VictorJuiz/thesis huggingface dataset:
Exploiting chirp spread spectrum and error detection in LoRa collision recovery

LoRa is a prominent radio technology for wide-area IoT applications. LoRa allows a gateway to receive packets from low-power transmitters over a range of miles. But when two transmissions collide, the gateway loses one or both of them. Collisions waste airtime and energy. This dissertation proposes two novel cross-layer techniques that enable LoRa receivers to successfully receive colliding packets with high probability. The first, called symbol querying, changes the interface between the LoRa demodulator and decoder. Symbol querying greatly improves the ability of a LoRa receiver to successfully receive the stronger frame in a collision. It does so by elevating the error detection capabilities of channel coding into error correction. For instance, a receiver using (8, 4)-extended Hamming codes can correct two, instead of only one, bit errors per codeword. The second technique, called symbol SIC, uses the unique discrete properties of LoRa symbols to enable the efficient reception of the weaker frame in a collision, by subtracting the stronger frame's peaks in the frequency domain. This dissertation presents a prototype LoRa receiver that includes symbol querying and symbol SIC using an inexpensive, off-the-shelf software-defined radio (SDR). When receiving colliding frames, this implementation receives up to 17x more frames than traditional LoRa receivers and symbol querying cuts the energy costs of communication by up to 4.6x compared to an SIC-only design

Keywords: Electrical Engineering.
Advisor: Levis Philip
Bambos Nicholas
Jamieson Kyle
Explorers for Life: The Long-Term Benefits of a Community Outdoor Education Program

There is increasing agreement among researchers and educators about the importance of outdoor experiences for youth. However, due to urbanization, technology, standardized testing, and lack of funding, outdoor education continues to be limited in accessibility nationwide. Research and evaluation are key to better understanding the benefits and long-term implications of this kind of programming, yet there continues to be a lack of longitudinal investigations in the field. In an effort to address both of these needs, this qualitative participant-perspective study worked with former members of Explorers Club, a program within Wild Whatcom, a community outdoor education organization located in Bellingham, Washington. I sought to answer the question: what are the perceived long-term benefits of an outdoor education program by former participants? I interviewed 23 Explorers Club members following a semi-structured protocol, five to ten years post-engagement. Findings revealed that participants believed the program provided them with cognitive skills in the form of ecological and technical knowledge, a personal connection with nature, and non-cognitive skills related to self- and social esteem. Furthermore, the responses suggested that these benefits were cyclical in nature such that the cognitive knowledge participants formed, facilitated a personal connection to nature as well as enhanced non-cognitive skills, and that together these two improvements have driven further engagement with the outdoors through enhanced pro-environmental attitudes, daily habits and practices, and overall life choices, effectively perpetuating the cycle. Specifically, participants emphasized the program provided them with elaborate plant identification and survival skills, contributing to greater comfort in nature and a sense of self-efficacy, which has motivated continual interaction with the environment through participants’ leisure activities, place of residence, and college/major of choice. These findings provide additional evidence for the contribution of community outdoor education to traditional schooling and suggest that this form of programming provides students with the early experiences necessary to become not only more socio-scientifically informed citizens, but also explorers for life.

Keywords:  Graduate School of Education
Graduate School of Education
Outdoor Education
Long-Term
Benefits
Youth
Community
Qualitative Interviews
Thesis
Advisor: Ardoin Nicole M.
Kelman Ari Y.
Exploring cellular structures on the nanoscale with stimulated emission depletion microscopy

Super-resolution fluorescence microscopy has proven to be a powerful tool to study biology. STimulated Emission Depletion (STED) microscopy is a super-resolution technique that is compatible with a variety of biological applications including imaging in multicolor and with live cells. In this thesis, I describe three such applications from imaging cell samples to whole tissue, beginning with a short primer on the scientific concepts that are fundamental to my thesis work. In Chapter 2, I then lay the foundation for the super-resolution projects I expound on in the rest of the thesis. In Chapter 3, I detail work done in collaboration with Dr. Colin Comerci, Dr. Bo Gu, and Dr. Saumya Saurabh to study proteins involved in genomic organization. CCCTC-binding factor (CTCF) and cohesin had been previously shown to be involved in organizing the so-called topologically associated domains (TADs) within chromatin in mammalian cells. Two-color STED microscopy combined with quantitative image analysis of endogenously labeled cells provides insight into the relationship between CTCF and cohesin in the nucleus. We demonstrate that CTCF and cohesion are organized into clusters, and a fraction of these clusters are coupled with a characteristic distance, which could perhaps indicate a molecular interaction. Through additional biochemical perturbations, we provide further insight into how transcription and other processes influence this relationship. In Chapter 4, I explain my contribution to Dr. Damien Garbett's larger study of actin and an ancient actin bundling protein, T-plastin. Dr. Garbett probed how cells are able to migrate across large gaps in the extracellular matrix (ECM). He found that T-plastin helps facilitate cell migration especially in the context of discontinuous ECMs. Here, I contributed super-resolution STED images to explore in greater detail the relationship between actin and T-plastin in protrusive areas as compared to the main cell body. In Chapter 5, I recount a preliminary study done in collaboration with doctors at California Pacific Medical Center studying immune checkpoint proteins that are the targets of a new immunotherapy treatment. Although promising, immune checkpoint immunotherapy is currently only effective in fraction of cancer patients. The variation in sub-cellular structure and density of immune checkpoint proteins in the tumor microenvironment could perhaps correlate with response to immunotherapy treatment. We utilize two-color STED microscopy to probe the nano-scale organization of the immune checkpoint protein Programmed Death-1 (PD-1) in metastatic melanoma tissue. We observe various degrees of nanoscale clustering of PD-1 on cells within the tumor microenvironment. Here, I also describe some challenges to two-color imaging in tissue samples

Keywords: Chemistry.
Advisor: Moerner W. E. (William Esco)
Bertozzi Carolyn R.
Cui Bianxiao
Exploring optical and optoelectronic properties in transition metal dichalcogenides

The interest in van der Waals (vdW) materials has been growing steadily over the past two decades due to their immense potential in electronics and optics. Corresponding, we have access to a growing library of vdW materials with diverse properties. Since these materials only have strong chemical bonds in two dimensions, these materials can be arbitrarily layered to combine and create new properties. Within the vdW library, direct band-gap monolayered (1L) transition metal dichalcogenide (TMDC) semiconductors of the form MX\(_2\) (M= Mo, W and X= S, Se, or Te) have attracted attention for their strongly tunable electronic and optical properties. Additionally, the lack of inversion symmetry in monolayer TMDCs results in unique spin and momentum properties usable in spintronics and the emerging field of valleytronics. Furthermore, due to the reduced Coulomb screening inherent to 2D materials, TMDCs exhibit strongly-bound excitons (correlated electron-hole pairs) which can be manipulated and used to study the material itself or even to store and convert information. This thesis presents an exploration of the properties of TMDCs and their combinations in relationship to their potential for device application

Keywords: Electrical Engineering.
Advisor: Heinz Tony F.
Pop Eric
Vuckovic Jelena
Exploring Sex Differences in Young Children's Reading Skills: Neuroscience EEG and Reading Assessment Measures

Academic research on sex differences in specific cognitive abilities spans multiple fields, each utilizing different research methodologies specific to the collective branch of science. This thesis draws on neuroscience, education, and sociology methodologies to determine the extent of differences in reading, language skills and brain processing on the basis of sex among young children. Utilizing both educational assessment data and neuroscience EEG data from 56 3rd-8th grade students attending a private school that seeks to counter gender stereotypes, there was an assessment of sight word efficiency, phonemic decoding, letter recognition, and lexical processing. Findings include statistically significant sex differences in letter recognition and lexical processing in EEG data. These results were in contrast with behavioral TOWRE-2 measures of oral sight word and pseudoword decoding efficiency in this sample, which, in contrast to the predictions of the literature on sex difference in reading, revealed equivalent performance across sexes. These results provide support for the use of neuroscience data in educational assessment, further exploration of sex differences in reading and language, and the reconciliation of multiple sources of data from different fields. Findings show promise for the budding field of educational neuroscience and methodical practices in EEG studies.

Keywords: Graduate School of Education
Stanford University
education assessment
neuroscience
education
sociology
EEG
sex differences
reading
language
lexical processing
letter recognition
interdisciplinary sciences
middle grade students
stereotype threat
egalitarian pedagogy
Thesis
Advisor: McCandliss Bruce
Freese Jeremy
Exploring solvable chaos in quantum mechanics

The understanding of strongly coupled many body quantum systems has been dramatically improved by the application of tools originally developed for seemingly unrelated purposes, for example quantum gravity and information theory. At the same time, to understand the possible types of information flow and properties of a quantum theory of gravity, it has become clear that one needs to understand aspects of the strongly coupled regime. In this thesis, we give three examples where the interplay of these ideas gives rise to a simple and quantitative understanding for different aspects of strongly coupled models. In Chapter 2, we make precise the idea (at high temperature) that thermalization is the loss of information about initial conditions, and in doing so explain the relationship between a quantum measure of chaos and thermalization. In Chapter 3, we explicitly compute the "size" (in terms of boundary operators) of operators deep in the bulk dual of a particular holographic (chaotic) model, and find an exact relationship between bulk symmetry generator matrix elements and size. In Chapter 4, we solve a model subject to arbitrary drive, and use it to study the formation of a wormhole, as well as more general features of the gravity dual

Keywords: Physics.
Advisor: Qi Xiaoliang
Hayden Patrick (Patrick M.)
Shenker Stephen Hart
Exploring the Li-S system for next-generation batteries

Lithium-sulfur (Li-S) batteries have a high theoretical energy density of ~2500 Wh/kg (vs. ~400 Wh/kg of Li-ion batteries) and are promising candidates for meeting future energy storage demands. However, the practical applications of Li-S batteries have been severely hindered by its poor cycling life and stability. In the first part of my thesis, I will discuss the lithium polysulfide dissolution problem, which is a major problem plaguing Li-S batteries causing fast capacity degradation and poor cycle life. Upon establishing a standard procedure to quantitatively compare the polysulfide adsorption capability of candidate materials, a useful strategy is developed to screen materials and allow for rational design of long cycle life Li-S batteries. In the second part, I will further explore the Li-S system via a novel battery scheme by utilizing a P/C nanocomposite anode and pairing it with a Li2S coated carbon nanofiber cathode. It is discovered that the red P anode can be compatible in ether-based electrolyte systems and can be successfully coupled to a Li2S cathode. The new design concept full-cell displays remarkable specific capacity, rate and cycling performances. In the final part, I will present a characterization method via rotating disk electrode to further study the Li-S system. This method can be generally applied to various sulfur species, current collectors and electrolyte systems to provide additional insight towards achieving superior rechargeable batteries that can eventually replace Li-ion batteries

Keywords: Materials Science and Engineering.
Advisor: Cui Yi
Brongersma Mark L.
Dauskardt R. H. (Reinhold H.)
Extending physicians' reach with passive and transparent transmissions

Magnetic resonance (MR) offers safe, high contrast imaging of soft tissue inside the body, often superior to both ultrasound (US) and computed tomography (CT). Today, MRI is largely used for diagnostic and preoperative imaging with limited ability to leverage MRI as guidance during surgical intervention. Poor access inside the bore prohibits tool manipulation while patients remain inside the machine. During MRI-guided needle biopsies of organs such as the liver or prostate, patients are removed from inside the bore for needle insertion and adjustment. Robotic systems enable new capabilities in minimally invasive surgery and create opportunities for teleoperation. Remote access inside the MRI bore, with the patient remaining inside the scanner, would enable biopsies with real-time MRI guidance, improving procedure sensitivity and reducing duration. MRI compatibility requirements, however, significantly constrain the choice of technologies and materials used in systems designed for MRI applications. Researchers have explored novel pneumatic and piezoelectric actuators to create MRI compatible robots. While significant strides have been achieved, these devices do not provide haptic feedback and are controlled through on-screen interfaces, isolating physicians from direct control of the needle. A versatile device that provides high-fidelity force feedback and access deep inside the bore remains a challenge. This thesis explores a new approach to in-bore MRI guided biopsy that employs hydrostatic transmissions to extend physicians' reach inside the machine. The systems created are passive: all energy comes from the operator, with motions and forces mapping one-to-one between the input and output

Keywords: Mechanical Engineering.
Advisor: Cutkosky Mark R.
Daniel Bruce (Bruce Lewis)
Okamura Allison
Extending the reach of the lasso and elastic net penalties : methodology and practice

The lasso and its successor, the elastic net, are two popular regularized regression methods which produce sparse models. We propose two different extensions to these methods that leverage feature information in the model-fitting process to improve predictive accuracy. The first method, the "principal components lasso" ("pcLasso"), combines the lasso penalty with a quadratic penalty that shrinks the coefficient vector toward leading principal components of each group. pcLasso is compatible with both overlapping and non-overlapping groups. We provide some theory for the method and illustrate the method on some simulated and real data examples. Next, we develop a general framework for organizing feature information into an auxiliary matrix and propose a method, called the "feature-weighted elastic net" ("fwelnet"), that uses it to adapt the relative penalties on the feature coefficients in the elastic net penalty. We present connections between this method and the group lasso, and also to Bayesian estimation. We then switch gears and explore how to relax another limitation of the lasso and the elastic net: the fact that the model's prediction must be a sparse linear combination of the input features. Motivated by reluctant interaction modeling, we propose a multi-stage algorithm, called "reluctant generalized additive modeling" (RGAM), that can fit sparse generalized additive models (GAMs) at scale. While the individual features are allowed to vary non-linearly with the response, the model remains additive in the input features, thus preserving interpretability. RGAM has an explicit bias toward simpler, linear relationships, with non-linearities only included if they improve predictive power. Unlike existing methods for sparse GAMs, RGAM can be extended easily to binary, count and survival data. Finally, we turn to the practical matter of computation. Earlier versions of the glmnet package, which implements the lasso and the elastic net in R, had specialized FORTRAN subroutines for fitting the models for popular model families, including the logistic regression and Poisson regression models. We describe how the elastic net penalty can be applied to any generalized linear model (GLM), and explain the computational approach needed to make model-fitting feasible in practice. We also show how this approach extends to fitting regularized Cox proportional hazards models for (start, stop] data and for stratified data

Keywords: Statistics.
Advisor: Tibshirani Robert
Owen Art B.
Walther Guenther
Failure as chance : Christoph Schlingensief's inoperative avant-garde in the age of neoliberal crisis

This dissertation presents a political history of the mature career of German director Christoph Schlingensief (1960-2010). It charts his turn in the late 1990s and 2000s from theater and film to avant-garde actions — a series of highly public, political performances attempting to integrate art and life. The dissertation analyzes these works in relation to their neoliberal political contexts, theorizing them as an "inoperative avant-garde" that stages its own failure as a generative political act — a project emblematized by Schlingensief's slogan, "Failure as Chance!" Confronted with a totalized market society, this inoperative avant-garde employed aesthetic strategies of ironic overidentification, critiquing neoliberalism by parodically adopting its ideologies and practices. Schlingensief also turned away from this ironic mode late in his career, ultimately leading to the integration of his avant-garde into the institutions of neoliberalism. This history of Schlingensief's avant-garde emerges through a series of case studies, including his interventions in German and Austrian electoral politics ("Chance 2000" and "Please Love Austria") and his late works in Namibia and Burkina Faso ("The African Twintowers" and the Opera Village). By situating Schlingensief's inoperative avant-garde within the history of global capitalism, this dissertation examines the potentials and limits of vanguard art in an era of neoliberal hegemony and interrogates the very possibility of an avant-garde in the 21st century

Keywords: Theater and Performance Studies.
Advisor: Smith Matthew Wilson
Daub Adrian 
Jakovljević Branislav
Faint galaxies and small halos : probes of galaxy formation and dark matter

This thesis addresses the intersection of dark matter and galaxy formation physics by modeling the faintest galaxies in the Universe in a cosmological context. In the first part of this work, I present an empirical model for the connection between faint galaxies and small dark matter halos. Combining this model with tailored cosmological simulations of Milky Way analogs and state-of-the-art satellite galaxy observations yields new insights into dwarf galaxy formation and hierarchical structure formation. Next, I show that these same dwarf galaxy observations place stringent constraints on microphysical dark matter properties including its warmth, self-interactions, Standard Model interactions, minimum particle mass, and formation epoch. Finally, I describe a unified framework that combines dark matter constraints from dwarf galaxies and strong gravitational lensing, paving the way for next-generation surveys of small-scale cosmic structure to deliver unprecedented insights into dark matter physics

Keywords: Physics.
Advisor: Wechsler Risa H. (Risa Heyrman)
Abel Tom G.
Blandford Roger D.
Fairness in algorithmic services

Algorithmically guided decisions are becoming increasingly prevalent and, if left unchecked, can amplify pre-existing societal biases. This thesis employs modern computational tools to examine the equity of decision-making in two complex systems: automated speech recognition and online advertising. Firstly, I demonstrate large racial disparities in the performance of popular commercial speech-to-text systems developed by Amazon, Apple, Google, IBM, and Microsoft, a pattern likely stemming from a lack of diversity in the data used to train the systems. These results point to hurdles faced by African Americans in using widespread tools driven by speech recognition technology. Secondly, I propose a methodological framework for online advertisers to determine a demographically equitable allocation of individuals being shown ads for SNAP (food stamp) benefits. In particular, I discuss how to formulate fair decisions considering budget-constrained trade-offs between English-speaking and Spanish-speaking SNAP applicants. Both application domains exemplify processes to ameliorate demographic-based disparate impact arising from decisions made by online platforms, with the ultimate goal of uplifting underserved communities

Advisor: Athey Susan 
Goel Sharad
Varian Hal R.
Fallouts of Deportations in Texas: Analyzing the impact of large-scale workplace raids on academic performance

Workplace raids are one of the most visible and traumatic immigration enforcement tactics taken by ICE; they can result in the detention of hundreds of immigrants at one time, sending shocks through the community and leaving children suddenly without their family. Despite the humanitarian concerns surrounding these raids and their impact on the well-being of children, there is a limited amount of research on the topic. Using test scores from schools in proximity to a raid taking place in Allen, TX, I employ a series of quasi-experimental designs to determine the effects of the raid on Hispanic students' academic outcomes. I conduct two difference-in-differences analyses and a difference-in-difference-in-differences analysis using distinct control groups. I find statistically significant evidence that the raids negatively impacted Hispanic students’ performance on the Texas STAAR testing for both reading and math. Additionally, I find that schools closer to the raid experienced a larger drop in scores.

Keywords:  Department of Symbolic Systems
immigration
ICE
legal violence
workplace raids
symbolic systems
sociology
Thesis
Advisor: Jackson Michelle
Guluma Beka