Digital Commons Network^™

Assessing The First And Last Mile Problem In Intercity Passenger Rail: Effects On Mode Choice And Trip Frequency, Lisa Lorena Losada Rojas

Open Access Theses

Passenger rail service is an integral part of intercity transportation networks, especially in areas where residents do not have access to cars or other intercity travel options. Some municipalities in the U.S. have experienced a decline in passenger rail service in recent years, which has prompted schedule reductions and entire abandonment of service in some cases. To improve the current intercity passenger rail service predicament, two alternatives can be considered: (1) improve the rail service itself (frequency, infrastructure, etc.) and (2) improve accessibility to the rail stations, which might be cheaper and more cost-effective overall. Improvements in accessibility can impact …

Inclusion Of Antibiotic Alternatives In Feedlot Cattle Diets: Impact On Health Status, Cattle Performance And Meat Quality, Josey Pukrop

Open Access Theses

Although antibiotics are effective at diminishing the incidence of both bovine respiratory disease and digestive disorders and can promote growth in feedlot cattle, public scrutiny and concerns about antibiotic resistance are driving the cattle industry away from their use in production. Natural antibiotic alternatives derived from plants, bacteria and yeasts are increasing in popularity for use in cattle feeding operations.

In this thesis, the effect of a yeast cell wall product on performance and health status of receiving steers was examined and the effect of supplementing an essential oils blend on finishing cattle performance, liver abscess incidence, carcass characteristics and …

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 …

Polyamines Regulate Chilling Response In Ripening Tomato Fruits By De Novo Transcription, Wan Mohn Reza Ikwan Bin Wan Hussin

Open Access Theses

Plants response to various abiotic stress, including chilling injury, by differentially regulating genes responsible for protection against these stresses. Polyamines (PAs); putrescine (Put), spermidine (Spd), and spermine (Spm), are ubiquitous metabolite in all organisms and have been implicated in abiotic stresses in plants. Dr. Handa laboratory has previously developed high Spd/Spm tomato fruits genotypes by expressing yeast S-adenosylmethionine decarboxylase (SAMDC). In present investigation, the role of Spd/Spm in chilling injury was evaluated by using two independent transgenic lines with high Spd/Spm (556 and 579) and isogenic parental Ohio 8245 (WT) genotypes. Fruits at onset of ripening (Breaker, BR) and fully …

Aging In Place In America: User Needs And Related Perceptions Concerning Showering Spaces, Denise Mcallister Wilder

Open Access Theses

The issue this study addresses is the apparent lack of curbless showers with grab bars and shower seats being displayed in builder’s model homes. Claims are they are excluded because consumers do not like to envision themselves as getting older or infirm. The purpose of the study is to query consumers of all age groups on their perception of photographed showers with and without curbs, grab bars and shower seats regarding safety, comfort and visual appeal. Data was collected using a survey instrument which featured several photographs of four different showers. Respondents were asked to rate their perceptions using a …

Novel Polymer/Bioactive Glass Composites For Bone Regenerative Engineering, Jessica Zuponcic

Open Access Theses

Bone-grafting procedures are necessary when injury to the bone, due to trauma or disease, surpasses the bone’s ability to auto-repair. These injuries are known as critical-sized defects. Using graft material from the patient’s own body, autografting, risks donor site morbidity and is size-limited [1, 2]. Using graft material from a donor or cadaver, allografting, carries some risk of disease transmission and availability is insufficient to meet demand [1]. These challenges have necessitated the development and use of bone graft substitutes which, ideally, can match the structural and mechanical properties of native bone and promote osteogenic differentiation of host cells – …

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 …

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 …

Developing And Measuring Effectiveness Of A New Evidence-Based Grain Storage And Handling Safety Curriculum Targeting Young And Beginning Workers, Yuan-Hsin Cheng

Open Access Dissertations

Research was conducted on the development, testing, and implementation of an original, evidence-based curriculum (Against the Grain) designed to reduce the frequency and severity of the most frequent types of injuries and fatalities involving young and beginning workers, ages 14-20, at grain storage and handling operations. This population has historically accounted for approximately 24% of documented entrapments, engulfments, asphyxiations, entanglements, falls, and electrocutions associated with grain handling and storage. This includes incidents during both workrelated and non-work or recreational activities. Curriculum contents were based upon data summarized from Purdue’s Agricultural Confined Spaces Incident Database (PACSID), review of relevant injury prevention …

Optothermal Energy Conversion And Transport In Plasmonic Structures, Chen Chen

Open Access Dissertations

Plasmonic structures can efficiently interact with electromagnetic waves at their interfaces, leading to strong light confinement and field enhancement, which has been crucial for many nanotechnology applications in manufacturing, lithography, data storage, biosensing, spectroscopy, molecular trapping and other molecular level studies. Due to the intrinsic losses of metallic structures, the strong light-matter interaction also generates significant energy dissipation, making the thermal management of the devices very challenging. The purpose of this dissertation is to study the optothermal energy conversion and transport in plasmonic structures, especially in structures at the nanoscale. We first investigate the general optothermal responses of plasmonic structures …

Learning Electron Transport Chain Process In Photosynthesis Using Video And Serious Game, Cecilia Espinoza Morales

Open Access Dissertations

This research investigates students' learning about the electron transport chain (ETC) process in photosynthesis by watching a video followed by playing a serious board game-Electron Chute- that models the ETC process. To accomplish this goal, several learning outcomes regarding the misconceptions students' hold about photosynthesis and the ETC process in photosynthesis were defined. Middle school students need opportunities to develop cohesive models that explain the mechanistic processes of biological systems to support their learning. A six-week curriculum on photosynthesis included a one day learning activity using an ETC video and the Electron Chute game to model the ETC process. The …

A New Method For Determining Hamaker Constants Of Solids Based On The Dynamic Approach Behavior Of An Atomic Force Microscope, Sean G. Fronczak

Open Access Dissertations

The Hamaker constant, A, is a very important parameter used to quantify the strength of the van der Waals (vdW) attractive interaction among particles and between particles and surfaces. Consequently, an accurate measurement of A is of fundamental importance to a wide range of research and manufacturing fields. Therefore, this dissertation primarily focuses on the development and application of a new method to determine Hamaker constants of solid materials using an atomic force microscope (AFM). While the direct contact or pull-off method is typically employed during an AFM force measurement, this contact-technique is highly dependent upon material properties that are …

Deceptive Memory Systems, Christopher N. Gutierrez

Open Access Dissertations

Unauthorized data destruction results in a loss of digital information and services, a devastating issue for society and commerce that rely on the availability and integrity of such systems. Remote adversaries who seek to destroy or alter digital information persistently study the protection mechanisms and craft attacks that circumvent defense mechanisms such as data back-up or recovery. This dissertation evaluates the use of deception to enhance the preservation of data under the threat of unauthorized data destruction attacks. The motivation for the proposed solution is two-fold. (i) An honest and consistent view of the preservation mechanisms are observable and often …

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 …

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 …

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 …

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 …

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 …

Exploring The Relationship Between Childhood Maltreatment And Adolescent Substance Use: Mediating Effects Of Family And Peer Relationships, Alexandra C. Marin

Open Access Dissertations

Child maltreatment is a key risk factor for maladaptive behaviors throughout the life course, including substance use. Although the effects of maltreatment on several domains of functioning have been thoroughly documented in past literature, the social mechanisms through which maltreatment affects individual trajectories have received considerably less attention, especially in relation to the contribution of different maltreatment dimensions (such as subtype, timing, and severity). Examining these dimensions and social mechanisms could hold the key to answering the question of why some maltreated children experience long-spanning negative developmental outcomes, while others maintain resiliency and are seemingly unaffected by these experiences. In …

Radical Manifest Destiny: Mapping Power Over Urban Green Space In The Age Of Protest, 1968-1988, Kera N. Lovell

Open Access Dissertations

My dissertation traces how conflicts concerning power over green space in the urban realm sparked a pattern of insurgent park creation as a form of political placemaking in the late Cold War era. While urban and environmental historians and spatial studies scholars have illuminated how cities became the context of political disputes over power and space in the twentieth century, my work sheds light on radical, community-driven environmental design as a method of protest between the late 1960s and late 1980s. While focused on a handful of central case studies across the U.S., my work situates them within a disconnected …

Development Of A Direct-Contact Triculture Model Of The Human Blood Brain Barrier And Potential Applications As A Preclinical Drug Screening Tool, Aimable Ngendahimana

Open Access Dissertations

Given the high cost and emerging ethical and public concerns associated with the use of animal models, the use of in vitro techniques is gaining considerable attention in research programs related to CNS drug discovery and development. More specifically, various in vitro cell culture models for studying and predicting drug transport across the Blood-Brain Barrier (BBB) were developed as preclinical research tools for neurological drug discovery and development. The main goal of the present studies has been to improve conventional in vitro methods used in mimicking the BBB physiology and functions by allowing physiologically complex interactions of the human BBB …

Mechanisms Regulating Dna Methyltransferases, Christopher James Petell

Open Access Dissertations

The expression of specific genes that are regulated by transcription factors and epigenetic modifications is critical for normal cellular functioning and homeostasis. DNA methylation is an epigenetic modification that in mammals is crucial for the regulation of gene expression in a specific cell type. Aberrant loss or gain of DNA methylation is linked to cancer and several epigenetic disorders. DNA methylation is established by the de novo DNA methyltransferases Dnmt3a and Dnmt3b; however, the mechanisms underlying their target specificity remain to be fully understood. Dnmt3a and Dnmt3b can be regulated through interactions with other proteins, including histone modifications, and by …

Experimental Demonstration Of Engineered Dipole-Dipole Interactions In Nanophotonic Environments, Ward D. Newman

Open Access Dissertations

Zero point fluctuations of the electromagnetic radiation field have profound effects on the electronic states of atoms and molecules. For example, vacuum fluctuations of the photonic radiation field stimulate the spontaneous decay of excited states of atoms (spontaneous emission), shift atomic energy levels (Lamb Shift), and allow nearby atoms and molecules to couple via dipole-dipole interactions (van der Waals interactions, Casimir effect, super radiance, F¨orster resonance energy transfer). The control and modification of vacuum fluctuations has been a long-standing theme in quantum engineering as one can then truly control single photon emission and alter dipole-dipole interactions spatial scaling with distance. …

Laser-Assisted Processing Of Multilayer Films For Inexpensive And Flexible Biomedical Microsystems, Rahim Rahimi

Open Access Dissertations

Flexible/stretchable electronics offer ideal properties for emerging health monitoring devices that can seamlessly integrate with the soft, curvilinear, and dynamic surfaces of the human body. The resulting capabilities have allowed novel devices for monitoring physiological parameters, improving surgical procedures, and human-machine interfaces. While the attractiveness of these devices are indubitable, their fabrication by conventional cleanroom techniques makes them expensive and incompatible with rapid large-scale (e.g., roll-to-roll) production. The purpose of this research is to develop inexpensive fabrication technologies using low-cost commercial films such as polyimide, paper, and metalized paper that can be utilized for developing various flexible/stretchable physical and chemical …

Determining Variation In Virulence, Persistence, And Stress Tolerance Among Salmonella Enterica And Listeria Monocytogenes From Food And Food-Associated Environments, Andrea J. (Ray) Etter

Open Access Dissertations

The U.S. food industry employs multiple strategies to prevent foodborne illness including the use of antimicrobials, sanitizers, and heat to reduce or eliminate pathogens in food products. However, Listeria monocytogenes and Salmonella enterica isolates have widely varying tolerance to common processing stresses. Additionally, both pathogens display considerable variation in virulence among serovars and strains. The goal of these studies was to characterize the range of virulence and persistence capabilities for L. monocytogenes and S. enterica isolates. To this end, we determined the prevalence of inlA mutations in L. monocytogenes collected from retail deli surfaces, and used PFGE to study the …

Prone To Drone: Unmanned Aircraft Systems' Effects On Public Support For The Use Of Military Force, William Shelby

Open Access Dissertations

Unmanned aircraft systems (drones) have seen widespread use by the United States in the “War on Terror.” Drones keep soldiers out of harm’s way and they reduce the financial cost of military operations, all while maintaining high levels of precision like regular soldiers. Because they provide the benefits of using force without the risks, drones could make the public more willing to support the use of force. If true, the public may be more prone to support using force rather than seek out other alternatives to solve a foreign policy crisis because they perceive less risk involved in using force. …

An Assessment Of The Subseasonal Predictability Of Severe Thunderstorm Title Environments And Activity Using The Climate Forecast System Version 2, Adam J. Stepanek

Open Access Dissertations

The prospect for skillful long-term predictions of atmospheric conditions known to directly contribute to the onset and maintenance of severe convective storms remains unclear. A thorough assessment of the capability for a global climate model such as the Climate Forecast System Version 2 (CFSv2) to skillfully represent parameters related to severe weather has the potential to significantly improve medium- to longrange outlooks vital to risk managers. Environmental convective available potential energy (CAPE) and deep-layer vertical wind shear (DLS) can be used to distinguish an atmosphere conducive to severe storms from one supportive of primarily nonsevere ordinary convection. As such, this …

Narrative Inquiry Into Understanding Chinese Teachers' Lived Experiences: Interculturalism, Intercultural Education, And Teacher Identity Development, Qing Wang

Open Access Dissertations

Globalization brings the trend that intercultural teacher recruitment and migration become more prominent, and teaching internationally is a worldwide phenomenon. My research is aimed at examining Chinese intercultural teachers’ lived experiences and identity development from a theoretical perspective of interculturalism. I employed narrative inquiry as the research methodology to explore the experiences of five Chinese teachers who have teaching experiences in China and in the U.S. To understand the Chinese teachers’ lived experiences and to explore their identity development, I examined the personal disposition and social contexts in which these teachers lived and worked, teaching practices in different cultures, and …