VictorJuiz/thesis huggingface dataset:
Albanese and Picard 1-Motives in Positive Characteristic

The goal of this Thesis is to develop the theory of Picard and Albanese 1-motives attached to a variety X defined over a perfect field of positive characteristic, and to relate these 1-motives to the etale cohomology groups of X. This should be viewed as a generalization of the classical theory of Picard and Albanese varieties attached to a smooth and proper variety X. Moreover, giving such a theory allows us to relate the dimension- and codimension-one etale cohomology groups in the most natural (`motivic') way possible; in particular, independence-of-l type results in dimension- and codimension-one are automatic once one has developed such a theory./nIn the case of a base field of characteristic zero, the corresponding 1-motives have been constructed and studied in previous work of Barbieri-Viale and Srinivas. When one deals with a positive-characteristic base field, new difficulties arise due to the fact that resolution of singularities in positive characteristic is still an open problem. This forces us to introduce new methods, especially a strong form of de Jong's results that allows us to resolve (in a weak sense) an arbitrary separated finite type k-scheme by a smooth Deligne-Mumford stack. A large part of this thesis is devoted to preliminary results on divisors and cycle class maps for Deligne-Mumford stacks that we need when applying the methods of Barbieri-Viale and Srinivas with stacks rather than schemes./nIn the end, we manage to construct the Picard 1-motives of an arbitrary separated finite type k-scheme with no additional assumptions, and prove various functoriality and compatibility properties for these 1-motives. The situation with the Albanese 1-motives is more complicated; over an arbitrary perfect field, we only manage to show that the Albanese 1-motives of X exist after possibly base extending X via a finite field extension. We show, however, that in the case that k is a finite field or an algebraically closed field, no such field extension is necessary. The case of a finite field uses a method for descending 1-motives along an extension of finite fields when the 1-motive is only given up to isogeny. This method may be of some independent interest.

Advisor: Olsson, Martin C
An Energy-Efficient Triple-Channel UWB-based Cognitive Radio

The proposed triple-channel UWB-based cognitive radio exploits spectral crowding and coexistence of other wireless devices as the number of sensors and wearable computing devices increases in 3.1GHz to 10.6GHz ISM band to achieve energy efficient 1Gb/s short-range wireless communication. A dual-resolution analog wavelet-based spectrum performs bandwidth-and frequency-agile band pass filter (BPF) to detect narrowband and wideband interferers with low power consumption. A charge-pump-based triangular waveform generators and a source follower type low pass filter (LPF) generates basis function for the spectrum sensing with 132MHz sensing resolution. A Low power integer-N QPLL with reduced reference spur by digital calibration on mismatch of the charge pump current supports the tuning frequencies with a linear tuned wide range two stage ring-VCO and a low power programmable true-single-phase-clock (TSPC) divider. The proposed Triple-channel UWB-based cognitive radio was fabricated in 1V 65nm CMOS GP process. The test chip size is 2.3×2 mm2, and the active area is 2.1mm2. The data rate by using triangular shaped BPSK data is 1Gb/s at 1m communication. The lowest FoM of the energy/bit is 61pJ/bit, and the highest FoM is 102pJ/bit. It achieves BER from 9.2×10-7 to 1.1×10-4 according to frequency allocation of the triple-channels. The triple-channel UWB-based cognitive radio can provide energy efficient high-data rate wireless communication even with over 20% channel occupation.

Advisor: Rabaey, Jan M.
Magnetic Particle Imaging with Advanced Tomographic Reconstruction Methods

Magnetic Particle Imaging (MPI) is an emerging imaging modality with potential clinical applications in rapid angiography, cell therapy tracking, cancer imaging, and inflammation imaging. While still in its infancy, MPI already has excellent contrast, safety, depth penetration, and sensitivity without the serious health risks posed by current modalities such as ionizing radiation and iodinated contrast agents./nWith any tracer imaging modality, high sensitivity is necessary to improve safety and enable new clinical applications. The first Magnetic Computed Tomography (MCT) system and experimental images were created in this work with the goal of improving sensitivity in MPI. MCT uses projection reconstruction algorithms similar to those in X-ray computed tomography to reconstruct 3D images from a projection MPI sytem. Analytical derivation and experimental evidence demonstrate that MCT has an order-of-magnitude higher SNR than previous 3D MPI methods for the same scan time as well as a 40% resolution improvement. The MCT experimental system acquisition speed was improved from initial work to acquire images twenty-fold faster at less than two minutes per 3D image./nCritical to any medical imaging technology is the reliability and accuracy of image reconstruction. Unfortunately, prior approaches to x-space MPI reconstruction suffer from image artifacts such as banding and haze. In this work, a priori knowledge of image continuity and non-negativity are introduced into a new optimization formulation to reduce these non-physical artifacts in 2D and 3D reconstructions.

Advisor: Conolly, Steven M
Programming Layout by Manipulation

Creating layouts for documents, GUIs, or data visualizations is a time-consuming and error-prone process. Non-programmers would like the customization and fine-grained control currently only possible with handwritten layout engines. Today, such engines are written by proficient programmers. This thesis introduces new techniques for specifying layout and generating efficient layout engines./nFirst, we present a new programming methodology which addresses the two central sources of bugs in layouts: ambiguities and conflicts. Then, we introduce a language of constraints in which we capture layout specifications formally. Finally, we show how to generate efficient layout engines automatically. We provide the following individual contributions:/n1) The Programming by Manipulation (PBM) paradigm targeted at non-programmers to establish specifications in visual domains such as layout. We introduce a new type of user demonstration---manipulation---which is resistant to users' imprecisions inherent in drawing. Instead of sketching the desired layout, users steer the exploration of potential layouts by pointing out what they would like to change./n2) L3, a declarative language for layout specifications. L3 is based on non-directional constraints in which the flow of computation is completely abstracted away./n3) A synthesis procedure---grammar modular synthesis---capable of generating layout engines from L3 specifications. Our new algorithm scales to realistic layout specifications and produces generic engines supporting languages of documents./nTo evaluate our work, we present two user studies showing not only that non-programmers can design interesting visualizations using PBM, but also that proficient programmers are more productive with PBM than with conventional constraint programming. We also compare the performance of our synthetized engines with state-of-the-art constraint solvers and show that our engines are up to two orders of magnitude faster.

Advisor: Bodik, Rastislav
Vehicle Parameter Identification and its Use in Control for Safe Path Following

This thesis develops vehicle parameter identification algorithms, and applies identified parameters to a controller designed for safe path following./nA tire-road friction coefficient is estimated using an in-tire accelerometer to measure acceleration signals directly from the tires./nThe proposed algorithm first determines a tire-road contact patch with a radial acceleration profile./nThe estimation algorithm is based on tire lateral deflections obtained from lateral acceleration measurements only inside the contact patch./nA new model is derived for the lateral deflection profiles, which provides robustness to orientation-variation of the accelerometer body frame during tire rotation./nA novel algorithm is developed to identify three inertial parameters: sprung mass, yaw moment of inertia, and longitudinal position of the center of gravity./nA correlation of inertial parameters is derived and is used for the identification algorithm./nInertial parameters and vehicle states are simultaneously estimated with a dual unscented Kalman filter based on a nonlinear vehicle model./nIn order to activate and de-activate different modes of the proposed/nalgorithm, a local observability analysis is performed with the nonlinear vehicle model./nThe performance and robustness of the proposed approach are demonstrated with extensive CarSim simulations and experimental tests on a flat road with a constant tire-road friction coefficient./nFollowing a curved road can be dangerous if autonomous vehicles do not take roll motion into consideration./nA control algorithm is designed to prevent a dangerous vehicle state induced by roll motion while following a curved road./nRoll motion is suppressed throughout cornering with model predictive control./nA four-wheel nonlinear vehicle model with roll dynamics and a tire brush model are utilized for the prediction of the vehicle state./nAn optimal balance in the trade-off between vehicle speed and/nroll motion is achieved with full braking as a control actuator./nIdentified vehicle inertial parameters are incorporated into the designed controller./nCarSim simulations illustrate the performance of the proposed controller and the effect of the vehicle parameter estimator.

Advisor: Hedrick, John Karl
Essays on Low_risk Investing

Low-risk investing refers to a diverse collection of investment strategies that emphasize low-beta, low-volatility, low idiosyncratic risk, downside protection, or risk parity. Since the 2008 financial crisis, there has been heightened interest in low-risk investing and especially in investment strategies that apply leverage to low-risk portfolios in order to enhance expected returns./nIn chapter 1, we examine the well-documented low-beta anomaly. We show that despite the fact that low-beta portfolios had lower volatility than the market portfolio, some low-beta portfolios had higher realized Sharpe ratios (over a 22-year horizon) than the market portfolio. This is can not happen in an efficient market, where long-run return is expected to be earned as a reward for bearing risk, if risk is equated with volatility. We expand the notion of risk to include higher moments of the return distribution and show that excess kurtosis can make low-beta stocks and portfolios riskier than higher beta stocks and portfolios./nIn chapter 2, we show that the cumulative return to a levered strategy is determined by five elements that fit together in a simple, useful formula. A previously undocumented element is the covariance between leverage and excess return to the fully invested source portfolio underlying the strategy. In an empirical study of volatility-targeting strategies over the 84-year period 1929-2012, this covariance accounted for a reduction in return that substantially diminished the Sharpe ratio in all cases./nIn chapter 3, we gauge the return-generating potential of four investment strategies: value weighted, 60/40 fixed mix, unlevered and levered risk parity. We have three main findings. First, even over periods lasting decades, the start and end dates of a backtest can have a material effect on results; second, transaction costs can reverse ranking, especially when leverage is employed; third, a statistically significant return premium does not guarantee outperformance over reasonable investment horizons.

Advisor: Anderson, Robert M.
Silicon Carbide Bipolar Junction Transistors for High Temperature Sensing Applications

There is a rising demand for harsh-environment integrated circuits and sensors for a wide variety of applications, ranging from structure health monitoring and process control to space navigation. The ability to continually obtain information in situ in high temperature environment such as a jet engine or a deep oil well can potentially save millions of dollars and even human lives. It also opens doors to space missions to locations with extreme conditions such as Venus, where devices would be required to operate around 500 °C. Wide bandgap materials are well suited for these applications due to their superior electrical and mechanical properties compared to the silicon incumbents. 4H-SiC, a polytype of silicon carbide (SiC), for instance, has a bandgap (3.2 eV) that is almost 3 times of that of silicon (1.12 eV). The wider bandgap results in a much lower intrinsic carrier concentration compared to that of silicon, which makes it an ideal candidate for high temperature (> 300°C) applications. These high temperature capabilities will be the main subject of investigation in this thesis. The overarching objective of the thesis is to develop 4H-SiC technologies for both transistor and sensor devices. Specifically, we investigate and develop the design, simulation, fabrication and characterization of 4H- SiC bipolar junction transistor (BJT) that is capable of operating at elevated temperatures up to 400°C. In addition, a high-performance temperature sensor based on 4H-SiC pn diode which can stably operate in a temperature range from 20°C to 600°C is demonstrated. This type of temperature sensor can be integrated with supporting circuitries to create a sensing module that is capable of working at extremely high temperatures.

Advisor: Pisano, Albert P
More Than Talking Heads: Nonfiction Testimony and Cinematic Form

This dissertation examines a body of formally and aesthetically innovative nonfiction and experimental films, videos, and installation works that have created new modes of cinematic testimony with new possibilities of viewer/listener engagement. I call such films cinematic testimony in order to make a distinction between them and the more common talking head interview film. When cinema is not simply a recording device but an aesthetically engaged practice, it creates a wholly new medium of testimony, something that cannot exist in any other form./nIf testimony is typically associated with speech and primarily verbal expression, cinematic testimony has a much broader expressive scope. It includes not just speech but the voices, bodies, and gestures that articulate and give rise to this speech. It also includes a vast array of evocative and epistemologically significant possibilities afforded by mise-en-scène, bodily or cinematographic movements in and across space, the staging of reenacted or imagined events, the cinematic depictions of mental as well as physical landscapes, and various aesthetic strategies through which cinematic testimony can be shaped. The works of cinematic testimony explored here (for the most part made between 1985 and 2006) take conscious creative and ethical responsibility for their use of the medium. In deliberately creating new forms of testimony, they also reflect on, and reveal something about, the very nature of testimony itself./nTestimony is important because it serves as a source of knowledge about a shared world from the perspective of other human beings and signifies the emergence of as yet unheard voices in the public sphere. However, testimony also functions as the representation of a mode of relating (in both senses of the term) and thus as a model of human exchange. As more and more testimonial encounters occur through the medium of moving images, attention to the rhetorical and aesthetic forms of this relating, this saying--verbal, vocal, gestural, and cinematic--and not only the content of the said, seems all the more crucial to the future of ethical relations both within documentary film and beyond. Ultimately, this dissertation argues for the centrality of cinematic form in the production, reception, and analysis of cinematic testimony. Cinema's use of its own language and voices, its own aesthetic forms, is as crucial as the embodied speakers' use of theirs when it comes to articulating testimony through moving images.

Advisor: Skoller, Jeffrey
Williams, Linda
Essays on Household Electrification in Developing Countries

This dissertation studies issues on household electrification in developing countries, an issue of utmost importance in the fields of development and energy economics. Chapter 1 provides the first empirical evidence that household electrification leads to direct and substantial welfare improvements via reductions in indoor air pollution. In the setting of a recent electrification program in northern El Salvador, we exploit a unique dataset on minute-by-minute fine particulate matter (PM2.5) concentration within the framework of a clean experimental design. Two years after baseline, overnight PM2.5 concentration was on average 63% lower among households that were randomly encouraged to connect compared to those that were not. This change is driven by reductions in kerosene use and, as suggested by our conceptual framework, the effects are larger among heavier kerosene users. As a result, the incidence of acute respiratory infections among children under 6 fell by 35-45% among encouraged households. Estimates of exposure measures suggest large health gains for all household members, but these gains are unequally distributed by gender. In addition, we show that when the electrification rate among the non-encouraged group caught up with that of the encouraged group, the effects in the former group were similar to those in the latter./nChapter 2 studies the effects of household electrification on time use, and explores the consequences of this resource reallocation. In particular we study the effects on investment in education and job choice. We find that electrification increases investment in education, by inducing school-age children to study more at home, which is reflected in improvements in a math skills index. Adult males reduce time allocated to leisure and independent farm work, while increasing time in other labor activities. This time reallocation is reflected in higher income. Electricity also leads to increased ownership of electronic appliances like TV sets, that improve leisure and access to information; as well as refrigerators, which improve nutrition through improved food storage and food safety, reinforcing the health gains from improved indoor air quality./nChapter 3 studies the role that a cost-sharing scheme like the vouchers used in our experiment play in adoption of electric connections and the potential consequences on infrastructure financing. We draft a model showing the conditions under which sharing part of the connection costs would increase the electric utility's revenues, by accelerating the connection rate, thus increasing the flow of revenues earlier than otherwise. In our the case at hand, offering a low discount resulted more profitable than not sharing any connection costs, and also more profitable than offering high discounts.

Advisor: Zilberman, David
Reinventing the Barbarian: Rhetorical and Philosophical Uses of the Yi-Di in Mid-Imperial China, 600-1300

This dissertation proposes a new framework for understanding changing Chinese ideas about barbarians (Yi-Di) and barbarism during the Tang (618-907) and Song (960-1276) periods. Much previous scholarship has drawn a sharp contrast between what is characterized as a "cosmopolitan" early Tang period (618-755) and the growing xenophobic ethnocentrism ascribed to the late Tang (756-907) and Song periods. I argue that this view underestimates the importance of ethnocentric tropes in early Tang political rhetoric and also overlooks the emergence of a new and arguably less ethnocentric interpretation of the classical Chinese-barbarian dichotomy in the late Tang and Song. This new interpretation originated as a rhetorical trope in the ninth century before developing into a true philosophical concept in the eleventh, the key figures in this process being the polemicist Han Yu (768-824) and the Daoxue moral philosophers (or "Neo-Confucians"). The new interpretation of the Chinese-barbarian dichotomy was characterized by a fluid, shifting boundary between Chineseness and barbarism, predicated on Classicist ("Confucian") moral standards rather than ethnic, racial, or geopolitical boundaries. Modern historians have termed this interpretation of Chinese identity as "culturalism," on the assumption that it was centered on "culture" instead of "race," and have followed Han Yu and the Daoxue philosophers in identifying Confucius himself as its originator. My dissertation revises this picture by demonstrating that the so-called "culturalist" interpretation was the product of a new discourse on ideological orthodoxy and morality that involved representing any deviation from Classicist values as a descent into barbarism. The core of this new discourse was thus an attempt at making Classicist ideology and morality (not "culture" per se) essential to the definition of Chinese ethnic identity, but its users also generally chose not to undermine their ethnic identities by acknowledging the possibility that barbarians could become Chinese by becoming good Classicists. The resulting tension or dilemma between moralistic and ethnocentric understandings of barbarism remained unresolved until the Mongol conquest of the Southern Song (1127-1276) led to the ethnocentric understanding's temporary eclipse.

Advisor: Nylan, Michael
Tackett, Nicolas O.
Imaging Tools for Probing Glycosaminoglycans In Vivo in Developing Zebrafish

Glycosaminoglycans are linear polysaccharides that decorate the surfaces of all animal cells. The heterogeneity of the polysaccharide, especially the pattern of sulfation on the distal end of the chain, endows these glycans with diverse biological functions including essential roles in signaling during animal development. Thus, glycosaminoglycans represent an extremely important and interesting class of glycans to probe using metabolic labeling in concert with bioorthogonal chemistry./nThis thesis describes the extension of the metabolic labeling strategy to glycosaminoglycans (GAGs). Prior to the work described herein, GAGs could not be metabolically labeled because xylose, the monosaccharide specific to these glycans, lacks a salvage or biosynthetic pathway capable of converting xylose derivatives, or other simple sugars, to the ultimate sugar donor UDP-xylose. In order to label GAGs, the UDP-xylose derivative itself must be delivered to cells. However, the charged nature of nucleotide sugars prevents passive diffusion through hydrophobic membranes, and eukaryotic cells lack a plasma membrane nucleotide sugar transporter to provide facilitated or active transport. Prior research in our lab, however, had demonstrated that unnatural nucleotide sugars could be delivered to cells by microinjection into the yolk sacs of developing zebrafish embryos. In addition to providing a tractable solution to deliver nucleotide sugars, zebrafish are a well-established vertebrate development model organism with excellent properties for molecular imaging./nIt was hypothesized that GAGs could be metabolically labeled by microinjecting unnatural variants of UDP-xylose into zebrafish embryos. To this end, three analogs of UDP-xylose were synthesized, microinjected into zebrafish embryos, and analyzed for incorporation onto zebrafish embryo cell surfaces by reaction with fluorescent cyclooctyne probes. Two of the analogs, UDP-2-XylAz and UDP-3-XylAz, did not provide azide-dependent labeling. UDP-4-XylAz did provide azide-dependent labeling, and the azide replacing the C-4 hydroxyl group inhibits extension of the GAG polysaccharide beyond the initial xylose unit. Therefore, UDP-4-XylAz functions as a selective metabolic inhibitor of GAG biosynthesis. The phenotypic consequences of aberrant GAG production were ascertained and these results add to our understanding of the importance of GAGs during normal vertebrate development.

Advisor: Bertozzi, Carolyn R