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Nuclear Fission and Tunneling Phenomena
No full textThesis (Ph.D.)--Michigan State University. Physics - Doctor of Philosophy, 2025The fission of neutron-rich heavy, and superheavy, nuclei is hypothesized to impact -process nucleosynthesis. However, the lack of experimental data for these nuclei demands theoretical predictions with quantified uncertainties. Nuclear energy density functional theory (DFT) has had success predicting fission lifetimes and yields for many -process nuclei by representing the process as a tunneling problem in a collective space. In this dissertation, I will describe the current DFT framework we use and introduce an implementation of the nudged elastic band technique. I then discuss the application of the nudged elastic band to calculate fission lifetimes and yields to study nuclei with competing modes of fission. Then, I discuss recent progress towards improving our theoretical framework of fission using an instanton approach to model nuclear fission. Furthermore, I will highlight possible overlaps of this approach with nuclear dynamics. I propose an algorithm to find mean-field instanton solutions and I conclude with future directions for the instanton approach for nuclear fission and future applications of the nuclear DFT approach to fission lifetimes and yields.Description based on online resource. Title from PDF t.p. (Michigan State University Fedora Repository, viewed ).Includes bibliographical references
EVALUATION OF THE SAFETY IMPACTS OF SPEED LIMIT INCREASES ALONG HORIZONTAL CURVES ON RURAL FREEWAYS IN MICHIGAN
No full textThesis (M.S.)--Michigan State University. Civil Engineering - Master of Science, 2025In May 2017, the State of Michigan enacted legislation that increased the maximumposted speed limit from 70 mph to 75 mph on approximately 614 miles of rural limited-access freeways. While previous studies have evaluated the broader operational and safety impacts of this change, limited research has focused on its effects on roadway segments with geometric constraints\u2014particularly horizontal curves. These curves are recognized as high-risk locations due to reduced sight distance, elevated lateral acceleration demands, and speed compliance challenges. This study addresses that gap by assessing the safety impacts of the speed limit increase specifically on horizontal curves. The analysis used crash data spanning five years before (2012\u20132016) and five years after (2018\u20132022) the speed limit change. A total of 116 horizontal curve segments were selected as treatment sites, while 81 comparable segments served as controls. Two analytical approach was employed: a cross-sectional regression analysis to identify key predictors of crash frequency and severity, and a before\u2013after evaluation using the Empirical Bayes (EB) method to adjust for regression-to-the-mean and other confounding factors. Site-specific Safety Performance Functions (SPFs) were developed using data from control sites to predict expected crashes across total crashes, fatal and incapacitating injury crashes (KA). The EB analysis revealed a 46.4% statistically significant increase in total crashes across all treatment sites after the speed limit increase. KA crashes rose by 36.5%, though this increase was not statistically significant. In summary, this study provides strong empirical evidence that speed limit increases on horizontal curves can lead to higher crash frequencies. The findings emphasize the importance of incorporating geometric assessments and targeted safety countermeasures\u2014such as advisory speed signs\u2014when modifying speed policies. These insights are especially relevant for transportation agencies seeking to enhance safety while maintaining efficient travel on rural freeway networks.Description based on online resource. Title from PDF t.p. (Michigan State University Fedora Repository, viewed ).Includes bibliographical references
METHODOLOGY FOR OPTIMIZATION OF PARTICLE OVENS AND NEUTRAL FLUX IN ELECTRON CYCLOTRON RESONANCE MACHINES
No full textThesis (M.S.)--Michigan State University. Accelerator Science and Engineering \u2013 Master of Science, 2025The Facility for Rare Isotope Beams is making developments every year to increase the beam power on the production target to support its nuclear physics program. And, at the heart of the rare isotope production, we will require continued research into the ion sources being utilized. There are currently two Electron Cyclotron Resonance ion sources (ECRIS) in use at FRIB, with plans for a third machine as well. These machines generate a highly charged ion beam from the vapor of an isotopically enriched solid material samples. The method of production for this type of neutral flux involves various particle ovens. This study is aimed to find methods to characterize the vapor production within the scope of the ECR machines, in order to understand and optimize the capture efficiency of the neutral vapor in the ECR plasma. In doing so, a method was developed with the use of a 6 MHz quartz microbalance system to record the instantaneous flux of neutral vapor from particle ovens within a vacuum setting. A setup was developed specific to the dimensions of the vacuum chamber used, as well as the placement of the ovens relative to the plasma formation in the ECRIS. Results from this study showcase a relation between crucible design and flux across the solid angle. A Low temperature Oven (LTO) using a large stable heating mass and a simple resistive oven using Rhenium Tungsten wire were used and compared for this study, using Calcium and Zinc as source materials. The simple resistive oven, using Calcium compared deposition rates and flux change with-and without the oven nozzle. Further testing was done to compare the abilities of the LTO and resistive ovens. Zinc metal was also utilized in the oven setup to generate data on how finite temperature control influences the neutral flux recorded by the microbalance. A vapor pressure curve and theoretical calculations verified the increase observed within the system. The processes and methods exhibited in this thesis can be utilized going forward by the department to benchmark current oven outputs, as well as inspire future designs.Description based on online resource. Title from PDF t.p. (Michigan State University Fedora Repository, viewed ).Includes bibliographical references
UTILIZING UV RADIATION AND TEMPERATURE AND CO2 TO REGULATE EXTENSION GROWTH AND YIELD OF SPECIALTY CROPS
No full textThesis (M.S.)--Michigan State University. Horticulture - Master of Science, 2025The wholesale value of greenhouse grown specialty crops such as potted and fresh cut culinary herbs and herbaceous perennials has seen tremendous growth over the past two decades. One issue with their production is the management of extension growth and yield without the use of chemical plant growth regulators (PGR) or inefficient energy inputs. PGRs are not labeled for use on culinary herbs and their use on ornamentals is increasingly being scrutinized. Therefore, we investigated methods to reduce internode elongation of potted culinary herbs and perennials or increase biomass production of fresh cut herbs using ultraviolet (UV) radiation or air and nutrient solution temperature (NST) and carbon dioxide (CO2) manipulation, respectively. In the first study, basil \u2018Genovese\u2019 and \u2018Nufar\u2019 (Ocimum basilicum) was exposed to UV-A (385 nm) radiation overnight for 6 h at an intensity of 20 \u3bcmol\ub7m\u20132\ub7s\u20131 for a total of 134 kJ\ub7m 122\ub7d 121. We found that exposure to UV-A radiation during the third week of growth was most effective in reducing internode elongation with minimal effects on chlorophyll content index and biomass. The second study investigated the effects of air average daily temperature (ADT), NST, and CO2 concentration on culinary herb yield. We determined that increasing the air ADT from 20 to 23 \ub0C increased shoot fresh mass (SFM) of basil, sage (Salvia officinalis), and parsley \u2018Giant of Italy\u2019 (Petroselinum crispum), but not cilantro \u2018Santo\u2019 (Coriandrum sativum). Generally, increasing the NST above 24 \ub0C or doubling CO2 to 900 \u3bcmol\ub7mol\u20131 was detrimental or had no impact on SFM. However, the SFM of cilantro and parsley were greatest at a NST of 28 \ub0C or at a CO2 concentration of 900 \u3bcmol\ub7mol\u20131, respectively. Lastly, the third study focused on reducing the stem elongation of herbaceous perennials using UV-A or -B radiation. Two weeks after transplant, plants of coneflower \u2018PowWow White\u2019 (Echinacea purpurea), coral bells \u2018Timeless Night\u2019 (Heuchera sp.), Shasta daisy \u2018Snowcap\u2019 (Leucanthemum superbum), and catmint \u2018Kitten Around\u2019 (Nepeta faassenii) were exposed to 120, 90, or 60 kJ\ub7m 122\ub7d 121 of UV-A (365 and 330 nm) or UV-B (280 nm), respectively, for one or two weeks. We found that one week of UV-B (280 nm) was sufficient to reduce internode elongation of coral bell, Shasta daisy, and catmint, but two weeks were required to reduce the height of coneflower. These studies show that ADT, NST, and CO2, and UV radiation can regulate biomass accumulation and plant growth without the use of chemical PGRs.Description based on online resource. Title from PDF t.p. (Michigan State University Fedora Repository, viewed ).Includes bibliographical references
THE WEIGHT OF ENGLISH : STORIES THAT TRACE THE CONTOURS OF SRI LANKA\u2019S ENGLISH CURRICULUM
No full textThesis (Ph.D.)--Michigan State University. Curriculum, Instruction, and Teacher Education - Doctor of Philosophy, 2025In this dissertation, I tell stories tracing Sri Lanka\u2019s English curriculum. In some ways, the stories I share perform similarly to musical \ue9tudes and shamanic performances. The analogy of mallum, a Sri Lankan dish (food-medicine-magic), helps me frame this exercise through a non-Western, anti-patriarchal, anti-feudal, anti-casteist, anti-racist, and anti-colonial orientation. Mallum, a mixture of diverse greens, is a good enough analogy to work out a trace of Sri Lanka\u2019s English curriculum\u2014a blend of colonial legacies, anti-colonial resistance, nationalist and elitist aspirations, desires of/for white patriarchal modernity and development, and medicine and magic for (re)building the nation-state in/after war and politico-economic crisis. Sri Lanka\u2019s English curriculum, conceptualized here as mallum, comprises a blend of texts that constitute the linguistic and literary canons of colonial, settler-colonial, and (post)colonial Englishes. Diverse iterations of such literary canons share space with textbooks designed to teach British, American, and Sri Lankan English; stacked in bookshops, libraries, and classrooms. Added to this blend are repetitive assessments from kindergarten to college and beyond\u2014some labeled English Literature, others General English, English as a Second Language, Business English, Academic English, and so on. Posters, leaflets, and online advertisements that promise mastery of English have proliferated over the years. Disciplinary boundaries created around English for analytical and educational purposes get messy as they blend and blur into each other. Such is my process in creating this work. I approach this research as both memory work and archival work\u2014a critical engagement with newspaper articles, textbooks, university sessional papers and yearbooks, policy documents, etc. Similarly, my conversations with English teachers, particularly those in Sri Lanka\u2019s public universities, have figured into this work.Description based on online resource. Title from PDF t.p. (Michigan State University Fedora Repository, viewed ).Includes bibliographical references
CHILDREN\u2019S LITERATURE IN THE ESL CLASSROOM : EXPLORING LANGUAGE TEACHER AGENCY FOR CULTURALLY SUSTAINING PEDAGOGY
No full textThesis (Ph.D.)--Michigan State University. Curriculum, Instruction, and Teacher Education - Doctor of Philosophy, 2025This dissertation examines the decision-making process of a bilingual Latino teacher in teaching children\u2019 literature in his K-4 grade English as a Second Language (ESL) pull-out classroom. Specifically, it focuses on how his identities and ideologies shaped both his book selection process and his instructional practices, and the extent his practices aligned with culturally sustaining teaching. To examine how this bilingual Latino teacher may support the pluralistic and hybrid language and literacy practices of multilingual learners, this study adopts a conceptual framework rooted in Language Teacher Agency as Transformative Praxis for a Culturally Sustaining Pedagogy (CSP). Through this lens, the study investigates how my focal ESL teacher\u2019s pedagogical decisions\u2014mediated by his identities, ideologies, and the context\u2014sought to resist monolingual monocultural language and literacy practices, and instead nurture the plurality of literacies, cultures, and experiences that his multilingual learners brought into the classroom. My findings revealed the tensions between the teacher\u2019s identities and conflicting ideologies that hindered language teacher agentive action toward CSP, while at other times offering glimpses into culturally relevant and responsive practices enacted in the ESL classroom. The study also highlights the assimilative forces embedded in the fabric of the education system, manifested through contextual factors, that pose challenges to reimagining the traditional monolingual, monocultural curricula of ESL settings. This study offers implications for teachers, administrators, teacher educators, and researchers committed to exploring pathways toward an education of multilingual learners for sustenance rather than assimilation.Description based on online resource. Title from PDF t.p. (Michigan State University Fedora Repository, viewed ).Includes bibliographical references
UNDERSTANDING READING MOTIVATION AMONG STUDENTS WITH AND WITHOUT READING DIFFICULTIES : A TWO-STUDY DISSERTATION
No full textThesis (Ph.D.)--Michigan State University. Educational Psychology and Educational Technology - Doctor of Philosophy, 2025This dissertation presents two independent studies centered on developing a more complex understanding of reading motivation among students with and without reading difficulties (RD). In Study 1, a systematic review and meta-analysis was conducted to (a) examine how motivational differences among students with and without RD have been investigated in prior studies over the past 45 years, (b) quantify overall effect sizes of motivational differences among students with and without RD, and (c) investigate the extent to which the motivational differences among students with and without RD are moderated by different forms of motivation, domain specificity of motivation measures, criteria used to identify students with RD, and students\u2019 grade level. Results of the synthesis indicated that self-concept was most frequently studied among various forms of motivation and most studies measured motivation within a reading-specific domain among populations of upper elementary students. Results of meta-analysis revealed that overall, students with RD had significantly lower levels of motivation. Results of meta-regression indicated that differences between students with- and without RD with regard to self-concept were significantly larger than differences with regard to other forms of motivation including attributions, intrinsic- utility- and cost value, mastery goals, as well as intrinsic and extrinsic regulation. Motivational differences among students with and without RD were observed to be significantly larger when the criteria used to identify students with RD included decoding difficulties as opposed to comprehension difficulties. In Study 2, a latent profile analysis was conducted to examine (a) what types of motivation profiles shaped by mindset, self-efficacy, intrinsic value, and three types of achievement goals emerge among fourth and fifth-grade students, (b) whether RD status predicts integrative motivation profile memberships, and (c) how the integrative motivation profiles are related to reading comprehension and reading anxiety for students with (n = 70) and without (n = 39) RD. The results indicated that three distinct profiles were identified: (a) Confident, Interested, Growth Oriented profile (36%), (b) Moderate All profile (30%), and (c) Confident, Interested, and Multiply Goal Oriented profile (34%). Students with RD were more likely to belong to the Moderate All profile than the Confident, Interested, Growth Oriented profile. Students in the Confident, Interested, and Growth Oriented profile had significantly higher reading comprehension and lower reading anxiety than students in the other two profiles. Together, these studies contribute to helping educators better understand similarities and differences in reading motivation among students with and without RD, as well as how motivation might be best supported for all students. Furthermore, this dissertation highlights some challenges in the field and raises several questions for future investigation.Description based on online resource. Title from PDF t.p. (Michigan State University Fedora Repository, viewed ).Includes bibliographical references
Creative Dissent : Art, Environment, and Activism in Thailand
No full textThesis (Ph.D.)--Michigan State University. Anthropology - Doctor of Philosophy, 2025This dissertation explores how Thai artivists (art + activism) use visual and performing arts as a form of creative dissent to spotlight social-political-ecological issues that are otherwise erased or silenced. Climate and extinction crises, air and water pollution, over-extraction of resources, and unsustainable practices threaten the well-being of more-than-human communities around the globe. Born out of the necessity to fight for justice and protect natural and cultural heritage, community members, organizers, and activists experiment with radically creative interventions to call for change. This dissertation expands upon scholarship of Southeast Asian environmentalisms and activisms by illustrating how artists take on roles of archivists, educators, community organizers, and activists and make friendships through their production and circulation of environmentally focused artwork and relational practices. The arts-based research methodology included participant observation, surveys, informal interviews, structured interviews, community-engagement projects, visual analysis, and artistic collaborations. This multimodal dissertation includes an introduction chapter, three articles for submission to journals, a co-curated exhibit at the MSU Broad Art Museum, and multiple public and applied anthropology projects including community engagement workshops and art exhibitions. The introductory chapter describes the research methodology, field sites, key individuals and groups, theories and frameworks from visual anthropology, applied anthropology, community-engaged scholarship, art theory, and political ecology; and provides an overview of the subsequent article manuscripts. The first journal manuscript explores emotional responses to biodiversity loss in Thailand through the story of experimental ethnographic research and artistic collaboration. The second manuscript \u201cArts-based Research in Anthropology: Lessons from Thailand\u201d examines the forms of knowing afforded by engagement with artists and arts-based methodologies, including research and archiving practices among artists addressing issues of environment and social justice. The third manuscript, \u201cWeaving the Mekong,\u201d investigates how textiles tell the story of how climate change and hydropower development are changing long-standing human-environment relationships for a Tai-Lue community living along the Mekong River of northern Thailand, focusing on weaving, a place-based craft-based livelihood, and weavers\u2019 adaptations to social, cultural, and ecological change. The dissertation references public and applied anthropology projects that use visual strategies to share research data, including workshops and exhibits focused on environmental art and activism in Thailand and the United States. This includes an upcoming co-curated exhibit, \u201cMekong Voices: Transnational River Justice in Mainland Southeast Asia,\u201d to be held at the MSU Broad Art Museum.Description based on online resource. Title from PDF t.p. (Michigan State University Fedora Repository, viewed ).Includes bibliographical references
SPATIOTEMPORAL DYNAMICS OF LANGERHANS CELL REPOPULATION DURING SKIN WOUND REPAIR IN LIVE MICE
No full textThesis (Ph.D.)--Michigan State University. Cell and Molecular Biology - Doctor of Philosophy, 2025Langerhans cells (LCs), the primary antigen-presenting cells of the epidermis, play essential roles in immune surveillance and tissue homeostasis. However, how LCs respond to skin injury and re-establish their network during wound healing remains poorly defined. In this dissertation, I investigate the behavior, origin, and transcriptional diversity of LCs during epidermal regeneration in live mice. In Chapter 3, I demonstrate that LCs near the wound edge undergo autonomous, directional migration into the regenerating epidermis during re-epithelialization. This challenges the longstanding view that LCs are passively displaced or replaced post-injury. I show that this migration is Rac1-dependent and occurs independently of epithelial cell movement, positioning LCs as active contributors to tissue restoration. In Chapter 4, I reveal that both embryonic and monocyte-derived LCs cooperate to reconstitute the LC network after injury. Using inducible lineage tracing, I show that monocyte-derived LCs integrate into the epidermis and acquire steady-state characteristics over time, while embryonic LCs remobilize from adjacent skin. Through single-cell RNA sequencing, I uncovered distinct transcriptional programs between LC subsets, reflecting their different origins and functional states during repair. These findings provide the first in vivo evidence of dual-origin LC reconstitution in wounded epidermis, highlighting unexpected cellular plasticity within this niche. In Chapter 5, I identify Cxcr2 as a previously unrecognized regulator of intraepidermal LC migration. I show that embryonic LCs rely on Cxcr2 signaling to enter the wound, and that pharmacological inhibition of this pathway blocks their recruitment. This work not only identifies Cxcr2 as a key component of the molecular machinery guiding LC relocation but also uncovers a functional axis between the wound epithelium and immune cell positioning that had not previously been defined. Altogether, these findings redefine LCs as dynamic and responsive players in epidermal regeneration.Description based on online resource. Title from PDF t.p. (Michigan State University Fedora Repository, viewed ).Includes bibliographical references
Cross section measurements of neutron-induced reactions on 12C using a diamond detector
No full textThesis (Ph.D.)--Michigan State University. Physics - Doctor of Philosophy, 2025Background: Single-crystal chemical vapor deposited (sCVD) diamond detectors offera unique method to study cross sections of reactions on carbon since they can be used as active targets. Previous studies analyzing neutrons on carbon using these detectors were primarily focused on lower energy neutrons and reactions, and some of these did not have sufficient energy resolution to isolate the contributions of reaction channels with similar Q values. Purpose: This work extends neutron-induced reaction cross section measurements to higher energies, relevant to rare isotope facilities. These measurements can be used to inform and benchmark simulation of experiments that require neutron detection, particularly those utilizing organic scintillators. For some experiments, simulations are used to extract physics information from experimental data, reinforcing the need for accurate simulations. Methods: Two sCVD diamond detectors were used as active targets at LANSCE, where neutrons up to 800 MeV are produced via spallation. Results: Relative cross sections are reported from incident neutron (kinetic) energies En = 12 MeV up to 55 MeV for 12C(n,\u3b10), up to 46 MeV for 12C(n,d0), and up to 27 MeV for 12C(n,p0) and 12C(n,p1). These measurements extend these cross sections to higher energies than previous studies. Conclusions: Good agreement is found between this work and recent experimental data from the EXFOR database in the neutron energies where the studies overlap. This work supports the need to update the Evaluated Nuclear Data File (ENDF) evaluation for the (n,\u3b10) channel with more recent data, and provides data that could allow for an evaluation of the (n,p0), (n,p1), and (n,d0) channels. These cross sections will increase the accuracy of simulations by extending the energy range for which empirical cross sections are available and including new reaction channels.Description based on online resource. Title from PDF t.p. (Michigan State University Fedora Repository, viewed ).Includes bibliographical references