Digital Commons Network^™

Metabolic Engineering For Aromatic Amino Acids In Cyanobacteria, Jeremiah Vue

Open Access Theses

Phenylalanine and tryptophan are valuable chemicals in the beverage, pharmaceutical and animal feed industries. Currently, engineered heterotrophic microorganisms produce phenylalanine and tryptophan from carbon sources, such as sugars. As an alternative production strategy, we are investigating photosynthetic cyanobacteria to produce aromatic amino acids from CO2. We are combining directed and evolutionary approaches. Initially, we performed chemical mutagenesis on the cyanobacteria strains Synechococcus sp. PCC 7002 and Synechocystis sp. PCC 6803 and selected colonies for resistance to tryptophan (Trp) or phenylalanine (Phe) analogs. The resistant colonies were subsequently screened for overproduction of the aromatic amino acids. The mutants resistant to phenylalanine …

Digimesh Reliability In High Speed Vehicular Applications, Bogdan A. Visan

Open Access Theses

In a fast-paced technological society, advances in wireless networking show potential to save lives. Communication is key to notifying Emergency Medical Services of a potentially deadly accident in near real-time. This paper will discuss the use of low powered wireless devices transmitting life-saving information autonomously. Current and planned technologies used in vehicles are built-in, costly, and vulnerable to physical destruction. Using an independent system can offer both old and new vehicles primary and secondary communication. The results from this research study show that vehicles can use DigiMesh as a viable solution, although relative velocity affects its performance.

Generational Shadow, Conflict, And Succession Planning In Farming Businesses, Youzhi Wang

Open Access Theses

The goal of this thesis is to examine the relationship among succession progress, generational conflict, and generational shadow and concentrate on the effects of the latter two on succession planning progress in small and medium sized family farms. Generational shadow refers to “the prior generation’s excessive and inappropriate involvement in a farm” (Davis & Harveston, 1999) – essentially, it reflects the incumbent’s unwillingness to transfer the business. Because of the suspected simultaneity, I employ a multivariate probit model and test for endogeneity. I found that the level of generational shadow is exogenous to the level of conflict and the succession …

Leveraging Uas For 3d Orthomosaid Aircraft Images To Support Maintenance Activities, William Weldon

Open Access Theses

As high ultra-high resolution aerial imaging becomes inexpensive and easily acquired through unmanned aerial systems, UAS, inspection industries are presented with the opportunity to reduce cost without reducing inspection quality. UAS technology allows for images to be taken at a relatively low cost with accuracy equivalent to laser scanning systems. A UAS equipped with a camera can be used to create a three dimensional orthomosaic model of an aircraft. This model has the potential to: increase the speed of visual inspections, increase the safety of visual inspections, improve maintenance training practices, and allow for aircraft condition tracking. The creation of …

Direct Extraction Spray Analysis Of Lipid Biomarkers In Injury Rat Spinal Cord, Pengqing Yu

Open Access Theses

Lipids are crucial components of our bodies, not only as the building component of the cell membrane, but also as signaling molecules and an energy storing unit. The study of lipids may bring great improvement for life science. Moreover, lipids may also be a key factor in many diseases, including cancer, Alzheimer’s disease, and neural diseases.1 Qualitative and quantitative lipid analysis of infected tissue is very important when uncovering the cause and mechanism of disease, and can therefore bring great success for the development of diagnosis and treatment of disease.

In this research, we used a photochemical reaction to help …

Turning A Multivalent Lens Toward Depictions Of Artificial Intelligence (Ai) In Film, Ashley Ann Albrecht

Open Access Dissertations

With innovations in the field of artificial intelligence (AI) advancing at an exponential rate, it is ever the more pertinent to interrogate the ramifications and potentialities of these developments. Luciano Floridi, known as “the Google philosopher,” considers this phenomenon an integral part of the digital information age or the “Fourth Revolution.” We are now forced to confront the following problems: What is the relationship between humans and AI? What does it mean to be “human”? What futures are possible given our current coevolution with AI? Such questions motivate close philosophical consideration. Here, the theoretical polarization of the doomsday neo-Luddite versus …

Elucidating The Biosynthetic Routes And Biological Mechanisms Involved In The Release Of Phenylpropanoid/Benzenoid Volatiles From Plant Cells, Funmilayo Adebesin

Open Access Dissertations

Sessile organisms, such as plants, have developed intricate means of responding and interacting with their environment in order to grow, reproduce, and survive environmental stresses such as attacks by other organisms and competition for resources with neighboring organisms. Plant volatile organic compounds (VOCs) play vital roles in resolving these evolutionary constraints associated with the sedentary nature of plants by attracting pollinators and seed dispersers necessary for reproduction. VOCs also mediate plant-plant interactions and provide defense against biotic stresses (pathogens, predators, and herbivores) and abiotic stresses (oxidative stress, high temperature stress, drought). Beyond the importance of VOCs to plants, humans have …

Game On: Massively Multiplayer Online Games (Mmog) As Tools To Augment Teaching And Learning, Papia Bawa

Open Access Dissertations

The study investigated the use of Massively Multiplayer Online Games (MMOG) in English and Business classrooms in Higher Education from the context of learners’ performance outcomes, as well as stakeholders’ (learners, administrators, and faculty) perceptions pertaining to their experiences when using an MMOG based curriculum. The findings strongly suggest that MMOGs helped enhance learner performances in statistically significant ways, and provided valuable insights into elements of interest and concerns of stakeholders about MMOG usage in classrooms. Based on these insights, I designed a practitioners’ guide to assist future scholars interested in this curricular approach. This guide provides innovative tips on …

Fish Consumption And Accessibility And The Implications For Household Nutrition And Food Security In Ghana And Tanzania, Akua Sakyiabea Akuffo

Open Access Dissertations

This dissertation empirically investigates aquaculture adoption on food security, fish demand and fish accessibility in Ghana and Tanzania. There are three separate chapters, each discussing a specific issue relating to food security and fish consumption. Data for chapters two and three are from the round 6 of the Ghana Living Standards Survey (GLSS6) while chapter four uses the Household Budget Survey (HBS) for Tanzania.

The second chapter of this dissertation applies the Propensity Score Matching (PSM) approach in logit and probit frameworks to a cross section of 4,011 Ghanaian households, to analyze how fish farming is associated with household food …

Variability Of Persistent Temporal Correlation In Climate Data, Matthew C. Bowers

Open Access Dissertations

This dissertation examines manifestations of persistent memory in climate data. Persistence is characterized by a slow power-law decay in the autocorrelations of a time series. Its existence implies that the influence of past values in a time series extend into the distant future. It has numerous theoretical implications, notably that it changes the asymptotic decay in the variance of sample means, which can substantially impact the uncertainty in climate mean states. Its intensity can vary over space, time, and other dimensions, e.g. tree species. Variation in its intensity can be used for practical applications such as discriminating between steady and …

Improving The Policy Specification For Practical Access Control Systems, Haining Chen

Open Access Dissertations

Access control systems play a crucial role in protecting the security of information systems by ensuring that only authorized users are granted access to sensitive resources, and the protection is only as good as the access control policies. For enabling a security administrator to express her desired policy conveniently, it is paramount that a policy specification is expressive, comprehensible, and free of inconsistencies. In this dissertation, we study the policy specifications for three practical access control systems (i.e., obligation systems, firewalls, and Security-Enhanced Linux in Android) and improve their expressiveness, comprehensibility, and consistency. First, we improve the expressiveness of obligation …

Exploiting Science: Enhancing The Safety Training Of Pilots To Reduce The Risk Of Bird Strikes, Flavio A.C. Mendonca

Open Access Dissertations

Analysis of bird strikes to aviation in the U.S. from 1990 to 2015 indicate that the successful mitigation efforts at airports, which must be sustained, have reduced incidents with damage and a negative effect-on-flight since 2000. However, such efforts have done little to reduce strikes outside the airport jurisdiction, such as occurred with US Airways Flight 1549 in 2009. There are basically three strategies to mitigate the risk of bird strikes: standards set by aviation authorities, technology, and actions by crewmembers. Pilots play an important role as stakeholders in the prevention of bird strikes, especially outside the airport environment. Thus, …

A Collaborative Monocular Visual Simultaneous Localization And Mapping Solution To Generate A Semi-Dense 3d Map., Ruwan Janapriya Egodagamage

Open Access Dissertations

The utilization and generation of indoor maps are critical in accurate indoor tracking. Simultaneous Localization and Mapping (SLAM) is one of the main techniques used for such map generation. In SLAM, an agent generates a map of an unknown environment while approximating its own location in it. The prevalence and afford-ability of cameras encourage the use of Monocular Visual SLAM, where a camera is the only sensing device for the SLAM process. In modern applications, multiple mobile agents may be involved in the generation of indoor maps, thus requiring a distributed computational framework. Each agent generates its own local map, …

Effects Of Acute Aerobic Exercise On Whole Genome Nucleosome Maps, Transcriptomics And Acylcamitine Metabolomics In Skeletal Muscle Of Lean Vs Overweight/Obese Men, Prasad P. Devarshi

Open Access Dissertations

Skeletal muscle mitochondrial dysfunction, evidenced by incomplete beta oxidation and accumulation of fatty acid intermediates in the form of long and medium chain acylcarnitines, may contribute to ectopic lipid deposition and insulin resistance during high fat diet (HFD)-induced obesity. Anterograde and retrograde communication play a role in nucleo-mitochondrial crosstalk that determines skeletal muscle mitochondrial adaptations, specifically alterations in mitochondrial number and function in relation to obesity and insulin resistance. High fat diet (HFD) feeding affects the expression of nuclear-encoded mitochondrial genes (NEMGs) nuclear receptor factor 1 (NRF-1), 2 (NRF-2) and peroxisome proliferator receptor gamma coactivator 1 alpha (PGC-1α) thereby, playing …

Consensus Algorithms For Networks Of Systems With Second- And Higher-Order Dynamics, Michael Fruhnert

Open Access Dissertations

This thesis considers homogeneous networks of linear systems. We consider linear feedback controllers and require that the directed graph associated with the network contains a spanning tree and systems are stabilizable. We show that, in continuous-time, consensus with a guaranteed rate of convergence can always be achieved using linear state feedback. For networks of continuous-time second-order systems, we provide a new and simple derivation of the conditions for a second-order polynomials with complex coefficients to be Hurwitz. We apply this result to obtain necessary and sufficient conditions to achieve consensus with networks whose graph Laplacian matrix may have complex eigenvalues. …

Refresh: An Infrastructure To Build Self-Aware Robotic Systems, Yanzhe Cui

Open Access Dissertations

The programming of most robotic tasks is conceptually simple, but error recovery and the handling of unexpected events add enormous complexity to the programming burden. Furthermore, software is procedural, so the handling of unforeseen scenarios by the programmer is just not possible in most programs. The objective of this dissertation is to describe an infrastructure that guides systems engineers to conveniently program self-aware systems, reducing the workload necessary to program robotic tasks. In this dissertation, we present an infrastructure to enable self-awareness. The primary contributions of the work are four fold. First, an architecture with a programming framework is proposed …

Cultivating Asian Students' Willingness To Communicate In American Classrooms Using An Online Video-Based Pre-Arrival Course, Hui-Ching Kayla Hsu

Open Access Dissertations

The purpose of this mixed methods study was: 1) to document the design and implementation process of an online video-based pre-arrival course that was intended to cultivate Asian students’ willingness to communicate in American Classrooms; 2) to assess the effectiveness of the course by measuring students’ oral proficiency and willingness to communicate; and 3) to investigate their first-year classroom participation as well as their experiences with the pre-arrival course. This research inquiry was guided by two research questions: 1) How does completing an online pre-arrival course influence Asian students’ speaking abilities, willingness to communicate, and verbal participation in their first-year …

Applying The Ads-B Out To Facilitate Flight Data Analysis For General Aviation, Chenyu Huang

Open Access Dissertations

The International Civil Aviation Organization (ICAO) and major airlines believe that flight data analysis is an effective approach to mitigate the risk of aviation accidents (International Civil Aviation Organization, 2010; International Air Transport Association, 2016). In the United States, flight data analysis is encouraged by the Federal Aviation Administration (FAA) through the flight operational quality assurance (FOQA) program. Among all aviation activities, general aviation (GA) has the highest accident rate (National Transportation Safety Board, 2014). However, implementation of flight data analysis for GA not only requires expensive investment on flight data recording devices, but also increases long-term labor cost due …

Static Analysis Of Android Apps With Text Analysis And Bi-Directional Propagation, Jianjun Huang

Open Access Dissertations

While smartphones and mobile apps have been an integral part of our life, personal security issues on smartphones become a serious concern. Privacy leakage, namely sensitive data disclosures, happens frequently in mobile apps to disclose the user’s sensitive information to untrusted, even malicious, third-party service providers, leading to serious problems. Besides, stealthy behaviors that are performed without the user’s acknowledgment may cause unexpected phone charges or leakage of sensitive information.

To address these problems, many approaches have been proposed. However, previous mobile privacy related research efforts have largely focused on predefned known sources managed by smartphones. More specifcally, they focus …

A Web-Based Intervention With Culturally Tailored Messages To Improve Mental Health Among Asian International Students With Mild-To-Moderate Depression: A Pilot Randomized Controlled Trial, Lan Jin

Open Access Dissertations

The study aims to: 1) design, develop, and test culturally tailored messages to address the mental health needs of Asian international students (AIS); and 2) assess the potential and acceptability of a web-based intervention (myCompass program) with culturally tailored messages to reduce depressive symptoms and improve related mental health outcomes among AIS with mild-to-moderate depression. The culturally tailored messages were designed, developed and tested through three focus groups (N=15), thirteen individual interviews (N=13), and an online survey (N=85) with AIS. Data was analyzed using the constant comparative method. The final cultural message themes used in the intervention arm included: 1) …

Investigating The Conversations That Occur During Undergraduate Research Experiences: A Case Study, Sara L. Johnson

Open Access Dissertations

Despite the increasing popularity of undergraduate research experiences across disciplines, little information currently exists to guide the design, evaluation, and improvement of these experiences. One challenge to generating such guidelines is the lack of evidence related to the processes and contexts in which undergraduate research experiences occur. My study sought to address this deficiency by exploring the norms of discourse that framed conversations between students and their mentors in biochemistry research as a model to understand the phenomenon of undergraduate research. I used a case-study approach to investigate the conversations that occurred between three student-mentor pairs as they engaged in …

Investigating The Role Of Induced Acinar Specific Transcription Factors In Pancreatic Tumor Cells And Their Target Gene Effects On Tumorgenic Development, Brad L. Jakubison

Open Access Dissertations

Pancreatic acinar cells synthesize and secrete prodigestive enzymes into the primary pancreatic duct where they traverse to the duodenum to continue the process to digestion. Due to the stress of constantly synthesizing large quantities of digestive enzymes, acinar cells must be well-equipped to address high protein production demands. The transcription factors (TFs), MIST1, PTF1a and E47, are required to maintain the pancreatic secretory homeostasis. All three are basic helix-loop-helix (bHLH) TFs which are required for the function of the pancreas. Specifically, MIST1 promotes cell polarity, cell communication, and regulated exocytosis. PTF1a dimerizes with E47, and this protein complex is required …

Exploring Transformative Learning Pedagogies To Teach Human-Centered Design: A Collaborative Action Research Approach, Cole Hatfield Joslyn

Open Access Dissertations

In this research, I present the problem that a culture of disengagement endemic in engineering and engineering education (see Cech, 2014) is exacerbated by deeply rooted habits of mind and their underlying assumptions that are at odds with social justice ideals and resistant to change, thus, perpetuating the status quo (see Riley, 2008). Furthermore, current engineering education curricula focusing primarily on mathematics, science, and engineering sciences (see Sheppard, Macatangay, Colby, & Sullivan, 2009) further entrench this culture along with these habits of mind and assumptions. In an attempt to address the culture of disengagement, I propose a framework for humanizing …

Engineering Play: Exploring Associations With Executive Function, Mathematical Ability, And Spatial Ability In Preschool, Zachary Samuel Gold

Open Access Dissertations

Engineering play is a new perspective on preschool education that views constructive play as an engineering design process that parallels the way engineers think and work when they develop engineered solutions to human problems (Bairaktarova, Evangelou, Bagiati, & Brophy, 2011). Early research from this perspective supports its use in framing play as a key learning context. However, no research to date has examined associations between engineering play and other factors linked with early school success, such as executive function, mathematical ability, and spatial ability. Additionally, more research is needed to further validate a new engineering play observational measure. This study …

Equalization Techniques For Cmos Optical Receivers With Integrated Silicon Photodiode, Bong Chan Kim

Open Access Dissertations

Optical links are progressively penetrating into short-range communication applications largely due to the advancement in silicon (Si) photonics technology. Si photonics provide a small footprint and cost-effective solutions. However, improving the speed of the photodiode remains as one of the biggest challenges in Si photonics. In this thesis, we present a finite impulse response (FIR) filter based on segmented photodiodes for Si photodiode equalization. The photodiode-based FIR filter utilizes the segmented photodiodes which serve as current sources and capacitors, and realizes a high-pass FIR that partially compensates for the frequency-dependent gain loss due to the physical and the electrical bandwidths …

Reciprocal Relationships Between Parental Psychological Aggression And Adolescent Behavioral Problems, Yoonyoung Kwak

Open Access Dissertations

An extensive body of research has shown that parents’ harsh parenting and children’s behavioral problems are bidirectionally associated. These findings are in line with the transactional process theoretical model. Parental psychological aggression (PPA) is a nonphysical type of harsh parenting that is more prevalent among adolescents than corporal punishment and has rarely been tested for bidirectional relationships with diverse behavioral problems. This dissertation includes an investigation of the bidirectional relationship between PPA and four adolescent behavioral problems (delinquency, alcohol use, smoking, and running away) separately using samples from two different cultural contexts. The first sample is 591 adolescents who had …

Imaging Cholesterol Metabolism And Trafficking By Stimulated Raman Scattering Microscopy, Hyeon Jeong Lee

Open Access Dissertations

Cholesterol is an essential component of mammalian cells which is tightly regulated. However, our understanding of cholesterol transport and metabolism is still incomplete, partly due to lack of suitable tools for studying cholesterol dynamics in living cells and organisms with spatio-temporal information. My dissertation work applied spectroscopic imaging of cholesterol in human tissues, living cells, and model organisms to unravel new insights of cholesterol metabolism and trafficking. Using stimulated Raman spectroscopic analysis of lipid droplets in human prostate cancer patient tissues, we observed an aberrant accumulation of cholesteryl ester in metastatic lesions. Inhibition of cholesterol esterification in prostate cancer cells …

Global Optimization Of Large-Scale Complex Nonlinear Systems: Algorithms And Applications, Jianfeng Liu

Open Access Dissertations

Many practical applications involving large complex systems are naturally formulated as mixed-integer nonlinear programming (MINLP) problems. These optimization problems are inherently large-scale and non-convex, and can be extremely difficult to solve. Efficient algorithms, especially global solution strategies, for MINLP problems play important roles in many real-world applications. Although a number of optimization tools have been developed for general MINLP problems, their performance may vary significantly on different problem instances. Moreover, computational experience has suggested that for MINLP problems with certain particular properties, customized algorithms can significantly outperform general MINLP solvers. In this thesis, we focus on developing and applying problem-specific …

Developing And Testing A K-12 Engineering Epistemic Frame To Uncover Engineering In The Interactions Of A High School Summer Session, Tamecia Raishuan Jones

Open Access Dissertations

Educational reform has expanded K-12 standards to include engineering. Not only will K-12 teachers have to be trained to teach engineering concepts, but assessments must evolve to reflect the various aspects of engineering. Engineering as a profession is expressed via multiple dimensions of an epistemic frame, such as skills, knowledge, identity, values, and epistemology, but many of these elements are not measured in K-12 formal and informal spaces. In a summer session of a college preparatory program, a research project revealed that although students had design journals, storyboards, and traditional assessments, the in situ video recordings captured decisions, evolution of …

Remote Sensing Of Soil Moisture With Signals Of Opportunity (Soop), Yao-Cheng Lin

Open Access Dissertations

The measurement of soil moisture is essential for studying the hydrological cycle. Passive microwave radiometry is the most mature technology for the remote sensing of soil moisture, as demonstrated on ESAs Soil Moisture and Ocean Salinity (SMOS) satellite and the Soil Moisture Active Passive (SMAP) mission from NASA. Global Navigation Satellite System-Reflectometry (GNSS-R) has been demonstrated as an alternative approach to the remote sensing of soil moisture, through several airborne and ground-based experiments. All of these systems operate in L-band (1575.42 MHz for GNSS) which has a penetration depth in soil of only a few cm. GNSS signals are also …