VictorJuiz/thesis huggingface dataset:
Low-cost growth of III-V and II-VI semiconductor thin films [electronic resource]

This dissertation explores methods to obtain high-quality, low-cost III-V and II-VI semiconductor thin films. Silicon is the predominant semiconductor material of choice for most electronics applications, but non-silicon semiconductors may be more well-suited to certain applications. III-V materials such as GaAs and InP have favorable optoelectronic properties but are currently too expensive to compete in the market. Methods that could separate III-V thin films from their substrates could lower these costs significantly. In the first section InP single-crystal thin films are separated from their substrates with the selective absorption of a short and intense laser pulse, a process called epitaxial laser liftoff. The physical mechanisms driving laser liftoff are explored and compared with GaAs liftoff, and spatially-resolved measurements of the threshold fluence for liftoff and transmitted intensity through a wafer are devised. Conversely, II-VI based semiconductors like Cu2ZnSnSe4 are more defect-tolerant and simpler than silicon to manufacture, but are not efficient enough to be cost-effective. Alloying this material with Cu2ZnGeSe4 could allow for tuning of the properties for improved performance. In the second section Cu2ZnSn(1-x)Ge(x)Se4 thin films in the composition range 0< x< 1 are grown by co-sputtering and reactive annealing. Growth conditions are described that yield single phase films for all values x, tunable band gaps in the range 1.0 to 1.5 eV, or composition gradients through-thickness for band gap grading. The mechanisms for growth and recipe to produce dense thin films with large, faceted grains are also provided.

Keywords: Materials Science and Engineering.
Advisor: Clemens B. M. (Bruce M.) primary advisor. Thesis advisor
Lindenberg Aaron Michael advisor. Thesis advisor
Salleo Alberto
Low-power coherent optical links for data center interconnects [electronic resource]

Hyperscale data centers built to accommodate variable traffic patterns supporting virtualization and cloud computing are evolving to employ a flatter network topology, comprising fewer layers of switches, but with much more interconnection between them. The requirements of these networks, coupled with expected compound annual growth rates of 32% for data center-to-data center IP traffic in the next five years, necessitate scaling the per-wavelength bit rates of optical links beyond 100 Gb/s while keeping power consumption and cost low. Coherent detection can offer the requisite performance demanded by future intra- and inter-data center links, but current implementations consume too much power and are too costly for optical transceivers needed for future data center networks. In the first part of this dissertation, we address the transmitter side of future coherent optical transceivers by designing and validating silicon-based Mach-Zehnder modulators. We leverage the efficiency of the silicon modulator to configure submillimeter-length coherent modulators that can be driven by low-power CMOS drivers and show that their performance can match existing lithium niobate modulators for coherent transmission. We further leverage the efficiency of the silicon-based modulators by segmenting them and showing that higher-order modulation formats can be generated by driving segmented modulators with only binary signals, precluding the need for expensive and power-hungry linear drivers and digital-to-analog converters. The second part of this dissertation addresses coherent receivers for future optical transceivers. We propose various analog coherent receiver architectures that do not employ the high-speed DSP and analog-to-digital converters that make existing DSP-based coherent receivers power-hungry and costly. Implementing these analog coherent receivers for data center links requires performing functions, such as carrier recovery and polarization demultiplexing, that are typically done using DSP. We propose and simulate a marker tone-based polarization demultiplexing solution using an optical polarization controller consisting of a sequence of phase shifters.

Keywords: Electrical Engineering.
Advisor: Kahn Joseph M. (Joseph Mardell) primary advisor. Thesis advisor
Fan Shanhui
Miller D. A. B. advisor. Thesis advisor
Machine learning models for analyzing chromatin and RNA structure data [electronic resource]

Chromatin and RNA structure play key roles in regulating gene expression. Recently developed experimental assays for genome-wide probing of chromatin and RNA structure provide data at base-pair resolution. However, the data are typically sparse and noisy at practical sequencing depths. In this thesis, we develop methods based on powerful machine learning techniques - deep learning and probabilistic graphical models - that enable us to fully leverage the richness of these high-dimensional, sparse, and noisy datasets to predict histone modifications and RNA secondary structure. We first introduce the GenomeLake system for efficiently streaming genomics data into deep learning models. GenomeLake simplifies model development by eliminating the need to pre-extract data into intermediate files, and by providing a convenient interface for randomly accessing data at arbitrary genomic loci. Next, we describe Chromputer, an integrative deep learning model based on convolutional neural networks for predicting histone modifications from chromatin structure data. We show that Chromputer achieves high predictive accuracy on a subset of modifications typically associated with active chromatin, within and across different cell-types, and in an epidermal differentiation time-course. Chromputer models trained on orthogonal DNase-seq and MNase-seq datasets also obtained high predictive accuracy, suggesting a fundamentally predictive relationship between chromatin architecture and histone modifications. Finally, we describe CONTRAfold-SE, a probabilistic model for RNA secondary structure prediction that models RNA structure-probing data as observations of possibly unknown secondary structures. This model can then be learned from datasets containing only structure-probing data, or a mix of known structures and probing data. We train CONTRAfold-SE on various combinations of structure probing data and complete structures and find that while genome-wide structure probing data provides modest improvement in prediction performance, with sufficiently dense probing data alone it is possible to learn a model that approaches the performance of energy-based methods.

Advisor: Kundaje Anshul
Batzoglou Serafim advisor. Thesis advisor
Greenleaf William James advisor. Thesis advisor
Magnetic effects at complex oxide interfaces [electronic resource]

Control, manipulation, and measurement of the spin state of electrons, termed spintronics, has been critical to the development of magnetic memory devices which have dominated non-volatile data storage in computers, servers, and often even media formats. Likewise, performing computational operations using electron spins is under active development to supplement, or in some cases replace, traditional charge based logic. Complex oxides are a powerful tool for spintronics as their strong electron interactions and correlations lead to unique and powerful spin functionality. The myriad interesting phenomena observed in complex oxides, from multiferroics to high Tc superconductors, suggests not only their viability as spintronic materials but also the ability to couple the relevant spin operations to a wide variety of novel functionalities. In this work, complex oxide materials are investigated to explore two spintronics opportunities. The first half of this research attempts to introduce a spin-polarized conducting interface between two diamagnetic, insulating materials. The second half explores spin-pumping behavior in the previously unutilized spinel ferrites. One avenue for the development of spintroincs is the concept of "materials by design" where material properties and functionality are tuned or introduced through their nanostructure or interfaces. A leading example of this paradigm is the LaAlO3/SrTiO3 interface where conductivity is observed between two insulating materials. Magnetic ordering at the interface has been inconsistently observed in previous studies, however generation of a spin-polarized conduction layer on-demand would be extremely useful for spintronic devices. Therefore, this work pursues this emergent spin phenomenon by introducing magnetic dopants at the interface. The system is observed to be electrically and magnetically unaffected by the presence of the dopants however. Furthermore, no evidence for magnetic ordering is observed in undoped LaAlO3/SrTiO3 systems, drawing into question the intrinsic origin of the previously observed magnetic moments. The remainder of this work is devoted to characterizing spin pumping in a previously unexplored class of materials, the spinel ferrites. Here "pure" spin currents, where spin moments are transported without net charge flow, are generated in adjacent metals, and the efficiency is characterized through the spin-mixing conductance at the spinel-ferrite/metal interface. The order-of-magnitude improvement in intrinsic damping and a spin-mixing conductance competitive with literature-leading systems indicate Ni0.65Zn0.35Al0.8Fe1.2O4 to be a viable spin-pumping material. The design parameters of this model system can be extracted to myriad other spinel materials and paves the way for future all-oxide spin-pumping systems.

Keywords: Materials Science and Engineering.
Advisor: Suzuki Yuri (Applied physicist) primary advisor. Thesis advisor
Wang Shan
Hwang Harold Yoonsung
White Robert advisor. Thesis advisor
Make Russia Great Again: Russia's Politics of International Intervention

In a globalized world where states’ domestic problems can and will have international consequences, how do governments resolve the tension between state sovereignty and the protection of human rights? In the context of Russia, what factors drive its leaders to use or refuse humanitarian intervention? This thesis analyzes Russia’s conception of international intervention predicated on humanitarian ideals in three parts: first, the Soviet legacy of the Brezhnev Doctrine; second, how the text of Russia’s foreign policy conceptions is formulated to propagate Russia’s role in the world; finally, analysis of two relevant case studies. The first, of Russia’s intervention in Crimea in 2014, finds Russia using its conception of the “Russian world” to justify its unilateral intervention. The second, of Syria, reveals a more complicated case where Russia utilizes its power in the U.N. Security Council to block humanitarian intervention, but at the same time sends its troops to Syria to assist President Bashar al-Assad’s forces. The author’s findings were that Russia uses military intervention ostensibly predicated on humanitarian ideals as a political tool in service of the goal of stability, interpreted as a continued hold on power. Further, when Russia condemns international humanitarian intervention, it preserves for itself power and influence on the world stage—and prevents a precedent of military intervention being established, in order to avoid its application to Russia’s own illegitimate interventions.

Keywords: Stanford Global Studies
Center for Russian East European and Eurasian Studies
Russia
international
humanitarian
intervention
Ukraine
Crimea
Syria
foreign policy
Brezhnev Doctrine
Thesis
Advisor: Patenaude Bertrand
Weiner Amir
Making more than a market [electronic resource] : environmental marketization and the politics of landscapes and distribution in the Brazilian Amazon

Creating new markets is an increasingly prevalent strategy to address environmental degradation. This dissertation examines the politics and social significance of one prominent environmental marketization policy—the System of Incentives for Environmental Services (SISA) in the Amazonian state of Acre, Brazil. SISA allowed for the issuance and sale of "carbon credits, " which represent reductions in climate-changing emissions from deforestation and forest degradation, to outside polluters and other buyers. Yet SISA entailed much more than making a market in carbon, this dissertation reveals. SISA's approach made carbon credits and ecosystem services—often dismissed as neoliberal—into tools of redistribution that expanded and reshaped the state through providing rural welfare. SISA's redistributive approach also undermined rural residents' ability to claim rights to carbon revenue, instead assigning them the precarious government-granted status of "beneficiary." SISA's use of "incentives" to intensify production to protect the forest also contained its own contradictions and exclusions. It favored field over forest and expertise over rural knowledge, threatening to increase deforestation and benefit wealthier landholders. However, such wide-ranging marketization efforts were not implemented without impediment. Rather, Acre's landscapes and politics mediated carbon's marketization through rural people's every day negotiations and land use practices, in ways that challenge both theory of environmental markets and critiques of them. This ethnography shows how environmental marketization can constitute a key and undetermined arena of moral struggle and collaboration between the state and those it governs.

Keywords: Anthropology.
Advisor: Curran Lisa Marie
Yanagisako Sylvia Junko
Ferguson James
Hecht Susanna B. advisor. Thesis advisor
Mathews Andrew S. advisor. Thesis advisor
Making sense of slavery [electronic resource] : slavery studies before civil rights

"Making Sense of Slavery" is the first full history of the study of slavery in America from the rise of abolitionism to the start of the civil rights movement—a century during which questions about slavery were open for debate in a way that they had not been before and have not been since. The story unfolds in two parts. Part 1, "Slavery, " looks at the origins of the study of slavery while the institution still existed. This was the period when political pressures encouraged the development of new arguments both for and against slavery that ended up having ramifications for society as a whole—and helped lead to the Civil War. Part 2, "Freedom, " examines how the study of slavery was incorporated into the modern research university from about 1865 to 1935—after emancipation ended slavery but before the civil rights movement asserted black equality as an incontrovertible fact. Scholars seeking to navigate the social and political changes of Reconstruction and the Progressive Era looked back to slavery as a way of thinking about race relations and industrial capitalism. Here I start with the historian Herbert Baxter Adams and his students at Johns Hopkins University, who were the first university scholars to study slavery. Then I turn to Ulrich Bonnell Phillips, a Georgia-born historian who made himself into the first modern scholar of slavery. I also look at how other scholars—especially Carter Woodson and W. E. B. Du Bois—started to undermine Phillips's work and lay the foundation for the kinds of slavery studies that emerged during the civil rights movement and continue to be written today.

Keywords: History.
Advisor: Winterer Caroline
Campbell James T.
White Richard
Mapping Poverty with Satellite Imagery

Poverty eradication is the first of 17 Sustainable Development Goals set by the United Nations to reach by 2030. Measuring poverty is an important step to alleviating poverty, as it helps to inform research studies, target aid efforts, guide policy decisions, and generally monitor the progress of such an initiative. In the developing world, where the need for poverty data is the most pressing, poverty data is particularly scarce due to the resource cost associated with conducting surveys.
This data gap is one of the crucial challenges to overcome in order to alleviate poverty. This thesis aims to cover a variety of methods towards closing this poverty data gap using remote sensing and satellite imagery data. We introduce a high-resolution poverty mapping method using only publicly available satellite data. The approach utilizes transfer learning to leverage knowledge from data-rich sources and combat the data gap. We also attempt to reduce the data gap by incorporating additional data, detailed in preliminary work using multiple resolutions of satellite imagery to improve predictive performance. We develop a semi-supervised method which narrows the data gap by utilizing abundant unlabeled satellite imagery. We show that can use this method to also take advantage of spatial correlations of poverty measures to improve our model predictions.
Experiments are conducted on a variety of real-world datasets, as well as poverty measure prediction problems for 5 African countries - Malawi, Tanzania, Uganda, Nigeria, and Rwanda - demonstrating that our methods based on only publicly available data can approach the predictive performance of surveys conducted in the field and potentially transform efforts to track and alleviate poverty. Finally, we detail the implementation of a deployment pipeline system designed to support automated production of global scale poverty maps that is flexible enough to incorporate any dataset and model. This represents the first step towards providing up-to-date poverty maps to guide the decision-making process of nonprofit organizations and policymakers.

Keywords:  Department of Computer Science
Poverty
Satellite
Imagery
Mapping
Convolutional
Deep Learning
Neural Network
Semi-supervised
Gaussian Process
Deep Kernel Learning
Africa
Stanford
Computer Science
School of Engineering
SUSTAIN
Nighttime Light
Artificial Intelligence
Science
Sustainability
Machine Learning
Thesis
Advisor: Ermon Stefano
Mass bone-working industry in the Western Zhou period (1046-771 BC) [electronic resource]

This dissertation attempt to address the operation of mass bone-working craft industry and its interaction with other social aspects in an early urbanized society during the Western Zhou period (ca. 1050-771 BC), late Bronze Age China. This research is mainly based on the new archaeological findings from the excavation and survey at the Yuntang bone-working locus in ancient Zhouyuan city. Multiple archaeological approaches were used, including zooarchaeological analysis, chaîne opératoire analysis, as well as microscopic characterization. Economically, the procurement of raw materials for bone-working was closely intertwined with other forms of exploitation and consumption of animal resource in city context. In terms of technology, The Yuntang bone-working production was a highly specialized technical system. Meanwhile, the bone-working industry was probably a royal-controlled property, functioning as the tool to help the maintenance of central government's economic superiority.

Keywords: East Asian Languages and Cultures.
Advisor: Liu Li
Hodder Ian advisor. Thesis advisor
Seetah Krish advisor. Thesis advisor
Material remains [electronic resource] : narrating the dead at al-Qaşr al-Kabīr

My research begins in the observation that there is a prevalence of corpses in the narrative of the early modern Western Mediterranean, and that those corpses frequently coincide with moments when narrators grapple with questions of authority and credibility. My argument is that corpses became a source of epistemic certainty as a mechanism to compensate for insufficiencies in narrative authority, and particularly for insufficiencies in the credibility of eyewitness testimony. In this dissertation, I explored the use of corpses and human bodies as repositories of epistemic certainty in accounts of the battle of al-Qasr al-Kabir, which took place in 1578 between Portuguese and Moroccan forces. Following this event, the corpses of kings and soldiers played a central role not only in determining the very viability of three Mediterranean monarchies, but were also fundamental to how stories about it were told. Using a methodological approach that combines literary analysis with a sociolinguistic understanding of presence and a historicized understanding of the epistemological status of testimony and witnessing, my project traces a shift in how reliability and authority were constructed across Portuguese, Spanish, and Arabic traditions. I argue that the stories told about al-Qasr al-Kabir mark a watershed moment in how narrative was written during the early modern period, a legacy that has come down to us in canonical texts like Don Quixote and the Comentarios reales.

Keywords: Iberian and Latin American Cultures.
Advisor: Surwillo Lisa primary advisor. Thesis advisor
Greene Roland
Key Alexander (Alexander Matthew) advisor. Thesis advisor
Materials and devices for stretchable electronics and electronic skin [electronic resource]

Mechanically compliant electronics enable exciting new technological opportunities, especially in the field that integrates electronics with soft, irregular, and moving objects such as the human body. Wearable, implantable, and prosthetic devices benefit from engineering the mechanics to match that of biology to minimize measurement errors, reduce inflammation, and promote lifelike characteristics, respectively. Chapter 1 of this thesis gives an overview of the current status of mechanically compliant materials and sensors. Chapter 2 describes preliminary efforts toward creating stretchable transistors using polymeric semiconductors. The role of semiconductor mechanics on the stretching behavior of the transistor is investigated, and we found that brittle semiconductors could form microcracks that lead to strain-independent stretching characteristics after an initial preconditioning step. Contact resistance plays a large role in the device performance and the stretching performance; larger contact resistance is typically associated with lower performance, but more constant performance with strain. Chapter 3 describes stretchable transistors composed entirely of carbon nanotubes and elastomers. By combining carbon nanotubes, which have very high mobility, with thermoplastic elastomers, we were able to create devices with exceptional toughness and tear resistance. We investigated the limiting factors for device performance in stretchable devices by varying the semiconducting CNT diameter. We found that at small CNT diameters, the devices are limited by the low charge densities in the channel caused by the use of low-capacitance dielectrics. At large diameters, the devices were limited by low doping levels and contact resistance. In addition to data analysis elements such as transistors, wearable and bio-integrated electronics require sensors such as pressure sensors. Chapter 4 describes a novel type of resistive pressure sensor based on microstructuring conductive polymers to make them elastic. When pressure is applied to a counter-electrode, the contact area increases, decreasing the resistance across the interface. These sensors have excellent sensitivity and minimal temperature dependence. Creating electronics that communicate in the same way as biological organisms could facilitate seamless integration between technology and the human body. Toward this end, we prepared an artificial analogue of biological mechanoreceptors. The system combines flexible circuits with pressure sensors that have been engineered to modulate the frequency of voltage pulses created by the flexible circuits. The artificial mechanoreceptor could communicate pressure information to neurons in vitro, demonstrating the potential of the approach for bio-integrated electronics.

Keywords: Materials Science and Engineering.
Advisor: Bao Zhenan primary advisor. Thesis advisor
Salleo Alberto
Chueh William