Digital Commons Network^™

Rising Cancer Burden Among Older Adults In Saudi Arabia: A Longitudinal Analysis Of Incidence Rates By Demographics, 2013–2022, Hissah A. Alzahrani

Saudi Medical Journal

ABSTRACT Objectives: To analyze cancer incidence trends in Saudi Arabia from 2013 to 2022 by age group, gender, and nationality, identify significant temporal patterns or shifts, and determine the most prevalent cancer types across age groups and years. Methods: A retrospective analysis was conducted using data from the Saudi Cancer Registry, which included 185,567 reported cancer cases between 2013 and 2022. Descriptive statistics, generalized estimating equation (GEE), and Joinpoint regression were used to examine the crude incidence rate (CIR), age-specific incidence rate (AIR), and age-standardized rate (ASR) across demographic subgroups. Results: Saudi nationals had higher cancer rates than non-Saudi residents, …

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 …

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 …

Evaluation Of Graphite And Activated Carbon As Suitable Water Purification Media For In-Situ Resource Utilisation (Isru) On Mars, Ciaran Archenoul

The Plymouth Student Scientist

Eventual human missions to the red planet will require large-scale in-situ resource utilisation to meet their objectives. Perhaps the most critical element for developing a sustainable architecture is propellant production from the products of water electrolysis and atmospheric carbon dioxide. The purpose of this study was to assess how graphitic materials may be used as porous filters to remove solvated ions from Martian water prior to electrolysis, reducing the overall complexity of ISRU systems. The two materials under study were PG25 graphite and activated carbon powder.

A comprehensive three-technique characterisation of both materials was performed, using helium pycnometry, N_{2 …}

Mechanical Properties Of Sintered Lunar Regolith Simulant Lhs-1 When Moulded Under Different Temperatures And Time At Constant Pressure, Jasper Stevens

The Plymouth Student Scientist

Humans are returning to the Moon for the first time since 1972. And when they arrive, In-Situ resource Utilisation (ISRU), the philosophy of using local materials and resources will be required to help maintain a more permanent presence on the Moon. Lunar regolith is the homogenous layer of inorganic ‘soil’ that covers nearly the entire Lunar surface, making it the most readily available material for ISRU. This report investigates the effect of changing time and temperature applied to samples of lunar regolith simulant LHS-1 formed as freestanding samples under constant pressure, before sintering into a consolidated sample. Compressive testing on …

Application And Suitability Of Using Paraffin Wax In A Thermal Store For Residential Buildings In The Uk, Cameron Edwards

The Plymouth Student Scientist

Heating costs and pressure to reduce carbon emissions are rapidly increasing. A possible solution is the implementation of efficient energy storage systems for UK residential buildings. Paraffin wax-based thermal energy storage offers a promising solution due to its low-cost, high-energy density, and long-term stability. However, its low thermal conductivity significantly reduces its practicality. Multiple upgrades, such as implementing highly conductive particles and nanotubes, have been previously studied but lack the inclusion of cost-effectiveness and real-world feasibility. This paper reviews current research and develops a numerical model using the Enthalpy method and a 2D finite difference approach, utilised in Python. It …

Vacuum-Assisted Resin Transfer Moulding (Vartm): Can Ultrasonic Vibration Decrease Fill Time, Increase Composite Properties, And Reduce Void Formation, Iulia D. Precup

The Plymouth Student Scientist

This study investigated the potential of ultrasonic vibration (28 kHz) to optimize the Vacuum-Assisted Resin Transfer Moulding (VARTM) process. The aim was to assess whether introducing ultrasonic vibration during the resin infusion phase could reduce fill time, improve mechanical properties, and minimize void formation in glass fibre-reinforced polyester composites. Two flexible tooling systems were compared: a reusable silicone membrane and a traditional vacuum bag. Composite plates were manufactured with and without ultrasonic vibration for both systems. Fill time was observed, and post-cured samples were subjected to mechanical testing for flexural modulus, flexural strength, and interlaminar shear strength (ILSS). Void content …

Analysis Of Organic Compounds Extracted From Recycled Polypropylene Via Gc-Fid/Ms And Pyr-Gc-Ms For Future Pharmaceutical Applications, India E. Hateley

The Plymouth Student Scientist

A mandatory target for 30% of plastic packaging to be recycled has been proposed by 2030, in order to mitigate the problem of plastic waste being incinerated or deposited in landfills. However, during the recycling process additives are added and with polypropylene being used for plastic packaging and surgical masks, these additives need to be analysed for the presence of contaminants. Examples include VOCs, PAHs, phthalates, and brominated diphenyl’s, all of which have health issues. Two samples of recycled polypropylene pellets were obtained from a national recycling company, along with a reference pellet purchased through Sigma-Aldrich. All pellets underwent ultrasound-assisted …

A Generational Analysis Of Psychological Motivators Influencing Seafarer Retention, Perisah Tahanci

The Plymouth Student Scientist

Seafarer retention is a growing concern amid increasing global demand for skilled maritime officers. This study investigates the generational differences in psychological motivators influencing seafarer retention, where ‘psychological motivators’ encompass the cognitive factors, including mental and physical wellbeing, work-life balance, compensation, working conditions, and external factors, that shape retention intentions. A cross-sectional survey (n=214) combined quantitative and qualitative analyses to systematically assess how the perceived importance and experience of these factors vary across Generation Z, Millennials, Generation X, and Baby Boomers.

The findings reveal that significant generational differences exist across most factors, particularly in work-life balance and mental wellbeing, in …

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 …

Scaling Wind Farm Layout Optimisation To Meet Uk Energy Demands, Grace Richardson

The Plymouth Student Scientist

This research aims to explore the Wind Farm Layout Optimisation Problem (WFLOP) through both single- and multi-objective optimisation, to show that it can be used to create farm layouts that provide enough power for all homes in the UK. We highlight the intricacies of the problem, including the application of different algorithms and models, and the challenges of scaling the models to achieve optimal results. We employ both a Hill Climbing Algorithm (HCA) and an evolutionary algorithm (NSGA-II) to obtain wind farm layouts, and compare these to the well-known results proposed by Mosetti et al. Moreover, we present a novel …

Design And Validation Of An Industrial Out-Of-Plane Permeability Test Rig Of Fibre Preforms For The Development Of Next Generation Aircraft Structures, Callum Park

The Plymouth Student Scientist

Despite composites comprising 50% of modern aircraft structures, the absence of a standardised method for measuring out-of-plane permeability frequently results in manufacturing defects in early-development aerospace components, directly impacting safety, manufacturing efficiency and costs. This study aimed to address this gap, by designing and commissioning a compact, vacuum-assisted, mass flow test rig, capable of evaluating the saturated out-of-plane permeability of a variety of materials. This design incorporated learnings from theory, previous studies and discussions with industry experts. E-glass, a Metyx unidirectional carbon and the Teijin ITS55 carbon were investigated, where E-glass exhibited the highest permeability of 1.88E-12m², while …

On Solving The Vertical Generalized Linear Complementarity Problem Associated With A Vertical Block P-Matrix, Mark K. Horlu

Masters Theses and Doctoral Dissertations

In Ebiefung et al. (2017) an algorithm was developed to solve the vertical generalized linear complementarity problem (VGLCP) when the associated matrix is a vertical block P-matrix (VBP). The objective of this study is to implement the algorithm on a large scale using the Python programming language. We also use a Python code to generate test VBP- matrices Ebiefung et al. (2022), and used them to implement the algorithm. On a representative example, every computational step including basis updates, pivot selection, and vector analysis is recorded. The Python implementation exhibits precise convergence. The final results verifying the correctness of the …

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 …

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 …

Factors Influencing Teacher Professional Autonomy And Career Satisfaction: The Effects Of Unrealistic Professional Expectations Surrounding Student-Centered And Technology Implementation Tropes, Karla Gabriela Lopez

Theses and Dissertations

The research problem is to investigate to what extent unrealistic professional expectations stemming from a predominant emphasis on the tropes of student-centeredness and technology integration impact teachers’ experiences of professional autonomy and career satisfaction. The purpose of this study is to find out what factors impact teacher autonomy and career satisfaction while also considering how teachers can be effectively supported to improve these areas. Utilizing a narrative inquiry approach, this qualitative study will be held in the Rio Grande Valley and will analyze interviews of both current teachers and teachers who have recently left the profession. Therefore, this study will …

Navigating Cultural And Professional Identities: A Study Of Hispanic Women's Experiences In Aerospace Internship Programs, Jennifer Becerra

Theses and Dissertations

This phenomenological study investigated how Hispanic women navigated cultural identity and professional development during National Aeronautics and Space Administration (NASA) internship programs, examining the role of culturally responsive mentoring in supporting retention. The research question was, How do Hispanic women in aerospace-internship programs navigate the intersection of cultural identity and professional development as they transition from academic science, technology, engineering, and mathematics (STEM) programs to aerospace careers, and what role does culturally responsive mentoring play in supporting their retention?

Using Anzaldúa’s nepantla concept, Duncan-Andrade’s critical-hope theory, and Ladson-Billings’ culturally relevant pedagogy as theoretical frameworks, in this study, I employed semistructured …

Collective Agency And Community Resilience Among Farmworkers In The Lower Rio Grande Valley, Angel Velazquez

Theses and Dissertations

This research assesses how farmworkers in the Lower Rio Grande Valley of Texas use everyday practices to build resilience and adapt to changes in their lives. I apply two interconnected theories, White’s (2017, 2019) framework of collective agency and community resilience and Castro and Sen’s (2022) framework of everyday adaptation actions, to study these practices. I conducted 19 semi-structured interviews with Latino farmworkers and professionals who work with local farmworker organizations in the Rio Grande Valley (RGV) of Texas. Interview transcripts were analyzed to determine if and how Latino farmworkers in the RGV can work towards community resilience and implement …

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. …

A Picture Tells A Thousand Words—, But Ecg Signals Have More To Say, Ashley N. Gomez

Theses and Dissertations

With the increasing adoption of deep learning classification models in the medical domain, a critical challenge remains: achieving high predictive accuracy while maintaining clinical Inter-pretability. This study examines how model architecture, dataset origin, and the use of full versus subset data affect both classification performance and Interpretability in Electrocardiogram (ECG) signal analysis. ResNet18 is evaluated using an open-source ECG Image Dataset, thus a custom dataset derived from digitized ECG images. Post-hoc explainability methods, such as Integrated Gradients, are applied to determine which time steps have the most significant influence on model decisions. The findings demonstrate that model architecture and dataset …

Efficient Self-Supervised Representation Learning For Large-Scale Time Series Classification, Kevin Garcia

Theses and Dissertations

Recently, there has been a significant advancement in designing Self-Supervised Learning (SSL) frameworks for time series data to reduce the dependency on data labels. Among these works, hierarchical contrastive learning-based SSL frameworks, which learn representations by contrasting data embeddings at multiple resolutions, have gained considerable attention. Due to their ability to gather more information, they exhibit better generalization in various downstream tasks. However, when the time series data length is significant long, the computational cost is often significantly higher than that of other SSL frameworks. In this paper, to address this challenge, we propose an efficient way to train hierarchical …

Interpretable Alignment Of Textual Weather Reports With Local Sensor Time Series For Extreme Weather Event Visualization, Juan Luis Garza

Theses and Dissertations

This thesis presents an automated and interpretable pipeline that links natural-language weather narratives with local meteorological sensor time series. Using large language models, NOAA-style event reports are transformed into structured records capturing event type, timing, descriptive context, and uncertainty. Each extracted event is aligned with harmonized temperature, precipitation, and wind measurements from nearby weather stations, enabling systematic comparisons between narrative evidence and observed atmospheric conditions.

Across roughly fifty stations and more than two thousand events, the analyses show that discrepancies between narrative descriptions and sensor behavior arise primarily from spatial separation rather than from temporal offsets, sensor preprocessing artifacts, or …

Fractals, Reachability, And Computation In Models Of Dna Self-Assembly And Chemical Reaction Networks, Ryan Arlie Knobel

Theses and Dissertations

This thesis serves as the bridge between results compiled across varying models of tile self-assembly, molecular computation, and game complexity. As such, this thesis is broken into three chapters. In the first part, we show how to generate any Discrete Self-Similar Fractal (DSSF) with a feasible generator in the seeded Tile Assembly model, a model limited to single tile attachments and pairwise state transitions. In the next part, we study models of molecular computation, where we consider the problem of reachability in Chemical Reaction Networks and similar model extensions. The final part is a game-complexity analysis of Celtic! and k-ago, …

Ai-Driven Electromagnetic Design And Performance Prediction Of Microstrip Antennas, Eduardo Javier Vazquez

Theses and Dissertations

This thesis investigates the application of Deep Learning to automate and accelerate microstrip antenna inverse design. The initial investigation was to predict microstrip antenna performance from its geometry parametric input, and found out that forward prediction with adopted geometric representation results in ill-posed scenario, high ambiguity and unstable mapping. The study later mostly focuses on the inverse prediction by machine learning from S11 parameter input to predict antenna patch geometry parameters instead.

A dataset of 5,000 ANSYS HFSS simulated antennas (later filtered to 4,136 valid samples) was generated using cubic spine -described geometry profiles. Multiple neural architectures were adopted for …

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 …

Seagrass Preference Among Pinfish In The Lower Laguna Madre, Nathaniel Garza

Theses and Dissertations

Pinfish (Lagodon rhomboides) is a common estuarine fish species found from Massachusetts to the Yucatan, Mexico. As juveniles, pinfish spend a significant portion of their life in coastal seagrasses which provide both shelter from predators and food. Along the Texas coast, there are three major species of seagrass- turtle grass (Thalassia testudinum), manatee grass (Syringodium filiforme) and shoal grass (Halodule wrightii) that differ in structural complexity. The goal of this study was to determine if pinfish associate more with one seagrass species than the others. A year-long field study was completed using twelve sample sites in the Lower Laguna Madre, …