2019 MU dissertations - Access restricted to UM
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Item Insights into atomic orbital polarization in polyatomic dissociation from DC slide velocity map imaging(University of Missouri--Columbia, 2019) Weeraratna, Hashini Chaya; Suits, Arthur G., 1954-[ACCESS RESTRICTED TO THE UNIVERSITY OF MISSOURI SYSTEM AT REQUEST OF AUTHOR.] "The field of chemical reaction dynamics is based upon understanding the details of elementary chemical reactions. It seeks to answer fundamental questions such as, what pathways does the reaction follow? what product states are formed? what determines the energy disposal, and the angular distributions of the products? State-of-the-art experimental methods developed over time along with theoretical techniques and advanced computational methods provide a toolset to address these questions. Achieving deep insight into reaction mechanisms ultimately permits the control over their chemical reactivity. One way of apprehending these processes is to characterize the potential energy surface (PES) since they completely embody the forces between the constituent atoms. .. Photodissociation of small molecules has been studied using variety of detection methods, such as, photofragment translational spectroscopy, [4,5] Laser-induced fluorescence (LIF), [6] Doppler-related methods, [7] Rydberg tagging, [8,9] photofragment ion imaging [10] and photoelectron imaging. [11] Photofragment imaging is now the most widely used method to study photodissociation dynamics. In the simplest illustration, it maps the recoil velocity distribution of the state selected product onto a position sensitive detector plane and energy and the angular distributions information are extracted by reconstruction of the experimentally observed images. The main objective of the this work is to study the vector correlations of photodissociation using photofragment ion imaging technique."--Introduction.Item Testing the efficacy of self-determination theory as a counter-propaganda interdiction tool(University of Missouri--Columbia, 2019) Wilbur, Douglas S.; Cameron, Glen T.[ACCESS RESTRICTED TO THE UNIVERSITY OF MISSOURI SYSTEM AT REQUEST OF AUTHOR.] This dissertation experimentally tests a new theoretical approach to resistance to persuasion in the context of extremist recruitment propaganda. This study leveraged the self-determination theory (SDT) of human motivation, adapting it for usage in a strategic communication context. It was proposed that a new type of counterpropaganda could be employed to interdict the effects of propaganda at the psychological level. The SDT mechanism involved was to bolster a person's sense of autonomy, which would thereby trigger resistance to controlling propaganda messages. A mixed design repeated measures experiment was conducted on (N = 387) Caucasian participants from a Mechanical Turk online panel. The experiment divided participants into three conditions: Psychological reactance support message, autonomy support message and a control condition. Each participant saw and assessed the same two extremist propaganda posters on the dependent variables: state psychological reactance, state autonomy, state competence and message credibility. The results revealed that the autonomy support message was particularly effective at reducing propaganda message credibility and increase perceptions of state autonomy. Also, of considerable significance were that the positive effects of the autonomy support message were sustained over time through the administration of both propaganda posters. This paper yields an import theoretical development for SDT as an expansion into human communication and persuasion theory. It also yields practical benefits by providing some initial evidence into a potential valuable counterpropaganda tool that can be employed as strategic communication on a mass level.Item Human trust model of collision warning through pupillary and electromyography responses(University of Missouri--Columbia, 2019) Yang, Xiaonan; Kim, Jung Hyup[ACCESS RESTRICTED TO THE UNIVERSITY OF MISSOURI SYSTEM AT REQUEST OF AUTHOR.] This pioneering work on human trust in automation was modeled by two main physiological measurements responses to collision avoidance warning as observed by pupil and electromyography (EMG) signals long regarded as meaningful physiological responses to danger. As an advanced driver assistance system (ADAS) becomes popular, distraction-related crashes caused by frequent false warnings make drivers' trust in ADAS is likely to deteriorate. In particular, trust is one of the most important driver cognitive characteristics that can determine the willingness to rely on and use the ADAS. Hence, it is important to investigate the driver's trust changes related to the collision warning. Previous research was limited to a single physiological response, or survey responses, and ocused on measurements of simple physical reaction instead of on human trust in automation. Accordingly, the driver's trust in a collision avoidance warning system under complex driving circumstances was not well studied. This study extended and enhanced past studies to multiple physiological responses to explore driver trust in collision warning and the role trust plays in avoidance of potential hazards and vulnerability. The purpose of this research was to assess drivers' dynamic learned trust of a collision avoidance warning system through physiological responses. In this multi-phase study, the Tobii eye-tracking device and Myo armbands were used to collect pupillary and EMG responses. During phase 1 study, aftermarket ADAS devices were used to collect drivers' natural responses to the collision warnings under open road real driving. A significant pattern changing of pupil EMG data only exits when drivers responded to warning. The findings of phase 1 demonstrated that pupillary and electromyography responses could be used together as effective indicators when drivers received valuable information and chose to make a physical response to the warning. The study noted that drivers often responded only to a warning in which they identified a potential hazard in situations characterized by uncertainty and vulnerability. As the lab offering an opportunity for simulated danger while studies in natural environments occur under conditions that are largely safe, the phase 2 study was designed as laboratory-based with under controlled environmental factors, to reveal the underlying pupillary and electromyography responses under potential hazards. For the model development, the time series features of pupil dilation and EMG data were extracted as independent variables, while the frustration based trust level was set as a dependent variable. Fuzzy linear regression models were built as quantitative measures of drivers' trust in the collision warning by using pupillary and EMG data. Classification rates of different fuzzy linear regression models were compared to the traditional linear regression model in both development and validation scenarios. Results indicate that the prediction models of drivers' trust, is improved upon by this study's possibility linear regression method (PLR) with waveform length time-series feature of pupil and EMG data as inputs, to more effectively predict drivers' trust in their collision warning system. New understanding of human dynamic learned trust in collision warning systems may provide benefits by improving driving safety and the usability of ADAS. Results from this study could contribute to future software algorithm development in a next-generation smart vehicle that can identify not only potential surrounding hazards, but also drivers' trust status, in order to provide a safer driving experience. Additionally, the findings of this study are anticipated to lead to the improvement of collision warning system development to enhance safety and improved device-user interaction.Item Developing molecular genetic tools for gene discovery in soybean (Glycine max)(University of Missouri--Columbia, 2019) Nguyen, Cuong X.; Stacey, Gary, 1951-; Stacey, Minviluz G.[ACCESS RESTRICTED TO THE UNIVERSITY OF MISSOURI SYSTEM AT REQUEST OF AUTHOR.] Soybean (Glycine max (L.) Merr.) is one of the most valuable crops grown worldwide for seed protein and oil production and can fix atmospheric nitrogen. The completed genome sequence and the availability of transcriptomics and proteomics data for genomic and physiological studies have made soybean a feasible model legume plant. The soybean genome is large (~978Mb) and highly duplicated, with ~75% of predicted genes present in multiple copies, and 50% of these paralogs are sub-functionalized. In addition, the relatively low genetic diversity in soybean relative to other major crops (e.g., corn) limits the available phenotypic variations that can be exploited for discovering genes, gene function and crop improvement. Thus, developing a feasible, efficient molecular genetic tool for gene discovery in soybean is required. In this dissertation, along with fast neutron mutagenesis, a dual gRNA CRISPR/Cas9 genome editing system was developed as a molecular genetic tool for gene discovery and crop improvement in soybean. In order to demonstrate the efficiency and ability to simultaneous by edit homeologous genes using a CRISPR/Cas9 system in soybean, GmFAD2 genes were chosen as targets for testing. Our CRISPR/Cas9 system showed 100% of T0 transgenic plants, obtained using the cotyledonary node transformation method, harbored induced mutations in either or both GmFAD2 genes. Importantly, 40% of the T0 plants harbored homozygous or biallelic mutations in both genes and these mutations were heritable in T1 and T2 progenies. Seeds derived from double homozygous mutant plants showed a typical high oleic acid (83.3%) phenotype compared to wild-type seeds (20.2%). In addition to generating new alleles for crop improvement, the use of CRISPR/Cas9 in conjunction with fast neutron mutagenesis allowed the identification of causative genes for observed fast neutron-induced phenotypes. Through forward genetics, we identified a deleted DNA fragment in chromosome 17 that co-segregated with the production of big seeds and leaves in the fast neutron mutant line K83. CRISPR/Cas9 gene editing system was employed to unveil the function of GmKIX1 in controlling seed size in soybean. Loss of function gmkix1 soybean plants obtained by CRISPR/Cas9 mutagenesis phenocopied the seed and leaf phenotypes of mutant K83. In addition to editing genes associated with above-ground traits through stable transformation, this work also demonstrated the efficacy of CRISPR/Cas9 system in mutating genes associated with root traits when coupled with hairy root transformation. Using GmUOX1 and GmXHD1 as targets, we were able to induce homozygous or biallelic mutations in 59% and 69% of transgenic roots, respectively. GmUOX1 and GmXHD1 encode enzymes involved in ureide biosynthesis, the form of fixed nitrogen that is transported from root nodules to other parts of the plant. Characterization of nodule development in roots carrying mutations in GmUOX1, obtained using fast neutron and CRISPR/Cas9 mutagenesis, and GmXDH1, obtained by CRISPR/Cas9 editing, indicated a critical role of the ureide biosynthetic pathway not only in incorporation of fixed nitrogen but in the successful development of functional, nitrogen fixing nodules. Results from these studies showed that the dual-gRNA CRISPR/Cas9 system developed from this dissertation indeed offers a rapid and highly efficient genetic tool to discover unknown genes and molecular mechanisms underlying important agronomic traits such as drought tolerance, yield capacity and seed quality in soybean.Item Targeted therapeutics for non small cell lung carcinoma(University of Missouri--Columbia, 2019) Mukherjee, Soumavo; Kannan, Raghuraman[ACCESS RESTRICTED TO THE UNIVERSITY OF MISSOURI SYSTEM AT REQUEST OF AUTHOR.] "Lung carcinoma, also known as lung cancer, is a malignant tumor of lungs characterized by uncontrolled call growth in lung tissue. Tobacco smoking is the reason for nearly 85% of cases of lung cancer. The rest 10-15% are usually a combination of genetic factors, secondhand smoke, environmental pollutants, asbestos and radon gas exposure. Chest radiography and CT scan with confirmation by biopsy are the ways to detect the cancer. The type of cancer, degree of spread and the overall health weigh in on the outcome and eventual possible cure. Still now, most cases are not curable. Surgery, chemotherapy and radiotherapy are the treatments of choice for all types of lung cancer. Being the most common form of cancer in men and second most common form in women, after breast, data of the year 2012 showed 1.8 million incidences of lung cancer resulting to 1.6 million deaths worldwide, with the most common age of diagnosis being 70 years. 5-year survival rate in USA is 17.4%. ... Studies has been done to unravel the downstream effect after knocking down the oncogene via siRNA(42). Malignant cells have a number of secondary pathways, along with the primary pathway, which remain dormant till the disruption of the primary pathway(43). A complex mechanism controls this function which is triggered by the change in downstream protein and gene expression levels. This makes the cancer cells develop drug resistance(44). In this project, we developed a gelatin-based nanoparticle (GelNP) that will act as a vehicle to deliver targeted siRNAs against NSCLC cells in combination with Cisplatin. The cetuximab (Ab), an EGFR targeting antibody, shall be attached to the surface. The AXL and FN14 SiRNAs shall be conjugated to the antibody by the thio-ether linkage. The cetuximab antibody shall be used to specifically target the cell and also to protect the siRNAs from degradation. We predict that 146kDa cetuximab antibody will shield the 15kDa siRNAs and prevent it from exposure to environment. Since AXL and FN14 has been observed to be related to EGFR, we hypothesize that knocking down AXL and FN14 will block EGFR and thus allow the TKI to continue its course of therapeutic action."--Introduction.