit whole numbers, but many are unaware of the essential features inherent in understanding the base-ten place-value system (i.e., grouping, place value, base). Understanding these features is crucial to understanding and teaching number and place value. The research aims of this paper are (1) to present a local instructional theory (LIT), designed to familiarize PTs with these features through comparison with historical number systems and (2) to present the effects of using the LIT in the PT classroom. A theory of learning …

Localizing Little Landmarks With Transfer Learning, Sharad Kumar

Dissertations and Theses

Locating a small object in an image -- like a mouse on a computer desk or the door handle of a car -- is an important computer vision problem to solve because in many real life situations a small object may be the first thing that gets operated upon in the image scene. While a significant amount of artificial intelligence and machine learning research has focused on localizing prominent objects in an image, the area of small object detection has remained less explored. In my research I explore the possibility of using context information to localize small objects in an …

Capillary Migration Of Large Confined Drops In Non-Wetting Wedges, Logan John Torres

Dissertations and Theses

When confined within containers or conduits, drops and bubbles migrate to regions of minimum energy by the combined effects of surface tension, surface wetting, system geometry, and initial conditions. Such capillary phenomena are exploited for passive phase separation operations in micro-fluidic devices on earth and macro-fluidic devices aboard spacecraft. Our study focuses on the migration and ejection of large inertial-capillary drops confined between tilted planar hydrophobic substrates. In our experiments, the brief nearly weightless environment of a drop tower allows for the study of such capillary dominated behavior for up to 10 mL water drops with migration velocities up to …

Localized Photoemission In Triangular Gold Antennas, Christopher M. Scheffler

Dissertations and Theses

With the development of ultra-fast laser technology, several new imaging techniques have pushed optical resolution past the diffraction limit for traditional light-based optics. Advancements in lithography have enabled the straightforward creation of micron- and nanometer-sized optical devices. Exposing metal-dielectric structures to light can result in surface plasmon excitation and propagation along the transition interface, creating a surface plasmon polariton (SPP) response. Varying the materials or geometry of the structures, the plasmonic response can be tailored for a wide range of applications.

Photoemission electron microscopy (PEEM) has been used to image excitations in micron-sized plasmonic devices. With PEEM, optical responses can …

The Impact Of Infrastructure On Habitat Connectivity For Wildlife, Leslie Lynne Bliss-Ketchum

Dissertations and Theses

While roads can present weak to complete barriers to wildlife, depending on the animal and traffic volume, mitigations such as under-crossings and green bridges on highways at least partially increase the permeability of the landscape to some of these species. The few studies evaluating the effectiveness of these structures for at least three years typically focused on a single species. Here, we monitored the crossing structure under Boeckman Road, in Wilsonville Oregon, for wildlife activity across summer seasons for ten years, since construction of the road and subsequent opening to traffic. This long-term multi-species dataset, which includes monitoring when the …

Jet Rebound From Hydrophobic Substrates In Microgravity, Karl Jeffrey Theodore Cardin

Dissertations and Theses

We experimentally investigate the phenomena of large jet rebound, a mode of fluid transfer following oblique jet impacts on hydrophobic substrates. We initially seek to describe the jet rebound regimes in tests conducted in the weightless environment of a drop tower. A parametric study reveals the dependence of the flow structure on the relevant dimensionless groups such as Reynolds number and Weber number defined on the velocity component perpendicular to the substrate. We show that significantly larger diameter jets behave similarly as much smaller jets demonstrated during previous terrestrial investigations is some parameter ranges while the flow is fundamentally different …

High-Speed Video From Asynchronous Camera Array, Si Lu

Computer Science Faculty Publications and Presentations

This paper presents a method for capturing high-speed video using an asynchronous camera array. Our method sequentially fires each sensor in a camera array with a small time offset and assembles captured frames into a high-speed video according to the time stamps. The resulting video, however, suffers from parallax jittering caused by the viewpoint difference among sensors in the camera array. To address this problem, we develop a dedicated novel view synthesis algorithm that transforms the video frames as if they were captured by a single reference sensor. Specifically, for any frame from a non-reference sensor, we find the two …

Good Similar Patches For Image Denoising, Si Lu

Computer Science Faculty Publications and Presentations

Patch-based denoising algorithms like BM3D have achieved outstanding performance. An important idea for the success of these methods is to exploit the recurrence of similar patches in an input image to estimate the underlying image structures. However, in these algorithms, the similar patches used for denoising are obtained via Nearest Neighbour Search (NNS) and are sometimes not optimal. First, due to the existence of noise, NNS can select similar patches with similar noise patterns to the reference patch. Second, the unreliable noisy pixels in digital images can bring a bias to the patch searching process and result in a loss …

Systems Thinking As A Design Process, Elizabeth Lockwood

Systems Science Friday Noon Seminar Series

During my master’s degree I analyzed sustainable practices in the built environment. What came from that work was a deep level of understanding that the current practices and rating systems appeared to be technical approaches to a larger system at play. I realized I have a gift to see hidden connections and find links between systems. Currently I use systems mapping as part of the design process to unearth the hidden elements in a system. I believe it is important to understand where designers, clients and stakeholders can insert themselves into a system. Part of this understanding is having empathy …

Predicting Time To Dementia Using A Quantitative Template Of Disease Progression, Murat Bilgel, Bruno Jedynak

Portland Institute for Computational Science Publications

Introduction: Characterization of longitudinal trajectories of biomarkers implicated in sporadic Alzheimer's disease (AD) in decades prior to clinical diagnosis is important for disease prevention and monitoring.

Methods: We used a multivariate Bayesian model to temporally align 1369 AD Neuroimaging Initiative participants based on the similarity of their longitudinal biomarker measures and estimated a quantitative template of the temporal evolution cerebrospinal fluid (CSF) Aβ_1-42, p-tau_181p, and t-tau, hippocampal volume, brain glucose metabolism, and cognitive measurements. We computed biomarker trajectories as a function of time to AD dementia, and predicted AD dementia onset age in a …

Remote Sensing Of Water Use Efficiency And Terrestrial Drought Recovery Across The Contiguous United States, Behzad Ahmadi, Ali Ahmadalipour, Glenn Tootle

Civil and Environmental Engineering Faculty Publications and Presentations

Ecosystem water-use efficiency (WUE) is defined as the ratio of carbon gain (i.e., gross primary productivity; GPP) to water consumption (i.e., evapotranspiration; ET). WUE is markedly influential on carbon and water cycles, both of which are fundamental for ecosystem state, climate and the environment. Drought can affect WUE, subsequently disturbing the composition and functionality of terrestrial ecosystems. In this study, the impacts of drought on WUE and its components (i.e., GPP and ET) are assessed across the Contiguous US (CONUS) at fine spatial and temporal resolutions. Soil moisture simulations from land surface modeling are utilized to detect and characterize agricultural …

Sound Propagation, Reflection, And Its Relevance To Ultrasound Imaging, Thomas Allen, Alex Chally, Bradley Moser, Ralf Widenhorn

Physics Faculty Publications and Presentations

The labs presented here build on a simple speed of sound activity and models medical ultrasound imaging by demonstrating how multiple reflections propagate in a closed system. A short sound pulse is emitted into a pipe that is closed at one end and contains one or more partially reflecting surfaces within the pipe. The variety of reflections and transmissions that occur can be measured with a microphone at the pipe entrance.