VictorJuiz/thesis huggingface dataset:
Snacktime for Hungry Black Holes: Theoretical Studies of the Tidal Disruption of Stars

A star that wanders too close to the massive black hole (BH) in the center of a galaxy is headed for trouble: within a distance rT ~ r*(MBH/M*)1/3 (where r* and M* are the star's radius and mass, and MBH is the BH's mass), the BH's tidal gravity overcomes the binding gravity of the star, and the star is shredded into a stream of stellar debris. Studying this process of tidal disruption has the potential to give us insights into how central BHs and their surrounding stellar population grow and evolve. Motivated by new and upcoming rapid-cadence optical transient surveys, which should detect and allow study of tidal disruption events (TDEs) in unprecedented detail, I make theoretical predictions of the observable properties of these events to aid in their detection, identification, and interpretation. I find that stellar debris falling towards the BH is likely driven off again by radiation pressure at early times when the feeding rate is super-Eddington: this outflow has a large photosphere and relatively cool temperature, producing a luminous (~ 1043 - few × 1044 erg s-1) transient event at optical wavelengths. I predict that new transient surveys such as the Palomar Transient Factory are likely to find tens to hundreds of these events. I further predict the spectroscopic signature of super-Eddington outflows&mdash broad, blueshifted absorption lines in the ultraviolet&mdash which should help confirm and teach us more about TDE candidates. Finding that the observable appearance of TDEs depends not only on BH mass but on pericenter radius of the star's last fateful orbit, I derive a theoretical expression for the disruption rate as a function of pericenter and apply it to the galaxy NGC 4467 using real observational data, laying the groundwork for more extensive studies in the future. Finally, I also present my work on the debris disk surrounding the star AU Mic, in which I propose an explanation for the physical processes of dust dynamics that give rise to the observed disk profile.

Advisor: Quataert, Eliot
Perceptually Based Tone Mapping for Low-Light Conditions

We present a perceptually based algorithm for modeling the color shift that occurs for human viewers in low-light scenes. Known as the Purkinje effect, this color shift occurs as the eye transitions from photopic, cone-mediated vision in well-lit scenes to scotopic, rod-mediated vision in dark scenes. At intermediate light levels vision is mesopic with both the rods and cones active. Although the rods have a spectral response distinct from the cones, they still share the same neural pathways. As light levels decrease and the rods become increasingly active they cause a perceived shift in color. We model this process so that we can compute perceived colors for mesopic and scotopic scenes from spectral data. While our tone mapping operator works with spectral data from any source, we show how to produce spectral data of static scenes using multiple images and a camera with known spectral sensitivity. If the spectral sensitivity isn't provided by the camera manufacturer, we describe a one-time calibration procedure to estimate the sensitivity. Should obtaining spectral data of a scene be infeasible, we also describe how the effect can be approximated from high dynamic range RGB images by learning a mapping from RGB to rod and cone responses. Once we have determined rod and cone responses either directly or through our approximation process, we map them to RGB values that can be displayed on a standard monitor to elicit the same color perception when viewed photopically. Our tone mapping method focuses on computing the color shift associated with low-light conditions and leverages current HDR techniques to control the image dynamic range. We include results generated from both spectral and RGB images as well as experimental data.

Advisor: O'Brien, James F
Political Thought and Political Action: Michael Walzer's Engagement with American Radicalism

This dissertation provides an account of the historical development of the political thought of Michael Walzer from the 1950s to the present day. It situates Walzer within an American tradition of social democratic thought and argues that only when he is so situated can his thought be understood fully. Walzer's engagement with that tradition, most notably through his work on Dissent magazine, has structured how he has responded to many of the major developments in political life over the course of his career, including the decline of movement politics, the rise of neoliberalism, the recent waves of immigration to the USA, and the increased salience of civil society following the demise of the Soviet Union./nUnderstanding Walzer in this way recovers the egalitarian aspirations of his theory, which are lost in those academic accounts that are inspired by analytic philosophy. Particularly in the analysis of liberal political theorists, Walzer's commitment to interpreting the shared understandings of the communities of which he is a part is seen as sitting uncomfortably with his social democracy. The dissertation argues that when Walzer's conception of equality is taken seriously, the path of interpretation is closely allied to it. If we wish to instantiate equality in political practice, rather than refining the philosophical concept ever more closely, we have no choice but to take seriously the interests, desires, and passions of citizens and of citizen-activists. That is why his conception of equality, which is more sociologically robust than the dominant liberal alternative, has more chance of being appropriated by radical movements./nIn the dissertation, consideration is also given to Walzer's just war theory, to the impact of his Judaism on his thought, and to the relationship between these things and his continued adherence to a version of democratic socialism.

Advisor: Bevir, Mark
Ancient Egypt, Sacred Science, and Transatlantic Romanticism

Ancient Egyptian culture has been a powerful influence on a major tradition of English literature that runs from Edmund Spenser's The Faerie Queene (1596), one of whose major iconographic centers is the temple of Isis, to John Crowley's four-volume novel Ægypt (2007). My dissertation focuses on the Romantic period - the midpoint of this trajectory - because it is an extremely intense moment of this influence. In addition to the visions of Egypt presented in the Bible, Greco-Roman writers, and travel narratives, ancient Egypt reached American and British culture of the time through a variety of channels, such as (1) Napoleon's invasion of Egypt in 1798, which allowed a stream of Egyptian monuments to travel into Europe and America; (2) the deciphering of the hieroglyphics in 1822; (3) an Egyptian-inspired freemasonry, which wielded a major effect on political revolutions in the USA, France, and Haiti; and (4) revived interest in heterodox Alexandrian traditions such as alchemy, gnosticism, and hermeticism. These channels transmitted a mediated Egyptian "sacred science," which can be defined as a transdisciplinary form of knowledge that does not aim to study external objects or manipulate abstract signs and empirical processes, but rather strives to the catalyze the transformation and expansion of consciousness itself, with the final goal being the divinization of the human. This project explores the work of a series of canonical British and American Romantic figures most deeply engaged with this legacy of ancient Egypt. In interlinked chapters on Samuel Taylor Coleridge's Ode on Astronomy, Kubla Khan, and Rime of the Ancient Mariner, Walt Whitman's Leaves of Grass, and Herman Melville's Moby-Dick, I argue that Egyptian sacred science provided a conceptual foundation for spiritualized representations of, respectively, the natural world, the self, and deific powers (or "gods") that link these two domains and situate them within a network of larger cosmic dynamics.

Advisor: Otter, Samuel
Post-transcriptional regulation of gene expression by the DExD/H-box protein Dhh1

By repressing translation and promoting mRNA decay, cells are able to modulate gene expression and respond swiftly to changing environmental signals and developmental cues. Although translation, storage and degradation of mRNAs are key steps in the post-transcriptional control of gene expression, how mRNAs transit between these processes remains poorly understood./nDuring my thesis I functionally characterized the DExD/H box ATPase Dhh1, a critical regulator of the cytoplasmic fate of mRNAs. Using mRNA tethering experiments in yeast, I showed that Dhh1 is sufficient to move an mRNA from an active state to translational repression. In actively dividing cells, translational repression is followed by mRNA decay, however, deleting components of the 5' to 3' decay pathway uncoupled these processes. Interestingly, Dhh1's ability to inactivate an mRNA coincided with its ability to move mRNAs into cytoplasmic processing bodies (P bodies)./nI also examined the role of ATP hydrolysis in Dhh1's ability to repress translation and activate mRNA decay. While Dhh1's ATPase activity is not essential for translational inhibition and mRNA decay in dhh1Δ cells, I found that ATP hydrolysis regulates P body dynamics and the release of Dhh1 from these RNA-protein granules. Surprisingly, I found that the presence of a wild-type copy of Dhh1 rescues the abnormal P-body localization of a Dhh1 ATPase-mutant. Additionally, the Dhh1 ATPase mutant no longer reduces mRNA and protein levels when tethered to an mRNA in the presence of a wild-type copy of Dhh1. My results place Dhh1 at the interface of translation and decay controlling whether an mRNA is translated, stored or decayed.

Advisor: Weis, Karsten
Enemies of the Lineage: Widows and Customary Rights in Colonial Korea, 1910-1945

My dissertation examines Korean widows and their legal rights during the Japanese colonial rule (1910-1945), focusing on widows and their lawsuits over property rights, inheritance and adoption. Utilizing civil case records from the Superior Court of Colonial Korea, I argue that women's rights were diminished by the Korean customs adopted by the judicial system under the Japanese colonial state. By examining the production process of Korean customs in the colonial civil courts, I emphasize Korean agency in the transformation of family customs during the Japanese colonial period./nWomen's property and inheritance rights developed in close relationship with the Japanese family policy, which aimed to disintegrate the lineages in Korea into nuclear households. The Japanese colonial state strengthened the household system by protecting customary rights that allowed widows to become house-heads. Protecting rights of widows that straddled the ambivalent position between the lineage and the nuclear family, the colonial civil court effectively solidified boundaries between households that cut through traditional ties of family. Therefore, civil cases that involved widow rights became the battleground where the conflict between the proponents of the Korean lineage system and the family nuclearization policy of the colonial state unfolded./nAs colonial family policy developed into the 1920s and the 1930s, women's rights became increasingly subjected to the patriarchal constraints of the nuclear household. The Japanese colonial state moved its attention from widow rights (which, after all, was too closely linked to the agnate adoption custom of the lineage system) to daughters' rights by promoting son-in-law adoption as a way to expand women's inheritance rights. Meanwhile, the colonial state denied women's demands for full inheritance rights that would infringe upon the rights the house-head of the nuclear household. The 1939 Civil Ordinances Reform, which implemented son-in-law adoption and household names, therefore, was the culmination of the family nuclearization policy of the Japanese colonial state.

Advisor: Barshay, Andrew E
Choosing Transit: The Influence of Past Travel Behavior, Attitudes and Habits on Present Choices

In this study I have examined the role of prior experience in the use of transit using a combination of survey research and focus groups. In some ways this influence is examined directly. Otherwise, it is investigated through individuals' desire to locate near transit stations. While considering travel times and costs of available modes, this dissertation also looks at which features of transit are most likely to influence non-transit users to change their habits and use transit and which features are essential for keeping those who already use transit. These questions are explored for all trips and specifically for work trips./nOne specific area of past experience that is examined in this research is the role of exposure to transit during high school, college and immediately after college. Does this exposure have a lasting influence on mode choice later in life?/nI have found that, as previous research has shown, transit cost and time are the primary economic motivators of mode choice. Beyond these considerations, mode comfort, the ability to use travel time productively and perceived safety from crime are important determinants of mode choice. Childhood experiences proved to have little direct influence, but this is mostly due to the fact that few participants had exposure to transit during childhood. Exposure in college and immediately after proved to have an influence on mode choice for individuals who were exposed to it during this time.

Advisor: Deakin, Elizabeth
The Electron-Phonon Interaction from First Principles

In this thesis the ground state electronic properties, lattice dynamics, electron-phonon coupling and superconductivity of a variety materials are investigated from first principles. The first chapter provides an introduction to the material and concepts of this thesis as well as motivation for the work done herein. Additionally, an overview is given on the theoretical background governing the calculations of this work. This includes overviews of the topics of density functional theory, the pseudopotential approximation, density functional perturbation theory, and applications of these approaches to the calculations of superconductivity. In the second chapter the mechanics of actually performing calculations within the methodology of chapter one are explained. This is accomplished through a detailed description of the computer software EPW. This software has been developed to allow computationally efficient approaches for calculating the electron-phonon interaction. A description of the software package, the particular quantities which it calculates and example calculations are given. The following two chapters present the results of calculations regarding electron-phonon coupling and superconductivity in bulk carbon compounds. The occurrence or absence of superconductivity is found to be related in these compounds to Fermi surface nesting and carrier concentrations. In chapter five we investigate the role of the fluorine dopant in the recently discovered (1111) Fe-pnictide superconductors. Contrary to the results of the literature published shortly after the discovery of these compounds, the presence of the dopant is found to actually result in a net decrease in the electron concentration on the Fe-plane within the local density approximation to density functional theory. In the two chapters which follow, we investigate the limits of two dimensional superconductivity in the recent experiments on ultra-thin Pb samples. Chapter six details calculations on freestanding Pb slabs constructed as thin as two monolayers. A useful formula predicting the electron-coupling strength and therefore estimating the superconducting transition temperature is developed. While in the next section a superconducting system is investigated wherein the important Pb-Si(111) interaction in ultra-thin Pb layers is taken into account. The observed superconductivity is explained by electron-phonon coupling and isotropic Migdal-Eliashberg theory. The observance of superconductivity in the nearly two-dimensional material is shown not to conflict with the predictions of the Mermin-Wagner theorem. In the final chapter, the phonon-assisted absorption of bulk silicon is calculated from first-principles. The calculated results are found to be in excellent agreement with experiment, and lead the way for the possibility of many first-principle studies on phonon-assisted optical processes in important technological devices.

Advisor: Cohen, Marvin L
Powering mm-Size Wireless Implants for Brain-Machine Interfaces

Over the last couple of years, Brain-Machine Interfaces (BMI) based on microelectrode arrays have been shown to have the potential to substantially improve the quality of life for people suffering from debilitating conditions such as spinal cord injuries or limb loss. One of the most critical parts of a BMI system is the neural sensor. It is ideally implanted underneath the skull, reads out neural signals from the brain and transmits them wirelessly to a receiver outside the skull. The requirements on the electronics of such a sensor are extremely stringent, especially with respect to size and power consumption. Ideally, the overall size of the implanted sensor node is limited by the size of the sensor itself, rather than the electronics and the power source./nThis work investigates powering options for implants of sizes ranging from 10 mm by 10 mm down to 1 mm by 1 mm. Wireless power transfer is identified as the most promising option of doing so and is investigated in detail. It is shown, that for a given implant antenna size, an optimum combination of external antenna and frequency of operation exists that minimizes the overall link loss. In combination with limitations on the maximum transmit and received power due to health concerns, the maximum power available to mm-size implants as a function of size is derived. Two different AC-to-DC conversion circuit topologies, covering the expected input power and frequency range, are analyzed in detail and design guidelines for each are given./nFinally, a 1 mm3 proof-of-concept implementation of a wirelessly powered neural transponder is presented. It was tested in air and in animal and provides enough extra DC power to power a neural sensor front-end while supporting a 2 Mbps radio link. The presented tag is the smallest wireless neural tag reported to date and prooves the feasibility of remotely powered mm-size wireless neural implants.

Advisor: Rabaey, Jan M.
Design and Implementation of a Hypervisor-Based Platform for Dynamic Information Flow Tracking in a Distributed Environment

One of the central security concerns in managing an organization is protecting the flow of sensitive information, by which we mean either maintaining an audit trail or ensuring that sensitive documents are disseminated only to the authorized parties./nA promising approach to securing sensitive data involves designing mechanisms that interpose at the software-hardware boundary and track the flow of information with high precision --- at the level of bytes and machine instructions. Fine-grained information flow tracking (IFT) is conceptually simple: memory and registers containing sensitive data are tagged with taint labels and these labels are propagated in accordance with the computation. However, previous efforts have demonstrated that full-system IFT faces two major practical limitations --- enormous performance overhead and taint explosion. These challenges render existing IFT implementations impractical for deployment outside of a laboratory setting./nThis dissertation describes our progress in addressing these challenges. We present the design and implementation of PIFT (for Practical Information Flow Tracking) --- a hypervisor-based IFT platform that achieves substantial performance improvements over previous systems and largely eliminates the problem of kernel taint explosion. PIFT takes advantage of spare CPU cores to track the flow of information asynchronously and in parallel with the primary instruction stream./nTo the best of our knowledge, PIFT is the most efficient full-system IFT platform available at the time of writing and is the only implementation that supports real-time tracking of information flow in graphical desktop environments.

Advisor: Shenker, Scott
Familiar Strangers: The Georgian Diaspora in the Soviet Union

The experience of the Georgian diaspora in the Soviet Union is a story of the paradoxes of Soviet empire. On the one hand, the arrival of the Red Army in Tbilisi in 1921 brought Georgia's brief period of independence to an abrupt end. On the other hand, membership in the newly-constituted Soviet Union opened up new opportunities for Georgians and other ethnic minority groups. Such opportunities were seized upon most effectively by an internal Georgian diaspora within the Soviet Union, a small but highly mobile and visible community. The Georgians, who traveled to Moscow from the periphery of the Soviet empire, could be seen at the center of Soviet life at every stage of Soviet history. Georgians headed the state that built socialism, provided the food and entertainment when Soviet citizens desired new forms of consumption and leisure, dominated the burgeoning second economy, and were among the first to seek an exit from the Soviet Union amidst the rising nationalism that accompanied its demise. By examining the aspects of Soviet life where Georgian prominence was greatest, the dissertation explores the broad sweep of Soviet history from the perspective of this dynamic ethnic minority./nThe dissertation begins by introducing the concept of internal diasporas in Soviet history and outlining the unique roles played by the Georgians. Subsequent chapters explore the rise of Georgians in the Soviet political elite, the dissemination of Georgian food and drink through institutionalized Georgian social networks, the unique forms of ethnic entertainment created by Georgian cultural entrepreneurs, and the vital role played by Georgian traders in the second economy of the Soviet Union. The final chapter looks at how Georgian ambitions, bred in the Soviet context, led the republic's intelligentsia to eventually seek an exit from the Soviet Union, and an epilogue takes the story of the Georgian diaspora up to the present day./nWhile scholars in the past have focused on the periphery as a way of challenging theories of revolution and society based on the Soviet empire's Russian core, this project looks at how a multiethnic center was created by groups from the periphery, and how lines between center and periphery, as well as those between colonizer and colonized, were particularly blurred in the Soviet context. Unlike earlier studies of nationality, the dissertation looks not at a particular group in a specific territory in isolation from all others, but rather examines the interplay of diverse ethnic groups across geographic boundaries. It also brings into focus social and cultural factors previously neglected in the study of nationality and empire, including entertainment, everyday life, and material culture. Finally, the Georgian case challenges our understanding of the concept of diaspora. Rooted Soviet cosmopolitans, members of the Georgian diaspora maintained and capitalized on their connection to a specific territory and culture even as they traveled beyond the borders of their native republic.

Advisor: Slezkine, Yuri