https://etd.auburn.edu/handle/10415/1 2026-07-14T04:43:26Z 2026-07-14T04:43:26Z Harrison, Kenneth https://etd.auburn.edu/handle/10415/10434 2026-07-13T18:50:43Z 2026-07-13T00:00:00Z

Kinetics and Cognition in Aging Gait: The Role of Executive Function and Running Experience Harrison, Kenneth Background: Aging is associated with a characteristic reorganization of lower limb biomechanics during gait, known as the distal-to-proximal shift, where ankle power generation decreases while hip power increases. While traditionally viewed as compensation for peripheral neuromuscular changes, emerging evidence suggests this shift may reflect central nervous system adaptations influenced by cognitive-motor interactions. However, traditional biomechanical measures (A2/H3) are confounded by walking speed, limiting our understanding of true age-related neuromuscular changes and their relationship to cognitive function. Purpose: This dissertation: (1) Measured the role of executive function and cognitive load on the distal to proximal shift in joint power that occurs with aging and (2) determined whether lifelong running preserves cognitive-motor integration during dual-task walking in older adults. Methods: 58 participants (22 young adults 18-35 years, 22 older adult nonrunners aged 60 and above, with an additional 14 older runners aged 60 and above) completed comprehensive gait analysis under single and dual-task conditions (verbal fluency) using 3D motion capture and force plates. Executive function was assessed through standardized cognitive batteries. Novel collision phase power measures (H1/K1) capturing collision dynamics were compared with traditional A2/H3 propulsive measures across multiple walking speeds. Significance: This research established speed-stable biomarkers for clinical assessment of age-related mobility decline, elucidated the neuromechanical mechanisms underlying the distal-to-proximal shift, and identified whether exercise-related protection extends beyond physical to cognitive-motor domains. These results inform targeted interventions addressing both biomechanical and cognitive aspects of mobility preservation in aging populations.

2026-07-13T00:00:00Z Hildebrandt, Andrew https://etd.auburn.edu/handle/10415/10433 2026-07-13T16:42:44Z 2026-07-13T00:00:00Z

Networks in Transition: Adaptive Cycles, Organizational Traps, and the Mechanisms of Supply Chain Resilience Hildebrandt, Andrew The inability of organizations to adapt to disruptive change represents one of the most consequential challenges in supply chain management. Motivated by the widespread failure of supply chains during the COVID-19 pandemic, this dissertation examines why organizations become entrapped in maladaptive configurations and explores the structural, behavioral, and communicative mechanisms that either enable or prevent adaptive response across three interconnected studies. Chapter 1 examines oscillatory reconfiguration in healthcare procurement, investigating how U.S. hospitals cycle in and out of Group Purchasing Organization (GPO) memberships in response to shifting structural conditions. Drawing on the Structure-Conduct-Performance paradigm and Dynamic Capabilities Theory, the study finds that hospitals engage in adaptive procurement cycling reflecting strategic responses to environmental pressures, with implications for operational resilience and supply chain disruption exposure. Chapter 2 develops a conceptual theory of how organizational learning processes produce and resolve adaptive cycle traps. Grounding the analysis in the socio-ecological adaptive cycle framework, the study identifies four traps — dissolution, rigidity, poverty, and vagabond — and theorizes that each corresponds to a distinct learning failure mode. Qualitative interview data from supply chain managers provides empirical grounding for the propositions. Chapter 3 reports a 2 × 3 between-subjects experiment with 685 supply chain professionals examining whether supervisor-delivered organizational nudges shape managers' long-term collaborative intent during disruption. Results demonstrate that adaptability-oriented supervisor communication produces significantly greater collaborative intent than agility-oriented communication, that agility orientation actively suppresses long-term collaborative thinking, and that nudge type drives behavioral contagion across supply chain boundaries. Across the three studies, this dissertation advances understanding of adaptive failure as a multilevel phenomenon rooted in structural procurement behavior, organizational learning dynamics, and everyday supervisor communication — offering theoretical and practical contributions for supply chain resilience in an era of persistent disruption.

2026-07-13T00:00:00Z Elrick, Brian https://etd.auburn.edu/handle/10415/10432 2026-07-13T14:20:49Z 2026-07-13T00:00:00Z

Sound Advice: A Multi-Dimensional Analysis of Hearing Conservation, Knowledge, Behaviors, and Laboratory Safety Culture Among Agricultural Mechanics Teachers Elrick, Brian Agricultural mechanics laboratories pose a continuous acoustic hazard to teachers in the field. Nevertheless, the profession continues to experience a recurring cycle of silence concerning audiological safety. This three-article dissertation examined the technical, behavioral, and cognitive barriers to hearing conservation among agricultural mechanics instructors. Article One employed a quantitative survey targeting two distinct cohorts of agricultural mechanics educators: a group from Georgia (n = 97) and a second group comprising teachers whose teams qualified for the National Agricultural Mechanics Contest at the 98th National FFA Convention and Expo (n = 32). The purpose was to evaluate their technical understanding of sound levels. The findings revealed a significant calibration error, as teachers consistently underestimated tool decibel (dBA) levels while overestimating safe exposure durations in accordance with NIOSH guidelines. Article Two analyzed the Modeling Paradox within the same cohorts. Results indicated that educators uphold high safety standards in professional environments where students are present; however, they often neglect the use of personal protective equipment (PPE) in non-professional settings. This observation implies that safety is predominantly regarded as a professional obligation rather than an internalized personal value. Article Three examines the cohort's understanding of health literacy, emphasizing the relationship between noise-induced hearing loss (NIHL) and cognitive decline associated with dementia. The results demonstrate that the majority of respondents maintained a neutral position on this correlation, while the national cohort recorded no responses in the 'Strongly Agree' category regarding the connection between NIHL and cognitive decline. The lack of awareness of long-term neurological repercussions represents a substantial barrier to behavioral change. Recommendations include shifting professional development from traditional PPE Training towards comprehensive health literacy advocacy. By integrating neurological outcomes into safety discussions, the profession can transition from mere compliance to building a culture of conviction, ultimately protecting the long-term health of agricultural teachers. Creating a healthy work environment is critical for increasing teacher longevity and success (Clemson et al., 2020).

2026-07-13T00:00:00Z Li, Yu https://etd.auburn.edu/handle/10415/10431 2026-07-13T13:40:39Z 2026-07-13T00:00:00Z

3D Printed Textile Composites Development for Wearable Product Applications Li, Yu The purpose of this study was to explore the development process of 3D printed textile composites and examine potential of this new material for wearable product application. The specific objectives were to: (a) identify commonly used filament-textile combinations by pairing filaments for 3D printing with conventional textile substrates, (b) develop 3D printed textile composites using the Fused Deposition Modeling method by optimizing key design features to enhance printability, (c) examine the material properties of 3D printed textile composites through objective material evaluation, and (d) assess users’ sensorial perceptions of these newly developed materials through subjective material evaluation. This study was conducted in two phases. Study 1 focused on the development of 3D printed textile composites. Based on a literature review, one filament for 3D printing and five conventional textile substrates were identified and paired, resulting in five commonly used filament-textile combinations for developing 3D printed textile composites. The 3D printed textile composite samples across five filament-textile combinations were created using a 3D printer, with geometric features and printing parameters optimized to improve printability. Study 2 was the evaluation of 3D printed textile composites through objective and subjective material analyses. The objective evaluation examined the effects of filament-textile combinations on adhesion strength, bendability, elongation, and drapability, as well as the impact of 3D printed layer deposition on bendability, elongation, and drapability of 3D printed textile composites compared with their corresponding conventional textiles. The subjective evaluation, involving 26 participants, assessed users’ sensorial perceptions of 3D printed textile composites, specifically perceived temperature, surface properties, flexural properties, and bulk properties, across different filament-textile combinations, and compared these perceptions with those of the corresponding conventional textiles. The results of Study 1 indicated that thermoplastic polyurethane paired with knitted cotton, woven cotton, knitted polyester, woven polyester, and polyester mesh represent commonly used filament-textile combinations used by designers and researchers in the development of 3D printed textile composites for wearable applications. The findings also demonstrated that geometric features and printing parameters significantly influence the printability and overall quality of 3D printed textile composites during the 3D modeling and printing process. The results of Study 2 further revealed that the 3D printed layer deposition process significantly affects both the material properties and users’ sensorial perceptions of 3D printed textile composites compared with their corresponding conventional textiles. Additionally, the findings indicated that variations in filament-textile combinations lead to distinct mechanical performances and users’ perceived sensorial characteristics. This study contributed to the development of 3D printed textile composites for wearable products in several ways. First, it proposed a comprehensive integrated theoretical framework and provided practical guidelines for designers to optimize the material development process, thereby improving the printability and overall quality of 3D printed textile composites. Second, the study identified and examined commonly used filament-textile combinations, offering valuable insights for designers in selecting appropriate filaments for 3D printing and conventional textile substrates to achieve optimized mechanical performance. Third, the study deepened the understanding of the 3D printed layer deposition process and its impact on both mechanical behavior and users’ sensorial perceptions. These findings highlight the strong potential of 3D printed textile composites as wearable materials in wearable product design, enabling designers to intentionally control material properties and users’ sensorial properties. In summary, this study is original, unique, and innovative in addressing important gaps in the literature as one of the few comprehensive scientific studies devoted to systematically developing, evaluating, and applying 3D printed textile composites for wearable product applications. This study advances the growing field of 3D printed wearable product design by deepening the understanding of the development process, mechanical performance, and users’ sensorial perceptions of 3D printed textile composites. Ultimately, the findings further expand the potential of 3DP in the apparel and textiles industry, laying the groundwork for future innovations in 3D printed textile development and next-generation wearable technologies.

2026-07-13T00:00:00Z