Digital Commons Network^™

Computational Algorithms For Improved Representation Of The Model Error Covariance In Weak-Constraint 4d-Var, Jeremy A. Shaw

Dissertations and Theses

Four-dimensional variational data assimilation (4D-Var) provides an estimate to the state of a dynamical system through the minimization of a cost functional that measures the distance to a prior state (background) estimate and observations over a time window. The analysis fit to each information input component is determined by the specification of the error covariance matrices in the data assimilation system (DAS). Weak-constraint 4D-Var (w4D-Var) provides a theoretical framework to account for modeling errors in the analysis scheme. In addition to the specification of the background error covariance matrix, the w4D-Var formulation requires information on the model error statistics and …

Lexical Bundles In Applied Linguistics And Literature Writing: A Comparison Of Intermediate English Learners And Professionals, Kathryn Marie Johnston

Dissertations and Theses

Lexical bundles (fixed sequences of three to four words) have been described as building blocks of discourse, both written and spoken (Biber & Barbieri, 2007), and as a useful mechanical device for creating writing that is suited for its academic field (Hyland, 2008). Having noticed that the academic theses of my students at Longdong University in Qingyang, China seemed very different from professional writing in their fields, I created a thesis project that addressed the question of how professionals in their fields were using bundles and how the learners' use of these bundles in terms of frequency, structure, and function …

Investigating The Relationship Between Supervisor Status And The Modus Operandi Of Juvenile Sexual Offenders: A Routine Activity Theory Perspective, Kelly E. Stewart

Dissertations and Theses

A significant proportion of child sexual abuse perpetration is committed by juvenile sexual offenders (JSOs), a subgroup of offenders whose patterns of offending, or "modus operandi," have been found to be markedly different compared to their adult counterparts (Kaufman et al., 1996; Kaufman et al., 1998). Many of these JSOs commit sexual abuse perpetration while acting as a babysitter, or a temporary supervisor to their victim. The present study investigates the routine activities of JSOs and their victims’ caregivers that are associated with the JSO being placed into a supervisory role. The study also investigates subgroup differences in the use …

Land Use Mix And Pedestrian Travel Behavior: Advancements In Conceptualization And Measurement, Steven Robert Gehrke

Dissertations and Theses

Smart growth policies have often emphasized the importance of land use mix as an intervention beholding of lasting urban planning and public health benefits. Past transportation-land use research has identified potential efficiency gains achieved by mixed-use neighborhoods and the subsequent shortening of trip lengths; whereas, public health research has accredited increased land use mixing as an effective policy for facilitating greater physical activity. However, despite the celebrated transportation, land use, and health benefits of improved land use mixing and the extent of topical attention, no consensus has been reached regarding the conceptualization and measurement of this key smart growth principle …

Application Of Numerical Modeling To Study River Dynamics: Hydro-Geomorphological Evolution Due To Extreme Events In The Sandy River, Oregon, Sarkawt Hamarahim Muhammad

Dissertations and Theses

The Sandy River (OR) is a coastal tributary of the Columbia River and has a steep hydroshed 1316 square kilometers which is located on the western side of Mount Hood (elevation range 3 m to 1800 m). The system exhibits highly variable flow: Its average discharge is ~40 m³/s, and the highest recorded discharge was 1739 m³/s in 1964. In this study I model the geomorphic sensitivity of an 1800m reach located the downstream of the former Marmot Dam, which was removed in 2007. The hydro-geomorphic response to major flood has implications for system management and …

Synthesis And Characterization Of The 2-Dimensional Transition Metal Dichalcogenides, Robert Browning

Dissertations and Theses

In the last 50 years, the semiconductor industry has been scaling the silicon transistor to achieve faster devices, lower power consumption, and improve device performance. Transistor gate dimensions have become so small that short channel effects and gate leakage have become a significant problem. To address these issues, performance enhancement techniques such as strained silicon are used to improve mobility, while new high-k gate dielectric materials replace silicon oxide to reduce gate leakage. At some point the fundamental limit of silicon will be reached and the semiconductor industry will need to find an alternate solution. The advent of graphene led …

Root-Enhanced Infiltration In Stormwater Bioretention Facilities In Portland, Oregon, Ted David Hart

Dissertations and Theses

I evaluated the effectiveness of plant roots to increase infiltration rates within stormwater bioretention facilities (SBFs), roadside planter compartments that filter stormwater. SBFs attenuate harmful effects of stormwater by reducing peak flow and retaining pollutants, with increased infiltration that improves both these functions. Researchers have shown that roots can increase infiltration within greenhouse, lab, field, and test SBF settings. However, no researchers have yet measured either the extent to which different root characteristics can increase infiltration or the variation in root characteristics and their effect on infiltration rates among plant assemblages within currently functioning SBFs.

To determine if root-enhanced infiltration …

Exploring Mathematical Capital: An Essential Construct For Mathematical Success?, Marla Ann Lasswell Baber

Dissertations and Theses

In the United States students have traditionally struggled with mathematics. Many students leave the educational system with limited mathematical literacy that can adversely affect their success as a college student, a consumer and citizen. In turn, lack of mathematical literacy affects their socioeconomic status. Through improving their mathematical literacy, students can be more successful not only in mathematics but, it seems in many aspects of their lives. Many researchers have defined mathematical literacy; yet, we need to understand more about how mathematical literacy develops. This study explores a model that identifies four key components that seem to be associated with …

Power-Aware Datacenter Networking And Optimization, Qing Yi

Dissertations and Theses

Present-day datacenter networks (DCNs) are designed to achieve full bisection bandwidth in order to provide high network throughput and server agility. However, the average utilization of typical DCN infrastructure is below 10% for significant time intervals. As a result, energy is wasted during these periods. In this thesis we analyze traffic behavior of datacenter networks using traces as well as simulated models. Based on the insight developed, we present techniques to reduce energy waste by making energy use scale linearly with load. The solutions developed are analyzed via simulations, formal analysis, and prototyping. The impact of our work is significant …

Quadded Gasp: A Fault Tolerant Asynchronous Design, Kristopher S. Scheiblauer

Dissertations and Theses

As device scaling continues, process variability and defect densities are becoming increasingly challenging for circuit designers to contend with. Variability reduces timing margins, making it difficult and time consuming to meet design specifications. Defects can cause degraded performance or incorrect operation resulting in circuit failure. Consequently test times are lengthened and production yields are reduced.

This work assess the combination of two concepts, self-timed asynchronous design and fault tolerance, as a possible solution to both variability and defects. Asynchronous design is not as sensitive to variability as synchronous, while fault tolerance allows continued functional operation in the presence of defects. …

Hydrodynamic And Water Quality Modeling Of The Chehalis River Using Ce-Qual-W2, Sarah Van Glubt

Dissertations and Theses

The Chehalis River Basin is located in the southwest region of Washington State, originating in the Olympic Mountains and flowing to Grays Harbor and the Pacific Ocean. The Chehalis River is over 125 miles, exists within five counties, and flows through agricultural, residential, industrial, and forest land areas. Four major rivers discharge to the Chehalis River, as well as many smaller creeks, five wastewater treatment plants, and groundwater flows.

Flooding is a major problem in the relatively flat areas surrounding the cities of Chehalis and Centralia, with severe consequences for property, safety and transportation. As a result, construction of a …

Development Of A Technology Transfer Score For Evaluating Research Proposals: Case Study Of Demand Response Technologies In The Pacific Northwest, Judith Estep

Dissertations and Theses

Investment in Research and Development (R&D) is necessary for innovation, allowing an organization to maintain a competitive edge. The U.S. Federal Government invests billions of dollars, primarily in basic research technologies to help fill the pipeline for other organizations to take the technology into commercialization. However, it is not about just investing in innovation, it is about converting that research into application. A cursory review of the research proposal evaluation criteria suggests that there is little to no emphasis placed on the transfer of research results. This effort is motivated by a need to move research into application.

One segment …

Achieving Operational Seismic Performance Of Rc Bridge Bents Retrofitted With Buckling-Restrained Braces, Ramiro Andrés Gabriel Bazáez Gallardo

Dissertations and Theses

Typical reinforced concrete (RC) bridges built prior to 1970 were designed with minimum seismic consideration, leaving numerous bridges highly susceptible to damage following an earthquake. In order to improve the seismic behavior of substandard RC bridges, this study presents the seismic performance of reinforced concrete bridge bents retrofitted and repaired using Buckling-Restrained Braces (BRBs) while considering subduction zone earthquake demands. In order to reflect displacement demands from subduction ground motions, research studies were conducted to develop quasi-static loading protocols and then investigate their effect on structural bridge damage. Results suggested that subduction loading protocols may reduce the displacement ductility capacity …

Novel Compound, 84f2, Inhibits Calmodulin Deficient Ryr2, Robert Carl Klipp

Dissertations and Theses

The cardiac ryanodine receptor (RyR2) plays a key role in excitation-contraction coupling (ECC). Mutations in RyR2 are known to be linked to the arrhythmogenic disorder, catecholaminergic polymorphic ventricular tachycardia (CPVT), a deadly disease which is characterized by a leak of calcium from sarcoplasmic reticulum and a decrease in calmodulin (CaM) binding. A novel drug, 84F2, shown to inhibit arrhythmias in RyR2-R176Q heterozygous CPVT mouse hearts (2.5 µg/kg), decrease spark frequency in cells derived from CPVT mice (IC₅₀ = 35 nM), and inhibit RyR2 single channel activity at low nanomolar concentrations (IC₅₀ = 8 nM). When CaM is added …

Building A Multivariable Linear Regression Model Of On-Road Traffic For Creation Of High Resolution Emission Inventories, James E. Powell

Dissertations and Theses

Emissions inventories are an important tool, often built by governments, and used to manage emissions. To build an inventory of urban CO₂ emissions and other fossil fuel combustion products in the urban atmosphere, an inventory of on-road traffic is required. In particular, a high resolution inventory is necessary to capture the local characteristics of transport emissions. These emissions vary widely due to the local nature of the fleet, fuel, and roads.

Here we show a new model of ADT for the Portland, OR metropolitan region. The backbone is traffic counter recordings made by the Portland Bureau of Transportation at …

Effects Of Spatially Distributed Stream Power On Check Dam Function In Small Upland Watersheds: A Case Study Of The Upper Laja Watershed, Guanajuato, Mexico, Zachary Andrew Herzfeld

Dissertations and Theses

Watershed restoration comes in a variety of forms depending on which set of problems are sought to be remedied. Severe soil erosion, in the form of gullying and/or headcutting, can be mitigated through constructing check dams in well-selected locations. This practice has been used throughout the upland subwatersheds within the Upper Laja River watershed in Guanajuato, México. The present study employed Wolman pebble counts to systematically assess the effectiveness of 21 check dams located near the city of San Miguel de Allende. Particle size distributions taken directly downstream and upstream of each check dam were differentiated, aggregated and compared--with the …

Teacher And Student Perceptions Of World Englishes (We) Pronunciations In Two Us Settings, Marie Arrieta

Dissertations and Theses

The present study investigated the perceptions and attitudes of two groups each of ESL teachers and students in the United States regarding World Englishes (WE) pronunciations before and after watching a video on WE accents. Data gathered via online surveys were analyzed using a combination of quantitative and qualitative methods. The results show that the perceptions of the teachers in the study ranged from somewhat negative to mildly positive, both pre- and post-video, which is consistent with Brown's (1993) findings that teachers' perceptions changed little if at all after being briefly exposed to WE stimuli. The education of the teachers …

High-Quality Chemical Vapor Deposition Graphene-Based Spin Transport Channels, Lester Florian Lampert

Dissertations and Theses

Spintronics reaches beyond typical charge-based information storage technologies by utilizing an addressable degree of freedom for electron manipulation, the electron spin polarization. With mounting experimental data and improved theoretical understanding of spin manipulation, spintronics has become a potential alternative to charge-based technologies. However, for a long time, spintronics was not thought to be feasible without the ability to electrostatically control spin conductance at room temperature. Only recently, graphene, a 2D honeycomb crystalline allotrope of carbon only one atom thick, was identified because of its predicted, long spin coherence length and experimentally realized electrostatic gate tunability. However, there exist several challenges …

Charles A. Moose: Race, Community Policing, And Portland's First African American Police Chief, Douglas Jon Kenck-Crispin

Dissertations and Theses

In 1993, Charles Moose became Portland, Oregon's first black police chief. A nationally recognized student of the developing theories of community policing, Chief Moose's promotion was also hoped to help strengthen the diversity of the Portland Police Bureau. Ultimately, Portlanders were unable to look past Moose's public outbursts and demeanor and recognize his accomplishments. As a city, they missed an opportunity.

This thesis uses transcripts of speeches and policy papers to present some political history to the reader, but also letters to the mayor's office, letters to the editor and the like to consider the social history of 1990's Portland. …

Out In "The Numbers": Youth And Gang Violence Initiatives And Uneven Development In Portland's Periphery, Dirk Kinsey

Dissertations and Theses

Incidence of youth and gang violence in the Portland, Oregon metro area has increased dramatically over the past five years. This violence has recently become more spatially diffuse, shifting outwards from gentrified, inner city neighborhoods, towards the city's periphery. These incidents exist within the context of a shifting regional political economy, characterized by a process of gentrification associated displacement and growing, and distinctly racialized and spatialized, inequalities. While gang researchers have long argued a corollary between the emergence of gangs and economically and culturally polarized urban landscapes, the ongoing suburbanization of poverty in American cities suggests a new landscape of …

Disability Poetry: An Exploration In Three Parts, Daniel Sarmiento

Dissertations and Theses

No abstract provided.

Are Weevils Picky Eaters? Community Structure And Host Specificity Of Neotropical Saproxylic Beetles (Coleoptera: Curculionidae), Jhunior A. Morillo

Dissertations and Theses

Abstract Primary saproxylic beetles play a major role in forest nutrient cycling and making deadwood accessible to other decomposers. Understanding beetle host preferences and patterns of community assembly is critical for their conservation, and for predicting which species might become invasive. This project aims to investigate the ecological and host specificity, as well as the community composition of curculionids in a mosaic of old-growth (OG) and secondary forest on the Osa Peninsula, Costa Rica. The subfamily Scolytinae was expected to be the most species-rich and abundant. Ambrosia beetles were expected to have more generalist species than other curculionids. Old growth …

Marsh-Exported Dissolved Organic Matter Fate In Estuaries, Laura Ann Logozzo

Dissertations and Theses

Dissolved organic matter (DOM) is a significant driver of estuarine productivity and nutrient cycling. The colored component of DOM, chromophoric dissolved organic matter (CDOM), impacts coastal optical properties, ocean color, and light attenuation. While marshes are largely considered sinks for carbon due to their high productivity and low soil carbon degradation rates, laterally they are sources of carbon as optically and chemically distinct DOM to surrounding aquatic ecosystems; these inputs are often essential in sustaining a net heterotrophic system. However, the photoreactivity and bioavailability of marsh-exported DOM is largely uncategorized, thus making it difficult to quantify its impacts on estuarine …

Public Art Between Authoritarianism And Democracy (The Case Of The Maidan Protest In Ukraine), Asia Bazdyrieva

Dissertations and Theses

This thesis explores the spatial organization and public art of Kyiv’s Independence Square to address broader social and political realities after the Maidan protests of 2013-14. Using theories of power and ideology, this study demonstrates how the discourse on public art reflects the political situation of post-revolutionary Ukraine, and how public engagement with urban space signals a paradigmatic shift in the developing country’s process of self-identification. The purpose of this thesis is threefold: first, to identify the Soviet ideological approach embedded in the spatial organization of Kyiv’s administrative center (including the Maidan); second, to examine artistic interventions at the site …

Taurine's Effect On Cocaine Reward And Neurogenesis In The Adolescent Male Rat Brain., Avery E. Villa-Gonzalez

Dissertations and Theses

Adolescence is a developmentally critical transition from childhood to adulthood including both maturation of the body and the brain. Neuroplastic changes result in dynamic organization of the brain during adolescence, leaving them vulnerable to development of mental illness and drug-seeking behavior. According to the United Nations Office on Drugs and Crime, the psychostimulant cocaine is the second most popular illicit drug in the world. Cocaine, amongst having many detrimental effects, has shown to also decrease hippocampal neurogenesis, resulting in decreased neuroplasticity and cognitive dysfunction. Previous students in our laboratory have shown that treatment of adult male rats with the essential …

Influence Of Fibroblasts On Metastatic Cancer Cell Drug Resistance In A 3d Microfluidic Cell Array, Elizabeth C. Benoy

Dissertations and Theses

Modeling an accurate depiction of the tumor microenvironment, (TME), is essential to observe the effect external factors might have on the tumor in vivo. In cancer therapy specifically, the outcomes of clinical treatments are heavily dependent on drug testing methods despite the cytotoxic effects these methods might have on the patient. Our lab has previously developed a three layered microfluidic cell array (3D μFCA) to reconstruct the relevantly spatial configuration of tumor and microvasculature found in vivo in order to develop a more efficient tool of high throughput drug discovery and screening. In this study, we optimized this device to …

Enzymatically Active Microspheres For Self-Propelled Colloidal Engines, Jungeun Park

Dissertations and Theses

Micro- and nano-motors have attracted numerous attentions from various scientific areas due to their potential applications. Most studies on self-propelled colloidal engines have exploited catalytic decomposition of hydrogen peroxide to drive the motor. Since the hydrogen peroxide is caustic, it is not suitable to use in biological applications, encouraging people to develop “greener” fuels. The aim of this research is to study a new transduction mechanism for self-propulsion not tied to hydrogen peroxide, and which can in particular be used with biological molecules as fuels. In this study, we focus on making particles with enzymatic activity which can effectively decompose …

Ionic Liquids Tethered To Activated Carbon For Capture Of Airborne Toxins, Devin Peck

Dissertations and Theses

Ionic liquids (ILs) were investigated for functionalization of activated carbon (AC) adsorbents for the filtration of warfare toxins. Preliminary steps were taken by testing absorption capacity of neat ILs and tethering ionic liquids to the surface of AC. AC is known to have good adsorption ability for warfare agents. Functionalizing the AC with ILs could enhance the capture ability significantly. ILs have been found to be good absorbents for a variety of gaseous species. The absorption selectivity and capacity can be tuned by changing the anion-cation pair. By tethering ILs to AC, the beneficial properties of gas absorption from ILs …

A New Thin Layered Structural Coating On A Metal Substrate For Enhanced Hydrogen Production From Steam Methane Reforming, Michael A. Lugo-Pimentel

Dissertations and Theses

In the past decade the use of hydrogen has become more ubiquitous. Its applications range from the upgrading of fossil fuels, to the production of ammonia, to the hydrogenation of fats, to the production of muriatic acid and methanol, all without including the efforts being taken to move towards a hydrogen economy. Its widespread use and its increasing demand lays pressure to find more efficient techniques of hydrogen production. Because the overwhelming majority of hydrogen produced nowadays comes from the steam reforming of natural gas (SMR), it appears that the most adept way to improve yields is by improving the …

Property Analysis Of Silylamine Type Reversible Ionic Liquids For Use As A Thermal Safety Switch In Batteries, Showmik Podder

Dissertations and Theses

The increased capacity of the modern battery system has also brought about safety apprehensions. Uncontrollable runaway reactions are a big concern in these systems; these reactions are the result of in situ heat generation and very much increase the risk of explosions and device failures. The concept of this work is to provide a preliminary understanding into the use of a type of switchable solvent known as reversible ionic liquids (RevILs) and their feasibility in being used in electrolytes as a thermally-controlled reversible safety switch. In their pure forms these switchable solvents experience a dramatic change in their properties upon …