VictorJuiz/thesis huggingface dataset:
An assessment of late Pleistocene to middle Holocene lake level fluctuations in Surprise Valley, California
Keywords: Pluvial Lakes
Geochronology
Isotopes
Uranium
Geological and Environmental Sciences
Thesis

Knowledge of Earth’s climate history and sensitivity, combined with modeling past and future climate, are central to informing policy decisions regarding future climate change. The hydrologic response to future warming scenarios due to increased anthropogenic CO2 emissions remains uncertain. Freshwater availability in the arid western United States is projected to decrease in availability as increased agricultural, urban and industrial uses continue to stress supplies. Motivated by the potential for dramatic future hydrologic changes, studies recording the abrupt transitions between different equilibrium states of natural past climate variability shed light on our understanding of the modern climate system.
The presence of pluvial lakes in the Basin and Range Province, in the western United States, during the late Pleistocene (40 to 10 ka) indicates far greater moisture availability during the Pleistocene glacials. This study investigates the timing and magnitude of the most recent pluvial lake cycle that filled Surprise Valley, California using geophysical, geochemical and geochronologic tools. Spanning 31.2 to 4.6 ka, this new lake level record places the highest lake level, at 180 meters above present day playa, at 13.9 ± 1.2 ka. This age appears to be nearly synchronous with highstands of Lake Lahontan to the south and the Chewaucan Basin to the north. Additionally, most of the Basin and Range lake highstands, including Lake Surprise, follow peaks in precipitation minus evapotranspiration (P-ET) by 8-10 kyr. By compiling a diverse set of paleoclimate data available for western North America, I found that the timing and geographic distribution of lake highstands is inconsistent with increased precipitation in response to shifting westerly winds, the current model for the genesis of large lakes in western North America. Rather, lakes levels are more strongly correlated with changes in summer insolation, suggesting that lake highstands were likely facilitated by colder temperatures and increased humidity due to the presence of continental ice sheets and increased atmospheric convergence. I compared the constraints from lake and soil-based records to Atmosphere-Ocean General Circulation Model simulations from the Paleoclimate Model Intercomparison Project 2. Based on model-proxy intercomparison, the Atmosphere-Ocean General Circulation Models, the same models used to also assess future climatic changes, poorly predict hydrologic quantities for the Last Glacial Maximum.
An Assessment of Late Pleistocene to Middle Holocene Lake Leven Fluctuations in Surprise Valley, California
Keywords:  Department of Geological and Environmental Sciences
School of Earth Energy &amp; Environmental Sciences
Pleistocene
California
Thesis

The presence of pluvial lakes in the Basin and Range Province, in the western United States, during the late Pleistocene (40 to 10 ka) indicates far greater moisture availability during the Pleistocene glacials. This study investigates the timing and magnitude of the most recent pluvial lake cycle that filled Surprise Valley, California using geophysical, geochemical and geochronological tools.
Analysis of the BOLD characteristics in pass-band balanced steady state free precession functional magnetic resonance imaging [electronic resource]
Keywords: Electrical Engineering

Magnetic resonance imaging (MRI) is a powerful medical imaging modality that provides unique and flexible tissue contrast. MRI provides anatomical images, and also provides other capabilities such as measuring physiological changes such as neuronal activation. Since Ogawa et al. suggested oxygenation level as a contrast mechanism underlying the correlation between brain activation and image intensity of gray matter in MRI, various methods have been proposed to improve the contrast. Currently, Gradient Echo (GRE) Echo Planar Imaging (EPI) is most widely-used for the purpose. Balanced Steady-State Free Precession (bSSFP) has recently been proposed as an alternative method to acquire BOLD contrast. Pass-band bSSFP fMRI utilizes the T2 sensitivity of bSSFP in a relatively wide and flat off-resonance frequency band of the bSSFP profile. The method has a potential to provide higher SNR efficiency with reduced imaging artifacts compared to conventional approaches. Previous experimental results suggested that the level of the functional contrast and its characteristics are significantly influenced by the sequence parameters. However, few of these contrast characteristics have been investigated systematically. In this study, a computer simulation was performed to investigate the sources of functional contrast and the influence of scan parameters on the functional contrast to elucidate the contrast characteristics of pass-band bSSFP fMRI. The results suggest that both intravascular T2 change and extravascular spin diffusion are contrast sources with the intravascular contribution covering more than 60% of the total signal change. The extravascular contrast is the main source of small vessel specificity in the pass-band bSSFP fMRI. The pass-band bSSFP fMRI with short TR is most sensitive to vessels with 2 to 5 [mu]m radius, equivalent to human brain capillary size. The extravascular contrast of the pass-band bSSFP fMRI also depends on flip angle, B0 field, and TE. Experiments were performed to validate the simulation results.
Analysis of zero emission power generation from SCWO of coal and development of an experimental facility for its investigation [electronic resource]
Keywords: Mechanical Engineering

Decarbonization of electricity production is vital for curbing the effects of emissions on global climate change. Most projected pathways toward meeting emissions targets include a large contribution from carbon capture and storage. Many capture technologies impose a large energy penalty to separate and compress carbon dioxide (CO2). Deep saline aquifers are the largest and most distributed reservoirs for CO2 sequestration. However, neat CO2 injected in an aquifer is buoyant compared to the aquifer brine and requires an impermeable seal to prevent it from escaping the aquifer. An alternative technology, recently proposed by Heberle and Edwards, burns coal in supercritical water pumped from a saline aquifer. The entire effluent stream is sequestered, capturing all carbon and non-mineral coal combustion products in the process. This stream is denser than the aquifer brine and therefore offers a higher level of storage security. Aquifers without suitable structural trapping could be opened up for storage as a result. This technology also increases energy security in the U.S., allowing for the use of its coal resources while avoiding atmospheric pollution. In this work, a complete architecture employing supercritical water combustion (SCWC) is proposed, including a liquid oxygen-pumped air separation unit and regenerator system that heats and desalinates the incoming brine. A thermodynamic model is used to calculate the overall thermal efficiency of the plant, including all separation and storage energy penalties. In addition, an exergy analysis determines the least efficient parts of the proposed system. The details and assumptions of the model are discussed. Insights from the model and these analyses elucidate how the proposed system may be operated as a zero-emission electricity source, and the technical challenges that must be addressed for deployment. In order to determine the operating characteristics of the supercritical water combustor, an experimental facility was developed. A test apparatus was designed to study turbulent, hydrothermal diffusion flames for use in a SCWC power plant. The lab-scale combustor operates at 250 bar, with up to a 50 kW fi ring rate and 1600 K burner outlet temperature. Initial combustion studies have provided autoignition temperature data of methanol in supercritical water.
Antibody adsorption at the silicone oil-water interface [electronic resource] : exploring the strengths and limitations of the quartz crystal microbalance technique
Keywords: Chemical Engineering

High-concentration antibody formulations for parenteral delivery are increasingly packaged and stored in pre-filled glass syringes due to the ease of dosage control and administration. A thin film of silicone oil provides a lubricious layer to prevent freezing of the syringe plunger. This layer is thought to cause several complications when in contact with the antibody solution, namely surface-induced aggregation of the antibody and silicone oil droplet formation, leading to visible particle formation, increased viscosity of the solution, and possible unintended immunogenic reactions once injected into the patient. In this work, we describe an experimental platform to study the fate of antibodies on a model hydrophobic surface. By combining acoustic (quartz crystal microbalance with dissipation) and optical (ellipsometry) surface-sensitive techniques, we can monitor not only the amount of protein adsorbing onto a surface, but also its state of solvation and mechanical coupling to the surface. By this approach, we can examine the orientation of adsorbed proteins and detect aggregation on the surface. This platform allows us to study the effects of formulation conditions and excipients on antibody-surface interactions, with the ultimate goal of minimizing aggregate formation.
Approximate equilibria in large games [electronic resource]
Keywords: Management Science and Engineering

The complexity of studying Nash equilibrium in large games often scales with the size of the system: as it increases, computing the exact Nash equilibrium can soon become intractable. However, when the number of players in the system approaches infinity and no individual player has a significant impact on the system, we can approximate the system by considering each single player no longer playing against other individual players but a single aggregation of all other players. In this paper, we apply this idea to study and approximate Nash equilibria in two large scale games. In part I, we consider a model of priced resource sharing that combines both queueing behavior and strategic behavior. We study a priority service model where a single server allocates its capacity to agents in proportion to their payment to the system, and users from different classes act to minimize the sum of their cost for processing delay and payment. As the exact processing time of this system is hard to compute and cannot be characterized in closed form, we introduce the concept of aggregate equilibrium to approximate the exact Nash equilibrium, by assuming each individual player plays against a common aggregate priority that characterizes the large system. We then introduce the notion of heavy traffic equilibrium as an alternative approximation of the Nash equilibrium, derived by considering the asymptotic regime where the system load approaches capacity. We show that both aggregate equilibrium and heavy traffic equilibrium are asymptotically exact in heavy traffic. We present some numerical results for both approximate equilibria, and discuss efficiency and revenue, and in particular provide a bound for the price of anarchy of the heavy traffic equilibrium. In part II, we study the reputation system of large scale online marketplace. We develop a large market model to study reputation mechanisms in online marketplaces. We consider two types of sellers: commitment sellers, who are intrinsically honest but may be unable to accurately describe items because of limited expertise; and strategic sellers, who are driven by a profit maximization motive. We focus on stationary equilibria for this dynamic market, in particular, on separating equilibria where strategic sellers are incentivized to describe the items they have for sale truthfully, and characterize the conditions under which such equilibria exist. We then complement our theoretical results with computational analysis and provide insights on the features of markets that may incentivize truthfulness in equilibrium.
Architectures and mechanisms for wireless coexistence [electronic resource]
Keywords: Electrical Engineering

Wireless has quickly become an irreplaceable medium for communication, but by their very nature, wireless transmissions are vulnerable to RF interference from various sources. This weakness is a growing problem for technologies that operate in unlicensed frequency bands, as these bands are becoming more crowded over time. The increasing density of radios, coupled with the growing number of different protocols, dictates that future wireless devices will require the ability to coexist and operate in a crowded and often unregulated electromagnetic environment. This dissertation presents a set of architectures and mechanisms for wireless coexistence. These mechanisms are intended as general primitives, enabling future wireless networks to be architected such that they are aware of who their RF neighbors are, what they are doing, and how to respond to them. We design and develop two systems, each demonstrating how changes at different levels across the network stack can provide significant gains. Degrees Of Freedom (DOF) is a robust and accurate technique to detect activity in any band of the relevant spectrum, while Picasso is an extensible radio design which allows the device to more easily exploit the fragmented bands which are available. This dissertation contributes to advancing the state of the art in wireless network design in multiple ways. First, the systems in this dissertation present novel algorithms that span signal processing, circuit design, and software systems. Not only do these algorithms enrich existing theory, they are designed with practical implementations in mind - helping to bridge the gap between theory and practice. Second, we present prototype implementations and testbed evaluations of our systems. Our results demonstrate that our systems deliver significantly improved performance in crowded interferencecentric environments, compared to the state-of-the-art. Finally, the work in this dissertation demonstrates that by having layers work cooperatively, rather than in isolation, common goals of high throughput and reliability in dense interference scenarios are much more practical to achieve. In particular, DOF demonstrates that more fine-grained information passed between the PHY and the MAC enables the MAC to make more informed and intelligent decisions regarding how to respond to the varying sources of interference. In the same vain, Picasso demonstrates that increased RF isolation can significantly lessen the burden on PHY filtering and MAC coordination - similarly allowing the three to share in the task of exploiting fragmented spectrum. We believe that the systems in this dissertation make a compelling and strong argument for cross-layer interdisciplinary wireless network design in order to solve the problems of wireless coexistence.
Are we there yet? Exploring English learners' journey to reclassification and beyond [electronic resource]
Keywords: Education.

Limited research exists about the time that English learners (ELs) take to acquire English proficiency, the factors that are related to students' English acquisition trajectories, and the relationship between reclassification as proficient in English and later academic outcomes. I use nine years of longitudinal, student-level data from the Los Angeles Unified School District, combined with interviews and observations from a cohort of San Francisco Bay Area students initially classified as English learners, to explore students' journey to reclassification. The data show that likelihood of reclassification is powerfully related to students' initial proficiency in English and in their primary language. For example, students who enter kindergarten with beginning levels of English proficiency have a 50% probability of reclassification after nine years in the district, compared to an 80% probability of reclassification for students who enter with intermediate levels of English proficiency. Meanwhile, although conventional methods suggest the reclassification is associated with higher academic achievement, I show that when regression discontinuity is used to remove bias from these estimates, there is no significant effect of reclassification on later academic achievement for my analytic sample. Finally, students reclassified at later grades describe the strong stigma they felt when placed in English Language Development classes at the secondary level, highlighting the need to scaffold instruction for ELs in ways that students do not experience as remedial.
At home in the margins [electronic resource] : Vasily Rozanov, autobiography and alterity
Keywords: Slavic Languages and Literatures.

In analyzing the works of Vasily Rozanov (1856-1919), this dissertation departs from the critical tendency to separate Rozanov's journalistic and philosophical works from his more famous autobiographical "trilogy": "Solitaria" (1911), "Fallen Leaves, Basketful I" (1913), and "Fallen Leaves, Basketful II" (1915). Addressing Rozanov's early writings, such as "In the Land of the Unclear and Undecided" (1901) and "The Family Question in Russia" (1903), as well as his problematic texts, such as "The Tactile and Olfactory Relation of Jews to Blood" (1914), in concert with his "Fallen Leaves" trilogy, the author points out the constancy, if not always in Rozanov's ideas, then in his performative self-presentation, which focused on the I's alterability and the autobiographer's interaction with figures of alterity. According to this reading, Rozanov emerges as part of a number of important 20th century trends that emphasize literary performance, the intersection of the body and the text, and the interaction of self and other. Rozanov's philosophical interest in physical intimacy and the body and his theoretical concern with the textual interrelations of self and other shape this dissertation's organization: Chapter 1 focuses on autobiography and the body and Chapter 2 considers the autobiographer's interactions with others' texts. Each section also counterposes Rozanov with other writers, such as his idol, Fyodor Dostoevsky, and literary theorists, such as Viktor Shklovsky, Mikhail Bakhtin, and Jacques Derrida. In this author's view, Rozanov not only influences Bakhtin, whose concept of the grotesque, carnival body is shockingly Rozanovian, but many aspects of his texts also emerge as a parallel to the writings of performative theorists like Derrida.
Atomistic simulations of interfacial defect structures of nanoscale solid oxide electrolytes [electronic resource]
Keywords: Mechanical Engineering.

A Hybrid Monte Carlo - Molecular Dynamics algorithm was developed to sample the equilibrium distributions of point defects near the (100) surface and two types of pure tilt grain boundaries ([sigma]5(310)/[001] and [sigma]13(510)/[001]) in nanoscale yttria-stabilized zirconia and gadolinia-doped ceria. The simulations predict the first large-scale equilibrium distributions of dopant cations and oxygen vacancies near the three types of interfaces where both kinds display considerable amounts of segregation. The results are compared with various experimental observations, which are qualitatively consistent with the theoretical predictions. The simulation results offer new findings that were not accessible by experiments such as elemental distributions on the atomic scale, the effects of pressure and doping level on dopant segregation, and the effect of defect segregation on the ionic diffusivity. The simulations also reveal the strong dependence of defect segregation on the microscopic structure of the interface. Dopant segregation is triggered by the high concentration of oxygen vacancies at the interface due to lower formation energies and elastic strain due to size misfit between host and dopant cations, but the final distribution profiles are largely determined by the interactions between point defects. The newly proposed segregation mechanism sheds light on the understanding of equilibrium defect structures in these ionic oxides.
Attitude and rate estimation for remote tumbling targets using line scan range measurements [electronic resource]
Keywords: Aeronautics and Astronautics

The work in this thesis enables the estimation of orientation and angular rates for tumbling targets using scanning range measurements. This general estimation problem is a vital part of enabling autonomous rendezvous for spacecraft. The primary focus of this work was to consider cases where data smearing is a problem. Data smearing occurs when scanning range measurements are taken from a continuously moving target. If the raw data are aggregated into a point cloud without motion correction, they no longer represent the target geometry accurately. The estimation framework presented considers individual, sequential measurements as opposed to aggregating range data into point clouds. This paradigm shift addresses the problem of data smearing in a general and robust way by applying a recursive estimation framework that inherently accounts for noise in the motion correction. This algorithm relies on knowledge of the target's shape, e.g. a CAD model, and general equations of motion. The estimator is fed solely by measurements from the ranging sensor. The estimation process is decomposed into an acquisition phase and a tracking phase, and filters are constructed for each. Specifically, a particle filter is developed for use in the acquisition phase and an extended Kalman filter is utilized for the tracking phase. The design and implementation of an experimental platform are also discussed. This platform can rotate a model through an arbitrary, specified trajectory while maintaining unoccluded visibility of the target for observation by external sensors. Details of the hardware, software, sensing, and closed loop control architecture are included. Both simulation and experimental results are presented which verify the successful performance of the proposed algorithms in the presence of realistic sensor noise and modeling uncertainty. The hardware experiments employ a continuously rotating target, which results in data smearing, and consider a limiting case where the sensor has only a line scan pattern.
Augmented self-regulation [electronic resource]
Keywords: Education.

Research in interactive technology most often enables humans to enact more, better, or new behaviors or to gain greater or more efficient insight into our environment. This dissertation develops the notion that technology can also help us develop greater self-awareness. Self-awareness, made tangible and observable by physiological self- regulatory processes, rests at the core of the human experience by supporting comprehension, actions, and intentions in the world around us. Without it, our health and behavior are victims of demands from our sociocultural environments or of flippant or self-defeating patterns of thoughts. This dissertation explores and evaluates methods of using wearable sensors and interactive feedback to augment human self-regulation, specifically respiratory self- regulation, primarily during information work but also in mobile contexts. This is a potentially powerful means of not only influencing health and behavior but also developing an inner sense of wellness independent of one's physiological, cognitive, or affective state. The over-arching contribution of this dissertation is to demonstrate the view that computers will have a more direct and pervasive impact on human psychophysiology than is currently practiced. Rather than strictly adapting to human physiological and affective state, future machines will explicitly induce changes in psychophysiological state to amplify their user's innate self-regulatory ability and skill. In this way, machines of the future will help humans be 'more human' rather than simply adding or enhancing existing human abilities.