VictorJuiz/thesis huggingface dataset:
Imaging current in materials [electronic resource]

Scanning superconducting quantum interference device (SQUID) microscopy is an incredibly sensitive way to image magnetic fields. One application of this technique is to spatially map magnetic fields which originate from moving electrons (i.e. electrical current), and interpret the pattern of current in order to learn more about how electrons behave in interesting materials. In lanthanum aluminate-strontium titanate, two insulators which can host a two-dimensional conducting state at their interface, we discovered locally enhanced conduction due to domain structure in the strontium titanate. 2D topological insulators are a class of materials which are predicted to host special conducting states along the edges of patterned devices, and we were able to image current along the edges of devices in two such materials: HgTe quantum wells and InAs/GaSb quantum wells. In InAs/GaSb, we found that backscattering in the edges was temperature independent and elucidated the presence of edge states in so-called 'trivial' regimes. These results call into question the prevailing interpretation of edge states in InAs/GaSb as topological, and conclude that better experimental evidence is required to definitively identify a 2D topologically insulating state in this material. Finally, we've investigated a fundamental property of Josephson junctions called the current-phase relation in few-mode InAs nanowire junctions. InAs nanowires which are in close contact with conventional superconductors are of great interest due to the possible realization of exotic particles called Majorana quasiparicles which may be of use for quantum computation. We've probed the disorder associated with adding superconductivity to nanowires by measuring the shape of the current-phase relation and finding that it fluctuates as a function of electron density and from junction to junction.

Keywords: Physics.
Advisor: Moler Kathryn A. primary advisor. Thesis advisor
Goldhaber-Gordon David
Qi Xiaoliang advisor. Thesis advisor
Imagining a cosmopolitan cosmos [electronic resource] : Chinese science fiction

This dissertation examines Chinese science fiction and its treatment in literary criticism from its beginnings in 1902 through the first decade of the twentieth century. It tells a story of how Chinese science fiction began with the cosmopolitan dreams of late-Qing intellectuals including Liang Qichao and Lu Xun, and how concerns for nation and world within Chinese sf evolved throughout the twentieth century to culminate in the fiction of Liu Cixin at the beginning of the twenty-first century. It argues that contemporary permutation of Chinese sf represented by Liu Cixin attempts to transcend nationalistic thinking and offers a cosmopolitan perspective on issues of global significance.

Keywords: East Asian Languages and Cultures.
Advisor: Wang Ban
Levy Indra A. advisor. Thesis advisor
Reichert Jim (James Robert) advisor. Thesis advisor
Song Mingwei advisor. Thesis advisor
Improving database performance and space efficiency in deduplicated and snapshotable memory systems [electronic resource]

In-memory databases have become increasingly important and prevalent because of the reduced cost of DRAM and the increasing demand for performance. Different from disk-oriented databases, in-memory databases treat main memory as the major storage for most or all of its data. This new storage organization faces several challenges, including DRAM scaling slowdown, concurrency control bottleneck, and index performance dilemma. To address these challenges, this thesis resorts to the recently proposed memory architecture called HICAMP. The HICAMP memory provides fine-grain data duplication, lightweight memory snapshots, and DAG structures in hardware. These features enable new ways to design and implement in-memory databases. This thesis introduces HicampDB, an in-memory database built from scratch to leverage HICAMP's architecture features. HicampDB organizes its storage and index on the HICAMP DAGs to benefit from the efficient tree traversal and data deduplication. HicampDB's bitmap index supports online updates while preserving high compaction ratio. Thanks to the hardware memory snapshots, HicampDB transactions run in full isolation and require no locking or database partitioning. The hybrid conflict detection used in HicampDB avoids the scalability bottleneck of OCC systems. In the experiments, HicampDB demonstrates 10x higher space efficiency, 16x better access speed, and 70% lower memory bandwidth consumption for database index. On the TPC-C benchmark, HicampDB shows near-linear scaling to 32 cores and 4.8x higher throughput when comparing with a state-of-the-art in-memory database.

Keywords: Electrical Engineering.
Advisor: Cheriton David R. primary advisor. Thesis advisor
Garcia-Molina Hector
Horowitz Mark
In Data We Trust?: The Big Data Capabilities of the National Counterterrorism Center

The National Counterterrorism Center (NCTC) sits as the central nexus for counterterror intelligence analysis and strategy for the entire American intelligence community (IC). It exists to offset the fragmentation issues that came to light in the aftermath of the 9/11 attacks. Its role is to integrate all types of intelligence information using traditional and computational Big Data techniques. Unfortunately, the NCTC is not in a position to take full advantage of contemporary Big Data analytics, severely reducing its analytical capabilities in the current information environment. These weaknesses stem from its organizational structure, not its technological capabilities.
The NCTC’s deficiencies manifest themselves both its internal structure as well as its position within the community as a whole. Internally, the NCTC does not have the information-sharing environment that it should and provides poor incentives for collaboration and innovation. Externally, it has a poorly defined role within the community and lacks the power that is required in order to truly centralize big data analytics. The private sector is leaps and bounds ahead of the government when it comes to the implementation of Big Data analytics. Internet giants such as Google and Facebook may serve as models for future improvements to the NCTC. With full understanding that certain limitations apply to government agencies, this thesis provides recommendations on how the NCTC may improve its ability to take advantage of large-scale data analytics and provide a better service to the rest of the Intelligence Community.

Keywords: Center for International Security and Cooperation
Big Data
Organizational Theory
Counterterrorism
Thesis
Advisor: Crenshaw Martha
In silico interaction of adaptive tissues and devices [electronic resource]

Finite element simulations were introduced in the aviation industry in the 1970s and soon found their way into other industries as well as biomedical research. Since then, constitutive laws have been developed with the goal of building realistic organ level models and ultimately creating a whole human model. The attempts to model the fibrous soft tissue in the human body has led to the development of anisotropic models as conceived by Fung or Holzapfel and active muscle models as developed by Hill. These models have led to a better understanding of the underlying biomechanics in both passive and active systems and their interaction with devices or changing boundary conditions during disease. However, the human body's ability to adapt to boundary conditions, particularly in conjunction with devices or disease, has been ignored in most of these models. Here, I present constitutive laws for soft tissue adaptation, their implementation into general purpose finite element codes, and applications to clinically relevant problems. I applied a continuum mechanics framework to model the in-plane area growth of skin upon overstretch, the adaptation of skeletal muscle to changes in its mechanical environment, and the effect of annuloplasty ring sizes during mitral valve repair surgery. Our results demonstrate how the finite element method can be applied to model the interaction of adapting soft tissue with medical devices and changing mechanical changes in ite environment. We anticipate our models to open new avenues in surgical planning and to enhance the treatment of patients in both plastic and cardiovascular surgery. Furthermore, I expect these models to be used by medical device manufacturers as part of their computer-aided engineering pipelines.

Keywords: Mechanical Engineering.
Advisor: Kuhl Ellen
Levenston Marc Elliot advisor. Thesis advisor
Steele C. R. (Charles R.) advisor. Thesis advisor
In the hands of God [electronic resource] : affect, agency, and faith among Brazilian migrants in greater Washington D.C.

"In the Hands of God" examines the relationship between Evangelical Christianity, migration, and affect in the United States. While the fact of increasing Evangelical religiosity among Latin Americans in the United States has been well documented, few studies have considered how this identity shapes, and is shaped by, the migrant experience itself, particularly for those without legal status. Scholars have long debated the political effect of Evangelicalism among Latin Americans, both in the United States and Latin America, emphasizing either its conservative or progressive influence. Such studies evaluate the extent to which converts become civically active, make more money, attain employment, or enhance their health as a result of Evangelical membership. While such research remains essential to understanding the broad phenomenon of Evangelical religiosity among migrants, it largely overlooks the deeply personal feelings, desires, and experiences of migrants themselves. Instead of considering what Evangelical religiosity produced economically, socially, or politically, my fieldwork set out to understand why migrants turned to Evangelicalism once in the United States, and how this newfound religious identity shaped their felt experience and identity as migrants. Based on 15 months of fieldwork among Brazilian migrants in greater Washington D.C., a "new immigrant gateway, " I analyze the following subjects: the affective experience of migration; the strategies pursued by Evangelical churches to attract adherents; and the multiple ways in which Evangelical faith mitigates the adversity faced by migrants. This research joins, and aims to expand, three main fields of theoretical inquiry: Migration Studies, Anthropology of Religion and Christianity, and Studies of Affect and Emotion.

Keywords: Anthropology.
Advisor: Luhrmann T. M. (Tanya M.)
Ebron Paulla A.
Garcia Angela
Rocha Marília Librandi advisor. Thesis advisor
Gin Lum Kathryn advisor. Thesis advisor
In Vivo Human Skull-Brain Dynamics During Mild Sagittal Skull Acceleration

Mild traumatic brain injury, or concussion, is one of the greatest medical challenges facing our society today, with diagnosed cases more prevalent than ever before, especially in contact sports. Previous studies have shown increased risk of neurodegenerative diseases such as Alzheimer’s in patients with a history of concussions, signifying the importance of better diagnostic tools and preventative equipment. Global kinematic variables and their variants have been historically used as indicators of concussion. The field of brain injury biomechanics rests on the assumptions that the brain is an almost incompressible material with little shear resistance. Together with the geometry of the relatively rigid skull, these assumptions have led to hypotheses that the brain is much more vulnerable to rotational rather than translational motions of the head. Previous animal experiments have shown higher rates of injury when rotational head accelerations were applied. Detailed finite element models have also predicted that rotational head motions lead to higher deformations in the brain. However, never before has this difference of dependence on skull input been shown experimentally. Here, we present the first study to experimentally investigate the decoupled effect of rotation and translation of the head on relative brain-skull displacement in live humans. Using high-speed fluoroscopy, we measured the brain's displacement as a result of head motions of up to 10g translational and 6 rad/s rotational velocities, which reach head motions near median soccer headers. Our results suggest that brain motion occurs predominantly due to the rotational head motion and relative motion of the brain is a function of the skull's rotational velocity. Furthermore, this experiment will allow us to validate our previous finding that skull–brain dynamics can be approximated by an under-damped system with a low-frequency resonance of less than 20 Hz. Our findings provide insight and suggest a new direction into designing smarter protective helmets based on the understanding of the complex dynamics of brain deformation rather than ad hoc injury correlations.

Keywords: Concussion
Traumatic Brain Injury
Firestone Medal for Excellence in Undergraduate Research
Thesis
Advisor: Camarillo David
Pelc Norbert J.
Deisseroth Karl
Incentive mechanisms for societal networks [electronic resource] : influencing behavior in transportation systems and organizational processes

Societal Networks, which we use every day and are critical for the orderly functioning of society, include transportation networks, energy grids, waste management networks, etc. Due to increased population and demand, they are preforming quite poorly recently. Therefore, it is important to restore the supply-demand balance of these networks to improve their efficiency. In this thesis, we consider demand management by incentivizing people to change their consumption behaviors. Our focus is on transportation networks, where we encourage commuters to avoid traveling in the peak hour. Our main contributions are (a) the development of a system, consisting of a back-end database and a user-facing front-end, designed for implementing large-scale "nudge engines", and (b) an analysis of the efficacy of the nudge engine in influencing commuter behavior. We apply our nudge engine to reduce peak hour congestion in Singapore's Mass Rapid Transit (MRT) system by encouraging commuters to travel off-peak. This program, called Travel Smart Rewards (TSR), has been running for close to 5 years with over 340,000 commuters and 86 companies as corporate members. The key ingredients of our approach are: (I) random monetary incentives paid out through games of chance, (ii) social influence and (iii) personalized rewards. Next, we apply our nudge engine to another setting of corporate learning and launch the A-Way program. It is used in conjunction with the employee training program of Accenture to train its management consultants. We describe the system and analyze its efficacy in improving outcomes of their training program.

Keywords: Electrical Engineering.
Advisor: Prabhakar Balaji
Osgood Brad advisor. Thesis advisor
Weissman Tsachy advisor. Thesis advisor
Income Shocks, Child Fostering and Education in Senegal

This paper examines the practice of child fostering in Senegal. Specifically, it looks at the treatment that fostered children are subject to in their host families relative to their host siblings. It compares the effect of exogenous income shocks on biological and fostered children in the same family. This comparison reveals whether there is a differential in educational investment between the two groups while accounting for any gap in treatment that might exist at baseline. Fluctuations in household economic conditions significantly change three variables for fostered children: their ability to read and write, their school enrollment, and their primary school completion rate. On the other hand, for biological children, these same metrics are mostly unchanged whether the shock is positive or negative. This leads to positive shocks shrinking the differences in educational ability, school enrollment and future earnings between the two groups by 0.21 points, 16 p.p. and 35 basis points respectively; negative shocks worsen the gap between them in the same magnitude. These results indicate that fostered children are less insured than their host siblings, although there is no difference in educational outcomes between the two groups absent any shock.

Keywords:  Department of Economics
Senegal
Children
Fostering
Education
Income Shock
Stanford Department of Economics
Thesis
Advisor: Dupas Pascaline
Indole antibiotic biosynthesis in edible plants [electronic resource]

The adept synthesis of antimicrobial small molecules is central to the sedentary lifestyle of plants. In the case of plants that we consume as food, these natural compounds are significant for human nutrition, too. Cruciferous vegetables, such as broccoli, mustards, and turnip, produce a bouquet of sulfur-containing molecules that restrict fungal pathogens and also possess drug-like activities in humans. Knowledge of the enzymes that assemble these natural compounds — termed the biosynthetic pathway — is crucial to understand their biological functions. Furthermore, elucidating a complete biosynthetic pathway would open the door to engineering plant metabolism for applications in sustainable agriculture and human health. Here I describe three studies that discover and characterize enzymes involved in the synthesis of plant antibiotics known as phytoalexins. These investigations employ a combination of mass spectrometry-based metabolite profiling, comparative genomics, gene expression analysis, and enzyme biochemistry. The three studies include: (i) uncovering a branch point for phytoalexin biosynthesis in the model plant Arabidopsis thaliana; (ii) identifying the first enzymes in the brassinin pathway from turnip mustard (Brassica rapa); and (iii) completing an entire pathway of Brassica phytoalexin biosynthesis. A set of ten enzymes is sufficient to engineer this pathway into a foreign plant, and future work will examine the valuable traits conferred by over 30 chemically diverse derivatives that are produced in cruciferous plants. The biochemical and genetic basis of phytoalexin biosynthesis elucidated here provides insights into the evolution and future engineering of the complex chemical communication among plants and their associated microbes.

Keywords: Chemical Engineering.
Advisor: Sattely Elizabeth primary advisor. Thesis advisor
Khosla Chaitan
Mudgett Mary Beth
Influence of host cell biology on bacterial infection [electronic resource] : listeria monocytogenes and the vascular endothelium

Vascular endothelial cells line the lumen of blood vessels and act as barrier that regulates the transport between the bloodstream and the underlying tissue. Thus, bacterial and viral pathogens that aim to reach such underlying tissue and cause infections distal to their initial site of entry must be able to subvert the barrier function of the vascular endothelium. We focus specifically on the bacterium Listeria monocytogenes, which has been shown to infect endothelial cells in vivo and exhibits myriad pathogenic strategies that contribute to its ability to travel from the initial site of infection, at the epithelial cells lining the small intestine, to distal organs such as the liver, spleen, brain, and placenta. We have developed culture-based models to study the molecular basis of L. monocytogenes infection of primary human endothelial cells (HUVEC). We have found that L. monocytogenes is directly internalized by endothelial cells in a phagocytosis-like process that is independent of bacterial invasion proteins and is regulated by Rho GTPase and the actin cytoskeleton, acting through focal adhesions and the formin family of actin nucleators. Further, we found that HUVEC display rapidly dynamic heterogeneity in susceptibility to such internalization; this heterogeneity results entirely from pre-existing HUVEC variability in susceptibility to L. monocytogenes adhesion and can be stabilized by perturbing cytoskeletal regulators. Finally, we developed an assay to examine how L. monocytogenes infected macrophages transfer bacteria directly to endothelial cells; surprisingly, and in contrast to direct invasion of bacteria, uptake of bacteria from infected macrophages is inhibited by actin polymerization in the recipient endothelial cell.

Advisor: Theriot Julie primary advisor. Thesis advisor
Ferrell James Ellsworth advisor. Thesis advisor
Rohatgi Rajat
The influence of lithology on the forms of hillslopes and drainage basins in soil mantled landscapes [electronic resource]

Much of the Earth's surface is blanketed by a mantle of soil and weathered rock. In these settings, topographic forms are typically smooth, with convex hillslopes grading subtly into the concave valley networks that define drainage basins. In 1877, G.K. Gilbert recognized that this smooth topography masked the underlying variability in geologic structure and proclaimed this the `Law of Divides.' Gilbert reasoned that in settings where rock weathered to soil faster than that soil could be eroded, topographic forms would be dictated by the processes transporting that soil rather than the variations in strength of the underlying rocks. There are exceptions to every rule, and this dissertation focuses on exceptions to Gilbert's `Law of Divides, ' situations where lithology influences the form of soil-mantled landscapes. I begin at hillslopes, demonstrating that if soil transport is sensitive to soil thickness, which in turn depends on underlying rock properties, variations in hillslope gradient can arise at geologic contacts, a phenomenon observed in some landscapes. Following this, I focus on the heads of valley networks and ultimately entire drainage basins. In the Gabilan Mesa, in the central Coast Ranges of California, properties of the weathered zone vary with slope aspect, placing rocks that favor headward channel growth close to the surface on south facing slopes. As a result, the preferential expansion of channel heads on south-facing slopes has led to a basin-scale topographic asymmetry. I conclude by measuring asymmetry in drainage basins in a number of other landscapes, and demonstrate that asymmetry in the structure of drainage networks is most pronounced in rock types that may be especially vulnerable to erosion. Hence, even at the largest scales, soil-mantled topography may encode some signature of the properties of underlying rocks.

Keywords: Geological Sciences.
Advisor: Hilley George E. primary advisor. Thesis advisor
Finnegan Noah J.
Graham S. A. (Stephan Alan)