Digital Commons Network^™

Pathways To Leadership: How Meaningful Experiences Shape Motivation In 4-H Teen Leaders, Trang Ta, Steven Krauss

Journal of Youth Development

Youth leadership development is crucial for empowering young people to thrive and contribute to society. Research on 4-H has demonstrated significant leadership growth among program participants, with effects persisting into emerging adulthood. However, little is known about what specific experiences shape 4-H youth’s motivation to lead. This qualitative study explores meaningful experiences—vividly remembered moments with positive and enduring effects—that nurture leadership motivation among 4-H teen leaders. Seven emerging adults aged 18-21 with extensive leadership experience in Missouri 4-H programs participated in semi-structured, in-depth interviews. Using a thematic analysis approach, we identified two categories of meaningful experiences, namely transformative moments and …

Evaluation Of Computed Tomography Radiation Dose Metrics In Saudi Arabia: Comparison To National And International Diagnostic Reference Levels, Mohammad Esmael Alsulimane

Saudi Medical Journal

ABSTRACT This review evaluates CT radiation dose levels in Saudi Arabia relative to national Diagnostic Reference Levels (DRLs) established by the Kingdom of Saudi Arabia (KSA) and the United Kingdom (UK). A total of 31 studies published between 2015 and 2025 were reviewed, covering adult and pediatric CT protocols for head, chest, abdomen, pelvis, and multiphase scans. The review highlights variations in the volumetric computed tomographic dose index (CTDIvol), and the dose-length product (DLP) values among different institutions in KSA. For adult protocols, fifteen studies reported dose metric values below the KSA NDRLs, while 8 studies reported values below the …

Pitch Modeling And Control Of Subcarangiform Robotic Fish, Margaret Grace Enderle

Master's Theses and Capstones

The development of biomimetic robotic fish has been an ongoing research topic for the last 30 years. Here, researchers have explored biomimetic propulsion and maneuverability mechanisms, studied energy efficiency in comparison to live fish, and developed autonomous control algorithms for these extremely nonlinear systems. This work studies a multi-linkage, single-actuator propelled biomimetic robotic fish, the Ghost Uncrewed Performance Platform Submersible (GUPPS), developed at the University of New Hampshire. A set of symmetrically driven, static pectoral fins are added to the original platform to enable diving and surfacing capabilities by controlling the vehicle Angle of Attack (AoA) through pitch and yaw …

Characterizing Sei Whale (Balaenoptera Borealis) Movement Patterns In The Gulf Of Maine, Emma Vergow

Master's Theses and Capstones

Sei whales are difficult to visually monitor due to their cryptic presence and lack of breaching. Passive acoustic monitoring has the potential to expand knowledge of sei whale movement ecology. The present study characterizes sei whale movement patterns related to migration dynamics in the Gulf of Maine. Five bottom-mounted Acoustic Long-Term Observatory landers, each equipped with a tetrahedral array of omni-directional hydrophones, were deployed throughout the Gulf of Maine as part of the Acoustic and Environmental Observation Network (AEON) in the Northwest Atlantic project. A combination of manual and automated detections was used to assess sei whale daily and seasonal …

Investigating The Performance Of Fibre Reinforced Plastic Repairs To Timber Marine Civil Structures At His Majesty’S Naval Base Devonport, Anna G. Walther

The Plymouth Student Scientist

This paper explores Fibre Reinforced Plastics (FRPs) as a composite repair method to restore and enhance mechanical properties of timber marine civil structures within the context of His Majesty’s Naval Base (HMNB) Devonport. To support this, timber composite specimens were manufactured and subjected to flexural and compressive strength tests. Comparisons are made to literature sources for initial predictions, in addition to hand calculations and Finite Element Analysis (FEA) models on SolidWorks. Data demonstrates that FRPs can be used as a cost-effective and beneficial method of repairing timber marine structures. Experimental data demonstrates an ability to restore compressive strength parallel to …

Microplastic Accumulation In A Mixed Species Seagrass Bed In The Tamar Estuary, Torpoint, Cornwall, Uk, Hannah G. Phillips

The Plymouth Student Scientist

Microplastic pollution is a major threat to UK seagrass habitats, which provide essential ecosystem services by supporting biodiversity and economically valuable fish species. Seagrass beds, acting as long-term ‘sinks’ for microplastics due to their dense canopies face a high risk of degradation. This study investigated microplastic accumulation in the sediment of a mixed species (Zostera marina and Nanozostera noltei) seagrass bed in the Tamar Estuary, Southwest England, considering the effect of sediment particle size. Microplastics were extracted by density separation using Sodium Bromide (NaBr) and sediment particle size analysis was used to investigate the seagrass bed sediment. FT-IR …

Effects Of Maternal Hypoxia On Developmental Plasticity, Matilda Powell

The Plymouth Student Scientist

Developmental plasticity enables organisms to adjust phenotypes to environmental cues, yet the transgenerational consequences of maternal effects remain unclear. Hypoxia, intensified by climate change and eutrophication, triggers taxon-specific plastic responses. Daphnia magna exhibits plasticity dependence, making it a critical model species for studying environmental responses. While maternal hypoxia (MH) influences generational plasticity, its long-term impacts on reproductive and physiological traits across generations remain insufficiently explored, limiting predictions of species resilience to environmental change. This study employed a controlled two-generation design: gravid F0 adults were exposed to moderate hypoxia (40% air saturation) or normoxia (100% AS) for 8 days, with reproductive …

All Rivers Reach The Sea: Can We Improve Ocean Conservation Through Improving Public Understanding Of The Connections Between Marine And Terrestrial Systems?, Lauren Hind

The Plymouth Student Scientist

With marine environments facing growing threats and their connections to terrestrial environments often disregarded, understanding public perceptions of these connections is crucial for effective ocean conservation. This study aimed to assess public understanding of the interconnectedness of marine and terrestrial environments and its influence on ocean conservation efforts. To achieve this, two questionnaires (N=560) were distributed among over 18’s (N=301) and under 18’s (N=259) evaluating their knowledge on the connections between marine and terrestrial environments, engagement with conservation and views on education and responsibility. The results indicated a limited understanding and awareness of marine-terrestrial connections, particularly among under 18’s. Current …

What Environmental Circumstances Generate Hazardous Wave Overtopping Conditions For Infrastructure Disruption: Dawlish (United Kingdom) Case Study, Zbigniew Tomasz Zielonka

The Plymouth Student Scientist

Coastal infrastructure faces increasing threats from wave overtopping due to climate change, rising sea levels, and intensifying storms. This research investigates the environmental conditions that drive hazardous wave overtopping using Dawlish, a vulnerable section of the UK’s railway, as a case study. Understanding these conditions is essential for improving knowledge, developing effective mitigation strategies, and enhancing the resilience of shoreline defences against future challenges. Using one-year observations from WireWall instruments, offshore wave buoy, and meteorological data, the research applies a Random Forest model to assess the influence of metocean conditions on overtopping. The results indicate that wave height, tidal level, …

Method Optimisation And Environmental Analysis Of Methanesulfonic Acid (Msa) In Rainwater By Ion Chromatography, Thomas Levett

The Plymouth Student Scientist

This research optimised a method of analysis for methanesulfonic acid (MSA) alongside common inorganic anions using ion chromatographic (IC) apparatus developed at the University of Plymouth. The aim was to assess whether MSA could be more easily and routinely monitored alongside common rainwater anions. The method’s analytical quality was evaluated through each development stage of the research and its limitations found. Historical rainwater samples collected at Penlee Point, Plymouth, UK (2015–2018) were also used for testing. The method successfully provided detectable ranges of MSA between 0.001 – 5 mg/L for F^-, Cl^-, NO_2-, Br …

Quantification Of Trace Metal(Loids) In The River Seaton, Cornwall, Uk And The Influence Of The South Caradon Mine On Ecological Risk, Bjorn Piñol

The Plymouth Student Scientist

Freshwater quality is critical to the health of aquatic ecosystems and human water security, yet anthropogenic activities, such as historic mining, continue to degrade aquatic systems. While extensive research has examined metal contamination in major rivers like the River Tamar, smaller tributaries affected by legacy mining remain understudied. This study investigates trace metal contamination and its controlling factors in the River Seaton, Cornwall, a small river influenced by historic mining from the South Caradon Mine. Water samples collected from four study sites along the river gradient and a reference site at Siblyback Lake were subjected to ICP-MS analysis and physico-chemical …

Assessing Overtopping Hazard To The Dawlish Railway Line: Integrating Wave Propagation Models For Coastal Metocean Condition Analysis, Matthew R. Owen

The Plymouth Student Scientist

With rising sea levels and increasingly frequent and intense storms due to climate change, coastal communities and structures are at an increasing risk of overtopping occurring. This study investigates the coastal metocean conditions responsible for overtopping at coastal defences, using Delft3D to model these processes with Dawlish as the case study site. Wave propagation models were employed to simulate metocean conditions from December 2021 to March 2022 to compare inshore wave conditions, alongside water level and wind parameters, with observed overtopping data from the WireWall system installed on top of the seawall, next to the railway line. The results indicate …

From Sea To Shore: Wind-Driven Aerosolization Of Harmful Algal Bloom Toxins In Qingdao, China, During The Winter Of 2019, Madeleine K. Martin

The Plymouth Student Scientist

In Qingdao, China, harmful algal blooms (HABs) are a known hazard to coastal communities. Aerosolization is a mechanism by which HAB toxins can be transported from the sea surface into the air when wind speeds exceed 5 m/s. Previous studies have analysed the composition of aerosolized marine biotoxins (AMBs) in the breathable air surrounding Qingdao, but the role of the onshore winds in transporting them there would benefit from further research. Ciguatoxin is one such AMB, and this study analyses the role of onshore winds in aerosolizing and transporting toxins inland from a ciguatoxin bloom in Aoshan Bay, Qingdao during …

Comparing The Effect Of Marine Aquarium Salts And Sodium Chloride On Vicia Faba Stress Response, Bethany Smerdon

The Plymouth Student Scientist

Soil salinity is a major abiotic stressor limiting agricultural productivity. Many salt stress studies rely solely on sodium chloride (NaCl) solutions, despite not accurately representing natural saline conditions. This study investigated the stress response of Vicia faba to NaCl and marine aquarium salt (MAS) solutions to assess the impact of a more complex ionic composition on plant physiology. Plants were cultivated in a controlled greenhouse and treated with either NaCl, MAS, or rainwater (control) for up to 55 days. Growth parameters, water status, proline accumulation, chlorophyll content, and root nodule weight were measured to evaluate stress responses. The results indicate …

Evaluating The Impacts Of The Invasive Macrophyte, Crassula Helmsii, On Macroinvertebrate Assemblages At Small Spatial Scales In Lentic Ecosystems, Keivan Rakhshani

The Plymouth Student Scientist

Freshwater ecosystems cover only three percent of the Earth’s surface yet support approximately ten percent of global biodiversity. These systems play a crucial role in maintaining native biodiversity across spatial and temporal scales but are increasingly threatened by anthropogenic stressors, including habitat modification, pollution, and biological invasions. The introduction of non-native macrophytes can fundamentally alter community structure by modifying habitat complexity, resource availability, and competitive interactions. This study assesses the impact of the invasive macrophyte Crassula helmsii on macroinvertebrate assemblages at small spatial scales within partially invaded ponds in Dartmoor National Park, southwest England. Three ponds with varying degrees of …

Assessing Jasmonic Acid Seed Priming In Brassica Napus: Impacts On Aphid Herbivory Resistance And Seedling Fitness Trade-Offs, Daisy Stradling

The Plymouth Student Scientist

Jasmonic acid (JA) is a key phytohormone involved in plant defence, offering a potential sustainable alternative to conventional chemical pesticides. While JA seed priming has been explored as a strategy to enhance herbivore resistance in certain plant families, its potential fitness trade-offs remain poorly understood. This study investigates the effects of JA seed priming on Brassica napus (oilseed rape), a key agricultural crop, focusing on seedling fitness and resistance to Brevicoryne brassicae (mealy cabbage aphid), a major agricultural pest. To assess potential fitness trade-offs, seeds were primed with 75 µM JA, and multiple seedling fitness parameters were measured. Germination monitoring …

Investigating Deception-Related Moral Conflict Using Electroencephalography (Eeg) Hyperscanning, Madie Ades

The Plymouth Student Scientist

Amplitudes of the early Bereitschaftspotential (BP) and deceptive behaviour have been theorised to be modulated by moral conflict experienced when making deceptive decisions, as the decision to lie can depend upon our moral perceptions of what is right and wrong (Panasiti et al., 2014). However, most Electroencephalography (EEG) deception paradigms lack ecological validity by utilising instructed lying and failing to incorporate genuine social interaction (Ganis & Keenan, 2009) and therefore may fail to elicit genuine moral conflict. The present study combined hyperscanning EEG with a competitive two-player social game, where participants freely chose to respond accurately or deceptively for …

Otherwise Than Human: Responsibility In The Wake Of Disaster, An Eco-Deconstructive Response To Climate Catastrophe, James W. Harris

Masters Theses and Doctoral Dissertations

This thesis will, firstly, assume a line of eco-deconstructive reasoning, which takes as its point of departure from other approaches to the environment the basic premises of deconstruction, which aim to de-center the ontological and epistemological assumptions of Western thought about the subject and language, and apply it to the concept of the human as a distinct and, most importantly, privileged being as this privilege has operated within language and culture, thereby demonstrating how climate catastrophe constitutes a fundamental rupture in traditional ontology. Secondly, I will turn towards the ethics of Emmanuel Levinas, as in present in his God, Death, …

A Phylogenetic And Taxonomic Analysis Of Parocnus Serus, An Extinct Holocene Sloth From Haiti, Julia L. Jones

Masters Theses and Doctoral Dissertations

Parocnus serus belongs to a unique radiation of extinct ground sloths endemic to the Antillean islands that was discovered in 1929, but, prior to this thesis, it had not been described in detail or had its phylogenetic and taxonomic relationships with other Antillean sloths extensively analyzed. This detailed description of skull and mandible specimens supported the distinctiveness of the genus Parocnus, and the existing size-based separation of the Antillean megalonychids. A morphological phylogenetic analysis of a sample of Antillean sloths supported the close relationship between P. serus and P. torrei but did not provide conclusive results on the relationships among …

Optimizing Xylitol Production: A Molecular And Experimental Study Of Xylose Reductase In Candida Tropicalis, Zackery Neal

Masters Theses and Doctoral Dissertations

Xylitol, a naturally occurring sugar alcohol, is widely used in the food and pharmaceutical industries as both an artificial sweetener and an anticariogenic agent. Traditional xylitol production relies on harsh chemicals and energy-intensive processes, making microbial fermentation a more sustainable alternative. This study explores the ability of Candida tropicalis to convert D-xylose into xylitol through the enzyme xylose reductase, with a focus on optimizing pH conditions to enhance conversion efficiency. To achieve this, both experimental fermentation and computational molecular dynamics simulations using GROMACS and the pHbuilder tool are employed. By analyzing the enzyme’s stability and structural dynamics across different pH …

Dna Methylation Markers Of Insulin Resistance Surrogate Measures In The Atherosclerosis Risk In Communities (Aric) Study, Jeewoen Shin, Jan Bressler, Megan L Grove, Michael Brown, Elizabeth Selvin, James S Pankow, Myriam Fornage, Alanna C Morrison, Chloé Sarnowski

Faculty, Staff and Student Publications

Insulin resistance (IR) is a risk factor for cardiovascular diseases and type 2 diabetes. Associations between DNA methylation (DNAm) and IR have been less studied in African ancestry (AA) populations than those of European ancestry (EA). We aimed to identify associations between whole blood DNAm and IR in up to 1,811 AA and 964 EA participants from the Atherosclerosis Risk in Communities (ARIC) study. We quantified IR using three surrogate measures: the homeostasis model assessment of insulin resistance (HOMA-IR), the triglyceride-glucose index (TyG), and the triglyceride glucose-body mass index (TyG-BMI). We used ancestry-stratified linear regression models to conduct epigenome-wide association …

Association Of Epigenetic Age Acceleration And Mitochondrial Dna-Based Aging Metrics Provides Insights Into Mechanisms Of Aging-Related Diseases, Mengyao Wang, Yinan Zheng, Meng Lai, Emmanuel Saake, Xue Liu, Xiuqing Guo, Kent D Taylor, Tianxiao Huan, Roby Joehanes, Drew R Nannini, Kai Zhang, Nicole J Lake, Christina A Castellani, Stephen S Rich, Jerome I Rotter, Yongmei Liu, Laura M Raffield, April P Carson, Myriam Fornage, Jiantao Ma, Dan E Arking, Lifang Hou, Daniel Levy, Chunyu Liu

Faculty, Staff and Student Publications

Investigating the interplay between mitochondrial DNA (mtDNA) variations and epigenetic aging metrics may elucidate biological mechanisms associated with age-related diseases. We estimated epigenetic age acceleration (EAA) metrics from DNA methylation data and derived mtDNA metrics, including heteroplasmic variants and mtDNA copy number (mtDNA CN) from whole genome sequencing. Linear regressions and meta-analyses were conducted to assess associations between EAA and mtDNA metrics, adjusting for chronological age, self-identified sex, and other covariates in 6,316 participants (58% female, 41% non-White Americans). Mediation analysis was conducted to examine whether EAA mediated the relationship between mtDNA CN and metabolic traits. A higher burden of …

Microinjection, Gene Knockdown, And Crispr-Mediated Gene Knock-In In The Hard Coral, Astrangia Poculata, Jacob F. Warner, Ryan Besemer, Alicia Schickle, Erin Borbee, Isabella V. Changsut, Koty H. Sharp, Leslie S. Babonis

Arts & Sciences Faculty Publications

Cnidarians have become valuable models for understanding many aspects of developmental biology including the evolution of body plan diversity, novel cell type specification, and regeneration. Most of our understanding of gene function during early development in cnidarians comes from a small number of experimental systems including Hydra and the sea anemone, Nematostella vectensis. Few molecular tools have been developed for use in hard corals, limiting our understanding of this diverse and ecologically important clade. Here, we report the development of a suite of tools for manipulating and analyzing gene expression during early development in the northern star coral, Astrangia poculata. …

Influence Of Peer-Led Team Learning In Students’ Chemistry Self-Efficacy, And Academic Achievement In General Chemistry Courses, Hector Leal

Theses and Dissertations

One of the most perplexing issues facing peer cooperative learning is dealing with student motivation and goal orientation. Sometimes the students who could most benefit from the positive effects of peer learning are the ones least likely to participate due to fear of exposing their academic weaknesses to others or even to themselves (Arendale, 2020). Exploring the complexity of student motivation is being carefully studied amongst elementary and secondary education student populations. However, this important construct is often ignored in the study of postsecondary education in general, and the provision of learning assistance, particularly at the college level. My purpose …

Educators’ Perceptions Of Mental Health Services For Middle School Students In A South Texas District, Norma Araceli Cabrera

Theses and Dissertations

The purpose of this phenomenological qualitative study is to examine teachers' and administrators' perceptions of school-based mental health services in one school district in South Texas. Within-case sampling was utilized to select the participants. The study examines educators' perceptions of the availability and effectiveness of mental health services for middle school students. Middle school is a period of intense social development, during which students strive to navigate peer relationships. Middle school children, aged 12-14, also undergo emotional development as they manage intense emotions, develop self-awareness, and learn to cope with stressors related to school, friends, and self-identity. Studies found that …

Characterizing The Germination Process And Establishing Best Practices For Seed Propagation Of Tamaulipan Thornscrub Species For Habitat Restoration, Saroj Dhakal

Theses and Dissertations

Tamaulipan thornscrub is an imperiled plant community of southern Texas and northeastern Mexico. Given its importance for biodiversity conservation, stakeholders have been involved in restoration programs using seedlings grown from wild seeds. However, stakeholders often report that insufficient seedling supply is a challenge. To address knowledge gaps in seed germination behavior limiting seedling production, this study was conducted on 18 Tamaulipan thornscrub species, identified by growers as difficult to germinate. Seeds of all studied species are orthodox except Amyris texana, which have recalcitrant properties. Nine species have physical dormancy that was successfully addressed with mechanical and/or chemical scarification. Other species …

Arthropod Communities Associated With Endangered Physaria Thamnophila (Zapata Bladderpod) And Its Nurse Plants, Cesar Adrian Hinojosa

Theses and Dissertations

Physaria thamnophila is a federally endangered plant whose associated arthropods are understudied and poorly understood. This study surveyed environmental conditions and the arthropod community within the Arroyo Ramirez Tract of the Lower Rio Grande Valley National Wildlife Refuge, assessed which environmental factors influenced the arthropod community, and sought arthropod taxa statistically associated with Physaria thamnophila. Sticky cards and pitfall traps were deployed for a 7 day period, and vacuum samplings occurred quarterly over the span of a year to collect arthropods that were identified to order and family level for Coleoptera, Hymenoptera, and Lepidoptera. Biotic and abiotic surveys were performed …

Determination Of An Effective Natural Boxelder Bug (Boisea Trivittata) Repellent, Reyna Chavez

Theses and Dissertations

This study investigates the use of ecofriendly repellant alternatives to pest management to control boxelder bugs (Boisea trivittata). This bug gathers by the thousands on warm surfaces of exterior suburban homes during early fall and late spring. I determined bug repellency to turmeric oil (Curcuma longa), catnip (Nepeta cataria), citronella (Cymbopogon nardus), and lavender (Lavandula angustifolia). The treatments consisted of essential oils containing 20% methanol. All treatments demonstrated repellency of Boxelder bugs. Citronella was the most effective and had the highest level of repellency range of 90-99%. Catnip was the least effective with a repellency range of 63-82%.

Clustering 24-Hour Ambulatory Blood Pressure Time Series With Dynamic Time Warping And Time Warp Edit Distance, John Knight

Theses and Dissertations

Ambulatory blood pressure monitoring (ABPM) captures dynamic circadian changes in blood pressure (BP) that are not reflected in static clinic readings. This study applied time-series clustering with two elastic distance measures—Dynamic Time Warping (DTW) and Time Warp Edit Distance (TWED)—to identify distinct phenotypes in 2,155 24-hour ABPM time series from participants in the Maracaibo Aging Study. DTW and TWED both yielded three clusters corresponding to non-dipping, moderate-dipping, and strong-dipping patterns. The non-dipping group showed elevated nighttime BP, associated with greater cardiovascular and cognitive risk, while the strong-dipping group was associated with higher education and younger age in baseline clinic measurements. …

Design And Evaluation Of Gamified Kahoot Modules For Improving Engagement And Conceptual Understanding Of Introductory Physics Students, Yaritza Villarreal

Theses and Dissertations

This study investigates the effectiveness of gamified learning modules in enhancing the engagement and conceptual understanding of introductory physics students. The first phase of this study focused on the design and development of gamified learning modules for selected topics in introductory physics. The modules were developed by integrating principles of Backward Design, following an escape-room theme with interactive scenarios, and incorporating classic game elements (e.g., points and leaderboards).

The second phase examined the effectiveness of the gamified Kahoot modules using a pretest-posttest control-group design. Sixty-eight (68) students were equally randomly assigned to the control and experimental groups. The experimental group …