Digital Commons Network^™

Effect Of Specimen Size On The Tensile Properties Of Selective Laser Melted Ti-6ai-4v, Timothy L. Tan

Master's Theses

Metal additive manufacturing (MAM) is a burgeoning industry. It is capable of manufacturing metal components with fine, intricate features and enables localized microstructural control. Due to its fine resolution and compatibility with common engineering alloys, selective laser melting (SLM) is one particular MAM process popular in academia and industry. The biomedical and aerospace industries have shown exceptional interest in the capabilities of SLM with the alloy Ti-6Al-4V. Because SLM Ti-6Al-4V components are aimed for use in critical applications, it is necessary to understand how SLM processing characteristics affect final part performance. One characteristic of SLM Ti-6Al- 4V that requires further …

Active Tectonics, Erosion Rates, And Topographic Metrics In The Hayword-Calaveras Fault Zone, Simone I. Yeager

Master's Theses

In northern California, the complex geometry of the San Andreas Fault system, and how it steps and propagates across the Earth’s surface, is revealed in the topography. Activity along the Mission and Arroyo Aguague oblique reverse faults, located where the right-lateral Hayward Fault steps to the left of the Calaveras Fault, are manifested in the Diablo Mountain Range. The high topography in the restraining step can be observed in lidar imagery and seismicity studies show these faults are connected at depth. In this study, we investigate active tectonics, erosion rates, and topographic metrics from the southern end of the restraining …

Mammal Response To Wildfire In Redwood Forests In Northern California, Kristine Doerr

Master's Theses

California has historically experienced recurrent wildfires that have shaped many of the region’s unique ecosystems such as coast redwood (Sequoia sempervirens) forests. Redwood forests, particularly old-growth redwoods, are vital habitats for many wildlife species. Still, these long-living, fire-resistant trees are facing altered fire regimes due to fire suppression and climate change. The 2020 CZU Lightning Complex Fire was a consequence of these changes and significantly altered the landscape of the Santa Cruz Mountain region. This study analyzes mammal recovery after wildfire in high and low fire severity locations of the CZU Fire using two camera trap grids. The high-severity grid …

Exploring Community Adaptation To Public Safety Power Shutoff Events: Findings From Two Case Studies Of Unincorporated Mountain Communities In Southern California, Ramiro M. Brown

Master's Theses

As aging electrical infrastructure in the US continues to succumb to unyielding weather patterns brought on by climate change, there is an urgency among Investor-Owned Utilities (IOUs) to reduce the likelihood of their equipment sparking a wildfire. Public Safety Power Shutoffs (PSPS) – the intentional de-energization of the electrical grid on high fire weather danger days – have become a staple in IOU Wildfire Mitigation Plans (WMPs) since 2018 as one way to avoid wildfire ignitions via electrical infrastructure. One criticism of PSPS events is that they create their own hazard by cutting off power to thousands – sometimes millions-of …

Relationship Between Depression, Rumination, And Emotionally Valenced Working Memory Performance, Dewey Tran

Master's Theses

Working memory is limited in capacity and easily disrupted such that mood states and competing cognitive processes can impair performance. Rumination is highly associated with depression that may contribute to impaired working memory but has not often been studied. The goal of this study was to elucidate the relationship between depression severity, ruminative state, and working memory performance. Participants completed a baseline assessment of depression severity, rumination (trait and state), and working memory then randomly assigned to a rumination or control groups, followed by a second assessment. I hypothesized working memory would be explained by an interaction between depression severity …

The Effects Of Stress On Attentional Networks, Alice Tsvinev

Master's Theses

The human brain has developed mechanisms to aid our survival, including attentional networks and stress response. Attentional shifts allow humans to react accordingly to their environment, following innate processes like fight or flight. Prolonged exposure to acute stress interferes with such cognitive processes as attention and working memory, impacting attentional systems. The present study examined the effects of acute stress on visual attention processes, specifically focusing on the orienting, alerting, and executive attention networks. 49 participants were randomly placed in either a stress or non-stress condition, then asked to reflect on either stressful or positive moments in their lives, respectively. …

Win-Win Ecology: Can Mosses Promote Dudleya Germination To Restore California Quarries?, Kate L. Worrell

Master's Theses

Human actions directly damage habitat for native plants; restoration ecology facilitates successful plant re-establishment in these environments. Open-pit mines leave behind steep, rocky, and nutrient-deficient habitats that are some of the most degraded ecosystems on the planet. Dudleya or ‘live-forevers’— a genus of native California succulent plants that contains many rare, threatened, or endangered species — grow on rocky cliffs and may create a successful reclamation-restoration story. However, Dudleya germination is poorly understood. Much of the literature on Dudleya cites a single field report suggesting that bryophytes facilitate germination, but no previous experiments have evaluated this proposal. In this study, …

The Impacts Of Recreational Infrastructure On Mammal Use Of Riparian Zones In Northern California Regional Parks, Emily A. Matthews

Master's Theses

Public lands have been important for the protection of riparian habitats; however, many public lands are also used for recreation, which can reduce mammal habitat use. Understanding how mammals are affected by recreation in riparian areas can help guide management decisions. The goal of this research is to understand the effect of recreation on mammal use of riparian habitats in two popular East Bay Regional Parks, Charles Lee Tilden and Wildcat Canyon, and to map the extent of that impact. Cameras were deployed in the riparian areas of a high, moderate, and low development site (Alvarado, Tilden, and Wildcat Canyon) …

Creatine And Depression In Rodents: A Meta-Analysis, Ruchika S. Tirupachur

Master's Theses

Traditional treatments for major depression are based on the monoamine deficiency hypothesis, and they fail to achieve remission in a substantial portion of patients. Newer evidence suggests the pathophysiology of depression is a more complex story, highlighting a need for research in alternative therapies. Mounting evidence shows a linkage between depression and the supplement creatine monohydrate (CRMH). Research in rodent models suggests that CRMH may both alleviate depressive symptoms and enhance the efficacy of standard antidepressants like SSRIs. The following study describes findings from a combined fixed- and random-effects meta-analysis based on four empirical studies investigating the effect of CRMH …

The Effects Of Full-Body Photo-Editing On Female Body Image, Claire E. Mcelhern

Master's Theses

Over the past decade, the use of photo-based social media sites has seen an exponential increase. Although these sites can be beneficial for connecting with others, the editing and modification of images posted to social media has also produced adverse effects on some who use them. The aim of the present study was to assess whether partaking in a full-body photo-editing task would have a significant effect on weight dissatisfaction, appearance dissatisfaction and body confidence, compared to a control condition. Female college participants were first asked about their general Instagram use, and then were given a baseline Visual Analog Scale …

No Change In Functional Ecology Or Body Size In Response To A Global Climate Event In The Late Maastrichtian Owl Creek Formation, William T. Rizza

Master's Theses

During the last 300 ka of the Maastrichtian, global temperatures increased and decreased by ~2℃, likely caused by a pulse of Deccan volcanism. The Owl Creek Type Section in Mississippi records some portion of the last 400 ka of the Late Maastrichtian. It is expected that marine invertebrates will demonstrate a taxonomic, ecological, or morphological response to rapid temperature change. I anticipate a decrease in taxonomic diversity and shell volume and an increased abundance of low activity-level species, similar to the ecological impacts observed in response to Large Igneous Province eruptions in the geologic record. Clumped isotope paleotemperature reconstruction recovers …

The Moderating Role Of Meaningful Work On The Relationship Between Loss Of Self-Identity And Psychological Well-Being In Retired Collegiate Athletes, Sarah M. Kurd

Master's Theses

Collegiate athletes are a focal point for many universities. These student-athletes work most of their lives to make it to the university level. Many collegiate athletes aspire to make it to the professional level after they graduate from college, but only a rare handful make it to the top. The rest of the athlete population retires and is placed into a world of “normalcy,” but the transition out of athletics can be very challenging, impacting a person’s psychological well-being. Most of these athletes will have to work a professional job after leaving sports. The present study aimed to examine the …

A Novel Reinforcement Learning Method For Efficient Cross-Training Between Real And Simulated Robots, Zhonglin Liang

Master's Theses

Training reinforcement learning policy in a simulated environment can be a go-to choice for many research topics, as a simulated environment provides flexibility and costs less than building a physical environment for training. However, policy trained in a simulated environment often fails to transfer to the real environment for problems that have a more complex dynamics. As the solution, Sim2Real was proposed and it categorizes techniques that improve the performance of the transfer from simulation to reality. Sim2Real is an area of study that focuses on utilizing simulation data to train models that can apply to real world environment. It …

The Impact Of Adverse Childhood Experiences On Later Desistance Among Serious Juvenile Offenders From A Broken Family Composition, Olivia Franklin

Master's Theses

The current study aimed to contribute to the overall knowledge of desistance patterns among juveniles by exploring them among serious juvenile offenders who come from a broken home. Utilizing the Pathways to Desistance (PTD) dataset, this study used logistic regression to examine the impact of family composition on later desistance while controlling for various adverse childhood experiences (ACEs) one might experience. Two research questions guide this study: (1) Does family composition (i.e., “broken homes”) impact later desistance among serious adolescent offenders, while controlling for important criminological predictors (i.e., self-control and antisocial peer influence)? (2) Is the quality of one’s home …

Using Noninvasive Calibrated Cuff Plethysmography To Observe The Effects Of Diabetes On Arterial Compliance, Jadon Bradford

Master's Theses

The prevalence of cardiovascular disease is on a continuous exponential growth across the globe. Thus, research into the underlying factors, effective methods of diagnoses, and preventive measures is necessary. Endothelial dysfunction is an early detector of cardiovascular diseases and can be used to inform people of preventative measures and early treatments before any extreme medical conditions occur. Something that is also on the rise and closely linked with cardiovascular disease is diabetes. There have been many past research studies that show the impact of diabetes on cardiovascular disease and more specifically endothelial dysfunction. A calibrated cuff plethysmography device is a …

Hypoxic Incubator: Improving Robustness/Reliability And Demonstrating Physiological Efficacy, Damon Dennis Tan

Master's Theses

The Microphysiological Systems Laboratory aims to develop colorectal cancer tumor models under a hypoxic environment to assess model response to pharmaceutical compounds in vitro. To perform relevant studies, researchers have attempted to use different hypoxic inducing strategies such as a nitrogen pod and hypoxic incubator to recreate in vivo physiological responses to hypoxia. However, studies would be interrupted due to incubator functionality failure. To ensure successful and physiologically relevant studies, I improved and verified the robustness and reliability of a hypoxic incubator previously designed and manufactured in the lab. Through the testing and iterating design processes, I engineered and implemented …

3d Printed Microfluidic Fabrication Methodology, Characterization, Mechanical Design, And Applications In Electrostatic Artificial Muscles And Benthic Microbial Fuel Cells, Terak B. Hornik

Master's Theses

The fabrication of microfluidic devices often requires specialized methods. The development of these methods requires careful characterization and understanding of the processes involved. Using primarily PolyJet 3D printing technology, microfluidics offers a wide scope of applications such as microfluidic benthic microbial fuel cells (MBMFCs) and electrostatic artificial muscles. MBMFCs benefit from the confinement of the microbes resulting in close proximity between the electrode and the organisms. Using a modular design called the Sponge, assembly and upscaling is possible. Electrostatic artificial muscles benefit from a microfluidic approach due to the non-linearity of electrostatic attraction creating disproportionate benefits when miniaturized. When designed …

Hardware Control Unit For Trusted Program Verification System, Jake Owen Alt

Master's Theses

Trust in the underlying hardware is the foundational step towards trusting the correctness and integrity of a software application. However, verifying that today's extremely complex processors work exactly as intended has not been feasible, as evidenced by several recent hardware bugs. Trustworthy, formally verified processors currently forego intricate performance enhancements such as out-of-order execution, hampering them substantially versus their less secure counterparts.

The Containment Architecture with Verified Output (CAVO) system solves this problem by isolating the host system and requiring the result of each instruction to be validated by a small, trusted hardware module called the Sentry. Any transmissions to …

Implications Of Persistent Micro-Bioplastics On Biogeochemical Properties Across Soil Types, Casandra R. Leach

Master's Theses

Terrestrial microplastics are increasing in abundance and are an emerging contaminant of concern, particularly in agriculture ecosystems where plastic use and subsequent soil contamination are prevalent. Plastic film mulches make up a significant portion of the plasticulture industry and are directly linked to soil microplastic pollution where negative effects to soil biotic and abiotic functions have been observed. In response to this issue, biodegradable film mulches have been promoted as a sustainable alternative to conventional polyethylene-based mulches. These biodegradable mulches, composed of various bioplastics, are designed to be tilled back into the soil where they are expected to decompose. However, …

Drivers Of Microparticles Abundance In Freshwater Fish And Macroinvertibrates, Elizabeth Kazmierczak

Master's Theses

Anthropogenic microparticles (MP) (i.e., particles < 5 mm) are defined as materials of manufactured origin found in the environment. They are widespread and a rapidly emerging global contaminant. MP include microplastics (< 5 mm), as well as other microfibers or particles, which can be synthetic, semi-synthetic and non-synthetic. Rivers are a critical source of plastics to oceans, and MP within rivers are retained in part though biological processes, including ingestion. MP ingestion by freshwater biota varies by proximity to point sources (e.g., wastewater treatment plants; WWTP), overall environmental concentrations, and trophic level and functional feeding groups, but few studies have examined these factors together. In our first study we examined fish collected in the North Shore Channel of the Chicago River to determine MP abundance within organisms. We then compared trophic position (i.e., δ15N) and proximity to a WWTP. With all species combined, MP concentration were not significantly different across study sites, but stable isotopes increased downstream. Considered individually, MP abundance relative to WWTP proximity varied by species, which we attributed to habitat preference and mobility. In a second project, we collected macroinvertebrates from three different watersheds in North America and compared the abundance of MP in macroinvertebrates to concentration within the environment (i.e., water column, surface, and benthic). Functional feeding groups were a significant predictor in the amount of microparticles found in macroinvertebrates. Additionally, the concentration of water column microparticles showed a positive relationship with all macroinvertebrate’s microparticle abundance. Results will aid in understanding the ecological impacts of MPs on aquatic food webs and the pathways in which they can enter.

Understanding Teachers’ Responses To Parental Demands In The Midst Of Competing Responsibilities, Kathryn Battafarano

Master's Theses

This study builds upon a plethora of educational research and focuses specifically on middle school grade level teachers. I predominantly utilized qualitative interviews to understand how teachers respond to parental demands; these answers were supplemented by some quantitative data about their schools. The study configures information about teachers’ school environments and requirements, teachers’ interactions with parents, and how teachers deal with parental demands in relation to other demands and requirements. Effort was made to investigate how teacher experience, teaching style, and subject matter as well as school type (e.g., socio-economic makeup of the school) and school location influence parental demands …

Associations Between Neighborhood Factors And Adherence In Youth With Spina Bifida: The Mediating Role Of Parental Stress And Youth Internalizing Symptoms, Breana Lyn Bryant

Master's Theses

Spina bifida (SB) is a birth defect that impacts physical, medical, and neuropsychological functioning. Physical complications like hydrocephalus and bladder dysfunction require daily adherence to complex medical regimens. Additionally, youth with SB are more likely to have symptoms of anxiety and depression which can impact their ability to master their regimens. Evidence in other pediatric populations have examined the impact of family factors, like parental stress, and individual-level predictors of self-management outcomes, yet few have examined how the broader context, like neighborhoods, impact outcomes. Therefore, the current study examined (1) the level of the neighborhood vulnerability and acute healthcare services …

The Skin Microbiome And Cutaneous T-Cell Lymphoma, Gail Hillary Lantaca Enriquez

Master's Theses

Skin microbiota is associated with disease activity in cutaneous T-cell lymphoma (CTCL). A common treatment for CTCL, narrowband ultraviolet B (nbUVB) phototherapy, has shown to shape the skin microbiome in association with disease improvement in other skin disorders such as atopic dermatitis. To assess the effect of nbUVB phototherapy on the skin microbiome, we performed a longitudinal analysis of skin samples of CTCL patients receiving nbUVB. We found that the treatment led to increased bacterial diversity and reduced abundances of Staphylococcus aureus and Staphylococcus lugdunensis, both bacteria known to be pathogenic. These findings imply that nbUVB treatment changes the skin …

Sadomasochistic Sensations: A Phenomenological Analysis Of Black Ontology, Embodiment, And Transcendence, Sam Forrey

Master's Theses

Over the past fifteen years, feminists have challenged the notion that sexual sadomasochism perpetuates racial and gender-based violence, and instead claim that the practice can be a powerful site to control and subvert oppression. In this thesis, I contribute to this growing discourse and argue that sensations experienced during practices of Black sexual sadomasochism and attention to the feelings and affects that arise from them can be used to mediate Black being in a violently antiblack United States. Through applications of Black feminist thought, Black anti-humanism, and phenomenology, I claim that antiblack oppression denies Black people the experience of tactile …

“Get Out Of The House Before It Kills You”: Haunted Housewives And The Feminist Gothic In Ira Levin’S Rosemary’S Baby And The Stepford Wives, Sarah Jeffries

Master's Theses

Ira Levin’s works Rosemary’s Baby and The Stepford Wives have been cultural touchstones since their releases in 1967 and 1972, respectively, with their legacy as iconic American horror stories cemented by successful film adaptations. At the surface level, these stories can be read as tales about unfortunate housewives that face unusual horrors. Rosemary Woodhouse finds herself trapped in a gothic New York City apartment building, the Bramford, where her husband and neighbors collude to force her to carry and birth Satan’s son, like a perverse Virgin Mary. Joanna Ebert is similarly stuck in suburban Stepford, Connecticut where she discovers the …

Rebuilding Risk Assessment Tools And Evaluating Their Effect On Recidivism In Illinois, Cristina Penate

Master's Theses

This study seeks to examine the relationship between alternative measures of criminal history and recidivism in a cohort of convicted individuals released from prison in Illinois between 2010 and 2015. The current study expands on prior research by examining the relationship between prior criminal history and recidivism using alternative measures of both to account for potential bias resulting from differential policing activities that may lead to convictions. Traditionally, risk assessment instruments have relied on an individual’s total prior convictions for any offense and any re-arrest after release from prison. The current research developed a more nuanced measure of prior convictions …

Regulation Of Spermatogenesis By The Btb Transcription Factor Ribbon, Madeline Kyung Hee Hakala

Master's Theses

The transcription factor Ribbon (Rib) plays an essential role in Drosophila testis development and function. Increased expression of rib throughout development results in significant morphology defects in the adult testis. If overexpression is limited to germ cells and somatic cells in the adult, more mild defects are observed. To better understand how Rib regulates spermatogenesis, we are interested in identifying its transcriptional targets in this context. Through bulk RNA sequencing, differential expression analysis, and subsequent filtering of results, we identified 301 genes with significant changes in expression when rib was overexpressed. Given the previously described role of Rib in the …

Impacts Of Stormwater And Land Cover On The Abundance, Transport, And Composition Of Anthropogenic Litter In Urban Watersheds, Bailey Austin Schwenk

Master's Theses

Anthropogenic litter (AL; trash) is defined as any manufactured item that ends up in the environment. AL consists of many different materials including glass, metal, and plastic, the latter of which typically represents a dominant constituent and has been a major focus of research. Plastic litter and other AL types are pervasive to all types of ecosystems, are persistent in the environment, and are increasing. Rivers are a major conduit transporting AL to oceans. However, rivers also retain and transform AL. More research is needed to understand AL dynamics within rivers, which will improve global models of AL movement and …

Enabling Emg-Based Silent Speech Transcription Through Speech-To-Text Transfer Learning, Alexander T. Garcia

Master's Theses

In recent years, advances in deep learning have allowed various forms of electrographic signals, such as electroencephalography (EEG) and electromyography (EMG), to be used as a viable form of input in artificial intelligence applications, particularly for applications in the medical field. One such topic that EMG inputs have been used is in silent speech interfaces, or devices capable of processing speech without an audio-based input. The goal of this thesis is to explore a novel method of training a machine learning model to be used for silent speech interface development: using transfer learning to leverage a pre-trained speech recognition model …

Investigation Of Temperature, Solution Strength, And Applied Stress Effects On Cation Exchange Processes In Different Geosynthetic Clay Liner Products, Kendra Fuller

Master's Theses

An extensive laboratory test program was conducted to analyze and compare the cation exchange processes in three different varieties of sodium bentonite (Na-B) geosynthetic clay liners (GCLs) over increased conditioning durations up to 32 days and investigate the effects of temperature, solution strength, and applied stress. The goal of this test program was to establish whether the variables of temperature, solution strength, and applied stress improved or degraded the engineering properties of GCLs in laboratory testing and municipal solid waste (MSW) landfill applications. The GCLs were conditioned in liquids of increasing ionic strength, using deionized water and 2, 50, and …