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Online and offline solidarities : Dignidad Rebelde’s multi-platform art-activism
No full textWith the advent of Web 2.0, users consistently connect with others and access information. Online applications, such as Social Media platforms, are a creative space for consuming cultural content, digital marketing, and spreading awareness. Social Media giant Meta, specifically their app Instagram, allows public and private photo and video sharing. How are artists and creatives manipulating Instagram as a national and global platform to forward political values and community goals? Artist-Activist collaborative Dignidad Rebelde’s artwork exemplifies the tension between offline and online methods for advocating for social justice issues through visual and rhetorical means. In this thesis, I demonstrate how Dignidad Rebelde’s performance on Instagram does more than spread information on their artistic production and personal lives by also creating and linking networks of solidarity through complementing their offline cultural work. Through crafting an online persona that rallies for Palestinian liberation, I question how performing solidarity online accumulates a form of social capital for the artists while simultaneously employing marketing strategies for their offline screen-printed work. This project focuses on three of Dignidad Rebelde’s transmedia images, Free Palestine/Viva Palestina Libre, We Teach Life, and Hola Gatita Dice Ceasefire, primarily looking at how the works operate as posts on their Instagram page (@dignidadrebelde) in conjunction with their physical presence at local events and exhibitions. Oakland First Fridays, Crosspollination Block Party, Hands Off Rafah Rally, and the exhibition Exist & Resist & Decolonize & Indigenize & Free Palestine are events where these images reappear throughout the Bay Area in 2024. The methods of the thesis are intentionally interdisciplinary. I draw on visual analysis from an art historical lens to dive into the composition of the images. I also incorporate scholarship from American Studies and Indigenous Studies to establish a historical background between the solidarities between Chicana/o/x and Indigenous peoples with Palestinians. I bring in Digital Media Studies through the discussion of how hashtags open spaces for creating networks but also leave behind a trail for possible censorship efforts. Interviews with both the artists are interwoven throughout the thesis as their input was crucial to the development of the project.Art Histor
Doctoral thesis recital (trombone)
No full textFour unidentified works for trombone and piano.MusicName of supervisor not provide
Associations between family stress, coping, and externalizing behaviors in Latinx adolescents
No full textLatinx youth and their families experience systemic stressors in the United States, such as acculturative strain, discrimination, and economic hardship. These stressors put strain on the family system and have the potential to affect family functioning. Disruptions in parenting have been shown to increase adolescent externalizing behaviors. While externalizing behaviors are normative during adolescence and tend to wane in adulthood, the co-occurring disruption to the family system can predispose adolescents to engage in these behaviors. Latinx families possess many valuable cultural resources that protect them from stress. These values can be represented through various metrics, including the retention of heritage language skills. However, uncontrollable, systemic stressors such as socioeconomic strain create family disruptions and put their adolescents at increased risk of externalizing. Similarly, while some individuals are biologically vulnerable to continuing externalizing behaviors into adulthood, conditions of persistent stress have been shown to erode biological systems that are implicated in emotion regulation, which can put individuals without inherent biological vulnerability at higher risk of engaging in externalizing behaviors. Hyporeactivity of the sympathetic nervous system with chronic stress exposure increases the risk of externalizing behaviors and affects conscious and unconscious emotion regulation attempts in times of stress. Those under conditions of chronic stress may use less effective attempts to regulate stress. As such, there is reason to investigate associations between coping skill usage and externalizing behaviors for those experiencing systemic and familial stress, in the context of existing protective family values. This study used longitudinal data from 129 Latinx families to determine whether interim adolescent coping skill usage mediates the relationship between initial family stress and externalizing behaviors 12 months later, and investigate how socioeconomic strain and Spanish-language retention affect initial family stress and externalizing behaviors. Specifically, the current study investigated whether the use of engagement coping, which includes primary control and secondary control coping, or disengagement coping, which tends to be associated with poorer psychosocial outcomes, affect the development of externalizing behaviors in the midst of stress and protective Latinx cultural processes. Structural equation models showed significantly greater perceptions of family stress for females than male adolescents, and that greater perceptions of family stress predicted lower proportional use of engagement coping. When outliers were removed from analyses, higher proportional use of secondary control coping predicted lower levels of rule-breaking, but not aggressive behavior. In models with outliers removed, more stressed participants used higher levels of secondary control coping behaviors, which were predictive of lower rule-breaking behaviors. Female gender was predictive of higher use of primary control coping, though females under conditions of high family stress used lower levels of primary and secondary control coping. Interestingly, Spanish-language retention, a proxy variable meant to represent the transmission of protective Latinx cultural processes, predicted higher use of primary control coping skills, but not other types of coping skills. Overall, the current study adds to the literature by describing how the experience of stress can influence the development of externalizing behaviors by predisposing individuals to use lower levels of effective coping techniques. Similarly, the current study advances the literature by demonstrating this effect in a group of Latinx adolescents from immigrant-origin families.Educational Psycholog
Time, space, and energy in computation
No full textTime, Space, and Energy are the three most important measures of cost for computation. In this dissertation, we explore multiple ways of understanding these costs as notions of complexity for classical and quantum computation. This includes traditional ideas that are well established within the field of theoretical computer science alongside new approaches inspired by modern computing environments and recent developments in stochastic thermodynamics. We do this by discussing topics including the spooky pebble game, quantum time-space tradeoffs for matrix problems, cumulative memory complexity, Brownian computation, and the entropy production of Boolean circuits.
The spooky pebble game characterizes time-space trade-offs for the quantum simulation of irreversible classical circuits using intermediate measurements. We show asymptotically tight upper and lower bounds on the number of steps (or time) needed to pebble the line graph with any given pebble (or space) bound. This gives a general technique for simulating any irreversible classical computation on inputs in superposition with a better time-space trade-off than would be possible only using reversible simulation. We also generalize the spooky pebble game to arbitrary DAGs and show that in general finding the minimum number of pebbles required to pebble a graph is PSPACE-hard to approximate.
We introduce a new technique for applying Zhandry's quantum recording query method to prove tight quantum time-space product lower bounds for matrix problems. Using this technique we prove that for any space bound S, there is at most a constant factor speed up between S bit classical algorithms and S qubit quantum algorithms that compute the matrix-vector product function f(x) = Ax or the matrix multiplication function f(A,B) = AB. We also introduce a new coloring technique that improves the best known quantum lower bound for Boolean matrix multiplication by a factor of S[superscript 1/4].
Cumulative memory complexity, the sum of the space needed per step of an algorithm, is a notion of time-space complexity originally formulated for password hashing. We justify cumulative memory as a modern measure of complexity for general algorithms that run on a shared device in the cloud or on a high performance computing system. We prove that virtually all known methods for proving unconditional time-space product lower bounds for classical and quantum algorithms, including our new bounds for quantum linear algebra, can be extended to give matching asymptotic bounds on the tighter notion of cumulative memory complexity. Thus, current techniques are insufficient to prove an unconditional asymptotic gap between cumulative memory and time-space product complexity.
Finally, we explore recent connections between the fields of stochastic thermodynamics and theoretical computer science to evaluate the energetic costs of computation. We provide an overview of how stochastic thermodynamics can be applied to computation and present a general strategy to build devices that can perform computation with an energy upper bound that only scales linearly with the size of the input and output regardless of the time complexity of the computation. We also consider the energetic costs of Boolean circuits, and prove that optimizing the energy efficiency of gates in a Boolean circuit is PP-hard and NP-hard to approximate.Computer Scienc
Multimodal spatio-semantic perception and team performance evaluation for hierarchical human-robot interaction in dynamic environments
No full textRobots are increasingly deployed alongside humans in dynamic environments. However, effectiveness in hierarchical teams–such as those in defense or disaster
response–is hindered by a lack of specialized perception systems and "in-the-wild" teaming studies. This dissertation addresses these limitations through three primary research thrusts: 1) the design and evaluation of a multi-object tracking framework to provide robust spatial perception of nearby persons in real-time; 2) the development of a novel spatio-semantic multimodal fusion method to enable hierarchical interaction by simultaneously estimating human roles, commands, and positions; and 3) an empirical user study to evaluate the effects of human-robot team structure on task performance. The tracking evaluation identified key performance tradeoffs for deployment on robot hardware and demonstrated that augmenting onboard robot sensors with data from human-worn sensors unilaterally improves tracking accuracy. The spatio-semantic perception system proved viable for fusing hierarchical information, but requires more advanced modeling to accurately estimate temporal communications from speech and gesture. Finally, the user study confirmed that team structure is a significant factor on human-robot team performance, and that human-robot team performance is strongly mediated by team communication and strategy
selection. Taken together, this dissertation demonstrates that effective hierarchical human-robot teaming should combine robust, context-aware spatio-semantic perception with an empirical understanding of team and environment dynamics. The findings provide a foundation and actionable insights for the design and deployment of human-robot teams in complex, realistic operating environments.Mechanical Engineerin
Multilayer part fabrication in the microscale selective laser sintering process
No full textMicroscale selective laser sintering (μ-SLS) is a metal additive manufacturing (AM) technique developed to address the trade-off between resolution and throughput in metal AM processes at the microscale. The process utilizes a digital micromirror device to project light patterns onto a layer of nanoparticle ink, selectively sintering the material. This work focuses on the development of key system components for the µ-SLS system to enable reliable multilayer fabrication, showcasing its 3D printing capability for producing interconnects in advanced microelectronics packaging. A central achievement was the development of a novel automated coating process capable of depositing uniform and repeatable sub-micron layers on top of previously sintered material. To ensure the geometric fidelity of parts, this system was integrated with advanced thermal control strategies that utilized grayscale modulation of the DMD. The successful fabrication of previously unattainable three-dimensional, multilayer geometries has validated this system's multilayer capability.Mechanical Engineerin
Domain wall based magnetic tunnel junction devices for neuromorphic computing
No full textArtificial intelligence is expanding in both scale and scope exponentially, and current implementations rely on CMOS technology to simulate neural networks which is inefficient and requires immense power. Neuromorphic computing seeks to alleviate this bottleneck by shifting the computing paradigm from von Neumann architecture to brain-like computing to approach the extreme efficiency and performance of a human mind. Domain wall (DW) motion allows for much more complexity in a single device than conventional CMOS transistors such as leaky-integrate-fire (LIF) behavior of neurons and nonvolatile multi-weight (MW) states of synapses which can be fabricated monolithically, allowing for complex and efficient neural networks. Here I show a novel fabrication method to retain pristine film performance in patterned nanodevices with high tunneling magnetoresistance (TMR) and DW control. By varying the magnetic tunnel junction (MTJ) and DW track shapes independently many variations of both neurons and synapses are fabricated monolithically. For synapses we show both linear and metaplastic devices with MW states using a single MTJ. For neurons we show both noise-resilient stochastic neurons and initial LIF prototypes. The primary achievement of this work is tunability. To begin with, the critical writing voltage variation for DW logic devices was shown to decrease an order of magnitude when a DW is first initialized with an external electrical Oersted Line. Additionally, stochasticity was also shown to be highly varied by pulse amplitude, allowing the full range of firing probability per pulse to be accessed in our DW-MTJ neuron device. Two variations of DW track shape were utilized in DW-MTJ synapse devices to achieve both linear and metaplastic switching behavior, allowing for highly specialized functions to be intrinsic and predetermined simply. Finally, LIF devices were explored capable of stochastic MW leaking and integration. Asymmetric notches were designed to allow for MW integration in one direction and leaking in the other to allow for higher functionality.Electrical and Computer Engineerin
Neutron activation of materials surrounding a molten salt research reactor
No full textThis Master’s thesis presents the neutron irradiation characterization of construction materials surrounding the Molten Salt Research Reactor (MSRR) at Abilene Christian University, conducted through the Natura Resources Research Alliance (NRRA). Neutron Activation Analysis (NAA) was performed to determine the elemental concentration and identify neutron-activated radionuclides of various materials of interest. The technique involved irradiating samples of unknown concentrations alongside standards of known concentration. Irradiation of these materials with neutrons will activate some of the elements in the material into radioactive isotopes that can be counted on a detector. Following irradiation, the gamma-ray spectra of the samples were obtained using a high-purity germanium (HPGe) detector. The elemental concentration of each material of interest was calculated using the comparator method. This thesis details the results from both Trial 1 and Trial 2. Trial 1 revealed that the iron-based aggregate and steel samples demonstrated significantly higher cobalt concentrations than the other materials (66-139 ug/g). The iron-based aggregate, select fill, sand, rock in SERC, cement, and fly ash samples were the only samples with traceable amounts of europium (0.2-5 ug/g). In contrast, the samples of the water seal, water stop, and waterproof tape did not have traceable concentrations of cobalt or europium. Trial 2 evaluated three iron-based aggregates for use in the heavy concrete shielding at the top of the reactor. Among them, M 3_2 Fine Steel Aggregate demonstrated the lowest activation potential, with no detectable europium and cobalt levels between 41.9 and 44.3 ug/g. M 3_2 Fine Steel Aggregate also contained the highest iron content (86.3%-95.1 %), beneficial for radiation attenuation. The primary objective of this work was to identify radionuclides produced by neutron activation in the construction materials surrounding the MSRR that must be monitored and disposed of as radioactive waste if they exceed regulatory limits. Furthermore, future dose rate calculations using the concentration data presented in this study are essential to ensure compliance with radioactive waste management regulations.Mechanical Engineerin
Doctoral thesis recital (piano)
No full textUnidentified work --- Piano sonata no.12 in F major, K 332 / Wolfgang Amadeus Mozart --- Unidentified work --- Variations on a theme of Corelli, op. 42 / Sergei Rachmaninoff.Musi
Symmetry-protected Topological Polarons
No full textWhen electrons move through a solid, they can distort the surrounding lattice and become trapped, forming composite particles known as polarons. These distortions were long assumed to be trivial, consisting of simple contractions or expansions of the lattice around the electron.
Previous ab initio simulations based on affordable large supercells (tens to hundreds of atoms) also confirmed this intuition. This view has changed with the recent discovery of vortex-like patterns in halide perovskites when the simulation scaled up to near a half of million atoms.
In this work, we show that such topologically nontrivial textures, characterized by integer-valued topological indices, are not unique to perovskites but are a general feature of polarons in a broad range of materials. All these demonstrations are only plausible for millions of atoms simulated at atomic scales, and they are made possible with one of the most powerful supercomputers in the world (i.e., Frontera).
The discovery of universal topological quantization in polarons opens new opportunities for using these quasiparticles as information carriers in post-Moore electronics and quantum information science.Texas Advanced Computing Center (TACC