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Optimal Control of a Differential-Drive Mobile Robot
No full textM.S.Point-to-point obstacle-free space path planning for a kinematic model of a differential-drive mobile robot to minimize input energy and energy\maneuver time is presented in this work. The optimal control problem is formulated in the scenario where the initial and final positions of the robot are specified. Notably, the terminal states are parameterized in the polar-form, which lies on a unit circle in the first quadrant. The necessary conditions for optimality are determined by using the Hamiltonian formulation and the Calculus of Variations, which resulting in a two-point boundary value problem and solved numerically. Furthermore, the analytical expression of optimal controls and state trajectories are obtained by using the Jacobi elliptic functions, which transforms the optimal control problem into nonlinear programming problem, which is solved for the unknown parameters and the results are compared with the shooting method based numerical solutions. Lastly, the resulting closed-form expression of control and state profiles are used to design the closed-loop controller utilizing the idea of Differential Flatness.**To request an accessible version of the file(s) associated with this item, contact [email protected]. Please include the item's persistent URL [http://hdl.handle.net/. . .] in your request.*
Effects of GIS Integration in Secondary School Classrooms: A Mixed-Method Study on Student Spatial Thinking Ability
No full textPh.D.To respond to the National Research Council's (2006) call on fostering a new generation of students who are equipped to think spatially, this study had the following four purposes: 1) to explore students' current spatial thinking ability, 2) to examine whether taking GIS integration lessons facilitates students' development of spatial thinking ability, 3) to investigate GIS related factors influencing students' spatial thinking ability, and 4) to investigate factors influencing teachers' GIS integration decision. This study applied quasi-experimental research design and a mixed-method. Spatial Thinking Ability Test and survey questions were conducted to 2149 middle and high school students, and 26 teachers were interviewed from two urban public school districts during years from 2017 to 2020. Rasch measurement, descriptive statistics, multiple linear regression, independent sample t-test, one-way ANOVA, one-way ANCOVA, structural equation modeling, and qualitative approaches were the analysis methods of the study. The results indicated that 1) secondary school students' spatial thinking ability were still very low, and it varied by gender, grade level, and associated with science course and science attitude, 2) Taking GIS integrated science and technology classes was effective in improving students' spatial thinking ability, and higher frequency of taking GIS integration lessons associated with a higher gain in spatial thinking ability, 3) students with higher GIS perceived ease of use and higher GIS perceived usefulness tended to have better ability in GIS use, and in turn, tended to have better spatial thinking ability, 4) teachers' GIS technology knowledge, content knowledge, time for practice, attitude toward GIS, and GIS perceived competence, curriculum alignment, students' engagement, and students' development were factors influencing teachers' GIS integration decision. The above findings make contributions to education research in several ways: 1) they allow educators and future researchers to have an in-depth understanding on secondary school students' current spatial thinking ability, providing a direction in improving spatial thinking ability, 2) they respond to the calls on incorporating GIS into students' learning, and add to the understanding of GIS's role in middle and high school students' spatial thinking ability development, and 3) they demonstrate the effectiveness of a holistic process from teacher GIS training to students' use of GIS, eventually leads to students' improvement of spatial thinking ability. The study builds a foundation for a long-term GIS use and spatial thinking ability research program.**To request an accessible version of the file(s) associated with this item, contact [email protected]. Please include the item's persistent URL [http://hdl.handle.net/. . .] in your request.*
Regulating Endodermal Cell Lineage Through Genetic Manipulation of Developmental Regulatory Gene Circuits (DRGC's)
No full textM.S.Human Pluripotent stem cells (hPSC's) are a very useful tool for regenerative medicine allowing for the replacement of damaged tissues by implantation of functional tissue or cells. Of specific interest is the ability to properly differentiate liver, pancreas, and lung cells which all derive from endoderm using hPSC's. One issue that arises, is a result from the heterogeneity in the gene expression of hPSC-derived endoderm which can severely compromise the downstream fate of differentiation. Improper differentiation protocols of embryonic stem cells have also been shown to produce unwanted tissue during transplants including skeletal muscle, bone cell subpopulations, gut epithelial-like structures and columnar cells. Hepatocyte Nuclear Factor 3b (Foxa2) is known as a Pioneer Transcription Factor (TF) due to its ability to bind albumin enhancers and open normally inaccessible heterochromatin, effectively priming such for a cascade of regulatory elements to further differentiation through necessary gene activation. Foxa2 has been shown to be required for developmental processes such as transitioning to air breathing at birth, differentiation of pancreatic a-cells, and control of differentiation of goblet and enteroendocrine cells in mice. In combination with Foxa2, Hepatocyte Nuclear Factor 3a (Foxa1) has been shown to equally vital. Using this knowledge, we attempt to show that de-differentiation of HepG2 cells may be possible when these cells are no longer under the control of these pioneer transcription factors. Aside from this we attempt to show that the knockdown of these key liver factors will allow us to hold our differentiating stem cells in an endodermal like state by blocking signaling pathways, in hopes of better studying what transcription factors are important in a more homogeneous endoderm population.**To request an accessible version of the file(s) associated with this item, contact [email protected]. Please include the item's persistent URL [http://hdl.handle.net/. . .] in your request.*
The Synthesis and Characterization of Organometallic and Inorganic Manganese and Iron Complexes; Probing Structural and Electronic Effects on Reactivity
No full textPh.D.Traditionally nature has used complex enzymes with ionic and paramagnetic centers to accomplish tasks like the activation of molecular oxygen and water splitting. Replicating these processes with biomimetic organometallic and inorganic metal complexes has been of interest to the scientific community for at least a century. This dissertation details the work towards this goal using manganese and iron complexes with varying structural and electronic properties to investigate the effect these perturbations have on reactivity. Early work by the author sought to synthesize a fully organometallic manganese-oxo heterocubane using cyclopentadienide as an ancillary ligand. While no cubane was ever synthesized, these experiments lead to a fundamental understanding of the nature between the manganese(II) center and the Cp ring slip in bis(cyclopentadienide) manganese(II). This work serves as the focus of Chapter 2. In Chapter 3, the focus of this work shifted to the synthesis of the biomimetic 2,2',2''-nitrilotris(N-arylacetamide) manganese(II) complexes with various R groups (R = NO2, Cl, Br, H, and OMe) on the para position of the aryl ring. These complexes were synthesized as bis(tetramethyl ammonium) salts and had axial acetate ligands. The NTANO2 variant of the ligand afforded the best crystals for diffraction and the structural details of the newly synthesized manganese and cobalt variants were compared to those of the previously synthesized iron and zinc variants. This led to the conclusion that the structural differences between these complexes is most likely due to the ionic crystal radii of the metal center and not the electronic effect of the ligand. The electrochemical studies also confirmed the lability of the acetate ligand, which was consistent with a previous work by the lab. These complexes demonstrated a liner free energy relationship via the construction of a Hammett plot between the electrochemical reduction potential and the electronic effect of the para substituent on the aryl ring. This relationship was also demonstrated for the previously synthesized iron(II) 2,2',2''-nitrilotris(N-arylacetamide) complexes with R = NO2, F, Et, and OMe. Finally, we sought to determine the nature of the mechanism by which iron NTAR reduces molecular oxygen. The two possible mechanisms for O2 reduction are inner sphere electron transfer and outer sphere electron transfer. The inner sphere mechanism is biologically relevant while the outer sphere mechanism is not. We proposed that our complexes follow the outer sphere mechanism which can be modeled by the Marcus cross relation. The focus of Chapter 4 was to determine the self-exchange rate constant of the iron complexes. In order for self-exchange occur the free energy of the system must be zero. Practically, this means that the two species are redox partners. It was determined that the dimeric species that forms as the product of the reaction between the iron NTAR complex and O2 was not a redox partner to the iron(II) monomer. Due to the lability of the acetate ligand in solution we attempted the synthesis of iron NTAR complexes with different axial ligands (X = NCS , CN , OH , Br , and Cl ) and only the NCS compounds were isolable. We also synthesized the potassium salts of the iron NTAR complexes which have an axial DMA ligand, which was confirmed via NMR spectroscopy. All of these iron NTAR compounds were unstable when oxidized and free ligand was formed instead of an iron(III) redox partner. Therefore, we synthesized a known iron(II/III) redox pair with a similar trisurea ligand. The self-exchange rate constant was determined via NMR spectroscopy to be 6.26 x 103 ± 1.39 x 102 M-1 s-1. This led to the calculation of the rate constant for the reduction of O2 via the MCR to be 1.49 M-1 s-1. This value is close to the experimentally determined value of 0.4 M-1 s-1 and we can conclude that the iron NTAR system reduces O2 via an outer sphere mechanism.**To request an accessible version of the file(s) associated with this item, contact [email protected]. Please include the item's persistent URL [http://hdl.handle.net/. . .] in your request.*
A Comparative Study of Novel Deep Learning-Based and Conventional Atlas-Based Automatic Segmentation in Head and Neck Radiotherapy Planning
No full textM.S.Purpose: To identify opportunities to improve automatic contouring of organs at risk for head and neck cancer patients by developing a convolutional neural network to conduct automatic contouring and comparing its performance to contemporary atlas-based methods. Methods: Using a cohort of 265 anonymized planning CT scans and their associated physician-defined structure set, with 19 set aside for evaluation, a convolutional neural network (CNN) was trained to predict contour data for eleven common organs at risk (OAR) in head and neck cancer patients. Once trained, the neural network predicted contours for the 19 CT scans that were in the evaluation dataset. A commercial deformable atlas-based automatic contour generation function was used to generate competing contour data for the same 19 CT scans. Each output was compared to approved physician-generated manual contours across three quantitative metrics: Dice similarity coefficient (DSC), mean surface distance (MSD), and 95th percentile Hausdorff distance (HD). Performance differences between the modalities on a given metric for each OAR were evaluated for statistical significance using a two-tailed t-test with a p-value threshold of 0.05 to define a statistically significant difference between the modalities. Results: The CNN scored better on all three metrics for both parotid glands and both submandibular glands. For the cochlea and brachial plexus, the CNN scored better on some metrics, and on some metrics, there was no statistically significant difference between the two modalities. For the brain, larynx, and spinal cord, the metrics showed no statistically superior modality. For the brainstem, the CNN contours scored statistically worse than the atlas-based method...Conclusion: Except for the brainstem, the CNN performed either superiorly to or not significantly different from the atlas modality. Deep learning methods demonstrate clear, significant improvement in contouring several OARs. Further pursuit of deep learning techniques for automatic contouring could deliver greater improvements in modern automatic contouring.**To request an accessible version of the file(s) associated with this item, contact [email protected]. Please include the item's persistent URL [http://hdl.handle.net/. . .] in your request.*
Symmetry Breaking in Cuprate High Tc Superconductors: Doping, Energy, and Temperature Dependence
No full textPh.D.We explore broken symmetries in cuprate high-temperature superconductors (HTS) by measuring changes in the polarization of transmitted light as a function of sample orientation. Earlier studies using THz [1] and near-infrared [2] polarization-sensitive measurements have discovered symmetry breaking in cuprate HTS. In two cuprate HTS, YBa2Cu3O7-x (YBCO) and La1-xSrxCuO4 (LSCO), we have found linear dichroism (LD), where the linear polarization of the probing radiation is preferentially absorbed along one direction. We have probed the LD signal in a wide range of dopings, from terahertz (THz) to mid-infrared to visible wavelengths, and at room temperature and down to 30 K. The LD signal is largest in underdoped films and there is a clear peak in the LD signal at around 400 meV in underdoped samples. In most samples, the LD signal increases as the samples are cooled, but for an overdoped YBCO film the LD signal decreases with cooling. The observations suggest that there is linear symmetry breaking that could be related to the pseudogap phase in underdoped samples. These results will provide the opportunity to study the broken symmetry in cuprate HTS in wide energy, temperature, and doping ranges and to test theoretical models of the symmetry breaking, which will likely provide new insights into the enigmatic behavior of cuprate HTS.**To request an accessible version of the file(s) associated with this item, contact [email protected]. Please include the item's persistent URL [http://hdl.handle.net/. . .] in your request.*
Light up the Brain: The Examination of Cognitive Dynamics During Video Composition with fNIRS
No full textPh.D.Digital Video (DV) is a valuable writing tool for the 21st-century classroom that expands learners' compositional choices with multimodal representation (Miller & Bruce, 2017). As a composition genre, the social and cognitive aspects of video composition are intertwined, similarly to the print composition process. Non-direct methods such as think-aloud protocols provide insights into learners' composition processes, yet these methods are not without limitations. With the advance of technology and the support of Educational Neuroscience (EN), an increasing number of studies have explored the potential of physiological measurements, such as functional near-infrared spectroscopy (fNIRS), to provide direct and consistent visualization and observation of brain activities, giving insight into learners' cognitive dynamics while composing (Lamb, Hand, & Yoon, 2017). Thus, this dissertation study analyzed 8 learners' hemodynamic responses measured by fNIRS, screen-recordings of learners' video composition processes, and post-interviews. Learners' videos were collected and analyzed through a mixed-method approach focusing on learners': (a) perceptions and performances of their video composition processes and videos; and (b) cognitive dynamics during the stages of video composition adapted from Bruce's (2009) model. Patterns of the video composition process and idiosyncratic composing styles were identified. Multimodal resources were orchestrated by learners to make design choices with the available resources. Each learner's cognitive dynamics showed significant differences during the various video composition stages. This exploratory study showed that fNIRS could provide a new and powerful direct access to examine video composition as an embodied learning experience in addition to non-direct measurements. This interdisciplinary study also shows the value of the collaboration of education, psychology, and neuroscience fields. The contributions to writing research and instruction are further discussed.**To request an accessible version of the file(s) associated with this item, contact [email protected]. Please include the item's persistent URL [http://hdl.handle.net/. . .] in your request.*
Longitudinal Dietary Patterns and Physical Growth Trajectories in Children with Autism Spectrum Disorders: A National Cohort of Children from Birth to Six Years Old
No full textM.S.BACKGROUND: Epidemiological studies have reported differences in nutritional intake and physical growth in children with Autism Spectrum Disorders (ASD). However, these factors have rarely been studied longitudinally. METHODS: We conducted a secondary analysis of 150 children with ASD and 8,800 children without ASD within the Early Childhood Longitudinal Study, Birth Cohort (ECLS-B) a national cohort of children born in 2001. The ECLS-B collected repeated data on children's early life experiences from birth to six years old through extracting birth certificates and age-specific visits when children were approximately 9 months, and 2, 4, 5, and 6 years old. Dietary patterns were assessed via parental report when children were 4, 5, and 6 years old, and physical growth measurements (weight, length/height) were collected via birth certificates and at each age-specific visit. Factor analysis was used to combine highly correlated diet variables and categorized for easier interpretation. Mixed-effects ordinal logistic regression models were used to estimate the association between ASD and tertile of dietary patterns. Mixed linear regression analysis was used to estimate the differences in the World Health Organization transformed growth trajectories in ASD and non-ASD children.RESULTS: Two dietary patterns were derived from the factor analysis appropriately named "western dietary pattern" and "healthy guideline pattern." The odds of having a healthy guideline diet was significantly lower in children with ASD at 4 years old: (OR: 0.55 [95% CI: 0.35, 0.88]); and 5/6 years old: (0.60 [0.37, 0.97]). No differences were found in the odds of having a western diet. Both ASD boys and girls had a significantly lower WAZ at birth compared to their non-ASD counterpart (boys mean difference: -0.62 [95% CI: -0.94, -0.29]) (girls mean difference: -1.47 [-1.94, -1.00]). Girls with ASD also had a lower WAZ at 9 months old (-0.95 [-1.35, -.055]). Girls with ASD had lower HAZ at 9 months (-0.90 [-1.29, -0.51]) and 2 years old (-0.49 [-0.85, -0.12]), however we found no difference in HAZ in boys with ASD and non-ASD. Girls with ASD had a significantly lower BMI-for-age z-score at all 9 months (-0.06 [-0.13, -0.00]), 2 years (-0.17 [-0.34, -0.01]), 4 years (-0.34 [-0.68, -0.01]), and 5 years old (-0.43 [-0.85, -0.02]). No differences were found in BMI-for-age z-score in boys with ASD compared to boys without ASD. CONCLUSIONS: The data from this longitudinal study suggests that the relationship between ASD and dietary patterns is similar in children at 4 years old and from 5 to 6 years old. Our study found a significantly lower consumption of healthy guideline foods in ASD children compared to children without ASD, however the healthy guideline dietary pattern and western dietary pattern may not be meaningful in differentiating between ASD and non-ASD children. This is supported by the finding that ASD children consumed a lower total intake of foods. This study also suggests an accelerated trajectory of weight from birth in ASD boys compared to non-ASD boys, however no difference in height and BMI at any age. Girls with ASD had significantly lower BMI from 9 months to 5 years old. If differences in dietary patterns and anthropometric measurements are confirmed in further longitudinal observational studies, recommendations should be made to monitor these factors.**To request an accessible version of the file(s) associated with this item, contact [email protected]. Please include the item's persistent URL [http://hdl.handle.net/. . .] in your request.*
Contracting Subjectivities: Que(e)rying Gesture, Affect, and Politics in French and American AIDS Literature
No full textPh.D.In this study, I most broadly seek to examine what AIDS as a biomedical and sociopolitical crisis has meant for the institution of democracy, literature, and the project of queerness by looking through the specific lenses of gesture, affect, and politics. Through critical queer hermeneutics, I perform a comparative literary analysis of a selected body of AIDS writing from France and America. The secondary methodology I utilize is an experimental mimesis of (auto)fiction and (auto)theory that both primary and secondary queer writers under study here have explored in their projects as a means of cultivating their ideas. This project can overall also be classified as an affective arching gesture, a kind of bearing witness and a taking up of the queer political projects that many AIDS writers and activists began in response to their specific oppression. I first develop what I call Raw Writing, which simply defined is a genre or style of writing deployed by queer and seropositive individuals that utilized queer excess in the form of sex, the body, language, and drugs in order to both make intelligible new subjectivities brought about by HIV as well as to manifest or perform the very potentiality inherent to literature and the act of writing. Through my examination of raw writing, I begin my initial probing of exposure that begins with the rawness of literature that exposes readers to knowledge specifically about living with, suffering from, and dying from HIV. Then, I develop what I call Sera-positivity, which is a multi-layered, multi-valent sense of subjectivity that while predicated on a radical particularity/singularity can come to inherently represent a fluctuating democratic sense of universality yet one that does not seek to exercise exclusion and homogenization in its constitution. I also further develop risk of exposure as underlying this new mediation of sociality and citizenship so as to rethink freedom through "post-AIDS" queer democracy. Lastly, I develop a sense of intergenerational AIDS trauma by queering postmemory and examining queer gesture. In doing so, I develop the idea of reading as fucking by looking at parallels of risk, exposure, and contamination between HIV and knowledge itself. The act of reading and the act of sex, understood through a queer lens of gesture and genre, become blurred and offer a means to understand what AIDS trauma of the everyday actually was as well as how it has been transmitted over time. I also find that PrEP (Pre-exposure Prophylaxis) has provided gay men with an opportunity to simultaneously combat the epidemic, alleviate AIDS trauma, and still hold space for new sexual projects. Ultimately, I conclude that the AIDS crisis was a virally imbued, passive genocide that created irrevocable changes in history, democracy, and emerging LGBT literature. I also conclude that despite the ongoing political projects of queers that come in the form of this very study, the current unfolding of the SARS-CoV-2 pandemic stands in as empirical evidence itself that the shifts brought about by HIV have yet to be fully realized or taken seriously in any arena. Moving forward during an age of COVID-19 all the while still trying to combat the HIV pandemic, I hold open the space of reading the dissertation as an act that will hopefully transmit the necessary knowledge to participate in abating these diseases as much as the social stigmatization that has come along with them.**To request an accessible version of the file(s) associated with this item, contact [email protected]. Please include the item's persistent URL [http://hdl.handle.net/. . .] in your request.*
Religion and Madness: Contests over Faith and Insanity in the American Cultural Imaginary, 1840-1920
No full textPh.D.This dissertation is a cultural history of the co-identification of religion and insanity overthe long nineteenth century. It examines how the medical and popular label of insanity or "religious insanity" was deployed to impugn, subvert and slate for imprisonment andinstitutionalization diverse new American religious identities. Furthermore, it analyzes how theinsanity label functioned to forward and undergird a constellation of gendered and racialpresumptions. The project moves chronologically from considerations of early 19th centurywhite evangelical revivalism, Second Adventism (Millerism) and Spiritualism to later nineteenthcentury examinations including post-Emancipation African American millenarian movements,Pentecostalism and Christian Science. Mad-labeled new religious individuals and groups actively contended with pathologized interpretations of their faith as a means of defending themselves from the cultural implications of madness. This work demonstrates how debates over religious insanity constituted a complex cultural reckoning regarding the diversity of expressions and interpretations within American religious life.**To request an accessible version of the file(s) associated with this item, contact [email protected]. Please include the item's persistent URL [http://hdl.handle.net/. . .] in your request.*