Digital Commons Network^™

The Role Of Experience In Processing Foreign-Accented Speech, Fernando Llanos Lucas

Open Access Dissertations

The present study examines the perceptual accommodation of the bilabial stop-consonant voicing contrast (i.e., /b/ vs. /p/), in several English- and Spanish-accented contexts, by native Spanish listeners with different degrees of experience with accented speech. In a series of four experiments, we confronted three potential mechanisms for the perceptual accommodation of foreign-accented sounds. According to the first mechanism (phonetic relaxation), listeners accommodate foreign-accented sounds by relaxing the phonetic boundary between native speech sound categories. According to the second mechanism (phonetic calibration), listeners accommodate foreign-accented sounds by adjusting the location of native perceptual boundaries according to the phonetic realization of native …

Nanophotonics For Dark Materials, Filters, And Optical Magnetism, Mengren Man

Open Access Dissertations

Research on nanophotonic structures for three application areas is described, a near perfect optical absorber based on a graphene/dielectric stack, an ultraviolet bandpass filter formed with an aluminum/dielectric stack, and structures exhibiting homogenizable magnetic properties at infrared frequencies. The graphene stack can be treated as a effective, homogenized medium that can be designed to reflect little light and absorb an astoundingly high amount per unit thickness, making it an ideal dark material and providing a new avenue for photonic devices based on two-dimensional materials. Another material stack arrangement with thin layers of metal and insulator forms a multi-cavity filter that …

Advances In Raman Hyperspectral Compressive Detection Instrumentation For Fast Label Free Classification, Quantitation And Imaging, Bharat R. Makani

Open Access Dissertations

Multiple prototypes of hyperspectral compressive detection (CD) Raman spectrometers have previously been constructed in the Ben-Amotz lab and have proven to be useful for fast, label-free chemical identification, quantitation and imaging. The CD spectrometer consists of a volume holographic grating (VHG) that linearly disperses the Raman photons into its component wavelengths and all wavelengths are focused onto a digital micromirror devise (DMD). The DMD is an optical modulator that consists of an array of programmable 10μm mirrors that can reflect photons in either +12° or -12° to the incoming light. The DMD is tilted such that the +12° photons go …

Investigation Of Cellular Microenvironments And Heterogeneity With Biodynamic Imaging, Daniel Alexander Merrill

Open Access Dissertations

Imaging of biological tissue in a relevant environment is critical to accurately assessing the effectiveness of chemotherapeutic agents in combatting cancer. Though many three-dimensional (3D) culture models exist, conventional in vitro assays continue to use two-dimensional (2D) cultures because of the difficulty in imaging through deep tissue. 3D tomographic imaging techniques exist and are being used in the development of 3D efficacy assays. However, most of these assays look at therapy endpoint (dead or living cancer cell count) and do not capture the dynamics of tissue response.

Biodynamic imaging (BDI) is a 3D tomographic imaging and assay technique that uses …

Methods To Facilitate Community Participation In Humanitarian Engineering Projects: Laying The Foundation For A Learning Platform, Andrea Mazzurco

Open Access Dissertations

Humanitarian engineering (HE) is a new interdisciplinary field that is rapidly emerging worldwide. Many not-for-profit organizations such as Engineers Without Borders, Practical Action, and International Development Enterprise have been flourishing with the goal of providing technological solutions to those who need them the most. In engineering programs across the U.S., HE, service-learning, community engagement, and similar programs are gaining popularity because they offer an efficient way to meet ABET accreditation criteria, while also teaching valuable technical and professional skills to engineering students. However, the cultural, social, and political differences among communities and engineers often add degrees of difficulty that cannot …

Laser Direct Written Silicon Nanowires For Electronic And Sensing Applications, Woongsik Nam

Open Access Dissertations

Silicon nanowires are promising building blocks for high-performance electronics and chemical/biological sensing devices due to their ultra-small body and high surface-to-volume ratios. However, the lack of the ability to assemble and position nanowires in a highly controlled manner still remains an obstacle to fully exploiting the substantial potential of nanowires. Here we demonstrate a one-step method to synthesize intrinsic and doped silicon nanowires for device applications. Sub-diffraction limited nanowires as thin as 60 nm are synthesized using laser direct writing in combination with chemical vapor deposition, which has the advantages of in-situ doping, catalyst-free growth, and precise control of position, …

Influence Of Dietary Polyphenols On Carbohydrate Intestinal Digestion And Absorption, Sydney E. Moser

Open Access Dissertations

Both epidemiological and clinical evidence support the notion that polyphenol rich foods and beverages may modify glycemic response, glucose homeostasis and subsequent risk of Type-2 diabetes. In vitro evidence typically derived from experiments with pure phenolics and phenolic rich extracts have pointed to this benefit being associated with two potential mechanisms: (1) the ability of specific polyphenolics to inhibit carbohydrate digestion (amylase and glucosidase) and (2) polyphenolic inhibition of intestinal glucose transport. While the high potential of these activities is evident, little is actually known regarding the extent to which these benefits are extendable to the actual food matrix these …

It Is "Broken" And "Accented": Non-Native English-Speaking (Nnes) Graduate Students' Perceptions Toward Nnes Instructors' English, Hyo Jung Keira Park

Open Access Dissertations

This study investigates the perceptions of non-native English-speaking graduate students towards non-native English speaking (NNES) instructors’ accented English. Students (N=161) who were enrolled in an oral English course at Purdue University participated in a survey. Follow-up interviews were conducted with voluntary participants (N=9) to examine the perceptions of NNES graduate students towards NNES instructors in depth. The findings in the survey showed that more than one third of the participants experienced difficulty with their NNES instructors due to their limited intelligibility and restricted command of English. Furthermore, one third of the participants expressed that they would transfer to another section …

Understanding Plant Response To Stress Using Gene Model Quality Evaluation And Transcriptome Analysis, Karthik Ramaswamy Padmanabhan

Open Access Dissertations

The overall aim of the project was to understand how plants reacted to environmental stress and evolved to overcome it. The land plants that we see today evolved from a green algal ancestor around 510 million years ago. Plants had to make significant changes to their cellular, morphological, regulatory and physiological processes during their adaptation to the terrestrial environment from an aquatic environment. The first part of the project was to find out how these changes were reflected on the protein makeup of the early land plants. The gene model sequence data of two early land plants, Physcomitrella patens (moss) …

Development Of Orthogonally Crosslinked Thiol-Ene Hydrogels For Encapsulation Of Pancreatic Beta-Cells, Han Shih

Open Access Dissertations

Type I diabetes mellitus (T1DM) is an autoimmune disease caused by auto-reactive T-cell-mediated destruction of insulin-producing β-cells. Effective encapsulation strategies can protect the transplanted islets from direct attack by host immune cells while maintaining insulin secretion. To achieve this goal, I have developed a hydrogel conformal coating using a visible light-mediated interfacial thiol-ene photopolymerization. Unlike conventional chain-growth visible light polymerizations, no additional cytotoxic co-initiator or co-monomer was required in thiol-ene gelation scheme for rapid gelation. More importantly, islets coated with thiol-ene gel maintained their viability and function in vitro. In addition to microencapsulate β-cells, the second objective of my …

Psychosocial Factors And Mental Health Of Muslims Living In The United States, Lamise N. Shawahin

Open Access Dissertations

Muslim Americans are at risk for experiencing systematic and interpersonal acts of discrimination (Rippy & Newman, 2006). Such experiences of discrimination can lead to the development of depressive symptoms. Thus, it is critical to understand factors that may influence the relationship between experiencing discrimination and developing depressive symptoms. The purpose of the present study was to examine the relationship between psychosocial adversities (i.e., perceived discrimination), psychosocial resources (i.e., coping strategies, religious community support) and depressive symptoms. Hypotheses regarding both the relationships among the variables, as well as the mediating role psychosocial resources play in the relationship between perceived discrimination and …

Coupling Qualitative And Quantitative Analyses Of Pharmaceutical Materials Enabled By Second Harmonic Generation Microscopy, Paul D. Schmitt

Open Access Dissertations

The detection and characterization of crystallinity is critical throughout the drug development process. From the initial establishment of an active pharmaceutical ingredient’s (API) crystal structure to stability testing and quality control, the phase of an API affects the solubility, bioavailability, stability, and efficacy of a drug product. Second harmonic generation (SHG) microscopy has recently been developed as a selective and rapid method for imaging crystallinity in drug formulations. While SHG microscopy can enable the high signal-to-noise (SNR) detection of crystallinity, the intrinsic chemical information content within SHG images is relatively low. In cases of trace crystallinity and/ or small crystal …

X-Ray Fluorescence For Quantification Of Lead And Strontium In Vivo, Aaron James Specht

Open Access Dissertations

Lead (Pb) is a toxicant well known for its effects on almost every organ system in the body. Pb use in industry has declined since removal of Pb from gasoline, but many developing countries still have significant use of Pb. Exposure to Pb has been linked with diseases causing neurodegeneration and thus have lasting effects long after the initial exposure. Another metal, strontium (Sr), has been linked with bone disease in particular situations and shown to have uses in treating osteoporosis as a supplement. However, there are no studies of the effects of Sr using a meaningful biomarker. The most …

Ultrasound And Photoacoustic Methods For Anatomic And Functional Imaging In Image Guided Radiation Therapy, Justin T. Sick

Open Access Dissertations

(MATERIAL and METHODS) First, we define the physical principals and optimal protocols that provide contrast when imaging with US and the transducer properties contributing to resolution limits. The US field of view (FOV) was characterized to determine the optimal settings with regard to imaging depth, focal region, with and without harmonic imaging, and artifact identification. This will allow us to determine the minimum errors expected when registering multimodal volumes (CT, US, CBCT).

Next, we designed an in-house integrated US manipulator and platform to relate CT, 3D-US and linear accelerator coordinate systems. To validate our platform, an agar-based phantom with measured …

Reflexivity: A First Demonstration, Melissa Jane Swisher

Open Access Dissertations

Currently, the emergent relation of reflexivity after training a set of baseline relations has not been demonstrated with any animal—human or nonhuman. True reflexivity can only be demonstrated if no identity (i.e., physically matching stimulus) relations are trained. In six experiments, the emergence of reflexivity and its opposite, anti-reflexivity, were explored. Pigeons received concurrent successive matching training on two or three arbitrary tasks: AB hue-form and BC form-hue (and AC hue-hue) matching. Once they had acquired these tasks, they were tested for BB (form-form) reflexivity or BB’ (form-form) anti-reflexivity matching. Most (10 of 13) pigeons that received three arbitrary tasks …

Evolutionary Potential Of A Dispersal-Restricted Species In Response To Climate Change, Lorena Torres Martinez

Open Access Dissertations

Habitat replacement and fragmentation associated with projected climate change pose a critical threat to global biodiversity. Edaphically limited plant species with restricted dispersal abilities will be especially handicapped to track their optimal climate spatially. Instead, the persistence of these species will depend on their capacity to adapt in situ to novel climate regimes. Here I evaluated the evolutionary potential of Lasthenia fremontii, an annual plant species restricted to ephemeral wetlands called vernal pools in California to adapt to the projected patterns of climate change. Across L. fremontii distribution there is a latitudinal gradient in precipitation which, combined with reduced …

Evaluating The Prevalence And Effectiveness Of Breed-Specific Legislation, Felicia E. Trembath

Open Access Dissertations

Dog bites pose a persistent public health problem, which some jurisdictions pass breed-specific legislation (BSL) to address. However, very little non-anecdotal evidence regarding the efficacy of BSL has been presented. Currently, BSL research is hampered by the absence of standard terminology, an established prevalence, or a scientific consensus on its effectiveness. The purpose of this study is to propose standardized terminology for BSL, establish the prevalence of each type of BSL in the USA, and conduct a systematic review of the effectiveness of BSL.

After review of terminology currently in use, as well as review of the regulatory actions of …

Exploring Animacy As A Mnemonic Dimension, Joshua Edward Vanarsdall

Open Access Dissertations

There is a great deal of evidence across cognitive science that animacy, or more generally, the features that make up what it means to be a living thing, is a foundational dimension of human cognition. In perception, animates both capture attention (Pratt, Radulescu, Guo, & Abrams, 2010) and are relatively immune to change blindness (New, Cosmides, & Tooby, 2007). Developmental work places the animate-inanimate distinction as one of the first categories children learn (Opfer & Gelman, 2011). Work in neuroscience points toward a fundamental role for animacy in semantic memory (Caramazza & Mahon, 2003), and linguists have identified animacy as …

Single-Conformation Spectroscopy Of Hydrogen Bonding Networks: Solvation, Synthetic Foldamers, And Neurodegenerative Diseases, Patrick S. Walsh

Open Access Dissertations

The hydrogen bond is one of the most important interactions in natural processes ranging from protein folding to chemical reactions. Two complementary methodologies are applied to understanding this important interaction: top-down and bottom-up. Top-down methods use large molecules, such as proteins, revealing secondary structure information. Bottom-up experiments are performed on small molecules, utilizing high-resolution spectroscopy to reveal underlying quantum mechanical effects. The complexity gap is formed between these two experimental regimes; between large and small molecules; between bulk and individual solvent molecules; between classical mechanics calculations and quantum chemical calculations. This dissertation will focus on the application of gas phase, …

Visual Clutter Study For Pedestrian Using Large Scale Naturalistic Driving Data, Kai Yang

Open Access Dissertations

Some of the pedestrian crashes are due to driver’s late or difficult perception of pedestrian’s appearance. Recognition of pedestrians during driving is a complex cognitive activity. Visual clutter analysis can be used to study the factors that affect human visual search efficiency and help design advanced driver assistant system for better decision making and user experience. In this thesis, we propose the pedestrian perception evaluation model which can quantitatively analyze the pedestrian perception difficulty using naturalistic driving data. An efficient detection framework was developed to locate pedestrians within large scale naturalistic driving data. Visual clutter analysis was used to study …

China Twenty Years After: Substance Use Under Rapid Social Changes, Xiaozhao Y. Yang

Open Access Dissertations

This dissertation discusses how China’s rapid modernization and social transformation over the last twenty years since a series of reforms at the end of 1980s contribute to the changes in substance use behaviors. Specifically, there are three individual empirical chapters in this dissertation, each exploring one dimension of social change and its association with substance use. First, I have demonstrated how substance use can be a protective factor against unemployment over the long term, especially against the background of massive layoffs among former socialist industrial workers and landless peasants during this period. Second, another chapter examines how social mobility (i.e. …

Learning From Data: Plant Breeding Applications Of Machine Learning, Alencar Xavier

Open Access Dissertations

Increasingly, new sources of data are being incorporated into plant breeding pipelines. Enormous amounts of data from field phenomics and genotyping technologies places data mining and analysis into a completely different level that is challenging from practical and theoretical standpoints. Intelligent decision-making relies on our capability of extracting from data useful information that may help us to achieve our goals more efficiently. Many plant breeders, agronomists and geneticists perform analyses without knowing relevant underlying assumptions, strengths or pitfalls of the employed methods. The study endeavors to assess statistical learning properties and plant breeding applications of supervised and unsupervised machine learning …

Quantum Coherence And Entanglement In Open Quantum Systems, Yiteng Zhang

Open Access Dissertations

We humans always want to believe that we can overpower nature. However, the reality is that nature outperforms humans in many aspects. Animals' abilities to navigate/orient and photosynthesis are two excellent examples in these aspects. However, the mechanisms underlying them are still unknown. For decades, scientists and researchers have made a lot of efforts to reveal these mysteries in nature.

Recently, quantum coherence and entanglement are believed to play a crucial role in such biological systems–avian compass and photosynthesis. Thus, nature might know more tricks to utilize quantum mechanics than humans. Studies on the mechanisms underlying avian compass and photosynthesis …

Physiological Bases And A Novel Genetic Determinant Of Water-Use Efficiency (Wue), Jie Yin

Open Access Dissertations

Water-use efficiency (WUE), the ratio of biomass to water loss, is a heritable but complex trait, the genetic basis of which is largely unknown. We utilized diverse accessions of the halophyte Eutrema salsugineum to ultimately identify a novel genetic determinant of WUE. E. salsugineum accessions from locations with low water availability, temperature, and radiation have lower transpirational water loss and greater biomass, resulting in higher WUE. High-WUE accessions also have lower stomatal density and index and larger thinner leaves than low-WUE accessions. We identified 14,808 single nucleotide polymorphisms (SNPs) between two accessions of E. salsugineum,Shandong (SH) and Yukon (YK), …

The Design And Statistical Analysis Of Single-Cell Rna-Sequencing Experiments, Faye H. Zheng

Open Access Dissertations

Next-generation DNA- and RNA-sequencing (RNA-seq) technologies have expanded rapidly in both throughput and accuracy within the last decade. The momentum continues as emerging techniques become increasingly capable of profiling molecular content at the level of individual cells. One goal of this research is to put forward best practices in the design of single-cell RNA-sequencing (scRNA-seq) experiments, specifically as it relates to choices regarding the trade-off between sequencing depth and sample size. In addition to general guidelines, an interactive tool is presented to aid researchers in making experiment-specific decisions that are informed by real data and practical constraints. Further, a new …

Mathematical Models Of Ebola Virus Disease And Vaccine Preventable Diseases, Yinqiang Zheng

Open Access Dissertations

This thesis focuses on applying mathematical models to studies on the transmission dynamics and control interventions of infectious diseases such as Ebola virus disease and vaccine preventable diseases.

Many models in studies of Ebola transmission are based on the model by Legrand et al. (2007). However, there are potential issues with the Legrand model. First, the model was originally formulated in a complex form, leading to confusion and hindering its uses in practice. To overcome the difficulty, the Legrand model is reformulated in a much simpler but equivalent form in this thesis. The reformulated model also provides an intuitive understanding …

Reactions Of Graphene Oxide And Buckminsterfullerene In The Aquatic Environment, Yingcan Zhao

Open Access Dissertations

Due to unique physical and chemical properties, carbon-based nanomaterials, including C60 and graphene oxide, now being used in an increasing number of applications. Considering their widespread use, nanoparticles will inevitably find their way to the natural environment. However, their environmental fate and transport have not been intensively explored, resulting in a general lack of knowledge regarding their risk assessment and life cycle exposure concentrations. To this end, this study has investigated: (i) the photo mineralization of aqu/nC60 clusters under photo irradiation, and (ii) environmental transformation of graphene oxide in the aquatic environment. This study shows that CO2 was produced from …

Early Parental Loss, Socioeconomic Stressors, And Health In Later Life: Evidence For Gender Disparity, Rong Fu

Open Access Dissertations

Drawing from the stress process model and the cumulative disadvantage theory, this dissertation examined how childhood and later life stressors affected cognitive and subjective health in older adults. Using three main articles, this dissertation investigated (1) the effect of early parental loss on cognitive well-being in Chinese oldest old; (2) the effect of intergenerational socioeconomic mobility on cognitive and subjective health in advanced age; and (3) the effect of different dimensions of socioeconomic status and perceived financial strain on subjective health in later life. Data were derived from the 2002 and 2005 waves of the Chinese Longitudinal Healthy Longevity Survey. …

The Role Of Phenotypic Plasticity In The Adaptive Evolution Of Fundulus Heteroclitus, David Isaac Dayan

Open Access Dissertations

Phenotypic plasticity is the ability of a single genotype to produce multiple phenotypes in response to the environment. Because phenotypic plasticity mediates the relationship between genetic variation and the traits that are ultimately subjected to selection, phenotypic plasticity has the potential to influence evolutionary trajectories and contribute to the accumulation and release of cryptic genetic variation. This dissertation investigates both of these themes using a combination of trait level approaches and population genomics. First, the dissertation focuses on variation at the trait level in chapters 2 and 3. Chapter two uses a genome wide association study to demonstrates that the …

A Landscape And Systems Ecology Approach For Predicting Fish Concentration In Seasonally Pulsed And Spatially Heterogeneous Wetlands, Simeon Yurek

Open Access Dissertations

Seasonal pulsing of hydrology in the Greater Everglades watershed produces dynamic, annual cycles of wetland flooding and drying, and of environmental conditions. Biota have adapted to exploit these pulses through movement and foraging behaviors. A primary ecological concern, pertinent to Everglades restoration, is to understand how sufficient concentration of aquatic biomass, particularly that of small fish and invertebrates, is produced under nutrient limited conditions, to support diverse and abundant communities of piscivorous predators, such as wading birds and herpetofauna. This question is investigated through computer simulation modeling of small−bodied fishes in the freshwater Everglades, and analyses of empirical monitoring data …