VictorJuiz/thesis huggingface dataset:
Convex methods for approximate dynamic programming [electronic resource]
Keywords: Electrical Engineering

his thesis studies the use of convex optimization in stochastic control problems. We propose methods based on convex optimization for approximate dynamic programming. Dynamic programming is a standard approach to many stochastic control problems, which involves decomposing the problem into a sequence of subproblems to solve for a global minimizer, called the value function. Traditional dynamic programming approaches focus on problems with finite state space and action space, and finding a solution gets prohibitively difficult as the state space or action space grows. With the exception of a few special cases, dynamic programming (DP) is difficult to carry out for general problems. In such cases, approximate dynamic programming (ADP) gives a method for finding a good, if not optimal, policy. In this work, we rely on our ability to (numerically) solve convex optimization problems with great speed and reliability. Using custom generated solvers we can speed up computation by orders of magnitude. In this thesis, we use convex optimization in conjunction with approximate dynamic programming to find the optimal (or suboptimal, but good) policies for an array of stochastic control problems. In the first part of the thesis, we consider applications where we have access to a good controller (which may be very complex): this could be a pilot controlling an aircraft, or a model predictive controller with a long lookahead horizon. In such cases, we can observe the actions chosen in different states, but we do not have access to the underlying objective function used by the controller (such as the pilot). We propose methods that use convex optimization to impute the underlying objective function. This results in a controller that can mimic the behavior of the original controller, often with the complexity reduced greatly. In the second part of the thesis, we develop the mathematical framework and present algorithms for carrying out projected value iteration using quadratic approximate value functions. Although there are no theoretical guarantees, we observe that in practice we achieve very good performance in a reasonable number of steps. We will consider problems in a variety of applications, such as consumer behavior modeling, robotics, finance, input-constrained control, and supply chain management.
Cosmic stellar explosions and galaxy cluster weak gravitational lensing [electronic resource]
Keywords: Physics

Observations of supernova (SN) explosions and galaxy clusters have been essential to the construction of the standard $\Lambda$-CDM cosmological model. Type Ia SN are powerful probes of the cosmic expansion history and were the tools used to discover cosmic acceleration more than a decade ago. They are the thermonuclear explosions of white dwarf stars, and regular patterns in their light curves and luminosities enable distance measurements with a precision of ~10%. Core-collapse SN, which signal instead the deaths of young, massive stars, also have use as cosmological distance indicators and can be detected, when accompanied by a GRB, to very high redshift. A very different technique for constraining cosmological parameters is to measure the distribution of galaxy clusters as a function of mass and redshift within well-defined X-ray or optical surveys. For this method, the current limiting systematic uncertainty is the calibration of galaxy-cluster mass proxies such as total X-ray luminosity or cluster richness. In this thesis, I discuss the discovery that SNe Ia found in more massive host galaxies are ~10% brighter, after light curve corrections for stretch and color, than those in less massive galaxies. I also demonstrate the existence of strong patterns among the explosion environments of core-collapse SN which point to the effects of progenitor mass and metallicity on massive stellar evolution. Finally, I present a weak-lensing mass analysis of 51 X-ray--luminous galaxy clusters. The inclusion of these lensing mass estimates in current cosmological analyses will improve significantly the calibration of X-ray mass proxies and increase both the accuracy and precision of galaxy cluster cosmological constraints.
Crime, punishment, and war [electronic resource]
Keywords: Political Science.

What explains public support for war? In my dissertation, I generate new insight into this question by developing a theory that treats war as one of the many kinds of violence that individuals regularly observe and experience over the course of their lives. I argue that the use of violence as punishment is pervasive throughout human society, and that individuals develop strong beliefs about the morality of punishment early in life. These beliefs then serve as a guide for forming opinions about the use of violence in three distinct domains: interpersonal, domestic and international. In particular, I focus on retributivism, a school of thought that justifies punishment on the basis of the moral value inherent in "just repayment" for an act of wrongdoing rather than on the basis of the positive future consequences that punishment will produce. Studies in a number of different fields have found that retributivism is the primary driver of support for harsh domestic criminal penalties in the United States. I build on this work by demonstrating that retributivism influences attitudes towards the kinds of punishment that take place between private individuals and between sovereign states, as well as the kinds of punishment that take place within an institutionalized system of criminal justice. This evidence is the subject of the first of three empirical chapters that comprise the dissertation. The second empirical chapter explores the implications of cross-national variation in popular retributivism for the use of military force by democracies, while the third empirical chapter investigates the cultural sources of that variation. The theories and evidence that I present in these chapters add a new dimension to the study of public opinion about war and generate new insights into the domestic sources of international conflict and the relationship between democracy and war.
Data-driven methods for modeling healthcare risks [electronic resource] : insights and applications in drug surveillance and breast cancer incidence prediction
Keywords: Management Science and Engineering

This dissertation develops data-driven methods for healthcare risk modeling to facilitate risk identification and evaluation, focusing on post-marketing drug safety surveillance and breast cancer incidence prediction. For risk identification, we first propose a novel methodology for post-marketing drug safety surveillance: "Follow the money'', which monitors cost in health insurance claims data to detect increased spending related to adverse drug events (ADE). By using real claims data from 2.4 million insured individuals, we demonstrate that this method enables early detection of signals of ADE. Second, we recommend statistical study designs to detect rare and time-dependent ADE resulting from long-term drug use and highlight statistical considerations that drug surveillance designers should focus on when implementing a long-term surveillance. We characterize statistical properties and compare performances of a variety of surveillance designs by applying them to simulated event data as well as real health insurance claims data. For risk evaluation, we develop a stochastic simulation model of the Surveillance, Epidemiology and End Results database to quantify the impact of menopausal hormone therapy (MHT) on U.S. breast cancer incidence. Our model quantifies the promoting effect of MHT on breast tumor growth and the reduced mammographic detectability. By modeling unobservable tumor natural history dynamics and simulating individual life history at a population level, we evaluate the contribution of MHT use cessation to the observed decline in breast cancer incidence between 2002 and 2003. We also predict U.S. breast cancer incidence in the absence of MHT.
Deadline [electronic resource] : crime, journalism, and fearful citizenship in Caracas, Venezuela
Keywords: Anthropology.

This dissertation traces the constitutive relationship between the press and populism in Venezuela through an account of crime journalism. Based on more than two years of research alongside journalists on the Caracas crime beat, it analyzes how demands for security mobilized disparate sectors of society around a common cause. The vital link between the politics of security and populist mobilization is something that scholars have only recently begun to recognize (Bottoms 1995; Garland 2002; Pratt 2007; Wacquant 2009). Although my analysis focuses specifically on Venezuela, I believe that it has implications for studies of crime and for studies of populism more generally. This dissertation sets out three interrelated findings. First, crime news creates victims. I mean this in a discursive sense: crime news reproduces the figure of the innocent, wholesome victim. A glance at the morning papers or the midday news confirms as much. Crime journalism is replete with images of grieving relatives and stories about good kids, hard-working men, and beloved mothers who were murdered for no reason at all. Anthropologists studying mass media representations of crime have looked almost exclusively at the figure of the criminal. We know where the category of the criminal leads—to the body of the young, poor, dangerous, black male. What can we learn by following the category of the victim? Second, in Venezuela victimhood becomes legible through the discursive practice of denunciation. We tend to think of victims as silent, passive objects; yet in Venezuela victimhood is anything but silent. To the contrary, the victim is an active performer, someone who voices sentiments of rage, grief, tragedy, and fear. To denounce is to assert one's victimhood publicly, usually through the medium of the press. Third and finally, denunciations made in the name of victims are the building blocks that form populist movements. In Culture & Truth, anthropologist Renato Rosaldo talks about how finding the rage in grief helped him understand the impetus for Illongot headhunting (Rosaldo 1993). I argue that by seeing the rage in victimhood, we begin to understand the impetus behind populist mobilizations against violent crime. The discursive practices of denunciation on the part of victims, journalists, pundits, and media moguls allow us to analyze this process. Rather than reducing the phenomenon to a moral panic or a mob mentality, an analysis of denunciation actually shows us the mechanisms and the micro-politics through which the populist movements take shape.
Decomposition kinetics of the rocket propellant RP-1 and its chemical kinetic surrogates [electronic resource]
Keywords: Mechanical Engineering

High-temperature fuel decomposition is an important aspect of fuel chemistry, and a thorough understanding of this process is necessary in order to accurately describe combustion chemistry. Two major motivations drive the study of kerosene decomposition. First, it is a vital building block upon which oxidation chemistry can be built, and second, it is used as a coolant in many rockets and high-speed aircraft. Measurements of fuel and ethylene time histories during decomposition of RP-fuels and their possible surrogate components were carried out between 1000 and 1500 K in two shock tubes. From these measurements, overall fuel decomposition rates for six fuels (RP-1, RP-2, JP-7, n-dodecane, methylcyclohexane, and iso-cetane) were determined and ethylene yields for four of these fuels (RP-1, n-dodecane, methylcyclohexane, and iso-cetane) were also determined. An RP-1 decomposition surrogate was formulated based on three targets: compound class, overall fuel decomposition rate, and ethylene yield. This resulted in a surrogate containing 32% n-dodecane, 59% methylcyclohexane, and 9% iso-cetane.
DeduceIt: A Tool for Representing and Evaluating Student Derivations
Keywords: DeduceIt
theorem-proving technologies
Thesis

Almost all automated online grading systems today are currently limited to multiple-choice problems or fill-in-the-blank answers. DeduceIt is a system directed at university-level math and engineering education that aims to allow students to enter substantial formal derivations which are then automatically checked. Current theorem-proving technologies are generally intended to support one expert in writing a potentially long and complex derivation; online education, however, requires a system that can be used without expertise in a field, and that can be effectively used by tens of thousands of students attempting to do the same exercise in many different ways. While DeduceIt borrows heavily from existing theorem-providing techniques, the special constraints of online education lead to unique challenges and a substantially different overall design.
Defining novel functions for the oncogenic variant EGFRvIII in tumor initiation [electronic resource]
Keywords: Cancer Biology.

Glioblastoma multiforme (GBM) is the most common and deadly primary brain tumor. Amplification and rearrangements of the epidermal growth factor receptor (EGFR) gene are frequently found in GBM, and the most common variant is EGFRvIII. Here we report that EGFRvIII is a novel cancer stem cell (CSC) or tumor initiating cell marker in GBM. EGFRvIII expression is restricted to sub-regions and sporadic cells within the tumor and EGFRvIII is frequently co-expressed in the putative CSC CD133+ population. EGFRvIII gene and protein expression can be maintained when primary GBM are cultured as tumor derived neurospheres and is lost when spheres are exposed to differentiating conditions. Furthermore, cells that express both EGFRvIII and CD133 display the greatest self-renewal and tumor initiating abilities when compared to the single positive or double negative populations. If amplification and rearrangement are early events in tumorigenesis, this implies that they should be preserved across the tumor despite focal expression. Unexpectedly, we found EGFR amplification and rearrangement throughout the tumor, including regions with no EGFRvIII expression. To study this phenomenon, we characterized three GBM cell lines with endogenous EGFRvIII expression. EGFRvIII defined a hierarchy and epigenetic mechanisms played a role in maintaining heterogeneous EGFRvIII expression, suggesting that drugs which modulate the epigenome might be used successfully in glioblastoma tumors. To assess a broad applicability of our findings to other tumor types, we investigated EGFRvIII expression and amplification in primary breast carcinoma. Our analyses confirmed the presence of EGFRvIII, but in the absence of amplification or rearrangement of the EGFR locus. Interestingly, EGFRvIII was often expressed in a subset of tumor cells and was co-expressed in the putative CSC CD44+/CD24-/low population. EGFRvIII-expressing cells had increased expression of stem cell and epithelial-mesenchymal transition (EMT) associated genes and increased in vitro sphere formation and in vivo tumor formation compared to non-expressing cells. Mechanistically, EGFRvIII mediated its effects through the Wnt/[beta]-catenin pathway. Collectively, this data suggests a novel function for EGFRvIII in tumorigenesis and further supports the use of EGFRvIII-targeted therapy in these tumor types.
Depositional architecture of deep-water slope systems [electronic resource] : examples from the quaternary Lucia Chica channel system, offshore central California and the upper Miocene Urenui formation, New Zealand
Keywords: Geological and Environmental Sciences.

Deep-water channels are submarine conduits that transport subaerial and shallow marine sediments into the deep-sea. Much of the sediment transport and deposition through deep-water slope channels occurs as turbidity currents that are recorded in deposits, termed turbidites. I utlize outcrop and seafloor turbidite datasets to investigate deep-water channel formation and fill in two different slope depositional systems--the Quaternary Lucia Chica channel system, offshore central California, and the upper Miocene Urenui Formation, New Zealand. Extensive exposures of the Urenui Formation along the northern Taranaki coast are used to investigate channel-fill architecture and influences on slope sedimentation in ancient mid- to uppermost-slope channels. Variations within sandstone and conglomerate lithofacies are interpreted to reflect relative position of channels on the paleo-slope. I generated a composite architecture at lithofacies-scale from the truncated Taranaki outcrops that suggests conduit development, phases of channelization, and channel abandonment within the slope channels. In contrast to the Urenui Formation outcrops, the Lucia Chica includes a mid-slope avulsion belt with four adjacent channels and a complicated pattern of scours imaged with Autonomous Underwater Vehicle high-resolution seafloor and outcrop-scale subsurface data. This extremely high-resolution imaging leads to new interpretations of avulsion sequence, distribution of turbidity currents, and channel development. The interpreted sequence of channel development involves erosional channel inception through scouring and incipient channels (defined by linear trains of scours) prior to development of continuous thalwegs. Channel narrowing, formation and growth of levees, increasing channel relief, and development of sinuosity occurred as channels evolved. These results challenge existing conceptual models of channel continuity, fluvial analogs, and channel inception, migration, and abandonment developed from other deep-water systems with lower-resolution imaging. Implications of this research extend to academic studies of deep-water channel development, reservoir-scale analogs of stacking patterns relevant to petroleum applications, and exploration of the modern seafloor.
Design and fabrication of nanostructures for light manipulation in solar cells and microelectromechanical systems [electronic resource]
Keywords: Applied Physics

This work is about nano-structuring of semiconductor devices for the improvement of their optical properties. The phenomenon of guided resonances in photonic crystal (PC) slabs will be introduced and ways of engineering these guided resonances for a variety of applications such as improved reflectivity in micro-electro-mechanical (MEMS) mirrors and increased absorption in thin-film solar cells will be discussed. The first part of the work focuses on the application of PCs in MEMS. A new process (GOPHER) that was developed to make low stress PCs out of monolithic silicon will be discussed. The advantage and ease of making multilayer PCs with Gopher will be illustrated and experimental results showing Gopher structures having spectra with broadband reflectivity (suitable for mirror applications) as well as sharp peaks (suitable for sensors) will be presented. Other applications of Gopher such as making waveguides etc., will be briefly discussed. The integration of a high quality PC mirror with a 1D resonant MEMS scanner will be demonstrated. Finally, the results of fabrication of a prototype wafer-scale encapsulated optical device will be shown. The Gopher process has a lot of potential for facilitating the integration of micro- and nano-scale photonics with CMOS circuitry. The second part of the work focuses on the application of PCs for light-trapping in solar cells. Thin-film photovoltaics has the potential to reduce cost by reducing the amount of photoactive material required and allowing for the use of material of poorer quality. Crystalline Silicon (c-Si) is an attractive material for photovoltaic cells due to its natural abundance, nearly ideal band gap, and leverage of existing process and materials knowledge. However, the poor optical absorption in the near-infrared spectral range requires the use of very efficient light trapping techniques. One such technique that is explored is to pattern the active layer into a 2D PC. Electromagnetic simulations are performed to show that an enhancement in integrated short-circuit current by a factor of 3 is possible when compared to a planar slab of equivalent volume. This is because the PC supports guided resonances into which incident radiation can couple which increases the absorption. Finally, the fabrication of an ultrathin c-Si solar cell where the active material is patterned into a square-lattice 2D PC is demonstrated. Both short-circuit current and external quantum efficiency measurements show an enhancement in optical absorption, especially at longer wavelengths. Scanning photocurrent maps confirm the improved optical absorption in the photonic structure over an unpatterned reference. Future applications of nanostructuring to thin-film cells that can be commercially realized is discussed.
Design and flight test of a cable angle feedback control system for improving helicopter slung load operations at low speed [electronic resource]
Keywords: Aeronautics and Astronautics

The ability of a helicopter to carry externally slung loads makes it very versatile for many civil and military operations. However, the piloted handling qualities of the helicopter are degraded by the presence of the slung load. This dissertation investigates the dynamics, handling qualities requirements, and control aspects of the helicopter/slung load system that contribute to the performance of piloted slung load operations. A control system is developed that integrates measurements of both slung load motions and conventional fuselage feedback to improve the handling qualities for hover/low speed operations. Despite the fact that this technology was developed 40 years ago, it has not been tested in a manned helicopter since the 1970s, due to problems with handling qualities and pilot perception. This dissertation leverages advances in fly-by-wire, complex control design procedures (direct multi-objective optimization), and recently developed work that relates handling qualities to dynamic response (specifications) to successfully flight test cable angle feedback technology in a manned helicopter. The key contributions of this work are developing an understanding of the handling qualities trade-offs for cable angle/rate control system design, implementing an approach to solve the problem with a novel task-tailored control system, and performing extensive piloted flight tests of the control system on a fly-by-wire Black Hawk. The flight tests demonstrated that average precision load set-down time was reduced by 50% for a light load, 30% for a heavy load, and the average handling qualities rating for the external load placement task was improved from Level 2 to Level 1 on the Cooper-Harper rating scale, a significant improvement.
Design and use of a combined scanning tunneling microscope - atomic layer deposition system [electronic resource]
Keywords: Mechanical Engineering

During my Ph.D. work, I designed, built, and operated a combined scanning tunneling microscope and atomic layer deposition system. A scanning tunneling microscope (STM) is a scanning probe technique that uses a sharp tip to image a surface at the atomic scale. Atomic layer deposition (ALD) is a thin-film growth technique that produces very dense films, with thickness controllable to the Angstrom scale. I will describe the design of the instrument through its two generations. I will present images from the combined instrument that track growth of individual 5 nm grains through 25 cycles of ALD over periods of up to three hours. I will show that the grain morphology shows a sensitivity to growth temperature, and will provide an interpretation of these results. The combined instrument was built for two purposes: characterizing the initial stages of ALD, and controllably growing nanoparticles by influencing ALD with the STM tip. We have achieved the former, and work remains to be done on the latter.