UC Riverside

This thesis examines how queer Chicanx artists negotiate belonging under inner-cultural control through lowrider visual culture in The Q-Sides exhibition. The first chapter, “Up in Flames: Iconoclastic Por Vida,” focuses on Manuel Paul’s mural Por Vida in San Francisco’s Mission District. I begin with a formal analysis of the three panels of the mural to show how Paul transforms traditional Chicanx imagery to represent queer intimacy, transgender visibility, and lesbian autonomy within a historically masculine cultural context. The chapter then goes into the mural's presence on Instagram, revealing how comments and reactions demonstrate digital control of visibility, and uses Koritha Mitchell’s “know-your-place aggression” to interpret efforts to regulate queer visibility in the community. It also traces how these issues led to acts of vandalism and arson, framing the mural’s destruction within a broader history of policing the intersectional queer and Latinx bodies in public spaces. The chapter concludes by considering the afterlife of Por Vida through photography and The Q-Sides exhibition, especially Fred Rowe’s photographic print and House of MORE!, exploring how queer Chicanx artists utilize reproduction and performance to reclaim agency and preserve collective memory that confronts the erasure of queerness in Chicanx spaces. The second chapter, “Disidentifying the Lowrider: Portraits from The Q-Sides,” explores how The Q-Sides photographic series reimagines lowrider visual culture from a queer perspective. I take photography, portraiture, and performance into account in how the photographs aim to reclaim visibility for queer and trans Chicanx and Latinx subjects within a traditionally heteronormative and masculine cultural context. I analyze two photographic prints from the twelve photographs in The Q-Sides, Volume 10 and Volume 3, by artists Vero Majano, Brown Angel, and Kari Orvik, to demonstrate how José Esteban Muñoz’s concept of disidentification embeds itself within the series. As with working on a lowrider, the artists rework the familiar visual language of East Side Story mixtape covers and modify imagery associated with heteronormative Chicanx identity into symbols of queer belonging. Chapter Two also contextualizes the photographs within the broader histories of criminalizing lowriders and the policing of Chicanx fashion. By looking at local queer and trans community members as documentary-style portraits, The Q-Sides broadens the visual archive of queer Chicanx photography. This series of photographs uses the medium of photography as a tool for collective affirmation for individuals of these intersecting identities. Together, these chapters demonstrate that queer Chicanx visual culture does not merely respond to complexities of visibility but actively reshapes the conditions of visibility imposed upon it. Artists in The Q-Sides use various mediums such as muralism, photography, and drag to assert queer belonging in lowrider visuals. Their art demonstrates that visibility is never neutral and interlocks with issues within systems that continue to control bodies over race and gender. By exploring how queer Chicanx artists address these challenges, this thesis contends that visual culture serves not only as a form of representation but also as a means of survival by self-representation in modern California.

Despite a two-fold increase in doctoral attainment among Latinas in the U.S. over the past two decades, disparities in completion persist compared to other racial-ethnic groups. A lack of social support in academia contributes to isolation and intentions to drop out among Latina doctoral students, highlighting the need to better understand and address their experiences. Guided by Latina/o Critical Theory, Community Cultural Wealth, and Ecological Systems Theory, this dissertation examined how Latina PhD students in U.S. social science programs navigate relationships with mentors, advisors, and peers, focusing on support and conflict. It also explored their use of social media for support and their interactions with institutional resources.This study addressed five research questions related to culturally responsive mentoring, advisor conflict navigation, peer support and conflict resolution, online social support, and institutional support. Using a multi-method design, Study A collected survey data from 214 Latina PhD students, and Study B conducted plática-style focus groups with 40 first-generation Latina PhD students to examine the mechanisms and cultural factors shaping relationship dynamics in academia. Notably, participants reported limited use of social media and minimal institutional programming to support relationship-building, and thus, these areas were examined descriptively. Findings highlight the complex, culturally embedded ways in which Latina PhD students navigate academic relationships. For mentoring, three themes emerged: adaptation and resources, relational mentoring, and critically conscious mentoring. Advisor conflict navigation was shaped by cultural dissonance, persistence, and resistance, and navigating whiteness and belonging. Peer support revealed five key forms, including academic mentoring, co-processing of racialized and inequality-based experiences, emotional support, companionship, and shared identity and understanding. Additionally, online emotional support was perceived as significantly higher than informational support. These findings offer insight into how Latina PhD students persist and navigate systems not designed with them in mind and contribute to the existing literature by demonstrating that relationship navigation is a dynamic, culturally grounded process shaped by social networks, cultural values, and hierarchical structures within academia.

I study the problem of partial identification in the presence of nuisance functions in terms of moment inequality models in three dimensions. First of all, I discuss the inference for partially identified parameters of interest in unconditional moment inequalities while there are point identified nuisance functions. The parameters of interest are partially identified by the confidence set of the true parameters of interest that satisfies the uniform asymptotic size control property. Secondly, I apply the method to develop a novel structure model to infer the partially idenfied interaction effects of radio stations in the U.S. while the conditional choice probabilities serve as the nuisance functions. Our empirical results indicate negative interaction effects among different radio commercial markets. In the third dimension, I discuss the inference for partially identified parameters of interest in conditional moment inequalities while there are point identified nuisance functions. The necessary parameters of interest are also partially identified by the confidence set of the true parameters of interest that satisfies the uniform asymptotic size control property.

The ability to simulate biological phenomena across a wide range of scales has been steadily improving for decades. The atom-level approach known as Molecular Dynamics (MD) has proven remarkably useful for rationally engineering proteins, studying peptide binding, and detailing protein folding and unfolding pathways. Though the utility of MD is difficult to overstate, its simulations are expensive, relying on integrating equations of motion across exceedingly small timescales. This creates a large discrepancy between the timescales accessible to MD, on the order of microseconds, and those of biomolecular phenomena, on the order of milliseconds to seconds. The work presented here serves as a deep dive into studying patterns in MD data, formulating approaches that extrapolate phenomena from short simulations and construct a platform by which new samples may be efficiently generated. The first half of this dissertation focuses on analyzing MD data from complicated molecular machinery, beginning with a deep dive into a CRISPR Associated Transposon (CAST) system called Cascade-TniQ. A set of approaches is implemented to unveil subtle binding sites that influence conformational changes and to demonstrate synchronous motions, yielding a detailed mechanistic basis for the thermodynamics of the DNA-binding process. A second deep dive into CRISPR/Cas13a inspired the development of a method studying cross-talk efficiency known as the Signal-to-Noise Ratio, detailing the dynamic allostery responsible for activating the complex upon DNA binding. The second half introduces a neural network, SurfNet, informed by these deep dives into Cascade-TniQ and CRISPR/Cas13a. SurfNet learns a function of atomic coordinates known as a collective variable (CV) to guide MD-based enhanced sampling methods. These methods efficiently explore the space of CV outputs but require good CVs, an unsolved problem for most proteins. SurfNet was validated on the prototypical test systems of Alanine Dipeptide and Chignolin using On-the-fly Probability Enhanced Sampling (OPES). Ultimately, the work presented here is meant to assist the sample generation and analysis journeys that computational biophysicists embark on to learn as much as we can about the brilliant molecular machines known as proteins.

Protein-protein interactions (PPIs) represent critical therapeutic targets in cancer and neurodegeneration, yet their large, flat, and dynamic interfaces pose fundamental challenges for drug discovery. This dissertation develops biophysics-guided inhibitors for two therapeutically relevant PPI systems: EphA4-ephrin, which is implicated in amyotrophic lateral sclerosis, Alzheimer's disease, and cancer, and KRAS-effector, which drives oncogenesis in pancreatic, colorectal, and lung cancers. An integrated pipeline combining nuclear magnetic resonance (NMR) spectroscopy, isothermal titration calorimetry (ITC), denaturation thermal shift assays (TSA), dissociation-enhanced lanthanide fluorescence immunoassay (DELFIA), sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE), mass spectrometry (MS), and X-ray crystallography (XRC) was employed to drive rational inhibitor design and validate binding mechanisms. To target the EphA4-ephrin PPI, starting from the disulfide-stabilized β-hairpin peptide APY-d3 (Kd = 138 ± 8 nM), structure-activity relationship studies replaced the flexible β-Ala8 residue with 4-amino-5-methylthiophene-3-carboxylic acid, yielding disulfide-free peptides that adopt stable β-hairpin conformations in solution. Lead compound 22 (151G10) exhibited near-zero binding entropy by ITC, indicating conformational pre-organization, while maintaining nanomolar affinity (Kd = 137 ± 2 nM). The 2.5 Å crystal structure (PDB 9CY8) confirmed the thiophene moiety occupies the β-turn position, preserving the binding mode of APY-d3. Compound 23 (151H3), incorporating a biphenyl substituent at position 6, induced larger conformational changes in the EphA4 JK loop as evidenced by ¹³Cε-Met NMR chemical shift perturbations. Both compounds demonstrated EphA4-selective agonism, inducing receptor phosphorylation in primary cortical neurons, with compound 23 showing significantly greater activity than compound 22. Selectivity profiling confirmed minimal binding to EphA2 and weak binding to EphA3. This work establishes thiophene-based constraints as a novel β-hairpin stabilizing strategy, expanding the toolkit for conformationally restricted peptide design. To target the KRAS-effector PPI, cyclic peptides derived from KRpep-2 were engineered to position aryl-fluorosulfate warheads for covalent modification of His95 in the KRAS switch-II pocket. The lead compound 26 demonstrated pan-KRAS engagement across G12C, G12D, and G12V mutants, confirmed by gel shift assays, mass spectrometry (+1973 Da adduct), and time-dependent DELFIA IC50 improvements (159.0 ± 30.3 nM to 12.1 ± 0.3 nM for G12D after 18-hour incubation). Thermal shift assays revealed dramatic stabilization (ΔTm > 20 °C) for covalent adducts versus modest shifts (ΔTm ~4–6 °C) for reversible binders. The crystal structure of compound 26 bound to KRAS G12V displayed continuous electron density from the aryl-fluorosulfate to the His95 Nɛ̝2 atom, providing definitive structural evidence of covalent bond formation. ITC measurements confirmed that fluorosulfate incorporation did not disrupt reversible binding affinity (Kd values: 314 ± 163 nM for G12C, 100 ± 16 nM for G12D, 294 ± 69 nM for G12V). The partial covalent modification observed for wild-type, Q61H, and Q61K mutants is consistent with the reported selectivity of KRpep-2 for oncogenic KRAS variants. This strategy demonstrates that His95 covalent targeting enables pan-KRAS inhibition beyond G12C-specific drugs, addressing a critical gap in KRAS-targeted therapeutics. This dissertation establishes that conformational pre-organization reduces entropic penalties in PPI inhibitors, which was effectively quantified by ITC entropy measurements approaching zero for constrained peptides. Site-specific covalent modification of histidine residues using aryl-fluorosulfates provides a generalizable strategy for expanding the druggable proteome beyond cysteine-targeting approaches. The orthogonal biophysical validation pipeline combining NMR spectroscopy for conformational analysis, ITC for thermodynamic profiling, DELFIA for time-resolved potency assessment, and X-ray crystallography for structural confirmation, provides a robust framework for PPI inhibitor development. Lead compounds identified in both chapters 2 and 3 exhibit favorable inhibitory and binding properties, supporting their potential as chemical probes and therapeutic starting points. The thiophene-based β-hairpin constraint and His95-covalent targeting strategies are broadly applicable to other PPI systems, demonstrating how biophysics-guided design can transform "undruggable" targets into tractable therapeutic opportunities.

Conservation of natural species requires an understanding of organisms' geographic ranges and existential threats that occur within these ranges. A species’ rarity or commonness is ultimately determined by taxonomy which defines boundaries between closely related species. As rare species tend to be at inherently greater extinction risk than widespread ones, taxonomy interacts heavily with conservation. Similarly, hybridization strongly interacts with taxonomy because it points to limitations in species boundaries. Hybridization also interacts directly with conservation in that hybrid individuals are difficult to classify in terms of legal conservation status, and outbreeding may be beneficial or harmful to species’ persistence depending on context. Thus, the topics of conservation, taxonomy, and hybridization are heavily intertwined, but they have not been expressly studied together as a conceptual framework. To develop this conceptual framework, I use the study system of manzanitas to investigate how these topics interact at three scales of observation. At the population level, I show that detecting hybridization led to the discovery of a new species of manzanita and ongoing hybridization poses a threat to its persistence. At higher scales of observation, hybridization could only be inferred indirectly but remained a prominent consideration. At the subregion scale, I show that the genetic distinctiveness of federally endangered Del Mar manzanita could only be observed after broad sampling and considering all neighboring manzanita species because they appear to be linked by hybridization. The study defines the range of Del Mar manzanita which is limited to the Coast of San Diego County. At the bioregional scale, I evaluate the phylogenetic relationships of 88% of species in the genus of manzanitas and find at least partial support for the majority investigated species. I can identify which taxa seem well-understood and which taxa require further study such as several widespread tetraploid species. Overall, the study suggests that for diverse systems with frequent hybridization, higher scales of observation are useful for identifying general patterns and complications such as cryptic hybridization, but taxonomic revision is better reserved until cases can be evaluated at small or intermediate scales, especially at the population scale where it is easier to directly observe hybridization.

This dissertation examines the maintenance of Asturian, a minoritized Romance language of northern Spain, among a digitally engaged and largely diasporic community of speakers. Drawing on a mixed-methods design that combines an online survey of sixty-four participants with twenty-fi ve semi-structured follow-up interviews, the study characterizes a speaker profile it terms the Asturian Heritage Speaker (AHS). Its central argument is that the diasporic Asturian speaker resembles the heritage speaker of Spanish in the United States far more closely than the neofalante of Galician or the euskaldunberri of Basque, the new-speaker fi gures produced by the other minoritized languages of the Iberian Peninsula.The analysis advances through three interlocking questions. The first concerns the new speaker and literacy: because Asturian lacks the institutional infrastructure (standardization, co-official status, and systematic schooling) that has generated new speakers elsewhere, it produces speakers who acquire the language orally at home but rarely consolidate it in writing. Nearly sixty percent of participants placed themselves at the two lowest proficiency levels, and fewer than half had ever attended a formal Asturian class, which most described as an elective offered, when at all, at the contingent margins of a Spanish-centered curriculum. The second and analytical core addresses diaspora and semantic maintenance, arguing that the language is sustained lexically and affectively rather than systematically: it concentrates in the domains of family and intimacy, is carried by a semantically cohesive core of words reproduced with notable consistency across participants, and is conditioned by physical proximity to the region. The third examines co-officiality, where overwhelming support coexists with an internal structure in which opposition is confined to the lowest-proficiency participants. Reading quantitative distributions alongside open-ended justifications, the study concludes that attitudes toward the language are negotiated through competing conceptions of what Asturian is and what it is for, returning to the structural absence from which the analysis began.

Effective communication of medical and environmental information remains one of the most persistent challenges in modern healthcare (Berkmann et al., 2011). While scientific and clinical knowledge continues to expand at an unprecedented rate, the translation of that knowledge into formats that are accessible, trustworthy, and actionable for the general public has not kept pace. This disconnect is particularly evident in communities disproportionately affected by environmental health risks, where residents must navigate complex, and often conflicting, information about exposures, long-term health consequences, and mitigation efforts.

Given a finite group G, an equivariant map between spaces with group actions is a map that preserves the G-action. We can keep track of the equivariant maps between the quotient sets of G using the orbit category. An isovariant map is an equivariant map that preserves isotropy groups. Yeakel defines the link orbit category, which records the isovariant maps between the quotient sets of G.The subdivision of the orbit category is a stratified version of the orbit category that explicitly encodes paths through the orbit category. The classifying space functor, B, assigns to each category a topological space and interprets functors as continuous maps, and a functor is a weak equivalence if its image under B is a homotopy equivalence.In this thesis, for finite abelian groups, I construct a weak equivalence from the subdivision of the orbit category to the link orbit category using Quillen's Theorem A.

This dissertation presents three studies on development economics in India. Each uses quasi-experimental methods to estimate a causal effect that standard measurement misses or that policy design failed to anticipate. The first essay evaluates the Kanyashree Prakalpa (KP), a conditional cash transfer program in West Bengal that pays girls Rs 25,000 to remain unmarried until 18. Using difference-in-differences with NFHS-5 (2019-21) data, I find the program increased marriage likelihood by 4-6 percentage points for girls aged 16-17. Early motherhood rose by 4 percentage points. Education gains were limited to Grades 7-9. KP-exposed brides married better-educated husbands with smaller age gaps, indicating families captured the program's value through improved matches rather than delayed timing. The results show that modest transfers conditional on marital age can backfire when marriage norms are strong and verification is weak. The second essay examines five decades of climate change and technological change in Indian agriculture using district-level panel data from 1966 to 2015 for rice and wheat across 260 districts. Rice loses 9.6 percent and wheat loses 8.9 percent of yields per 100 extreme degree days. Long-difference estimates attenuate toward zero, consistent with adaptation. Green Revolution technologies explain the pattern through crop-specific channels: HYV adoption for rice, irrigation for wheat. A technology that delivered climate resilience for one crop delivered none for the other through the same mechanism. Under a moderate-emissions scenario (SSP2-4.5), projected mid-century rice losses are 2.5 percent, absent further adaptation. The third essay estimates the causal effect of short-run PM2.5 exposure on physical functioning among older Indian adults. I instrument thirty-day PM2.5 with thermal inversion days using WHO SAGE Wave 3 data. A one-standard-deviation increase in PM2.5 reduces grip strength by 1.8 kilograms and walking speed by 0.07 meters per second, each about 8 percent of the sample mean. Effects on self-reports, chronic conditions, and healthcare contact are precisely estimated zeros. Short-run pollution reduces high-effort physical capacity while leaving the rest of the survey unchanged, identifying a health margin between mortality and self-report that prior work does not cover.