Electronic Thesis or Dissertation

Automatizing optimal neural architectures is an under-explored domain; the majority of deep learning domains base their architecture on multiplexing different well-known architectures together based on past studies. Even after extensive research, the deployed algorithms may only work for specific domains, provide a minor boost, or even underperform compared to the previous state-of-the-art implementations. One approach, Neural architecture search, requires generating a pool of network topologies based on well-known kernel and activation functions. However, iteratively training the generated topologies and creating newer topologies based on the best-performing ones is computationally expensive and out of scope for most academic labs. In addition, the search space is constrained to the predetermined dictionary of kernel functions to generate the topologies. This thesis considers neural networks as a weighted directed graph, incorporating the ideas of message passing in graph neural networks to propagate the information from the input to the output nodes. We show that such a method relieves the dependency on a search space constrained to well-known kernel functions over any arbitrary graph structures. We test our algorithms in the RL environment and explore several optimization forays, such as graph attention and PPO to let us solve the problem. We improve upon the slow convergence of PPO using Neural CA approach as a self-organizing overhead towards generating adjacency matrices of network topologies. This exploration towards indirect encoding (an abstraction of DNA in neuro-developmental biology) yielded a much faster algorithm for convergence. In addition, we introduce 1D-involution as a way to implement message passing across nodes in a graph, which further reduces the parameter space to a significant degree without hindering performance.

The relationship between neuronal function and energy metabolism is a field of intense inquiry and while bioenergetic per se are well understood, we lack a good understanding of the ways in which these mechanisms overcome the challenges presented by the unique morphology of neurons and their volatile energy demands. Here we examined the extent to which these challenges can be met through strategic mitochondrial placement and the support of a phosphagen system.
We examined fluctuations in energy demand of Drosophila larval motor neurons utilizing a combination of computational modeling and empirical analysis, and uncovered a neglected aspect of cellular energy metabolism that appears to accommodate the stress of highly volatile energy demands. Our findings highlight a reliance on the phosphagen system to buffer against rapid changes in the rate of ATP consumption induced by burst firing. The knockdown of a key element in the phosphagen system of invertebrates, arginine kinase, revealed a suppression of the mitochondrial proton motive force, and a more rapid decline in the presynaptic ATP/ADP ratio during burst firing. The knock down of arginine kinase also revealed metabolic shifts that indicated a compensatory increase in glycolysis, but, surprisingly, few consequences for either presynaptic Ca2+ handling or neurotransmission. In a final effort to ensure that we were imposing a metabolic load adequate to challenge these motor neurons, we developed an ex vivo calcium clearance assay and in vivo locomotor performance assay – currently in their final stages of validation.

This thesis focuses on identifying the presence of porotic hyperostosis in a sample made up of 119 individuals to a) assess the possible causes of porotic hyperostosis in the ancient Ecuadorian coastal societies, b) reconsider porotic hyperostosis as a nutritional stress marker, and c) propose bartonellosis as an alternative cause for the appearance of porotic lesions in the skull over 4,000 years in the Northern Andes. By applying the BoPLE (Bone Porous Lesions Evaluation) method, results obtained and clinical evidence propose that parasite infections and iron deficiencies are two of the probable causes of porotic hyperostosis in the prehistory of the Ecuadorian coast. Furthermore, the results suggested that a female skull associated with Valdivia culture phase II (3,300 – 2,800 BCE) is Ecuador's oldest record of this symptom. Likewise, the clinical characteristics of bartonellosis suggests it to be a plausible cause of porotic hyperostosis in ancient Ecuador.

Some Years Ago, My Mother was Possessed is a poetry chapbook exploring a familial lineage of abuse through fictional exit interviews taken after points of emotional and physical trauma or abuse. Through surreal landscapes and speculative futures, the poems explore the remnants of abuse, and the fear of being possessed by her family’s history of motherhood.

Cholesterol is a pivotal component of mammalian cell membranes and homeostasis. Due to its high concentration and heterogenous distribution in the brain, cholesterol is tightly regulated and its dyshomeostasis is frequently implicated in several neurodegenerative diseases. This dissertation reports the design, synthesis, and application of ten cholesterol naphthalimide probes (CND) to study cholesterol trafficking in live cells. The CND series was rationally designed by incorporating several of the structural features of endogenous cholesterol onto the naphthalimide (ND) scaffold conjugated via an ester bond. The modularity of the ND scaffold enabled all analogs to have the aliphatic tail of cholesterol, which is lacking in the most ubiquitously utilized probe, BODIPY-Cholesterol, a.k.a. Top-Fluor® Cholesterol (TFC). The CNDs were demonstrated to be optimal probes for cholesterol due to the ability to fluorescence exclusively in hydrophobic/membrane environments and exhibit low fluorescence in hydrophilic/aqueous environments. By incorporating a protonatable piperazine group on the C4 position of the ND scaffold, CND2 – CND4 possessed pH sensing capabilities, which were demonstrated to monitor intracellular vesicle turnover in neurons. The potential of the CNDs to bind to the lysosomal sterol transport protein NPC2 was investigated by molecular docking and molecular dynamics (MD) simulations. The docking pose with the CND’s aliphatic tail positioned inside the hydrophobic binding pocket was essential for mimicking endogenous cholesterol’s interactions and stabilizing the NPC2-ligand complex. Fluorescence confocal microscopy demonstrated a structure-dependent and cell-dependent intracellular distribution of the CND series in live cells.

Infant feeding is a universally recognized practice yet, it is profoundly influenced by culture. While it is well accepted that breast milk is the gold standard for infant feeding in the United States, the persistence of breastfeeding disparity among minorities, particularly among Black women in the U.S. is not well understood. According to the literature, Black mothers in the U.S. remain among the least likely to both initiate and exclusively breastfeed. Although infant feeding research related to African American women's practices has been widely explored, there is a paucity of knowledge related to the experiences and practices of foreign-born Black women in the United States. More studies are needed to examine factors influencing the infant feeding practices of foreign-born Black women. This research may identify new strategies for addressing breastfeeding disparity among Black populations. This ethnographic research employs Leininger's Cultural Care Diversity and Universality Theory and Bronfenbrenner’s (1994) Social-Ecological Model to explore influencing factors on Black Jamaican women’s infant feeding practices during the first six months of life. By applying these theories as a guide for inquiry, this study seeks to identify influencing factors on Jamaican women’s infant feeding practices in the United States. Data collection involved conducting semi-structured interviews and focus groups with 14 participants aged between 30 and 40 years. Five themes emerged from the data: (1) It’s What I Saw, It’s What I Know, (2) Me Personally, (3) Riding Out The Storm, (4) During the Storm, (5) On De Road and Outta Door. The findings highlight the need for culturally competent nursing care to promote infant health within this growing population in the United States.

Although the sensationalized term “Revenge Porn” is used by media outlets to spark conversation about consent and digital privacy, the nonconsensual distribution of intimate media, or “image-based sexual abuse” (IBSA), is the preferred term by scholars for its more accurate depiction of the variety of modes, methods, and damages. I argue that targeted women experience many of the same damages to their socioemotional, interpersonal, and professional well-being that targets of traditional, offline, sexual violence experience, and that the nature and affordances of digital technology often allow these harms to transcend the once isolated contexts in which offline cases of sexual violence occurred. Moreover, regulatory bodies often trivialize and dismiss IBSA, deeming it inconsequential despite the devastating professional and socioemotional effects targets experience. This research explored a) how women navigate and respond to IBSA in the workplace when boundaries of personal and professional identities are crossed nonconsensually and whether demographic differences influence approaches via fifteen interviews with IBSA targets and two organizational leaders. The findings revealed that organizational environment and attitudes were the most influential factors in female employees' decisions to report, and in turn, employee turnover, organizational commitment, and job satisfaction. Demographic characteristics, such as age and gender, influenced how and from whom targets sought informal, or emotional support. Therefore, this research demonstrates the need for, IBSA and its impact to be foregrounded in how traditional sexual violence and harassment are dealt with. Finally, to extend the IBSA and workplace sexual harassment literature further, I argue for the importance of an organizational climate that is not only understanding, but supportive of IBSA targets in establishing appropriate training, regulations, and policy for sexual harassment both online and offline, structured around target support, prevention, and bystander intervention.

Though general relativity (GR) is proven to be a successful theory in describing the macroscopical nature of our universe, it still has several problems to be resolved. One of them is known as the time problem of GR. GR is a pure constraint theory, and the time evolution of the system is a gauge transformation, without carrying any physical information. One potential resolution to this issue is the relational formalism, which considers the dynamics of a material frame by coupling it to gravity. This approach allows for constructing gauge invariant observables and subsequent quantization.
One realization of the relational formalism is the Brown-Kuchaˇr formalism. In this formalism, the gravity couples Brown-Kuchaˇr dust fields, and the Brown-Kuchaˇr dust fields play the roles as a family of observers. Then, one can introduce a gauge fixing scheme to the system and construct gauge invariant observables (Dirac observables) in the reduced phase Space. The probe time of the dust plays the role as the physical time of each point of the spacetime. In this thesis, we consider the Brown-Kuchaˇr formalism in an asymptotically flat background. A set of boundary conditions for the asymptotic flatness are formulated for Dirac observables on the reduced phase space. We compute the boundary term of the physical Hamiltonian, which is identical to the ADM mass. We construct a set of the symmetry charges on the reduced phase space, which encompass both the bulk terms and the boundary terms are conserved by the physical Hamiltonian evolution. The symmetry charges generate transformations preserving the asymptotically flat boundary conditions. Under the reduced-phase space Poisson bracket, the symmetry charges form an infinite dimensional Lie algebra AG after adding a central charge. A suitable quotient of AG is analogous to the BMS algebra at spatial infinity by Henneaux and Troessaert.

Iron and manganese redox chemistry are important drivers of sulfur cycling in marine sediments. Florida Bay sediments are extremely sulfidic, having been attributed to mass mortality of seagrass and oxygen depletion in the water column. This research used conventional sediment analyses and a diagenetic model to infer the overall capacity for Florida Bay sediments to eliminate hydrogen sulfide and prevent high rates of sediment dissolved oxygen consumption via hydrogen sulfide reoxidation. Previous studies have suggested that iron is important for buffering hydrogen sulfide in Florida Bay sediments, while the results of this project show for the first time that this phenomenon is relevant only in specific locations and times of the year. However, my research indicates that Fe has the potential to sequester sulfides and minimize hypoxia in the Everglades system. Thus, under a scenario that greater amounts of Fe are delivered to Florida Bay sediments from freshwater flows under Everglades restoration, Fe could be a component of ecosystem management.

Feed is a novel set in a fictional post-revolutionary Nebraska, at a time when the developments and progress of the revolution begins to come into question. The former revolutionaries must dive into an internet-like database, referred to as the Feed, in order to unearth memories critical to their survival.