VictorJuiz/thesis huggingface dataset:
Petcoil : a second-generation RF-penetrable TOF-PET insert for simultaneous brain PET/MRI

Simultaneous positron emission tomography/magnetic resonance imaging (PET/MRI) has shown promise in acquiring complementary multiparametric information of diseases. However, designing these hybrid imaging systems is challenging due to the propensity for mutual interference between the PET and MRI sub-systems. In addition, the current high cost of permanently-integrated PET/MRI systems limits their long-term development and deployment, as well as patient accessibility. To overcome these limitations, we explored a brain-dedicated PET insert for an existing MRI system to achieve simultaneous PET/MRI. Because of its brain-dedicated design, this insert also provides superior spatial resolution and sensitivity compared to whole-body scanners. The second-generation prototype builds upon the success of the first-generation prototype, which demonstrated radio-frequency (RF)-penetrability and MR-compatibility. The new design includes additional features such as a longer axial field of view, time-of-flight (TOF) functionality, and improved portability, resulting in improved PET performance but presenting greater technical challenges for MR-compatibility. This thesis presents the development of the second-generation brain-dedicated PET insert for simultaneous PET/MRI. Our objective is to achieve high levels of both PET performance and MR-compatibility. The detailed design, architecture, experiment setup, results and analysis of the second-generation brain-dedicated PET insert are presented, highlighting the progress towards realizing a cost-efficient and effective simultaneous PET/MRI system for neurological imaging

Keywords: Engineering.
Electrical Engineering.
Advisor: Levin Craig
Nishimura Dwight George
Rivas-Davila Juan
Photonic frequency engineering for efficient thermal energy and computation hardware

As information explosion and climate change bring increasingly detrimental impacts, my research is committed to sustainability goals to develop clean energy sources, sustainable building materials, and efficient computation hardware. This goal lies at the intersection of electromagnetics, thermal management, and photonic computing. Achieving these goals would significantly impact multiple fields such as carbon neutralization and artificial intelligence. However, it faces fundamental limitations such as unpredictable environments, inflexible controls, and spatial footprints to build photonic systems that can preserve energy sustainably and process information intelligently. During my Ph.D., to achieve these goals, my research focused on 1. passive radiative cooling-based nighttime power generation, smart buildings, and water harvesting and 2. photonic frequency dimension-based computational hardware that is compact and consumes minimum control energy. Driven by sustainable energy applications, I also bridged disciplines to solve fundamental scientific problems in near-field heat transfer and optical-mechanical control, which provide implementable and scalable solutions to thermal transport and light sails. Even though achieving these goals can bring a significant difference in overcoming the technological barriers, we are well aware that, many challenges remain unsolved before we could design energy generation and building systems in real-time at a large scale, to prevent information overload and climate crisis before it even occurs, and deploy scalable photonic computing architecture. This is the promise of my Ph.D. research: I integrate analysis, simulation, and experiment methods from materials and control for light and heat to generate and preserve high-grade energy, to enable compact high-speed photonic computation hardware, to comprehensively understand and rationally design multiscale and multimodal energy systems

Keywords: Engineering.
Electrical Engineering.
Advisor: Fan Shanhui
Fejer Martin M. (Martin Michael)
Lončar Marko 
Miller D. A. B.
Vuckovic Jelena
Photovoltaic subretinal prosthesis for high visual acuity : design, fabrication, and in vivo assessment

Retinal degenerative diseases, such as atrophic age-related macular degeneration (AMD), are the leading cause of incurable blindness due to the irreversible loss of photoreceptors. Photovoltaic subretinal prostheses have shown promise in restoring vision by electrically stimulating the second- order retinal neurons, specifically the bipolar cells. Clinical trials in AMD patients have demonstrated prosthetic vision with an acuity of up to 20/438, closely matching the 100 μm pixel size of the implant. To further improve and broaden the adoption of this technology, pixel sizes need to be reduced to below 50 μm, surpassing the US legal blindness threshold of 20/200. However, scaling down the pixels of the current design to below 75 μm in patients is not feasible, as the local return electrodes excessively confine the electric field, precluding the stimulation of bipolar cells within a safe charge injection range. In this thesis, I present two alternative pixel design strategies aimed at optimally shaping the electric field with smaller pixels. The objective is to enable effective stimulation of retinal neurons without compromising safety, contrast, or resolution. The first strategy involves a monopolar pixel array with current steering, replacing the circumferential local return electrodes in each pixel with a transient return path through neighboring dark pixels. This design allows for deeper field penetration while maintaining high spatial contrast. The second strategy employs 3-dimensional electrodes, such as honeycomb-shaped walls and pillars, to vertically shape the electric field. Anatomical and electrophysiological studies of these 3D arrays in vivo demonstrate their feasibility and long-term biocompatibility. Grating acuity tests with these new implants - planar and 3D - in blind rats have shown that the prosthetic acuity matches the sensor pitch with 40 μm pixels, while with 20 μm pixels, prosthetic acuity reaches the 28 μm limit of natural resolution in rats. Unlike stimulation mediated by bipolar cells, direct activation of third-order neurons, the ganglion cells, by subretinal implants does not yield high spatial resolution. Therefore, an electric field that is carefully optimized for effective and selective stimulation of bipolar cells is crucial for achieving a high visual acuity of up to 20/80 in AMD patients.

Keywords: Humanities and Sciences.
Physics.
Advisor: Chu Steven
Palanker Daniel
Hong Guosong
Kamins Theodore I.
Physics and machine learning based approaches to model energy storage systems

Energy storage systems ensure the effective and reliable management of power supply and demand. Despite the widespread adoption, energy storage systems face substantial challenges (e.g., safety concerns, limited capacity, environmental impact), stemming from their relatively brief history in academic research and industrial applications. Motivated by these challenges, this thesis explores and develops physics and machine learning based approaches to model energy storage systems, focusing on lithium ion batteries and fuel cells. We first scrutinize the impact of mechanical and thermal factors on lithium plating in lithium ion batteries, employing both 1D and 3D physics-based models. We find that mechanical deformation can accelerate the onset of lithium plating, with folds and boundaries of jellyrolls being particularly susceptible due to distinctive mechanical conditions. Next, motivated by the crucial role of mechanical deformation in lithium plating, we develop SenseNet, a physics-informed deep learning model, for shape sensing applications. SenseNet is crafted to monitor the mechanical deformation of arbitrary structures without relying on prior knowledge of loading conditions, but utilizing a discrete network of strain sensors. Finally, given the complex nature of multiphysics problems and the notable efficiency and accuracy of machine learning methods, we explore and compare diverse data-driven approaches for fuel cell modeling.

Keywords: Engineering.
Advisor: Linder Christian (Engineering professor)
Borja Ronaldo I. (Ronaldo Israel)
Sun Waiching
Platforming the People’s Perspectives: The Role of Public Comment in Meta Oversight Board Decision-making

The Meta Oversight Board has become a hallmark of innovative private governance and platform accountability. This independent, quasi-judicial body created to check Meta’s content policies and practices features some of the world’s most esteemed experts in human rights and governance. Less talked about is its public comment process as a means for engaging those beyond the Board. While there has been much scholarly work on public participation in government processes, there is less understanding of its role within the context of private tech governance and online content regulation. In this thesis, I apply a mixed-methods approach to investigate the role of public comment in Meta Oversight Board decision-making. I undertake 1) a quantitative analysis of public comments submitted to the Meta Oversight Board in conjunction with the outcomes of the Board’s recommendations, and 2) a qualitative analysis of interviews I conducted with internal Board members and staff and civil society stakeholders.
I find that currently, there is no observable relationship between public comment engagement, whether as a whole or from civil society, and the effectiveness of Board recommendations. However, as revealed through my interviews, public comments indeed help the Board build more informed decisions and increase the legitimacy of these decisions. Additionally, internal and external Board stakeholders agree that the barriers to Board engagement, whether via public comment or otherwise, must be lowered to truly foster an inclusive, collaborative engagement process. Finally, I identify key weaknesses in the Board’s transparency efforts when it comes to meaningfully communicating its impact to stakeholders. In sum, my findings suggest a need for the Board to more closely consider how it actualizes its values of transparency, accountability, and accessibility as it pertains to its relationship with external stakeholders, particularly civil society.

Keywords: Social media
Platform governance
Civil society
Content moderation
Meta Oversight Board
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Thesis
Advisor: Reich Rob
Playing children : displacement and the performance of childhood

Playing Children investigates shifting conceptions of childhood and nation-statehood amidst the backdrop of the escalating global refugee situation. Focusing on plays and films from four contested regions and their diasporic counterparts -- the Pashtun Belt, Syria, India-Pakistan, and Israel-Palestine -- I chart how cultural producers across disparate conditions figure the displaced child towards and against dominant national imaginaries. A relational approach allows me to trace South-South solidarities, even as they unfold in countries like the United States and United Kingdom. Chapter One considers the complex network of actors, affects, and aspirations involved in both the creation and reception of Malala Yousafzai's multiple personas to argue that Malala is best read as a consummate performer. Chapter Two posits that Syrian refugee children are sympathetic to distant Euro-American spectators to the extent they can be conscripted into an "adoptive gaze." In Chapter Three, the repeated trope of a child accidentally crossing the India-Pakistan border reveals an ambivalence around ethno-national identity in the subcontinent that dates to the 1947 Partition. Chapter Four argues that the very notion of childhood becomes entirely discursive and disembodied in the region variably called Israel and Palestine. Ultimately, I find that displaced children exceed the statist, recognition-based frameworks within which both childhood and nation-state belonging are defined, thereby revealing the limits of the concepts themselves. Categories of performance, childhood, and the nation-state constrain while they come apart at the seams; like a child outgrowing their clothes, any imagination of the world as divided by national boundaries, by 'their' children and 'ours, ' no longer fits

Keywords: Humanities and Sciences.
Theater and Performance Studies.
Advisor: Al-Saber Samer
Iyer Usha
Menon Jisha
Pluripotent stem cell morphogenesis in engineered hydrogels as a model of early human development

Human embryogenesis involves a series of complex morphogenetic events, wherein human pluripotent stem cells (hPSCs) give rise to all the tissues in the human body. Mechanisms of embryogenesis cannot be studied directly in human embryos due to ethical concerns and technological limitations. Yet, these mechanisms hold the key for taking stem-cell-based therapies to the clinic. To tackle this, there has been a tremendous effort recently toward developing hPSC-based models of the embryo, but current studies lack mechanistic insights as well as reproducibility, due to use of extracellular matrices such as Matrigel which are poorly defined and heterogeneous with limited tunability of matrix properties. In this dissertation, I will first demonstrate the use of engineered alginate hydrogels for studying the impact of hydrogel mechanical properties on hPSC behavior, with hPSCs forming human epiblast-like structures in specific hydrogels. The human epiblast forms a central fluid-filled lumen during embryogenesis which is crucial for proper establishment of the body axes. Using the hPSC-based model of human epiblast, I next unearth the mechanism of epiblast lumen formation. Overall, this body of work demonstrates the power of embryo models and engineered hydrogels, and greatly advances our understanding of the self-organization mechanisms that drive human embryo development.

Keywords: Engineering.
Mechanical Engineering.
Advisor: Chaudhuri Ovijit
Bhutani Nidhi
Levenston Marc Elliot
A plurisubharmonic analogue to Igusa's theorem

This dissertation is concerned with removing singularities of plurisubharmonic functions. Igusa demonstrated that there is an h-principle for functions without higher singularities, and later, Eliashberg and Mishachev extended these results. In this thesis, we prove an analogue of Igusa's theorem for families of plurisubharmonic functions on a complex manifold under an additional assumption restricting to the case when all singularities are of corank 1

Keywords: Humanities and Sciences.
Mathematics.
Advisor: Eliashberg Y.
Ionel Eleny
Manolescu Ciprian
Polymer materials design for lithium batteries

Battery technology is crucial for our modern world, enabling the storage of electrical energy and driving the transition to clean power sources. My research focuses on designing polymer materials to improve battery safety and energy density. I work on non-flammable polymer electrolytes for Li batteries and polymer coatings for the lithium metal anode. Chapter 1 provides background information, while Chapter 2 focuses on a specific safe polymer-based electrolyte design. Chapters 3, 4, and 5 cover the development of polymer coatings. Chapter 6 concludes the research and discusses future prospects

Keywords: Engineering.
Materials Science and Engineering.
Advisor: Bao Zhenan
Cui Yi
Qin Jian (Professor of Chemical Engineering)
Polymer physics driven design and understanding of biological materials

Polymers make up much of the world around us, from man-made materials like plastics and nylon to natural biological materials like mucus and DNA, and their physical behavior plays a large role in their function. Understanding how a polymer's composition can influence its final bulk physical behavior and function is crucial to creating novel classes of materials for new application spaces. Additionally, in the context of biology, knowing what structure-property relationships exist for biopolymer-based fluids can explain how and when there is a dysfunction. For example, the rheological properties of mucus, which lines every wet epithelial surface of our bodies, are carefully tuned to be a selective barrier to allow nutrients through and keep pathogens out, and small changes in elasticity could lead to infection. Connecting microscopic properties of a polymer chain to the macroscale physics of the polymeric material, however, still remains a challenge. In my dissertation, I present theoretical polymer physics models that link molecular-level parameters to predictions of bulk rheological behavior and combine these models with experimental techniques to develop a physical understanding of polymer-based complex biological fluids. I then demonstrate how this understanding can be leveraged to support certain therapeutic strategies.

Keywords: Engineering.
Chemical Engineering.
Advisor: Heilshorn Sarah
Spakowitz Andrew James
Fuller Gerald G.
Qin Jian (Professor of Chemical Engineering)
POROSITY AND PERMEABILITY CHANGES DURING CYCLIC LOADING AND UNLOADING OF CARBONATE RESERVOIRS FOR GAS STORAGE APPLICATIONS

Underground gas storage is utilized to level seasonal variations in the supply and demand of natural gas, or hydrogen, and provide energy stability and security. In such projects, the reservoir undergoes cyclic injection, storage, and production of the gas. Cycles vary between days to years. Due to the cyclic nature of injection and production from the reservoir, it is important to understand the effect of cyclic loading and unloading, and the accompanying changes in stress, caused by pressurization and depressurization on rock porosity and permeability.
In this report, we have examined the effect of cyclicity on two Texas Cream carbonate samples. To simulate reservoir conditions, we hold the confining pressure constant while loading and unloading the pore pressure within the elastic limits. We ran several cycles for each sample and the porosity and permeability were recorded during the cycle. The results show a slight decrease in the porosity and permeability with cycling. Results also emphasize that mechanical rock damage needs to be considered with the cyclic nature of the gas storage operation as it leads to rock fatigue damage and deformation.
Most of the research in this area focuses on reservoir depletion or one cycle of loading and unloading. Therefore, these results highlight the importance of considering the changes in rock characterization with pore pressure cyclicity. The characterization of the reservoir rock porosity and permeability change is essential for modeling and to set guidelines for better reservoir management.

Keywords: Porosity
Permeability
Loading and unloading
Underground gas storage
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Thesis
Advisor: Kovscek Anthony
Potential automorphy for general linear groups

We prove potential automorphy results for a single Galois representation of global Galois field with p-adic coefficients. The strategy is to use the p, q switch trick to go between the p-adic and q-adic realisation of a certain variant of the Dwork motive. We choose this variant to break self-duality shape of the motives, but not the Hodge-Tate weights. Another key point to prove is that certain p-adic representations we choose that come from the Dwork motives is ordinarily automorphic. The majority of the work is published on Inventiones Mathematicae volume 231, pages 1239--1275 (2023)

Keywords: Humanities and Sciences.
Mathematics.
Advisor: Taylor R. L. (Richard Lawrence)
Conrad Brian
Vakil Ravi
Power, exclusion, and identity : the politics of muslim marginalization in India

What are the causes and consequences of the political exclusion of marginalized groups? This dissertation studies this question by focusing on the over 200 million Muslims in India, the world's largest democracy. Over the past several decades, India has progressed in the political inclusion of several marginalized groups, including Scheduled Castes, Scheduled Tribes, and women. However, Muslims have experienced no measurable progress and their political and socio-economic condition has deteriorated. Indian Muslims further represent an understudied type of marginalized group: those who do not have institutional protections to help them gain political power. This dissertation studies the origins of the political exclusion of Indian Muslims, when they can break out of this exclusion, and why—even when they break out—they cannot sustain political power. I propose a framework to understand the causes and consequences of Muslim representation that considers how changes among elites and voters from the dominant and marginalized groups can help account for the contours of Muslim political representation in India. First, I theorize that structural factors, political incentives, and party characteristics help explain where, when, and through which parties Muslims can gain representation. Second, I challenge the conventional wisdom that power begets power by arguing that when a Muslim comes to power it can lead to a representation trap where they have a lower likelihood of subsequently winning. I argue that this process is driven by uniting Hindus and dividing Muslims. I test the argument using descriptive and causal analysis of election data across India, an original in-person survey of nearly 5000 Hindu and Muslim voters that contribute to natural and survey experiments, and 150 elite and voter interviews during a combined eight months of in-depth fieldwork. By providing a comprehensive story of Muslim marginalization in India, this project contributes to our understanding of political representation, identity politics, and democracy

Keywords: Humanities and Sciences.
Political Science.
Advisor: Weinstein Jeremy M.
Fearon James D.
Gulzar Saad
Laitin David D.
Prillaman Soledad Artiz
The pragmatics of image description generation

Finding true words that describe an image seems easy, but it is finding the right words for an image that poses a communicative challenge. Describing an image to make it accessible for someone who can't see it additionally carries a lot of social responsibility when selecting which information to put into words, since those words fundamentally determine what our interlocutor will learn and what they might miss. With recent advancements in computational vision-language models comes an opportunity for building systems that can describe the visual world (e.g., images) for us -- and that instantly. This bears special promise for advancing nonvisual accessibility for people who are blind or have low vision, as their access to visual content online is often restricted to rarely present alt text descriptions. In this dissertation, I argue that the development of vision-language systems that are useful for social needs such as accessibility needs to be centered around pragmatic communicative principles. This includes the datasets we construct, the way we design and train our models, and how we evaluate them. The opportunities are vast, but now is the time where we can start to center computational modeling progress around the intricacies and complexities that make our communication so rich and effective.

Keywords: Humanities and Sciences.
Linguistics.
Advisor: Potts Christopher
Goodman Noah
Jurafsky Dan