VictorJuiz/thesis huggingface dataset:
An Ideal Storm: overland flow modeling and a critical look at the Rational Method

Hydrological modeling is essential for a variety of water management challenges, from natural stream restoration to urban flood control. The widespread availability of high-frequency and/or high-resolution remotely sensed data provides an opportunity to improve hydrological modeling. While incorporating large amounts of data is computationally intensive, tools that distill information from remote sensing into useful empirical relationships, simple tools, or summary parameters allow for greater uptake in situations when resources are limited or practitioners prefer a simpler or quicker method./nThis dissertation approaches surface water modeling using simple process-based analytical and empirical models and remotely sensed data. High-resolution imagery is used to examine empirical relationships between in-channel wood length and channel width and characterize the differences in the role of large wood in spring-fed and runoff-fed streams. A model of overland flow on convergent/divergent surfaces is presented and verified via numerical and laboratory techniques. This method is then applied to examine the limits of applicability of the Rational Method, one of the most widely-recommended tools for predicting peak flows, in terms of the fundamental mathematical assumptions. This work identifies landscape properties that cause the Rational Method to perform poorly under idealized conditions and presents a framework for applying the Rational Method as an optimization.

Advisor: Thompson, Sally
Manga, Michael
Symmetry-Controlled Spin Entanglement in Quantum Materials

The demands for new technologies with fast computation, efficient data storage, and low energy cost encourage the search for new matter of phases as well as novel quantum mechanisms. Exotic phenomena, such as high-temperature superconductivity, colossal mag- netoresistence, and topological insulator, naming three examples out of many, of quantum materials open the route to achieve these goals in which the conventional materials can- not easily accomplish. The underlying physics of these novel properties originate from the crystal symmetry, band topology, and the interplay between different degrees of freedom in the condensed phase of matter including electron charge, spin, orbital, and lattice, can- not be explained by the traditional quantum theory. Understand the multiple role of these determinants in quantum materials is not only pivotal from the viewpoint of fundamental physics research, it also encapsulates potential for exciting future applications, such as fast electronics and spintronics./nAngle-resolved photoemission spectroscopy (ARPES) has shown its power of revealing the electronic band structure in the reciprocal space by measuring the energy distribution of photo-ejected electrons with respect to kinetic energy and momentum. The development of spin polarimetry and efficient association with the energy analyzer allow direct measurements of the spin, energy, and momentum of the photoelectrons at the same time. As the electron spin has become one of the focus in condensed matter research, direct probe of such degrees of freedom is essential. By utilizing the unique power of spin-resolved ARPES (SARPES), we show the impacts of the crystal symmetry on the electron spin in the selected quantum materials, one with strong atomic spin-orbit coupling (SOC) but the electrons are weakly correlated and another with strong electron-electron correlation but weak atomic SOC, in this dissertation./nContent is organized into six chapters. Chapter 1 gives an introduction to the symme- try operations and the symmetry-driven spin asymmetry in the condensed phase. Chapter 2 reviews the working principle and the corresponding efficiency of various spin polarime- ters including the home-built SARPES station which collected the data presented in chap- ters 3–5. Chapter 3 contains a brief discussion of topology physics and the detailed spin-momentum locking pattern of topologically trivial and non-trivial surface states of a strong three-dimensional topological insulator. Chapter 4 details the hidden spin texture found a high Tc superconductor. The strong spin polarization observed in such bulk centrosym- metric crystal with weak atomic SOC suggests the importance of local crystal symmetry which depends on the lattice distortion and atomic valency, which is addressed in Chapter 5. Finally, conclusions and future research directions are outlined in Chapter 6.

Advisor: Lanzara, Alessandra
Divergent small viral fusogens use different strategies to hijack the actin cytoskeleton to drive cell-cell fusion

Cell-cell fusion is indispensable for numerous stages of development, from fertilization to tissue development and maintenance. It is typically driven by fusogenic membrane proteins that have tall (>10 nm) ectodomains that bridge the distance between plasma membranes. These tall fusogens often resemble those involved in enveloped viral entry and undergo conformational changes that pull the two membranes into close contact and drive fusion. In contrast, some cell-cell fusogens, such as the fusion-associated small transmembrane (FAST) proteins from reovirus, have ectodomains that are short (<2 nm), smaller than the repulsive hydration barrier that prevents membranes from coming into close contact./nIn this dissertation, I investigated the mechanism of FAST protein-mediated cell-cell fusion. In the first part, I discovered that p14, the FAST protein from reptilian reovirus, hijacks the actin cytoskeleton by binding to the adaptor Grb2 through a phosphorylation-dependent motif in its cytoplasmic tail to drive cell-cell fusion. In the second part, I examined a related FAST protein that arose from a distinct gain-of-function evolutionary event more than 500 million years ago might and found that it also usurped the cellular actin machinery to drive cell-cell fusion. Findings from both studies suggest that these short cell-cell fusogens use force generated from localized actin assembly to overcome the intermembrane gap and bring the two membranes in close contact for fusion. This work establishes how short, non-canonical fusogens can use an alternative, non-conformational change-based mechanism to drive fusion of crowded plasma membranes, providing a mechanistic model for other short, physiological cell-cell fusogens like myomixer and myomaker.

Advisor: Fletcher, Daniel A.
Actuation and Localization of Resource-Constrained Autonomous Microrobotic Systems

With recent advances in miniaturized wireless system-on-chips, microactuators, sensors, and power supplies, autonomous microrobotic systems that can independently explore spaces and process information are approaching fruition. These systems, which can be smaller than 1 cubic centimeter, require actuation and localization modalities that are compatible with these strict payload and size requirements. The first part of this dissertation focuses on the development of millimeter-scale aerodynamic control surfaces actuated by electrostatic inchworm motors, intended for controlling pencil-size microrockets. The design and assembly process of these MEMS control surfaces is detailed, and they are demonstrated to produce 0.48 mN of aerodynamic lift force and induce a roll maneuver on a miniature rocket system./nThe second part of this dissertation focuses on the localization of microrobotic systems using the Single Chip Micro Mote (SCuM) and HTC Vive lighthouse localization beacons. The 5 mg SCuM is a 2 mm x 3 mm x 0.3 mm wireless system-on-chip that is a suitable control, computation, and communication platform for microrobotic systems. Its integrated optical receiver, originally designed to enable contact-free programming, can be used to detect structured infrared light pulses generated by HTC Vive lighthouse stations, which are commonly used for tracking users in virtual reality systems. With this light pulse information, the SCuM system can then localize itself relative to the lighthouse base stations. The development and performance of this system, which can provide localization accuracy of up to 3.1 cm, is discussed in this part of the dissertation. Continuing work on utilizing sensor fusion algorithms to incorporate inertial measurement unit (IMU) data into this localization system is also discussed. Finally, cooperative lighthouse localization methods are discussed for use in teams of resource-constrained robots.

Advisor: Pister, Kristofer S. J.
Artificial Woman in the Box

In this study, I analyze the containment of the artificial woman. In Western literature and cinema, artificial women appear as: mythical women, monstrous women, genetically engineered women, living dolls, living statues, female automatons, female androids, female robots and female cyborgs. Artificial women may also appear as human women, constructed to reflect patriarchal ideals of perfection. The artificial woman embodies the sociocultural ideals of female perfection relative to the male creator in the historical moment. Historically, Western literature and cinema have portrayed the male creator as: an alchemist, magician, engineer, scientist, sculptor, and god. Both the male creator and the artificial female have been variously figured. However, each of their characterizations appears to remain rather consistent over the centuries. Indeed, the ideal, artificial woman’s characterization has remained rather consistent, and, in turn, developed into a trope. The ideal artificial woman appears domestic, innocent, submissive and beautiful. If the artificial woman engenders these traits, she is often contained in marriage and in the home. If the artificial woman is wild and unruly, she must be contained, tamed, or destroyed (often by the male creator). The male creator symbolizes the patriarchy and seeks to establish control over the artificial woman. Whether a domestic wife or a wild woman, the artificial woman appears to be created and contained by the patriarchy. Therefore, the artificial woman seems to be kept metaphorically in a box. In the following, I analyze the containment of the artificial woman in Western works, particularly emphasizing German cinema. I argue that the woman’s portrayal as artificial in cinema confines and reduces her to a projection of male ideals. I examine the various forms in which women are displayed as artificial beings and consequently contained by patriarchal ideals. In my close reading of contained, artificial women in cinema, I draw upon archival texts and literature. In constellation, these works illuminate an age-old project–the patriarchy seeks to contain and control the real woman, who lives in the real world by rendering her artificial in films. Through this project, I show how characterizing a woman as artificial serves as a patriarchal mechanism of containment by conceptualizing and modeling a woman’s role in society. Furthermore, I find the containment of the artificial woman in literature and cinema is often emphasized by the inclusion of a box. The box-whether a magic box, toy box, glass box, convent, laboratory, or house-contains and domesticates the artificial woman physically and metaphorically. In the following chapters, I explore a trope, which I term “the artificial woman in the box.”

Advisor: Kudszus, Winfried
War in Pieces: Narrative Figures Across Media in the “War on Terror”

This dissertation addresses depictions of the first phase of the ongoing “War on Terror” (2001-2013). By focusing on the three narrative figures around which such media representations center—the journalist, the soldier, and the veteran—I examine the genres and modes that shape how the United States population tells itself stories about war and compare the reach and impact of different media forms, analyzing, for example, the disparity between YouTube videos with millions of hits and feature-film box office flops. “War on Terror” narratives raise critical ethical and moral issues around the mechanization of warfare, the global reach of American culture, and the impossibility of perpetual war, most clearly within individual media narratives that are too easily obscured by the framework of the larger media landscape. By re-sorting the films, television shows, and online videos that directly depict the “War on Terror” and grouping them by their central narrative figures, the narrative conventions repeated across media forms are more easily identified. For the journalist, I look to documentary modes to better understand the blurring of fact and fiction and the loss of appeal to journalistic objectivity. For the soldier, I dissect ideas about technologically enhanced contemporary vision in warfare, considering the telescopic views of very close and very far. And finally, for the veteran, I look to the melodramatic mode to understand the inversion of contemporary (failed) reintegration narratives. The project culminates in the uncomfortable conclusion that the United States does not yet know how to handle its traumatized and injured veterans, nor the reminder of the unpopular and amoebic war they represent. On the whole, my project critically examines the American public’s simultaneous fascination with and dissociation from the war, and our inability to deal with its legacy today. Ultimately, this project proposes that, while the narrative conventions bestow unifying legibility to the fragmented representations and a continuity in storytelling that affirms the United States as democratizing “good guys,” those narrative conventions ultimately serve to mask the fracturing and loss of a unifying mythology of American national identity. While these divisions grow more apparent daily, the divides seen today trace much further back, and are seen clearly in this project of analyzing media representations of the first phase of the “War on Terror.”

Advisor: Sandberg, Mark
Everyday Eloquence and Mediality in Stand-up Performance

When Aristotle labelled rhetoric as a techne, or technical art, it was because rhetoric involved observing particular acts of persuasion, and a subsequent theorization of the means through which those acts were achieved. Subsequently, rhetorical studies has concerned itself with the latter, the instruments of persuasion, for two-plus millennia, while neglecting the former: Rhetoric as study of compelling acts of artifice. Confusing techne for technology, rhetors have considered technical innovations in media as forms (e.g., literature, film, TV), ones with specific limitations and affordances for affecting public knowledge, belief, and action. However, the digital media forms of the twenty-first century reverse this historical trajectory. In becoming the rhetorical ecology of public discourse, this epoch of ubiquitous networked computing and participatory media confronts people with the unavoidable artificiality upon which their expressions of ideas and identity depends. This dissertation reconsiders the instrumental relationship between persuasion and technology by returning to rhetoric as techne—or craft guided by knowledge of that craft. Observing individuals who achieved rhetorical success with technologies in the period during which new media become dominant (roughly 2005-2020), this dissertation theorizes persuasion beginning with the fundamental technicity or artificiality of human being./nInsofar as stand-up comedians live in a condition between natural and artificial selfhood, their practice amplifies how the everyday experience of contending with the world, or oneself, is a matter of artifice that precedes any technological instruments or media. As such, they reveal that persuasion is a matter of conviction, effected through the artful presentation of oneself in one’s world, and not by convincing others via skillful use of through argumentative media. Taking stand-up comedians as interfaces, or technical media that do not mediate, this dissertation theorizes a tripartite process through which stand-up rhetoric qua techne intervenes in the normative cultural conceptions that ground social and psychic life. Comedic discourse arrests and deviates from what counts as normal, contributing original, provisional alternatives to the cultural fund of collective ideas that audiences draw from when realizing the always partial ground of their individual and public expression. The efficacy of stand-up as a personally and politically transformative practice lies, at core, in the destabilization and restabilization of depoliticized public discourses in which shared worlds are negotiated. This is true, too, of everyday eloquence in democratic cultures—from the agora of classical Athens to today’s digital global sphere.

Advisor: Trinh, Minh-ha T
Engineering the Properties of Two-dimensional van der Waals Materials

By virtue of their atomically thin structure, layered van der Waals materials with two-dimensionality (2D) exhibit a strong tunability of material properties beyond what can be achieved in their bulk counterpart. In this dissertation, I aim to realize and control the novel phenomena that are unique in such 2D layered materials. We achieved the exquisite property control by rationally tailoring the structural design of the devices. Toward this end, nanofabrication techniques are extensively employed to perform precise positioning and layer-by-layer stacking of the individual components to manufacture nanodevices from these van der Waals materials. A suite of advanced characterization techniques encompassing electrical transport, scanning probe microscopy, and spectroscopy (laser-based and synchrotron-based) are then used to study the great degree of properties tunability in the samples./nFirstly, we show the use of dielectric environment as a control knob to tune the bandgap of monolayer MoS2 by realizing a lateral heterojunction with implications in transport phenomena and future electronics. Secondly, we show the structural control of graphene-based 2D materials into moiré lattices and superstructures and demonstrated the use of an ultra-high-resolution implementation of scanning microwave impedance microscopy (i.e., uMIM) to reveal the detailed structure of such moiré systems. Thirdly, we discuss the control of electronic band structure in magic angle twisted bilayer graphene (tBLG) with the emergence of flat band near the Fermi level as probed with angle-resolved photoemission spectroscopy with nanoscale resolution (nanoARPES). Lastly, we provided an overview of future perspective and a highlight of recent results where other material parameters can be used to control the 2D material behavior. The possibility to engineer the material properties provides a fascinating route for on-demand application of the 2D nanomaterials in new multifunctional device concepts in electronics, optoelectronics, and quantum information science.

Advisor: Wang, Feng
Wu, Junqiao
Many-Body Ground States in Single-Layer Transition Metal Dichalcogenides

Transition metal compounds have long been known to host intriguing many-body ground states owing to a fine interplay between electron-electron interactions, electron-phonon coupling, and low dimensionality. Recent advances in van der Waals synthesis have enabled the experimental studies of transition metal dichalcogenides in the extreme two-dimensional limit. In this dissertation I will discuss experiments that probe novel many-body ground states in single-layer transition metal dichalcogenides via the use of scanning tunneling microscopy and spectroscopy (STM/STS). The first part of the dissertation focuses on charge density wave states in single-layer 1H-NbSe2, single-layer 1H-TaSe2, and single-layer 1T-TaSe2 and the mechanisms by which they arise. The second part of the dissertation discusses an exotic Mott insulator electronic ground state in single-layer 1T-TaSe2 and its collapse with increased temperature and/or the introduction of interlayer coupling. In the third part of the dissertation I present evidence supporting a novel many-body magnetic ground state called a quantum spin liquid in the spin channel of single-layer 1T-TaSe2. This gapless spin liquid state was probed by spectroscopic STM imaging as well as by its response to single magnetic impurities. The results discussed here establish new platforms for investigating correlation physics in two dimensions and provide insights into the intriguing many-body phases therein.

Advisor: Crommie, Michael F
Theoretical Understanding and Exploitation of Phase Transitions for Thermal Applications

Direct usage of thermal energy, instead of electricity, is intriguing to diminish total energy consumption with a benefit of reducing the number of energy conversions by directly utilizing such solar power and waste heat. Although various thermally driven systems have been suggested to overcome the problem of electricity-dependent systems, materials for the mechanisms limit the realization and effective operation of the systems. A more complete theoretical understanding of materials for thermal applications can suggest guidance to determine the bottlenecks of current materials and then ways to develop new materials. Among many computational methods, molecular dynamics (MD) simulations especially provide a molecular insight into structures of materials and phononic heat transfer at nanoscale./nIn this dissertation, I discuss unconventional phase transition materials for thermal applications. Here, I focus on two types of phase transition materials. The lower critical solution temperature (LCST) liquid-liquid transition of aqueous ionic liquids is a thermally responsive phenomenon with phase separation. The phase separation can be used for forward osmosis desalination which directly utilizes a low-grade of thermal energy. By using MD simulations, I describe the local molecular environment during the transition and the driving force. The unusual trend of osmotic strength of the ionic liquids is explained with a suggested definition of an apparent free ion ratio. MD simulations are also used to study the amorphous phases and their phase transition of sugar alcohols in nanopores. The nano-encapsulation is proposed to shift the melting temperature and here I suggest a methodology to determine the phase transition temperature of encapsulated materials. This thesis also uses a theoretical approach to explore the thermal conductivity of the nanoconfined composites. Phonon frequency analysis verifies the enhancement of heat transfer by the infusion of phase change materials to the frameworks due to additional heat pathways between the nanoporous structures. Finally, I propose a practical design for a thermal rectifier that can be realized by phase change materials and derive a general theory for the design. The general theory indicates the possibility to obtain a high thermal rectification from the design and introduces the critical parameters for theoretical maximal performance.

Advisor: Dames, Chris
Urban, Jeffrey J.