Digital Commons Network^™

Design And Statistical Analysis Of Mass Spectrometry Imaging Experiments, April Janae Harry

Open Access Dissertations

The goal of mass spectrometry-based imaging (MSI) is to characterize the chemical composition of biological samples such as tissues in spatial resolution, and changes in the composition between conditions such as the status of a disease. A single mass spectrometry image is a collection of mass spectra at gridded locations on a tissue. When acquired over multiple biological individuals, tissues, and conditions, the resulting datasets are tremendously complex in both scale and in the stochastic structure of the quantified spectral features. Accurate characterization of the biological and technical variation in these experiments is therefore key for deriving sensitive and reproducible …

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 …

Electron Spin Relaxation Of Donors In Silicon Nanoelectronic Devices, Yuling Hsueh

Open Access Dissertations

The environment interacts with the electron and leads to electron relaxation processes. To measure the relaxation rate the system is disturbed from equilibrium. T1 time characterizes the time for the system to restore equilibrium. Understanding and controlling the spin-relaxation mechanism is crucial for realizing a spin-qubit based quantum computer. The spin-lattice relaxation time (T1) is one of the two important timescales of a qubit, and in addition, it can provide valuable information about the qubit and its interaction with the device environment. Here, we investigate the T1 time of electronic spins bound to donors in silicon in a scanning tunneling …

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) …

Text-Based Spatial And Temporal Visualizations And Their Applications In Visual Analytics, Shehzad Afzal

Open Access Dissertations

Textual labels are an essential part of most visualizations used in practice. However, these textual labels are mainly used to annotate other visualizations rather than being a central part of the visualization. Visualization researchers in areas like cartography and geovisualization have studied the combination of graphical features and textual labels to generate map based visualizations, but textual labels alone are not the primary focus in these representations. The idea of using symbols in visual representations and their interpretation as a quantity is gaining more traction. These types of representations are not only aesthetically appealing but also present new possibilities of …

Development Of Biosensor Materials For Sensitive Detection Of Viral Rna And Foodborne Pathogen, Seon-Ah Jin

Open Access Dissertations

Pathogen detection for clinical diagnosis, vector surveillance and control is one of the important issues for public health and safety. Biosensing is considered as one of the promising techniques for pathogen detection due to its potential for rapid, simple, and relatively inexpensive detection. However, many biosensors still have limitations for commercialization. Development of materials and new detection methods are the ways to overcome these limitations [1, 2]. This study aims to develop rapid and sensitive material platforms for detection of the dengue viral RNA (Chapter 2 and 3) and the foodborne pathogen Escherichia coli O157:H7 (Chapter 4). Two different materials …

Rheological Behavior And Manufacturing Simulation Of Prepreg Platelet Molding Systems, Anthony J. Favaloro

Open Access Dissertations

Molding systems formed by cutting and slitting prepreg composite tape into the form of platelets have been shown to be beneficial in producing parts with moderate performance with moderate processing characteristics. However, the platelets forming the molding system are typically quite large compared to typical part thicknesses. Therefore, a challenge of scales exists in platelet molding systems that is absent in traditionally considered well dispersed fiber molding systems used in injection molding. In this dissertation, we consider the specific problem of determining the final orientation state of parts manufactured in compression molding from platelet molding systems along with identifying parameters …

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 …

Household Decision Making Under Stress: Three Essays On Agricultural Production In Southern Africa, Anna Leigh Josephson

Open Access Dissertations

Rural households in Southern Africa face numerous economic challenges, arising from a range of idiosyncratic and covariate risks. This research seeks to understand strategies employed by households to cope with different types of shocks, in the context of Zimbabwe and Malawi. I focus on several techniques used to cope with risk and shocks in an uncertain environment, including intra-household resource, land, and crop, as well as labor allocations. To provide insight on household decision making, I expand and adapt theoretical models. This helps me to better understand household decision making in the complex and risky environments in which they reside …

Investigating The Crystallization Propensity Of Structurally Similar Organic Molecules From Amorphous State, Arjun Kalra

Open Access Dissertations

Combinatorial chemistry and high-throughput screening approaches utilized during drug discovery have resulted in many potent pharmacologically active molecules with low aqueous solubility and consequently poor bioavailability. Enabling technologies, such as amorphous solid dispersions (ASD’s), can obviate these challenges and provide an efficient route to formulate the drug as an oral solid dosage form. However, high-energy amorphous materials have an inherent tendency to crystallize and in doing so can negate the apparent solubility advantage achieved by using such formulations. Crystallization can occur during (1) cooling the drug molecule from the melt state (such as during hot melt extrusion); (2) during storage …

Storage, Adverse Selection, And Buffer Stock Releases In Benin's Rural Maize Markets, Kadjo Didier Kadjo

Open Access Dissertations

This dissertation comprises three essays. I use data from 360 rural households in Benin to analyze households’ maize storage behavior and adverse selection for maize qualities sold in cereal markets. Then, I rely on data on maize prices and buffer stock releases to investigate the effect of the government’s intervention on maize prices.

Although I address the issues aforementioned in three independent studies, they are related in an agricultural season. Essay one discusses how storage losses and liquidity constraints affect households’ decisions to store maize after harvest. I find that rural households that store maize for food consumption only are …

Cyclic Nano-Indentation Investigation Of Plasticity In Case Hardened Bearing Steels, Thomas Kanaby

Open Access Dissertations

Demands for performance and reliability of bearings present a challenge for materials and process development in that a knowledge gap exists between the understanding ratcheting mechanisms that lead to crack initiation and mechanical predictions of bearing endurance. Current bearing research suggests the very high cycle fatigue endurance of low-inclusion content bearing steels is dominated by sub-micrometer plasticity and features uncharacterized by standard specifications. This effort investigates whether mechanical measurements on the scale of the sub-micron structures with cyclic nano-indentation relate to bearing steel fatigue performance. Cyclic indentation within the graded microstructures of case hardened steel samples is performed near the …

Hyperspectral Image Reconstruction From Rgb Data And Its Biomedical Applications, Tae Hoon Kim

Open Access Dissertations

Noninvasive label-free hyperspectral imaging of physiological changes in biological systems has been extensively used as invaluable tools in a variety of research areas, including medical and biological applications. However, conventional approach requires a critical, yet bulky, expensive, and slow optical component (i.e. a mechanical filter wheel, an imaging spectrograph, or a liquid crystal tunable filter) for capturing full spectral information. Therefore, this component limits development of compact, rapid, and cost-effective systems. In this respect, we propose to explore a possibility of spectrometerless (or spectrometer-free) hyperspectral imaging to map out detailed spatial distributions of biochemical absorption compounds or pigments, which are …

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 …

Contract Design In Inter-Organizational Relationships: Evidence From The U.S. Franchise Systems, Shiau-Ling Guo

Open Access Dissertations

This dissertation develops three essays about contract design in interfirm partnerships. Specifically, I develop the first essay, drawing on an asymmetric view of transactions, to understand the effects of asymmetric exchange hazards borne by different parties on contract design at a dyadic level. In the second essay, drawing from the logic of transaction cost economics and research on the “shadow of the future,” I develop hypotheses regarding the interplay between a firm’s transaction-specific factors and the predetermined contract duration that affect the need for complex dispute resolution provisions. In the third essay, going beyond the economic theoretical explanations regarding incentive …

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 …

Development Of Transgenic Black Ash (Fraxinus Nigra) For Resistance To The Emerald Ash Borer, And Genome Editing For Reproductive Sterility, Junhyung Lee

Open Access Dissertations

Black ash (Fraxinus nigra Marsh.) is valued for commercial hardwood products such as cabinets, paneling, flooring, and veneer, and for food and habitat for wildlife, specifically in riparian areas. The wood is preferred by Native Americans for making splints for basketry. The emerald ash borer (EAB), an aggressive exotic wood-boring beetle from Asia, is threatening all North American ash species. Since the first EAB infestation in the United States was confirmed near Detroit, Michigan in 2002, it has spread rapidly. In order to manage the EAB and conserve Fraxinus spp., there is a need to develop ash trees with resistance …

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 …

Design Of Microstructured Conducting Polymer Films For Enhanced Trace Explosives Detection, Jennifer S. Laster

Open Access Dissertations

The detection of trace amounts of explosive material is critical to national security. Ion mobility spectrometer (IMS)-based contact sampling continues to be a common method employed for the detection of explosives in high security checkpoint applications, such as airport security. In this process a surface of interest, such as a passenger’s hands or luggage, is probed by a swab or particle trap to collect and transfer residue to an IMS for analysis. The collection of residue on a sampling swab has been shown to be a limiting step in this detection process. As such, there is significant need to develop …

Hydrophobic Hydration And Aggregation In Aqueous Solutions, Joshua A. Long

Open Access Dissertations

Water mediated hydrophilic and hydrophobic interactions are important for biological systems, atmospheric, geological, and environmental chemistry, and pharmaceuticals formulation development. Open questions remain regarding the degree of water restructuring in hydrophobic cavities, the extent of hydration in self-assembled aggregates, and the influence of water restructuring on hydrophobic interactions. Here, we use Raman spectroscopy combined with multivariate curve resolution (Raman-MCR), partial molar volume, and fluorescence spectroscopic methods to detect and quantify changes in hydration extent and structure due to hydrophobic aggregation and hydrophobic cavity structure. Raman-MCR decomposes an aqueous solution spectrum into solvent (pure water) and solute-correlated spectra, the latter of …

Probabilistic-Based Modeling Of Human Perceptual-Motor Behaviors With Application To Wheelchair Targeting Locomotion, Chih-Wei Li

Open Access Dissertations

The objective of this thesis is to develop an empirically-based probabilistic model of the perception-action behaviors of human wheelchair locomotion and navigation over short distance ranges relevant for small space scenarios. More specifically, a probabilistic description and model is sought for the visual perception of distance and orientation with respect to objects, and for wheelchair locomotion based upon straight line and turning behaviors. Further, the specific behavior of manual wheelchair users boarding a small platform area, relevant for lifts and small elevators, is studied experimentally and in a probabilistic-based simulation. The approach taken consists of two parts. First, human subject …

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 …

Exploring The Genomic Basis Of Traits Relevant To Evolution And Ecology Of Chestnuts (Castanea) Using High-Throughput Dna Sequencing And Bioinformatics., Nicholas R. Labonte

Open Access Dissertations

Introduced pests and pathogens have devastated forest ecosystems in the temperate zone; in eastern North America, introduced pests and pathogens have led to the elimination of most mature elms (Ulmus), ashes (Fraxinus), hemlocks (Tsuga) and chestnuts (Castanea) over large areas where these genera were formerly abundant and important for local ecosystems. The restoration of species affected by introduced pests and pathogens requires the development and propagation of trees that possess heritable resistance. High-throughput DNA sequencing and genomics provide opportunities for researchers to identify resistance gene candidates, screen germplasm, and develop markers for marker-assisted selection in breeding programs, with the goal …

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 …

Digestibility Of Calcium In Feed Ingredients And Digestible Calcium Requirements For Pigs, Fengrui Zhang

Open Access Dissertations

The objective of this research was to compare different expressions for the digestibility of Ca in both pigs and chickens, and to determine the true total tract digestible (TTTD) Ca requirement for 10- to 20-kg and 20- to 40-kg pigs. In the first study, two experiments were conducted to compare apparent ileal digestibility (AID) and apparent total tract digestibility (ATTD) of Ca in pigs. In Exp. 1, three semi-purified diets with soybean meal, canola meal or sunflower meal as the sole source of Ca were formulated. Eighteen cannulated pigs (initial BW = 66 ± 5 kg) were assigned in a …

A Study Of Singularities In Drops And Bubbles Under The Influence Of Non- Newtonian Surface And Bulk Rheology, Pritish M. Kamat

Open Access Dissertations

Fluid-fluid interfaces are incredibly complex physical structures. Imbued with an excess energy—or in mechanical terms, a surface tension σ—these interfaces are considerably influential at small scales of droplets and bubbles, and in these systems, they are responsible for a plethora of beautiful and dramatically complex phenomena. The study of these interfacial phenomena, the so-called ‘free surface flows’, lends itself to a variety of applications which are at once, as mundane as liquid dripping from a faucet or rain splashing over the windscreen of a car, and at the same time extremely useful in industry and scientific analysis – some examples …

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 …