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Hillsboro: Bike and Pedestrian Implementation Recommended Strategy
Get PDFThis project presents a contextualized Bike and Pedestrian Implementation Strategy for the City of Hillsboro. The goal was to develop an actionable approach to expand and improve the City’s active transportation network. The strategy incorporates 23 criteria for project selection informed by existing conditions and the City’s priorities. Finally, the report culminates with a recommended implementation approach using two top scoring projects as examples
Wave-Phase Dependence of Reynolds Shear Stress in the Wake of Fixed-Bottom Offshore Wind Turbine via Quadrant Analysis
No full textThere has been an increase in recognition of the important role that the boundary layer turbulent flow structure has on wake recovery and concomitant wind farm efficiency. Most research thus far has focused on onshore wind farms, in which the ground surface is static. With the expected growth of offshore wind farms, there is increased interest in turbulent flow structures above wavy, moving surfaces and their effects on offshore wind farms. In this study, experiments are performed to analyze the turbulent structure above the waves in the wake of a fixed-bottom model wind farm, with special emphasis on the conditional averaged Reynolds stresses, using a quadrant analysis. Phase-averaged profiles show a correlation between the Reynolds shear stresses and the curvature of the waves. Using a quadrant analysis, Reynolds stress dependence on the wave phase is observed in the phase-dependent vertical position of the turbulence events. This trend is primarily seen in quadrants 1 and 3 (correlated outward and inward interactions). Quantification of the correlation between the Reynolds shear stress events and the surface waves provides insight into the turbulent flow mechanisms that influence wake recovery throughout the wake region and should be taken into consideration in wind turbine operation and placement
Electromagnetic Fields and Radiation from Localized Current Source Interacting with a Cosmic Axion Field in the Context of Massive Axion Electrodynamics
Get PDFElectromagnetic fields from localized current source interacting with an oscillatory cosmic axion field are studied, accounting for the possibility of a finite photon mass. In particular, focus will be on the dipole radiation from static current sources. The Proca theory is generalized to include the axion field and solutions to the modified EM field equations are obtained to first order in the axion coupling parameter. Analysis of the interplay between the two vanishingly small parameters – the axion mass (via the coupling constant and the oscillating frequency) and the photon mass – is carried out with reference to possible future detection of the cosmic axion and/or the photon mass via electromagnetic interaction with the axion
Development and Application of an Algae Multi-Metric Index to Inform Ecologically Relevant Nitrogen Reduction Targets
No full textNutrient enrichment can impair the biotic integrity of steams and rivers. Nutrients derived from land use practices have been identified as sources of water quality impairment in several Central California Coast watersheds resulting in excess algal growth. We developed an algae-based multi-metric index to assess the biotic integrity of streams and rivers in this region because algae often respond directly to changes in nutrient levels. Additionally, we apply the algal index of biotic integrity to the development of an effects-based nitrogen reduction target. Eleven individual metrics based on diatom autecologies, community structure, ecological guilds, tolerance, and intolerance were incorporated into the index. All algal production metrics failed reproducibility criteria for inclusion in the index. The index of biotic integrity was highly correlated with human disturbance (r = − 0.6213) and was significantly different between classes of least-, intermediate-, and most-disturbed sites. Piecewise linear regression showed a steep negative relationship between nitrate–N and the index with a breakpoint of 0.505 mg/L nitrate–N, above which the negative trend became insignificant. This change in the relationship between nitrate and the index of biotic integrity suggests that this breakpoint can aid the development of a reasonable effects-based criterion for nitrate–N in this region
Applying Decolonizing Theories and Methodologies in Archaeology to Two Collaborative Cultural Resource Management Projects
Get PDFDecolonizing theories and methods were employed during two separate graduate research projects. The methods of the initial project were informed by political ecology, the landscape-level historical ecology theory, Tribal sovereignty, traditional ecological knowledge (TEK), Indigenous archaeology, and community based participatory research (CBPR). The initial project was based entirely on CBPR and purposed to gain National Register of Historic Places (NRHP) nomination as a Traditional Cultural Property (TCP) over a portion of the traditional landscape. This project was cancelled before completion. However, several methods involved in CBPR were employed before then. The second project took on more of the historical ecology and CBPR theoretical approaches with some political ecology influences. This project was carried out to its conclusion and included a detailed analysis of all known archaeological sites within the Bering Land Bridge National Preserve (BELA) and structured reporting of the data for submission to the National Park Service (NPS). Although very different in methodology I frame discussion of both projects in similar theoretical terms to address the larger context of Indigenous self-determination in Cultural Resource Management (CRM) and my career as an anthropologist and Indigenous ally moving forward. Both projects presented challenges that will inform future research endeavors, particularly relating to time constraints, preconceived or etic ideas around adequate project timelines, Indigenous time and resources, and data analysis. However, the opportunities learned from these experiences are invaluable and will serve to make me a better CRM professional in the future
Large Length Scale Droplet Capillary Phenomena: Generation, Jump, and Capture
Get PDFUnderstanding the life cycle of droplets, from generation to capture, for example, is critical to understanding environments from the air-sea interface to the indoor environment of the International Space Station. Investigations have been performed in this work to provide insight into three droplet phenomena, each ubiquitous in both terrestrial and microgravity settings, through a lens of capillary flow. Each investigation attempts to disentangle the effects of gravity from the effects of surface tension. A drop tower test campaign is performed for each of the three investigations. Models are developed and simulations are performed to rationalize the observations. Each investigation is outlined below.
The first investigation considers a droplet impacting a fiber array. Droplets interacting with fiber arrays is common in nature, textiles, microelectromechanical devices, and fog harvesting. The phenomena of droplet impact on an equidistant array of fibers is experimentally studied. Drop tower tests are performed to characterize the droplet dynamics in the absence of the effects of gravity which could deform fibers and bias equilibrium configurations. Results show that contact line dissipation is largely responsible for arresting the droplet. Additionally, the penetration length is affected by fiber flexibility. A model is developed predicting the droplet penetration dynamics which shows good agreement with experiments.
The second investigation considers the jump of a droplet from a particle bed. Drop Tower experiments have been performed investigating droplet jump from a particle bed across a wide range of fluid viscosities. The presence of a particle layer is shown to affect contact line dissipation of the jumping droplet. Additionally, the study has identified the impact of the Ohnesorge number (Oh) on droplet morphology. The investigation has yielded results that not only validate a modified version of the spring-mass-damper model proposed by Jha et al. but also extend its applicability to previously unexplored initial conditions. In particular, the model predicts droplet jump time and velocity. Moreover, the presence of particle layers has been found to effectively eliminate contact line dissipation without introducing substantial additional forms of dissipation. Experiments have been conducted at the Dryden Drop Tower facility at Portland State University.
Lastly, the collapse of an air jet blown cavity and subsequent generation of a jet and jet droplets is investigated both experimentally and numerically. It is shown that surface tension forces alone are sufficient to generate a liquid jet from the cavity collapse. The dependence of the properties of the resulting liquid jet and jet droplets on the initial cavity geometry are discussed. Axisymmetric simulations of the Navier-Stokes equations for a simplified geometry are performed to look more closely at the evolution of the cavity geometry
Post-Wildfire Water Quality Dynamics: A Multiscale Examination and Predictive Modeling of Stream Temperature and Turbidity in Western U.S. Watersheds
No full textWildfires, exacerbated by climate change and human activities, pose significant threats to water-related ecosystem services in forested watersheds. This dissertation investigates the multifaceted impacts of wildfires on stream temperature and turbidity, two critical water quality parameters essential for maintaining aquatic ecosystem health and human water uses. By integrating a comprehensive literature review, empirical data analysis, and advanced machine learning techniques, this research provides a nuanced understanding of how wildfires affect hydrological processes across various temporal and spatial scales.
The findings reveal significant regional variability and the complex interplay between climatic, geographic, and anthropogenic factors. For instance, the literature review highlights the importance of fire severity, forest diversity, and human activities such as salvage logging in influencing post-fire water quality changes. Empirical data analysis across 101 burned watersheds in the Western U.S. over a 20-year period identifies local factors such as slope, canopy bulk density, and proximity to riparian areas as significant predictors of stream temperature trends. Advanced machine learning models, including Random Forest and Support Vector Regression, demonstrate the potential to predict post-wildfire stream temperature and turbidity with reasonable accuracy, although uncertainties remain due to the complexity of climate projections and landscape changes.
This work underscores the necessity for rigorous, long-term monitoring and the application of sophisticated modeling approaches to better predict and manage the impacts of wildfires on water quality. It emphasizes the importance of incorporating spatial and temporal variability in understanding the direction and magnitude of post-fire impacts. The dissertation contributes valuable insights for developing adaptive management strategies aimed at enhancing the resilience of watersheds and aquatic ecosystems in an era of increasing wildfire activity. By addressing scale-dependent knowledge gaps and recommending future research directions, this research lays the groundwork for more effective water resource management and policy-making in wildfire-prone regions, ultimately aiming to mitigate adverse effects on water quality and support the sustainable use of water resources amidst growing environmental challenges
Housing Instability Patterns Among Low-Income, Urban Black Young Adults in California and Associations with Mental Health Outcomes: Baseline Data from a Randomized Waitlist-Controlled Trial
Get PDFBackground: Deep-rooted racial residential segregation and housing discrimination have given rise to housing disparities among low-income Black young adults in the US. Most studies have focused on single dimensions of housing instability, and thus provide a partial view of how Black young adults experience multiple, and perhaps overlapping, experiences of housing instability including homelessness, frequent moves, unaffordability, or evictions. We aimed to illuminate the multiple forms of housing instability that Black young adults contend with and examine relationships between housing instability and mental health outcomes.
Methods: Using baseline data from the Black Economic Equity Movement (BEEM) guaranteed income trial with 300 urban low-income Black young adults (aged 18–24), we conducted a three-stage latent class analysis using nine housing instability indicators. We identified distinct patterns by using fit indices and theory to determine the optimal number of latent classes. We then used multinomial logistic regression to identify subpopulations disproportionately represented within unstable housing patterns. Finally, we estimated associations between housing experience patterns and mental health outcomes: depression, anxiety, and hope. Results We found high prevalence of housing instability with 27.3% of participants reporting experiences of homelessness in the prior year and 39.0% of participants reporting multiple measures of housing instability. We found the 4-class solution to be the best fitting model for the data based on fit indices and theory. Latent classes were characterized as four housing experience patterns: 1) more stably housed, 2) unaffordable and overcrowded housing, 3) mainly unhoused, and 4) multiple dimensions of housing instability. Those experiencing unaffordable and overcrowded housing and being mainly unhoused were more than four times as likely to have symptoms of depression (Unaffordable: aOR = 4.57, 95% CI: 1.64, 12.72; Unhoused: aOR = 4.67, 95% CI:1.18, 18.48) and more than twice as likely to report anxiety (Unaffordable: aOR = 2.28, 95% CI: 1.03, 5.04; Unhoused: aOR = 3.36, 95% CI: 1.12, 10.05) compared to the more stably housed pattern. We found that hope scores were similarly high across patterns.
Conclusions: High prevalence of housing instability and mental health challenges among low-income Black young adults demands tailored interventions to reduce instability, given widening racial disparities and implications for future well-being into adulthood
S157 - Developing Core Consensus Measures for Assessment of Psilocybin Services
No full textBackground Voter initiatives in Oregon and Colorado authorize legal frameworks for supervised psilocybin services, but no measures monitor safety or outcomes. Aims To develop core measures of best practices. Methods A three-phase e-Delphi process recruited 36 experts with 5 or more years’ experience facilitating psilocybin experiences in various contexts (e.g., ceremonial settings, indigenous practices, clinical trials), or other pertinent psilocybin expertise. Phase I, an on-line survey with qualitative, open-ended text responses, generated potential measures to assess processes, outcomes, and structure reflecting high quality psilocybin services. In Phase II, experts used seven-point Likert scales to rate the importance and feasibility of the Phase I measures. Measures were priority ranked. Qualitative interviews and analysis in Phase III refined top-rated measures. Results Experts ( n = 36; 53% female; 71% white; 56% heterosexual) reported currently providing psilocybin services (64%) for a mean of 15.2 [SD 13.1] years, experience with indigenous psychedelic practices (67%), and/or conducting clinical trials (36%). Thematic analysis of Phase I responses yielded 55 candidate process measures (e.g., preparatory hours with client, total dose of psilocybin administered, documentation of touch/sexual boundaries), outcome measures (e.g., adverse events, well-being, anxiety/depression symptoms), and structure measures (e.g., facilitator training in trauma informed care, referral capacity for medical/psychiatric issues). In Phase II and III, experts prioritized a core set of 11 process, 11 outcome, and 17 structure measures that balanced importance and feasibility. Conclusion Service providers and policy makers should consider standardizing core measures developed in this study to monitor the safety, quality, and outcomes of community-based psilocybin services
True Contraction Decomposition and Almost Eth-Tight Bipartization for Unit-Disk Graphs
Get PDFWe prove a structural theorem for unit-disk graphs, which (roughly) states that given a set D of n unit disks inducing a unit-disk graph ..