Stagnant student achievement in science education in the United States has placed an increased emphasis on teacher professional development. Since many elementary educators could benefit from improved science content knowledge—and given the challenge of providing this at a level scalable and sustainable through face-to-face delivery alone—this study sought to understand what types of online self-directed content-interaction strategies are of greatest learner satisfaction and provide the highest learning impact for teachers in grades three–six. Employing Anderson's Equivalency of Interaction Theorem, and looking at age, years teaching experience, and learning preferences via Kolb and Kolb's Learning Style Inventory 3.1 (2005), this descriptive study non-randomly sampled 85 educators who passed a series of self-paced interactive web modules to rate their preferences for five different types of content-interactive strategies: (a) simulations, (b) interactive reference, (c) hands-on, (d) personal feedback, and (e) pedagogical implications. Using an online survey and a pre- and postassessment instrument it was found that (a) as age and years teaching experience increase, teachers' preferences for personal feedback, interactive reference, and simulations increased, (b) teachers' content knowledge increased significantly after completing the web modules, (c) teachers' learning style moderately aligned with their preferences for content-interaction strategies, and (d) teachers least preferred the pedagogical implications component. Instructional designers and education administrators selecting professional development for teachers may find this informative. Data from this research support Anderson's theory that if the content interaction is rich, human interaction may be provided in diminished capacities. / Ph. D.

The present study was designed to investigate whether infants prefer their fathers’ voices over an unfamiliar male voice within the context of normal father-infant interaction, i.e., infant-directed (ID) speech. Twenty Caucasian male and female four-month-olds were tested in a visual-fixation preference procedure. Attentional preference was measured by the amount of time the infants watched a visual stimulus. It was found that infants did not show greater attentional or affective responsiveness to paternal ID over unfamiliar male ID speech samples. However, mothers and fathers appear to be very similar in their perception of father-infant interaction. According to these results, four-month-olds do not prefer their fathers’ voices to that of an unfamiliar male. This finding contrast sharply with the literature on maternal voice preference. The data was interpreted as supporting the hypothesis that multimodal stimulus cues are necessary for paternal voice recognition in infancy. / Master of Science

In nature, many social species demonstrate collective behavior ranging from coordinated motion in flocks of birds and schools of fish to collective decision making in humans. Such distinct behavioral patterns at the group level are the consequence of local interactions among the individuals. We can learn from these biological systems, which have successfully evolved to operate in noisy and fault-prone environments, and understand how these complex interactions can be applied to engineered systems where robustness remains a major challenge. This dissertation addresses a two-scale approach to study these interactions- one in larger scale, where we are interested in the information exchange in a group and how it enables the group to reach a common decision, and the other in a smaller scale, where we are focused in the presence and directionality in the information exchange in a pair of individuals. To understand the interactions at large scale, we use a graph theoretic approach to study consensus or synchronization protocols over two types of biologically-inspired interaction networks. The first network captures both collaborative and antagonistic interactions and the second considers the impact of dynamic leaders in presence of purely collaborative interactions. To study the interactions at small scale, we use an information theoretic approach to understand the directionality of information transfer in a pair of individual using a real-world data-set of animal group motion. Finally, we choose the issue of same-sex marriage in the United States to demonstrate that collective opinion formation is not only a result of negotiations among the individuals, but also reflects inherent spatial and political similarities and temporal delays. / Ph. D. / Social animals exhibit coordination often referred to as ‘collective behavior’ that results from interactions among individuals in the group. This dissertation has demonstrated how interactions can be studied using mathematical modeling, at the same time reveals that real-world interactions are even more complex. Mathematical modeling provides capabilities to introduce biologically inspired phenomena, for example, the implementation of both friendly and hostile interactions that may coexist; and the presence of leader-follower interactions, which is another determinant of collective behavior. The results may find applications in real-world networks, where hostile and leader-follower interactions are prevalent, for example international relations, online social media sites, neural networks, and biologically inspired robotic interactions. We further extend our knowledge regarding interactions by choosing real world systems, the first to understand human decision making, for example in public policies; and the second in animal group motion. Public policy adoption is generally complex and depends on a variety of factors, and no exception is same-sex marriage in the United States which has been a volatile subject for decades until nationwide legalization on June 26, 2015. We target this timely issue and explore the opinion formation of senators and state-law as they evolve over two decades to identify factors that may have affected the dynamics. We unravel geographic proximity, and state-government ideology are significant contributors to the senators opinions and the state-law adoption. Moreover, we build a state-law adoption model which captures these driving factors, and demonstrates predictive power. This study will help to understand or model other public policies that propagate via social and political change. Next we choose the system of bats to investigate navigational leadership roles as they fly in pairs from direct observation of bat swarms in flight. Pairs of bats were continuously tracked in a mountain cave in Shandong Province, China, from which three-dimensional path points are extracted and converted to one-dimensional curvature time series. The study allows us to answer the question of whether individuals fly independently of each other or interact to plan flight paths.

Coenzyme nicotinamide adenine dinucleotide (NAD, including the oxidized form-- NAD+ and reduced form--NADH) and the phosphorylated form--nicotinamide adenine dinucleotide phosphate (NADP, including NADP+ and NADPH) are two of the most important biological electron carriers. Most NAD(P) dependent redox enzymes show a preference of either NADP or NAD as an electron acceptor or donor depending on their unique metabolic roles. In biocatalysis, the low enzymatic activities with unnatural coenzymes have made it difficult to replace costly NADP with economically advantageous NAD or other biomimetic coenzyme for catalysis. This is a significant challenge that must be addressed should in vitro biocatalysis be a viable option for the practical production of low-value biocommodities (i.e., biohydrogen). There is a significant need to first address the coenzyme selectivity of the NADP-dependent dehydrogenases and evolve mutated enzymes that accept biomimetic coenzymes. This is a major focus of this dissertation. Establishment of efficient screening methods to identify beneficial mutants from an enzymatic library is the most challenging task of coenzyme engineering of dehydrogenases. To fine tune the coenzyme preference of dehydrogenases to allow economical hydrogen production, we developed a double-layer Petri-dish based screening method to identify positive mutant of the Moorella thermoacetica 6PGDH (Moth6PGDH) with a more than 4,278-fold reversal of coenzyme selectivity from NADP+ to NAD+. This method was also used to screen the thermostable mutant of a highly active glucose 6-phosphate dehydrogenase from the mesophilic host Zymomonas mobilis. The resulting best mutant Mut 4-1 showed a more than 124-fold improvement of half-life times at 60oC without compromising the specific activity. The screening method was further upgraded for the coenzyme engineering of Thermotaga maritima 6PGDH (Tm6PGDH) on the biomimetic coenzyme NMN+. Through six-rounds of directed evolution and screening, the best mutant showed a more than 50-fold improvement in catalytic efficiency on NMN+ and a more than 6-fold increased hydrogen productivity rate from 6-phosphogluconate and NMN+ compared to those of wild-type enzyme. Together, these results demonstrated the effectiveness of screening methods developed in this research for coenzyme engineering of NAD(P) dependent dehydrogenase and efficient use of the less costly coenzyme in ivSB based hydrogen production. / Ph. D. / NADP and NAD are two of the most important electron carriers in cellular metabolism, and they play distinctive roles in anabolism and catabolism, respectively. Most NAD(P)-dependent dehydrogenases exhibit a strong preference for either NADP or NAD. This coenzyme preference, however, make it nearly impossible to replace the costly NADP with less costly NAD or biomimetic coenzymes in the biocatalysis application. How to engineer dehydrogenases through directed evolution and effective screening method to accept NAD or biomimetic coenzymes, is critical and the focus of this dissertation. The use of in vitro synthetic biosystem (ivSB) to produce hydrogen form starch, is one of the most important in vitro synthetic biology projects, and it depends on NADP coenzyme. With other issues in this system solved, the efficient use of dehydrogenases along with low cost and stable coenzyme is the last obstacle to hydrogen production through industrial biomanufacturing. However, the 6-phosphogluconate dehydrogenase (6PGDH), one of the rate-limiting enzymes in this biosystem, exhibits a strong coenzyme preference for NADP⁺ . For producing low-cost hydrogen, the coenzyme engineering of this dehydrogenase is urgently required. Its activity with less costly NAD or biomimetic coenzymes must be improved. The establishment of an effective screening method is the most challenging task for coenzyme engineering of dehydrogenases. In this research, we developed a Petri-dish double-layer based screening method for coenzyme engineering of thermophilic 6PGDH for activity for NAD⁺ . This screening method was also used to improve the thermostability of a highly active glucose 6-phosphate dehydrogenase from a mesophilic host, where the evolved mutant had a greatly improved thermostability without losing activity. The screening method was further upgraded to develop for coenzyme engineering on biomimetic coenzyme NMN⁺ . The engineered mutant showing a more than 50-fold increase in catalytic efficiency on NMN⁺ was used to develop the first biomimetic coenzyme dependent electron transfer chain for hydrogen production. This screening method is suitable to change the coenzyme selectivity of series of NAD(P)-dependent redox enzymes and show great potential in improving other properties, such as thermostability, substrate scope and optimal pH, of different dehydrogenases. With this method developed, we can efficiently use the low cost stable coenzyme in the biocatalysis, and break the last obstacle to industrial biomanufacturing of hydrogen production.

No / This paper studies the selective maintenance problem for multi-state systems with structural dependence. Each component can be in one of multiple working levels and several maintenance actions are possible to a component in a maintenance break. The components structurally form multiple hierarchical levels and dependence groups. A directed graph is used to represent the precedence relations of components in the system. A selective maintenance optimization model is developed to maximize the system reliability in the next mission under time and cost constraints. A backward search algorithm is used to determine the assembly sequence for a selective maintenance scenario. The maintenance model helps maintenance managers in determining the best combination of maintenance activities to maximize the probability of successfully completing the next mission. Examples showing the use of the proposed method are presented.

A directed graph (digraph) G can primitively positively construct another digraph H if H is homomorphically equivalent to a first order interpretation of G that only uses primitive positive formulas. In this way, we define the poset of all finite digraphs ordered by primitive positive constructability. This poset, which is the object studied in this dissertation, is important for studying the complexity of constraint satisfaction problems and for studying clones ordered by minion homomorphisms. In this thesis I will introduce the poset and amoung other results I will present the three topmost levels of the poset and I will describe the subposet consisting of digraphs without sources or sinks.

The purpose of my dissertation study is to better understand the educational experiences of undergraduate engineering students within non-curricular learning environments, specifically in the form of extracurricular engineering groups or programs. I first conducted a content analysis of engineering education literature to identify where engineering design learning occurs, and to synthesize the implications of studies regarding engineering design learning. Aiming to fill a gap in the literature regarding non-curricular learning contexts, this study investigated what extracurricular groups and programs can educationally provide undergraduate engineering students by observing and interviewing students engaging in these environments. This study also aimed to identify if and how engineering students find navigational flexibility within engineering curricula, and how non-curricular learning environments might provide navigational flexibility. With regard to where engineering design learning occurs, the literature points to various educational contexts that effectively deliver engineering design education. Strategies that involve authentic and longer-term engineering design experiences tend to be the most impactful in terms of student outcomes and perceptions, however those experiences are not always implementable at larger scale. More traditional educational approaches to engineering design learning, though less impactful, are still effective delivery methods for introducing key aspects of engineering design education (e.g. modeling, global/societal/economic/environmental factors, communication skills). However, there was limited literature regarding more non-curricular learning experiences, such as learning in designed settings, outreach learning, learning media, and everyday informal learning. This literature review is one of the first attempts towards synthesizing where and how engineering design learning occurs, and has identified a significant gap in the literature regarding non-curricular educational settings. Addressing the identified gap in engineering education literature regarding non-curricular learning experiences, this dissertation study investigated five non-curricular engineering learning sites for undergraduate engineering students at a large research-driven state institution. Informed by the preliminary findings of a pilot study, I first investigated the salient features of engineering-related non-curricular activities from the students' perspectives using a self-directed learner autonomy framework to guide the study. Students participating in extracurricular engineering environments exhibited strong attributes of self-directed learners, particularly a willingness and ability to be challenged and to learn. The educational environments of the extracurricular opportunities cultivated these self-directed learning attributes by providing students a space to be exposed to an engineering community, authentic engineering work, and accessible resources. Findings from this portion of the dissertation indicated necessary modifications to the self-directed learner autonomy framework used to guide this study. The modified framework contributes a possible approach towards future assessment or research pursuits regarding non-curricular learning experiences in engineering. I also investigated the role non-curricular activities play in providing engineering students navigational flexibility through engineering curricula. Extracurricular engineering environments afford navigational flexibility by offering students opportunities to work on motivating challenges with and among supportive communities. By providing a space for students to express their engineering selves in primarily self-directed ways, extracurricular engineering experiences cultivate students' drive to find and pursue personally meaningful curricular and non-curricular educational experiences. However, institutional barriers, particularly time constraints and institutionally recognized achievements, stifle students' flexibility and willingness to pursue personally meaningful experiences. The findings of this study have helped uncover the various affordances non-curricular learning experiences provide engineering students, but more importantly, have identified the institutional barriers that prevent students from taking full advantage of non-curricular learning experiences. Based on these findings, I recommend that university and program level structures be reevaluated to encourage and provide students with more flexibility to find personalized learning experiences in and out of the classroom. / Ph. D.

Disease outbreaks caused by oomycetes can be catastrophic. The first part of this dissertation describes development of a system to identify potential new and durable resistance (R) genes against P. sojae in soybean germplasm. We developed a system to screen soybean germplasm for genes that recognize core Phytophthora sojae RXLR effectors that are conserved within the pathogen species and essential for virulence. R genes that recognize these effectors will likely be effective and durable against diverse P. sojae isolates. We developed a system to deliver individual P. sojae effectors by Type III secretion into soybean using the bacterium Pseudomonas, and we screened 12 core effectors on a collection of 30 G. max lines that likely contain new resistance genes against P. sojae. We identified candidate R genes against 10 effectors. Genetic segregation ratios from crosses indicated that three of these genes have a simple inheritance pattern and would be amenable to breeding into elite cultivars. The second part of the dissertation involves use of a model plant-oomycete system to study the genetic basis of susceptibility to oomycete diseases. We compared host transcriptomes from a resistant and a susceptible infection of Arabidopsis thaliana by the downy mildew pathogen Hyaloperonospora arabidopsidis (Hpa). We identified five gene clusters with expression patterns specific to the susceptible interaction. Genes from each cluster were selected and null mutants were tested for altered susceptibility to virulent Hpa. Most A. thaliana null mutants showed enhanced disease susceptibility, suggesting their involvement in pattern-triggered immunity (PTI). A knockout mutant in the AtGcn5 gene was completely resistant to Hpa Emco5 suggesting that the gene/protein is necessary for Hpa to successfully colonize the plant. This study provided new molecular insights into plant-oomycete interaction and revealed a plant gene that could potentially be engineered to provide enhanced resistance to oomycete pathogens. / Ph. D.

The goals of this research were 1) to produce hydrogen in high yields from cellulosic materials and water by synthetic pathway biotranformation (SyPaB), and 2) to increase the hydrogen production rate to a level comparable to microbe-based methods (~ 5 mmol H2/L/h). Cell-free SyPaB is a new biocatalysis technology that integrates a number of enzymatic reactions from four different metabolic pathways, e.g. glucan phosphorylation, pentose phosphate pathway, gluconeogenesis, and hydrogenase-catalyzed hydrogen production, so as to release 12 mol hydrogen per mol glucose equivalent. To ensure the artificial enzymatic pathway would work for hydrogen production, thermodynamic analysis was firstly conducted, suggesting that the artificial enzymatic pathway would spontaneously release hydrogen from cellulosic materials. A kinetic model was constructed to assess the rate-limited step(s) through metabolic control analysis. Three phosphorylases, i.e. α-glucan phosphorylase, cellobiose phosphorylase, and cellodextrin phosphorylase, were cloned from a thermophile Clostridium thermocellum, and heterologously expressed in Escherichia coli, purified and characterized in detail. Finally, up to 93% of hydrogen was produced from cellulosic materials (11.2 mol H2/mol glucose equivalent). A nearly 20-fold enhancement in hydrogen production rates has been achieved by increasing the rate-limiting hydrogenase concentration, increasing the substrate loading, and elevating the reaction temperature slightly from 30 to 32°C. The hydrogen production rates were higher than those of photobiological systems and comparable to the rates reported in dark fermentations. Now the hydrogen production is limited by the low stabilities and low activities of various phosphorylases. Therefore, non-biologically based methods have been applied to prolong the stability of α-glucan phosphorylases. The catalytic potential of cellodextrin phosphorylase has been improved to degrade insoluble cellulose by fusion of a carbohydrate-binding module (CBM) family 9 from Thermotoga maritima Xyn10A. The inactivation halftime of C. thermocellum cellobiose phosphorylase has been enhanced by three-fold at 70°C via a combination of rational design and directed evolution. The phosphorylases with improved properties would work as building blocks for SyPaB and enabled large-scale enzymatic production of cellulosic hydrogen. / Ph. D.

Ncd is a member of the kinesin family of motor proteins. Ncd is involved in the processes of meiosis and early mitosis in <i>D. melanogaster</i>. PCR-mediated site-directed mutagenesis was utilized to introduce specific mutations into pET/MC6, a construct containing the motor domain of ncd. Six mutations were generated, two at glutamic acid residue 656, two at proline residue 649, one at arginine residue 623, and one double mutant at arginine residue 623 and threonine residue 632. Mutants proteins were expressed in bacteria and further characterized. Mutagenesis of the proline or glutamic acid residues resulted in insoluble proteins. The one exception is the mutagenesis of glutamic acid residue 656 into a glutamine, which resulted in a partially soluble protein. Mutagenesis of the arginine residue into an alanine (MC6-A623) resulted in a soluble protein while the double mutation of the arginine and threonine was insoluble. MC6-A623 exhibited a similar S-sepharose ion exchange chromatography binding and elution profile as MC6. Peptide antibodies made to conserved ncd motor domain sequences also recognized MC6- A623. The affinity of MC6-A623 (under the conditions tested) for microtubules was less than MC6. Most interestingly, under the conditions tested, MC6-A623 did not exhibit an increased ATPase rate in the presence of microtubules, a hallmark of the kinesin family of microtubule motor proteins. Analysis of the published ncd crystal structure, other motor protein sequences, and the experimental results of the mutagenesis of arginine residue 623, suggest that this residue is involved in the binding of MC6 to microtubules. / Master of Science