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Collaborative Settler Colonialism: Japanese Migration to Brazil in the Age of Empires
No full textThough Japanese migration to Brazil started only at the turn of the twentieth century, Brazil is now the country with the largest ethnic Japanese population outside Japan. Collaborative Settler Colonialism examines this history as a central chapter of both Brazil’s and Japan’s processes of nation and empire building and, crucially, as a convergence of their settler colonial projects. Inspired by American colonialism and the final conquest of the U.S. Western frontier, Brazilian and Japanese empire builders collaborated to bring Japanese migrants to Brazil, which had the outcome of simultaneously dispossessing Indigenous Brazilians of their land and furthering the expansion of Japanese land and resource possession abroad. Bringing discourses of Latin American and Japanese settler colonialism into rare dialogue with each other, this book offers new insight into the Japanese empire, the history of immigration to Brazil and Latin America, and the past and present of settler colonialism.Fondren Librar
Seeing without revealing: Privacy-Aware Computational Cameras and Decentralized Learning Frameworks
No full textIntegrating cameras and vision algorithms into our daily lives has led to the development of a wide range of new applications but also has raised significant privacy concerns. This thesis reimagines these applications in a privacy-aware fashion, enabling optimal privacy-utility trade-offs. The solutions it explores leverage the design degrees of freedom offered by three domains: optics, electronics, and digital computing.
In the initial segment, the thesis delves into the utilization of optical computing to obstruct facial identity while facilitating downstream applications such as depth estimation, human pose estimation, person detection, and activity recognition. This optical computing is enabled by either a single-layer diffractive optical element or a metasurface whose parameters are optimized in an end-to-end learning pipeline using adversarial optimization. The results are computational cameras that achieve optimal privacy-utility trade-offs and are validated using proof-of-concept hardware.
The subsequent part of the thesis examines the application of an analog electronic chip designed to execute a shallow Convolutional Neural Network (CNN) for per-pixel analysis. This electronic NN is trained to output only pixels with non-private information, avoiding imaging faces. This method underscores the potential of electronic analog computing in enhancing privacy in vision systems.
Finally, the thesis presents a decentralized digital solution that facilitates the collaborative creation of global crowd-sourced Neural Radiance Fields (NeRFs). This involves the introduction of a novel federation scheme and a secure multi-party computation protocol, ensuring high-quality 3D reconstruction for immersive viewing without compromising the users' privacy
Welfare Prioritarianism
No full textThis dissertation defends welfare prioritarianism, a consequentialist theory of distributive justice that gives absolute priority to the worst-off individuals in a society. If utilitarianism’s slogan is “the greatest good for the greatest number,” then welfare prioritarianism’s is “the best for the worst-off.”
Chapter one locates welfare prioritarianism in logical space. Attention is given to its structural similarity to utilitarianism, some shared challenges for these views, and some strategies for addressing these. The intention is to acknowledge these problems but allow for later chapters to focus on prioritarianism, using utilitarianism as a foil.
Chapter two presents one version of the “separateness” objection to utilitarianism, the Argument from Cases. Of particular importance are the Utility Monster, who can convert resources into welfare with unusual efficiency, and the Utility Martyr, who requires vast resources to make minor welfare gains. I argue that, despite structural similarities, the monster grounds an objection to utilitarianism, but the martyr does not ground a corresponding objection to prioritarianism; instead, it supports the view.
Chapter three considers objections to the Argument from Cases. Questions here include: can utilitarianism answer the separateness objection; are the descriptions of certain cases inappropriate to questions of justice; and can sufficientarianism satisfy the prioritarian’s concerns? The most damaging objection is that the argument depends too much on interlocutors’ intuitions about the cases presented.
Chapter four presents a second form of the separateness argument—the Argument from Value Theory—which gives more direct, intuition-independent support for prioritarianism. I begin by arguing that a common utilitarian intuition about intrapersonal welfare aggregation is mistaken. Next, I consider utilitarian proposals for interpersonal welfare aggregation and reject each as inaccurate to human life. Then, borrowing from deontic views of social choice, I argue that the nature of human welfare requires the evaluative method of pairwise comparison, and that this method provides direct support for absolute prioritarianism.
Chapter five expands the scope of welfare prioritarianism to account for deaths in a population and justice over generations. Finally, chapter six addresses the problem of risk. Then it gives final statements of the view, both formally and in concrete, practical terms
Neutron Diffraction Studies of Kagome Metal FeGe
No full textThe two-dimensional kagome lattice is the operative characteristic in a large class of materials that exhibit a wide range exotic magnetic and electronic phenomena purely as a consequence of the unique corner-sharing triangle geometry and associated symmetries of the kagome lattice. Some kagome materials possess multiple degrees of freedom, enabling the study of the interplay between competing orders like superconductivity, magnetism, charge density wave (CDW), and topological phases among others. This thesis centers on neutron scattering experiments of the antiferromagnetically ordered (AFM) kagome metal FeGe that was recently found to host CDW order — a first in a magnetically ordered kagome material. A variety of supplemental experimental techniques were performed to aid in the characterization of various properties in FeGe including Raman spectroscopy, transport, resonant inelastic x-ray scattering (RIXS), scanning tunneling electron microscopy (STEM), muon spin resonance, and angle-resolved photoemission spectroscopy (ARPES). We additionally utilize a post-growth annealing process to tune samples from long-range CDW order to no CDW order repeatedly, acting as a powerful tuning parameter in our studies. Using elastic and inelastic neutron scattering, we uncover two competing magnetic orders at low temperatures, one A-type AFM and one screw-like order, previously believed to be a single double-cone order below TCanting. Additionally, the low temperature screw-like magnetic order is suppressed and enhanced in tandem with CDW order during annealing while the A-type order only exhibits a small enhancement at TCDW in samples with long-range CDW order. Our transport measurements reveal an order of magnitude enhancement of the anomalous Hall effect (AHE) in samples with long-range CDW order and the complete absence of AHE in samples with no CDW order. We find the AHE in FeGe is of intrinsic origin stemming from a large Berry curvature and mirrors the magnitude of the giant AHE in the related superconducting kagome family AV3Sb5 (A= K, Rb, Cs). Through a combination of Raman, ARPES, and neutron Larmor diffraction, we identify lattice instabilities and electronic band shifts at TCanting and TCDW in long-range CDW ordered samples suggesting a strong coupling between spin, lattice, and electronic degrees of freedom in the system. Lastly, we describe a microscopic mechanism for the suppression and enhancement of CDW via annealing through neutron scattering and STEM imaging. We find annealing at high temperatures creates Ge vacancies that inhibit the formation of CDW when spread uniformly throughout the sample. Upon annealing at lower temperatures, the vacancies coalesce to form large stacking faults favorable to CDW formation
Sub-THz Multi-User Access with Programmable Metasurfaces
Get PDFNext-generation wireless networks operating in mmWave and sub-THz bands
promise to deliver unprecedented data rates in densely populated networks, enabling
advanced applications such as immersive AR/VR and UAV communications. However, achieving this objective requires not only wide bandwidth, but also efficiency
gains of multi-user (MU) multiplexing vs. serving one user at a time. While MU
multiplexing is relatively well understood and widely deployed below 7 GHz, such
solutions rely on the rich scattering environment of lower frequency channels. To
date, beyond simple polarization multiplexing, there is no same-channel MU solution
for line-of-sight channels that are often encountered at higher frequencies.
This thesis targets the development of network architectures and capabilities based
on wavefront engineering to realize experimental multi-user wireless network above
100 GHz, thereby providing a foundational element for scaling to dense user populations. We develop two radically new and complementary architectures to experimentally realize the data plane for future sub-THz multi-user WLANs. In the first part of
the thesis, we porpose the first same channel MU multiplexing at the sub-THz spectrum by proposing a new approach that enables sub-THz multi-user access without
any RF chains. Our design consists of a programmable, transmissive metasurface and
a single monochromatic sub-THz source. We use the metasurface to modulate thephase and amplitude of the transmitted sub-THz wave using random voltage patterns,
producing high-entropy wavefronts that have unique angular-dependent patterns. We
show that generating these spatially diverse responses enables concurrent transmission of distinct information symbols to multiple users at different angular locations.
In the second part of the thesis, we introduce Multi-Spotlight, a novel system for
sub-THz MU networking to generate multiple, finely concentrated spotlights, each
precisely aligned with each user’s location. To do so, we exploit near-field wavefront
engineering available due to small wavelengths relative to the aperture size and design
high-resolution metasurfaces with phase profiles that combine linear and quadratic
phase distributions, optimized to focus each user’s signal precisely at their location.
We minimize inter-user interference by reducing overlap between the spatial footprints
of the spotlights, thereby enabling the multiplexing of users even with the same angle
of departure (AoD) at different distances from the transmitter. Our experimental
evaluation demonstrates that Multi-Spotlight increases the user’s rate up to 1.5 times
relative to traditional beam-steering approaches. Moreover, our results demonstrate
Multi-Spotlight’s ability to multiplex users sharing the same AoD with inter-user
separation as small as 50 wavelengths, and to deliver significant MU gains even under
low SNR conditions, ensuring high aggregate network performance in challenging and
dense environments.
We demonstrate the feasibility of our designs using both numerical simulations
and experimental studies, showcasing the ability to serve multiple users simultaneously with distinctive data streams, even for users sharing the same AoD from the
transmitter.Additionally, we provide system level analysis to study the limitations
and practical implementations of our system in future Sub-THz WLANs. We believe that our study will pave the way for new architectures that will enable sub-THz
multi-user communications for next generation wireless communications
Engineering protein components for living electronics
No full textLiving cells sense and respond to an astounding array of different molecules. Integrating these cells into digital devices to produce living electronics has the potential to create useful devices, such as bioelectronic sensors that combine the sensitivity and specificity of biological systems with the capabilities of conventional electronics. While there are diverse standardized silicon semiconductor components for electrical engineering, biological systems lack equivalents, which limits the functions of current bioelectronic devices. Protein electron carriers are attractive targets to adapt as bioelectronic components because they are mutable and because their output, electron transfer, is easy to interface with electronics.
Herein, I describe my efforts to engineer ferredoxin and flavodoxin electron transfer proteins as components in controlling electron flow in cells. In these studies, I probe the tolerance of a cyanobacterial flavodoxin to insertion of a small octapeptide, which elongates the primary structure. I find that flavodoxin sites do not tolerate insertion if they are proximal to residues that mediate cofactor or protein partner interactions. Additionally, I use protein engineering to create an allosteric ferredoxin through insertion of an anti-GFP nanobody. I demonstrate that a ferredoxin which contains a specific anti-GFP nanobody insert requires co-expression with GFP to display electron transfer activity.
These studies lay the groundwork for further development of biological components for living electronics. Mutation-tolerant sites identified in the flavodoxin study may be targeted for further engineering to produce allosteric flavodoxins. Additionally, the GFP-dependent ferredoxin produced demonstrates that insertion of nanobodies is a viable strategy for controlling protein activity through specific protein-protein interactions. Further successful application of this strategy has the potential to greatly expand our ability to regulate protein electron transfer for bioelectronics applications
The Gerber Method: Using Multipliers for Daily Box Office Prediction
No full textThe movie industry is important to the United States both culturally and financially. A core part of the movie industry is exhibition at the domestic box office. This paper proposes and implements a model to predict the daily box office gross of a film over the entire course of its time in theaters. Using a novel approach based on daily, weekly, and seasonal multipliers, the model creates a robust time series which it updates as new data becomes available. To do this, comparison movies are found using a K-nearest neighbors model; then the individual characteristics of these similar movies are combined with a set of predicted multipliers. The model is trained on a dataset of over 3,000 movies and their box office grosses from 2015 to 2025. This approach is not only novel, but the daily time series modeling is something no other paper has attempted. Overall, we find very strong results with a median weighted mean absolute percentage difference (WMAPD) of 0.2
Stochastic Assignment with Expiration
Get PDFThis thesis introduces a capacitated online stochastic bipartite matching problem, where offline nodes may be matched multiple times and expire at unknown stochastic times. This problem is PSPACE hard; thus we first focus on the subproblem where each offline node can be matched at most once and aim to develop algorithms that achieve large expected overall values from the matchings. A decision maker (DM) must balance obtaining a matching reward now and keeping enough possibilities for the future with possible expirations. Since this problem is intractable, we first provide a compact linear program (LP) formulation that upper bounds the expected value of an optimal algorithm. Based on this LP, we design a polynomial-time algorithm that guarantees an expected value of at least a fraction of the optimal expected value. We demonstrate the tightness of our LP-based analysis by providing tight integrality gaps as well as worst-case instances. Returning to the capacitated problem, we provide another LP relaxation. We generalize our previous algorithms to evaluate their numerical performance on the harder, capacitated problem. We observe that some natural ideas do not generalize, while others seem to remain competitive
Development of Snapshot Imaging Spectrometer Using High-Density 3D-Printed Waveguide Arrays
Get PDFSnapshot imaging spectrometers simultaneously capture spatial and spectral information, enabling applications in fields such as biomedical imaging and environmental monitoring. However, traditional designs often struggle to balance spatial-spectral sampling density with compactness, and their fabrication is typically complex, time-consuming, and reliant on bulky optical components. This thesis presents the development of two generations of miniaturized, waveguide-based imaging spectrometers fabricated using two-photon polymerization (2PP), a high-precision additive manufacturing technique.
The first-generation system demonstrates the feasibility of 3D-printed optical fiber arrays for spectral imaging, featuring a 40×80 array of air-cladded fibers with engineered void spaces for dispersion. This structure achieves efficient spectral sampling through a prism-based system and is validated using resolution targets and spectral imaging of multi-color samples. Building on this foundation, the second generation which is a cladded structure utilizing complete straight waveguides with the angled end-face, achieves groundbreaking miniaturization and sampling of 3D-printed waveguide structure with a 26,000-waveguide array featuring a 4 µm pitch, 2.5 µm core size, and vertical layer height variations of 32 µm to distribute spectral sampling across 40 pixels. The compact structure (852 µm × 552 µm × 4093 µm) offers new opportunities for integrating snapshot spectroscopy into portable devices while maintaining high performance, as evidenced by spectral and spatial resolution, crosstalk, as well as throughput measurements. Validation with the biological microscopic samples underscores its utility in real-world applications.
These advancements demonstrate the scalability and versatility of 2PP-based fabrication in addressing the limitations of conventional spectrometers, paving the way for more compact and integrated spectroscopy solutions
Low Energy Excitations of 1D Fermi Gases
Get PDFFermions in one dimension are vastly different from their higher-dimension counterparts. At the same time, many theoretical models in one dimension have the luxury of being integrable and exactly solvable, which makes them excellent test beds for quantum simulation. In using these test beds, we can understand and improve on the techniques of quantum simulation so that we move towards solving difficult problems that cannot be solved using other methods due to the sheer complexity of these systems.
In this work, we prepare one-dimensional fermions using cold atom techniques and probe low-energy excitations in such systems. We do so using the technique of Bragg spectroscopy, which enables us to probe the dynamical structure factor of the system directly, which in turn tells us about the density-density and spin-density correlations in the system. Utilizing the extreme tunability of cold atom experiments, we can study different regimes of these 1D Fermi gases. In particular, moving on from our previous investigations in the repulsive interactions, we investigate the attractive interaction side, where the attraction of the fermions causes bound states to form. The binding energy of these bound states causes a gap in the spin excitation, a hallmark of a new class of model: Luther-Emery liquid. We investigate weakly attractive Fermi gases close to the Luther-Emery limit and observe an inversion of the spin-charge separation hierarchy compared to the repulsive side, confirming expectations from exact Bethe ansatz solutions for the homogeneous gas at zero temperature, in which weakly bound fermion pairs are predicted.
The result presented here provides insight into physics in one dimension, an important realm that is well known to host many exciting physics and exotic phases