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ESSAYS ON TRADE AND INNOVATION
No full textThis dissertation examines the interactions between international trade and innovation, highlighting their rich heterogeneity. The first chapter introduces the distinction between research and development to the trade literature and shows that globalization shifts firms’ focus from research toward development. The second chapter, leveraging global firm-level data, confirms that foreign direct investment (FDI) facilitates cross-border knowledge diffusion while revealing its heterogeneous effects, which depend on factors such as host-country absorptive capacity and investment type. The third chapter provides empirical evidence that well-designed industrial policies can effectively stimulate firms’ innovation and export activities. Together, these chapters offer new insights into how firms’ innovation strategies adapt to international economic forces and policy interventions, with broader implications for trade and innovation policy.
In the first chapter, I show that globalization has shifted U.S. corporate innovation from scientific research to commercial development. Analyzing data from publicly traded firms, I find that substantial tariff reductions at export destinations following the ``Uruguay Round'' led U.S. firms to focus on a narrower range of technologies, reducing their emphasis on scientific research. To explain these findings, I develop a multi-product firm model that distinguishes between research and development. Globalization—represented by expanded market size or lower trade costs—reallocates profits toward products for which firms hold a competitive advantage. Consequently, firms increasingly prioritize developing core products over broader research. The model embeds a crucial welfare trade-off: development increases the supply of high-productivity products, but research enhances the overall innovation efficiency of the economy through knowledge spillovers. Calibration to U.S. manufacturing firms shows that allowing separate decisions on research versus development amplifies the productivity gains from globalization but reduces welfare gains. The welfare-maximizing policy suggests that research subsidies should exceed development subsidies, particularly after globalization, to counteract the decline in research share.
The second chapter (co-authored) investigates the impact of Foreign Direct Investment (FDI) on knowledge diffusion by examining how firm-level FDI activities influence cross-border patent citations. (This chapter is from a joint work with JaeBin Ahn, Nan Li, and Andrea Manera.) We construct a novel firm-level panel dataset that combines global utility patent data with project-level information on greenfield FDI and cross-border mergers and acquisitions (M\&A), covering 60 countries over two decades. Applying a new local projection difference-in-differences methodology, we find that FDI significantly enhances knowledge flows both from and to investing firms, with stronger effects observed for greenfield FDI compared to M\&A. Our results also reveal substantial heterogeneity in FDI spillovers: host countries with higher innovation capacity or greater technological similarity to the investing firm benefit disproportionately, while countries with lower absorptive capacity capture fewer gains. In addition, we also uncover knowledge spillovers beyond the targeted firms and industries, particularly in sectors closely connected in the technology space.
The third chapter (co-authored) empirically examines the impact of industrial policies on firm innovation and exports. (This chapter is from a joint work with Luis F. Jaramillo.) Specifically, we examine South Korea’s first “mission-oriented” R\&D program, implemented between 1992 and 2001, and its impact on innovation and economic outcomes. Using newly compiled textual data and a language model to identify targeted and control technological classes, we exploit an exogenous source of variation: some planned research projects were not implemented due to budget shocks. We apply a local projections event study to compare the outcomes of targeted and control technological classes. Despite no differential trends before the program, ten years after its extension, future-citation-weighted patenting output in the targeted classes had doubled, and real exports had tripled relative to the control classes. These findings remain robust in cross-country evidence. Moreover, we find that technological classes with less concentrated patenting activity before the program drive the results. Our findings suggest that technology policy played a crucial role in South Korea’s transition to a knowledge-intensive economy
FLEXIBLE INPUT FOR NOVEL VIEW SYNTHESIS
No full textSynthesizing novel views of a scene from a limited number of input images is a long-standing problem. It has enormous practical applications, such as virtual museums, online meetings, and sports event streaming. The emergence of virtual reality technology has also made it easier for people to observe and interact with virtual environments, highlighting the needs in robust and efficient view synthesis.In recent years, this field of research has seen large advances in neural radiance fields (NeRFs) and 3D Gaussian Splatting (3DGS). Although these methods achieve efficient high-quality view synthesis, they require careful and dense capturing in controlled environments. Therefore, much research effort has been made to relax the requirements, like allowing dynamic scenes and handling variance in lighting. This thesis presents our work along this path of enabling novel view synthesis from challenging inputs. In particular, we focus on three scenarios.
First, we tackle the problem of unwanted foreground objects, like moving people or vehicles present in front of a building. As these objects cast shadows and reflections, naively masking the objects leaves artifacts in background reconstruction. We propose a method to decompose foreground objects with their cast effects into separate 2D layers and a clean 3D background layer.
Second, we address view synthesis from very few inputs. With as few as three input views, we leverage recent developments in large image and video generation priors to interpolate in-between views for better supervising scene reconstruction methods. To improve both efficiency and quality, we use a feedforward geometry foundation model to obtain a dense point cloud that serves as condition images to the image priors. In addition, we introduce optimizable image warps and a robust view sampling strategy to deal with inconsistencies in generated images.
Lastly, we consider an extended problem of inverse rendering which decomposes the scene into geometry, material properties, and environment lighting. It not only enables synthesis of novel views via rendering, but also provides extended capacities like scene editing and relighting. We propose a simple capturing method by rotating the object several times when taking photos. With this setup, we show that the artifacts caused by ambiguity can be drastically reduced. We model the scene with 2D Gaussian primitives for computational efficiency and make use of a proxy geometry as well as a residual constraint to further improve handling of global illumination.
The works presented in this thesis improve the quality and robustness of novel view synthesis with challenging input data. Further research efforts can be made along the lines to enable casual capturing and lower the bars for creating and sharing digital content from the real world
INVESTIGATION OF DUAL ACTIVE BRIDGE (DAB) DERIVED POWER DENSE SINGLE-STAGE ISOLATED INVERTERS
No full textPower electronics converters are increasingly gaining importance in renewable energyapplications. Single-phase inverter, in particular, which converts direct current (DC) to alternating
current (AC) power or vice versa, is one of the most promising applications of power electronics
in avenues such as solar photovoltaic (PV) and electrified transportation. Traditionally, the
architecture of isolated single-phase inverters requires two discrete power conversion stages, i.e.
an isolated DC-DC stage with a voltage boost cascaded with an additional high voltage DC-AC
stage. This Ph.D. dissertation proposes a study of isolated single-stage inverters based on dual
active bridge (DAB) converters, which are typically used for DC-DC conversion. By studying
the impact of topological modifications using direct matrix variations, this study extends the
advantages of DAB converters for compact and high-efficiency inverter applications.
This dissertation makes several key contributions toward the development of compact,high-performance single-stage DAB-based inverters for grid-tied applications. A frequency
domain modeling framework is introduced to accurately capture the steady-state operation and phase-shift dependencies of DAB converters during AC line-cycle operation. Dual-phase shift
modulation is used to regulate power flow, and a numerical optimization routine is developed to
minimize current stress and switching losses while trying to meet zero-voltage switching (ZVS).
To facilitate real-time implementation, a three-dimensional lookup table (3D LUT) with trilinear
interpolation is employed to determine optimal modulation parameters across the AC line cycle.
The models and control strategies are validated through hardware implementation in a 400W
GaN-based inverter prototype.
The dissertation also addresses battery reliability in low-voltage charging systems, wheresecond-order current ripple (SOCR) can lead to increased losses and degradation. A bidirectional
single-stage AC-DC converter with an active boost compensation circuit is proposed to mitigate
SOCR while preserving system compactness. This solution eliminates the need for bulky passive
filters or large intermediate DC-link capacitors commonly used in two-stage converters. The
proposed architecture supports galvanic isolation and bidirectional power flow, making it well
suited for grid-to-battery (G2B) and battery-to-grid (B2G) applications. Experimental results
confirm significant ripple attenuation and reduction in internal battery power loss, validating its
application in residential storage and electric mobility.
Additionally, integrated power decoupling (iPD) topologies are proposed to address secondorder ripple in single-phase systems without relying on external bulky components or additional
active stages. These iPD configurations incorporate ripple buffering directly into the main power
flow path. Detailed analysis of capacitor sizing and current profiles demonstrates that iPD
topologies can significantly reduce system volume while maintaining performance. Overall, the
research establishes a unified, compact, and efficient framework for single-stage DAB-based
inverter systems in next-generation renewable energy and electrified infrastructure
Square Pegs, Round Holes: Making high-density offsite storage a solution to archival space constraints
No full textFor collection managers of special collections materials, Severn Library’s high density offsite storage presents solutions to archival space constraints, as well as unique challenges. Chief among these is the quandary of integrating what can be inherently non-standard material into storage designed to be highly standardized. Together, Severn Library and Hornbake Library personnel adapted our collection management processes around the constraints of a facility intended to house broader general collections. These adapted strategies can be of use to librarians considering offsite storage for mixed materials while also confronting challenges of space and place. This poster presentation illustrates how our libraries established collections housing standards, drafted selection guidance to identify materials for offsite storage, and created a project management workflow to facilitate shared understanding of processes and efficient transfer of materials. Among other processes, the workflow addresses identifying and engaging project partners, creating a project plan, facilitating transfer logistics, and tracking materials over the lifecycle of a transfer project. The poster also covers use of project management tools and collections management systems, as well as interpersonal considerations, including communication and interlibrary collaboration
SUPERORDINATE IDENTITIES: NATIONAL IDENTITY, EMOTIONS, AND WARTIME PUBLIC OPINION
No full textAlthough wartime public opinion has explored the various ways casualties influence wartime attitudes, international relations scholars have not yet paid sufficient attention to the influence of national identity and the effect of emotions on influencing and changing political attitudes. Understanding the relationship between identity saliency and emotions furthers the field by expanding influence and information studies and the of framing effects that may otherwise be ignored. I propose a theory focused on the relationship between identity saliency and emotional states in determining public attitudes in conflict situations. I argue that individual-level attitudes are informed by the identity held salient at that point in time which is influenced by the situational context as well as an individual’s emotional state. However, while I am speaking of individually primed emotional states, the focus is on collective emotions as related to their collective identities and how in general a member of the same group would react. I propose a model of wartime attitude formation expanding behind the logic that attitudes are informed by generalized values that determine specific foreign policy preferences (Peffley & Hurwitz 1993 and Hurwitz & Peffley 1987), these specific policy preferences are informed in addition by the situational and strategic context at hand (Herrmann, Tetlock, & Visser 1999) and that specific values are previously informed by our social identity categorizations (Trepte & Loy 2017, Billig & Tajfel 1973, Tajfel, Billig, Bundy 1971, Hornsey 2008). I extend this conversation by focusing on the impact of emotions on foreign policy attitudes across a spectrum of emotions, and the impact emotions have on national identity saliency
Insoluble Methylene Bridged Glycoluril Dimers as Sequestrants for Dyes
No full textContamination of water bodies by micropollutants including industrial dyes is a worldwide health and environmental concern. We report the design, synthesis, and characterization of a series of methylene bridged glycoluril dimers (G2W1 – G2W4) that are insoluble in water and that differ in the nature of their aromatic sidewalls (G2W4: benzene, G2W3: naphthalene, G2W1 and G2W2: triphenylene). We tested G2W1 – G2W4 along with comparator H2 as solid state sequestrants for a panel of five dyes (methylene blue, methylene violet, acridine orange, rhodamine 6G, methyl violet 6B). We find that catechol-walled H2 (OH substituents) is a superior sequestrant compared to G2W1 – G2W4 (OMe substituents). X-ray crystal structures for G2W1 and G2W3 suggest that the OMe groups fill their own cavity and thereby decrease their abilities as sequestrants. H2 achieved a removal efficiency of 94% for methylene blue whereas G2W1 demonstrated a 64% removal efficiency for methylene violet; both sequestration processes were largely complete within 10 minutes.We thank the National Science Foundation (CHE-1807486) for past financial support. We thank the National Institute of General Medical Sciences of the National Institutes of Health (R35GM153362) for current financial support of this project. S.P. thanks the University of Maryland for the G. Forrest Woods Fellowship and the Charlotte Kraebel PhD ’59 Endowed Award in Organic Chemistry
Power To The People: The Community's Role In Public Archeology
No full textIn the 1970s, the emergence of public archeology, a discipline within archeology aimed to engage the participation of the public, led many to raise questions about the public's role in the proper stewardship of cultural materials. The public is encouraged to not only be viewed as the audience, but as equal partners alongside archeologists. With final reporting, analyses, and curation of objects requiring specialized skills, broad participation in the final stages of projects has been limited. Generally, archeologists are viewed as the arbiter of significance in the collections management process and the public's role is challenged as their participation does not often lead to meaningful input into our understanding of the site or material. Using a post-processual theoretical framework, the questions I raise are how does the general public become involved in public archeology, and is the general public aware of its role in public archeology? If not, how can archeologists increase public participation levels? To answer the research questions, I reviewed responses from a questionnaire by the Texas Historical Commission (THC) and conducted an anonymous survey of the public, aiming to elicit the public’s opinion on public archeology. The results of the event and anonymous survey reveal that the public is limited in their participation levels by a lack of communication with archeologists and knowledge of what archeology entails. An analysis was conducted to provide reasons as to how both archeologists and the public can benefit from them volunteering alongside archeologists in the future, which includes empowering communities, expanding their knowledge, and raising awareness for archeology as a field of study
INVESTIGATING PRINCIPAL SUPERVISOR ACTIONS THAT SUPPORT PRINCIPAL INSTRUCTIONAL LEADERSHIP
No full textThis study investigated the role of principal supervisors in educational leadership within the K–12 Grand Royal School System (GRSS). It examined what principal supervisors do to build principals’ instructional leadership capacity—and to what extent their actions support principals in leading teaching and learning. Using a mixed-methods approach, including surveys, interviews, observations, and document analysis, the study explored the daily practices of principal supervisors and their interactions with principals.Findings show that GRSS principal supervisors value instructional leadership and often use goal-setting and formal observations to build principals’ capacity. However, their daily work is frequently consumed by operational demands, community concerns, and compliance tasks, which limit their ability to focus on instruction. Although most participants agreed that principal supervisors were accomplished instructional leaders, neither principals nor supervisors cited specific examples of support that led to instructional improvements. This gap was attributed to systemic barriers such as competing district priorities, ambiguous role expectations, and limited time.
In addition to these core findings, interviews revealed several unexpected insights, including supervisors’ lack of control over their schedules, inconsistent implementation of site visits, and a shared sense of nostalgia for earlier support structures. Supervisors also described the emotional toll of the role, marked by stress and strain from balancing competing demands without sufficient authority or systemic support. These perspectives provided valuable context for interpreting survey results and underscored the disconnect between the role’s intended purpose and its day-to-day realities.
While participants believed in the potential of the supervisor role to enhance leadership and improve learning outcomes, they acknowledged that current conditions often prevent it from functioning as intended. The study concludes with recommendations for restructuring the principal supervisor role and strengthening support for central office leaders who serve in this capacity.
INVESTIGATION OF GLYCOENZYME SUBSTRATE SPECIFICITY FOR GLYCOENGINEERING OF THERAPEUTIC ANTIBODIES
No full textImmunoglobulin G (IgG) antibodies have been exploited as drug candidates due to their target specificity and ability to elicit host cell effector functions. These Y-shaped glycoproteins possess two antigen-binding (Fab) regions for selective binding to epitopes and one constant (Fc) region for mediating effector functions. As glycoproteins, these antibodies are also N-glycosylated at position N297, where the Fc glycans modulate the stability and effector functions of the antibodies. However, due to the non-template synthesis of these antibody glycans, the resulting oligosaccharide composition and structures are highly heterogeneous. My work aims to leverage the substrate specificities of various glycosyltransferase enzymes to generate antibody preparations with homogenous glycan structures. For my first project, I performed a comparative study on three sialyltransferases, including two bacterial sialyltransferases from Helicobacter cetorum (HcST-22) and from Photobacterium damselae (Pd2,6ST), respectively, and the human -2,6-sialyltransferase (ST6Gal1), to determine which is more efficient at sialylating intact antibody Fc glycans. We found that HcST-22 was more efficient than Pd2,6ST and ST6Gal-1 at sialylating intact Fc glycans. For my second project, I contributed to a collaborative effort in generating intravenous immunoglobulin (IVIg) glycoforms. I incorporated two sialic acid derivatives, 2-keto-3-deoxy-D-glycero-D-galacto-nononic acid (KDN) and 9-azido-9-deoxy-Neu5Ac (9AzNeu5Ac), onto free glycan before transferring these glycans onto deglycosylated IVIg. The resulting azide-tagged IVIg was then further elaborated by the click addition of sialocomplex-type glycan asparagine with a DBCO tag (SCT-Asn-DBCO) to yield a final glycoform that extended the Fc glycan and increased the valency of the terminal native sialic acid. For my third research project, I designed a novel Fc-glycosylated site-specific antibody drug conjugate (ADC) design with a drug to antibody ratio (DAR) of 6. I achieved this by glycoengineering the Fc glycan of recombinant trastuzumab to generate a triantennary agalactosylated complex type glycan at the N297 position. Then, using a mutant N-acetylgalatosamine (GalNAc) transferase enzyme β1,4-GalT Y289L I transferred N-azidoacetylgalactosamine (GalNAz) to each glycan terminus of the triantenary Herceptin, then click-conjugated a cytotoxic payload onto each azide on the antibody Fc region, generating a trastuzumab ADC with a DAR of 6. Through a cell viability assay, we determined that this homogeneously glycosylated DAR-6 ADC showed potent anti-cancer activity
Floquet Theory Analysis of Rotor Blade Aeroelastic Stability at High Advance Ratios
No full textA compound rotorcraft operating at high forward speed may slow its rotor, resulting ina high advance ratio (μ). While this mitigates compressibility effects, it creates stability
challenges, which are explored in the present work. The aeroelastic stability characteristics
of rotor blades are analyzed in the rotating frame using Floquet theory for high-μ
flight. Linearized coupled equations of motion are derived for the flap, lag, and torsion degrees
of freedom for an isolated rotor system, with the assistance of symbolic manipulation
software. Periodic coefficients, reverse flow, unsteady aerodynamics, pitch-flap/ pitch-lag/
structural coupling, chordwise center of gravity, aerodynamic center, and other structural
and aerodynamic properties are considered. The flap trim state is found through periodic
shooting, and a stall model provides bounding for stability predictions. Through numerical
integration of the state transition matrix, the resultant eigenvalues and eigenvector motion
allow for the determination of the type of response to perturbations from trim. A novel
eigenvalue trajectory tracking method using a modal analysis of the periodic eigenvectors
allows for a consistent identification of roots as parameters are changed. Damping and
frequency response behaviors are evaluated, and rotor stability boundaries are presented for
numerous configurations, to include various articulated and hingeless blade types. Advance
ratios in excess of μ=3 are explored, with evaluations of both physical dynamic stability
and numerical stability. Trim and stability predictions are validated using historical analyses
and experimental results, a fundamental understanding of associated phenomena such
as parametric resonance is achieved, and recommendations regarding stable configurations
are provided