VictorJuiz/thesis huggingface dataset:
Interactive systems for data transformation and assessment [electronic resource]

In spite of advances in technologies for processing and visualizing data, analysts still spend an inordinate amount of time diagnosing data quality issues and manipulating data into a usable form. This process often constitutes the most tedious and time-consuming aspect of analysis. This dissertation contributes novel techniques for coupling automated routines with interactive interfaces to enable more rapid data transformation and quality assessment. In this dissertation, we first present an interview study with enterprise data analysts. We characterize the process of industrial data analysis, document how organizational features of an enterprise impact analysis, describe recurring pain points, and discuss design implications for visual analysis tools. Next we introduce Wrangler, an interactive system for creating data transformation scripts. Wrangler combines direct manipulation of visualized data with automatic inference of relevant transforms, enabling analysts to iteratively explore the space of applicable operations and preview their effects. We present user study results showing that Wrangler significantly reduces specification time and promotes the use of robust, auditable transforms instead of manual editing. Underlying the Wrangler interface is a declarative data transformation language that supports code-generation of executable code in a variety of runtime platforms. For large data sets, an analyst can build and test a script on a sample of data before applying the script to the entire data set. Often times, errors or other anomalies will appear in the data set that did not appear in the sample. We introduce and evaluate two methods to aid more rapid debugging of large-scale transformation scripts. Surprise-based anomaly detection applies a model to classify output records as exceptions. Rule-based transform disambiguation generates example records to help analysts refine transformation scripts iv before applying them. After transforming a data set, an analyst often inspects the result for other data quality issues. We present Profiler, a visual analytic tool for assessing data quality issues. We present Profiler's architecture, including modular components for custom data types, anomaly detection routines and summary visualizations. The system contributes novel methods for integrated statistical and visual analysis, automatic view suggestion, and scalable visual summaries that support real-time interaction entirely in the browser with millions of data points. Taken together, this dissertation contributes novel methods for integrating automated routines with interaction and visualization techniques to improve the efficiency and scale at which data analysts can work.

Advisor: Heer Jeffrey Michael primary advisor. Thesis advisor
Hanrahan P. M. (Patrick Matthew) advisor. Thesis advisor
Paepcke Andreas
Interface electronics for emerging sensor systems [electronic resource]

Sensor systems are a ubiquitous part of modern life and make huge impacts on how we deal with disease and injury, how we communicate and travel, and how we understand our environment and ourselves. This thesis presents research in two emerging areas, with contributions in front-end mixed signal interface electronics as well as measurement systems. The first project explores interface electronics for in vivo recording of neural signals in human and non-human subjects. Research tools created by IC designers are used to explore the function of the central and peripheral nervous systems, and make an impact in the way we diagnose, treat, and understand a broad range of neurological ailments such as epilepsy, chronic pain, obsessive compulsive disorder, and chronic neurodegenerative diseases. A new front-end circuit architecture based on switched capacitor filtering and windowed integrator sampling is presented. The circuit was integrated into a 96 channel neural recording ASIC, which acquires extracellular neural action potentials and local field potentials from a Utah Electrode Array (UEA) implanted in cortex. The front-end achieves 2.2uVrms input referred noise in a 10kHz bandwidth, and conditions signals before conversion at 31.25kSa/s by 10-bit SAR ADCs with 60.3dB SNDR and a Walden figure of merit of 42fJ per conversion step. This power and area efficient sensor interface consumes 6.4mW from 1.2V while occupying 5mm x 5mm in 0.13um CMOS, and is the cornerstone of the HermesE wireless neural recording platform, enabling basic neuroscience as well as neural prosthetics research. The second work described in this thesis relates to label-free biothreat detection based on transduction of vibrational mode information that couples to electron transport through electron-phonon interactions. This project proposes an ambitious, novel biosensing paradigm that is alternative to traditional micro-array systems, the current workhorse for resolving molecular biology, with potential advantages in specificity, sensitivity, portability, cost, throughput, and manufacturability. The sensor is based on a gold electrode coated with a self-assembled monolayer film, and is placed in an electrolyte solution prepared from a biological sample. The low magnitude of the vibrationally-assisted tunneling current and the need to reduce electronic interactions in the sensor have motivated a number of extensions to the conventional electrochemical instrumentation space, including noise suppressing potentiostat designs, a three-electrode AC measurement system based on a replica path scheme to reject blockers and errors, and a three-electrode DC current measurement system achieving sub-picoampere readout accuracy. These systems were implemented with a mixture of discrete integrated circuits, laboratory instrumentation, and custom software.

Keywords: Electrical Engineering.
Advisor: Murmann Boris primary advisor. Thesis advisor
Howe Roger Thomas advisor. Thesis advisor
Makinwa Kofi A. A.
Shenoy Krishna V. (Krishna Vaughn) advisor. Thesis advisor
Interframe compression of visual feature descriptors for mobile augmented reality [electronic resource]

Streaming mobile augmented reality applications require both real-time recognition and tracking of objects of interest in a video scene and many of these applications utilize local image features. Typically, local feature descriptors are calculated from the gradients of a canonical patch around a keypoint in the image. For mobile applications where data are transmitted over a network for feature detection and image matching, it is desirable that the amount of data sent is as low as possible to reduce the latency and the cost of the system. We first study the possible architectures for a system that uses a single image, and propose a novel architecture based on encoding canonical patches extracted on the mobile phone. Our system represents an intermediate solution between a system that sends the whole image to the server, and a system that extracts the feature descriptors on the phone. We then consider the problem of low bit-rate streaming mobile augmented reality, and present a two-stage solution. We propose a temporally coherent keypoint detector and illustrate its efficiency through the evaluation of the similarity between the temporally coherent canonical patches. Moreover, we design efficient interframe predictive coding techniques for canonical patches, feature descriptors and keypoint locations. In the proposed system, we strive to transmit each patch or its equivalent feature descriptor with as few bits as possible by simply modifying a previously transmitted patch or descriptor. Our solution enables server-based mobile augmented reality where a continuous stream of salient information, sufficient for image-based retrieval and object localization, can be sent over a wireless link at a bit-rate of about 20 - 30 kbps, which is practical for today's wireless links and less than one-tenth of the bit-rate needed to stream the whole video to the server.

Keywords: Electrical Engineering.
Advisor: Girod Bernd primary advisor. Thesis advisor
Apostolopoulos John G. advisor. Thesis advisor
El Gamal Abbas A. advisor. Thesis advisor
The interpersonal costs of indulgence [electronic resource]

A series of studies supported the hypotheses that those who indulge, either by purchasing luxury products or eating unhealthy foods, are seen as less trustworthy and lower in self-control. Across a wide range of indulgence manipulations including car brand (Studies 1a-1c), wedding budget (Study 2), the amount spent on household items and clothing (Studies 3-5), and food choice (Study 6), participants rated indulgent targets lower on various measures of trust and self-control, including a behavioral measure of financial trust (Study 3). These effects remained significant when the target's income was held constant across conditions (Studies 1b-2, 4). Mediation analyses revealed that the effect of indulgence on trust was explained by the fact that those who indulge were seen as having lower self-control. The trust effect was even stronger when the target indulged in violation of a self-restraint goal, and this difference was again driven by changes in perceived self-control (Study 6). Discussion focuses on self-control, other potential moderators of the observed effects, and implications for marketers and those looking to make favorable impressions on others.

Keywords: Psychology.
Advisor: Monin Benoît
Khan Uzma Aslam
Miller Dale T. advisor. Thesis advisor
Intracortical neural interface systems [electronic resource]

Acquisition of neuronal electrical activity via chronically implanted electrode arrays has enabled a wide range of advances in electrophysiological experimentation towards basic neuroscience as well as neural prosthetics. These tools are used to explore the function of the central and peripheral nervous systems and make an impact in the way we diagnose, treat, and understand a broad range of neurological ailments such as epilepsy, chronic pain, obsessive compulsive disorder, and chronic neurodegenerative diseases. There is research at Stanford involving the study of motor / premotor cortical activity and its application towards prostheses, enabled in part by the "Hermes" series of mobile neural acquisition systems, which aim to provide high-quality recording of ensemble neuronal activity in freely behaving primates over long periods of time. Physical size and battery-life constraints have thus far limited our capabilities to record only from a subset of the available channels, or to record a compressed version of neural activity in the form of threshold crossings. This work presents the final generation "HermesE" wireless multichannel neural recording system, which overcomes the aforementioned limitations through the design and use of a high channel count, high fidelity neural sensor interface IC that achieves state-of-the-art power consumption and noise performance while providing instrument grade neural recordings for the primary purpose of enabling neuroscience research. Switched-capacitor signal conditioning provides well-controlled frequency response and good channel-to-channel matching, obviating the need for calibration and easing its use by scientists and engineers in experimental settings. A 2.2 uVrms input-referred noise in a 10 kHz bandwidth is achieved, and the conditioned signals are digitized at 31.25 kSa/s by 10-bit SAR ADCs with 60.3 dB SNDR and 42 fJ /conv-step. The sensor interface occupies 25 mm^2 in 0.13 um CMOS and consumes 6.4 mW from 1.2 V while providing simultaneous access to 96 channels of broadband neural data. High data rate wireless communication is enabled by a custom, power efficient pulse ultra-wideband transmitter in 65 nm CMOS using simple OOK modulation. A low voltage FPGA frames and scrambles the data prior to transmission to aid the clock and data recovery process in the receiver. The mobile system consumes a total of 15.1 mW, more than an order of magnitude lower than the previous HermesD system, and at 3x the channel count. The system was validated by recording in vivo neural signals from rhesus macaques implanted with 96-channel Utah Electrode Arrays, successfully demonstrating its viability for a broad set of long duration and untethered experiments that are unachievable with bulky commercial off-the-shelf systems.

Keywords: Electrical Engineering.
Advisor: Meng Teresa H. primary advisor. Thesis advisor
Murmann Boris advisor. Thesis advisor
Poon Ada Shuk Yan
Investigating the bachelor's degree pipeline [electronic resource] : three papers on college access and student success

Both individuals and society benefit from postsecondary education; however, numerous obstacles hinder students from enrolling and succeeding in college. This dissertation consists of three papers and each addresses one of three different obstacles to obtaining bachelor's degree: financial, academic, and informational. The first paper discusses the financial barrier and examines whether low income students are responsive to a financial incentive to pursue a STEM major. Using regression discontinuity and a statewide longitudinal student dataset, I exploit two discontinuities in the eligibility requirements of the national SMART Grant. The results suggest that financial incentives late in the college career are not enough of a motivation for students to study a STEM field. The second paper addresses the academic barrier and presents a theoretical framework and empirical evidence related to how students use college credit earned in high school. Specifically, it uses the nationally representative Beginning Postsecondary Survey to examine the relationship between earning college credit through Advanced Placement (AP) courses and exams and postsecondary outcomes. Results indicate that that earning AP credits are positively related to graduating early, double majoring, and majoring in a STEM field. The third paper presents an experimental analysis of a college access program to determine whether a high school senior's amount of interaction with a near-peer college adviser affects the students college preparation and enrollment. The treatment group received on average approximately three more meetings with the adviser, but these do not result in observable increases in college enrollment.

Keywords: Education.
Advisor: Bettinger Eric primary advisor. Thesis advisor
Antonio Anthony Lising
Loeb Susanna advisor. Thesis advisor
Investigating the role of BPAG1 in axonal transport [electronic resource]

The intracellular trafficking of vesicles and organelles is essential for all cells. Neurons are especially reliant on cargo transport as a consequence of their extremely polarized morphology. Highlighting this point, disruption of axonal transport has been attributed to many neurodegenerative diseases. In recent years, tremendous progress has been made towards a better understanding of the fundamental elements of axonal transport. However, the regulatory mechanisms that control its dynamics remain largely unknown. One striking feature of the axonal transport system is that the retrograde transport of endosomes within axons proceeds with remarkable speed and uniformity, despite having to navigate a complex and crowded environment. In this dissertation, I propose a role for BPAG1n4, a massive 600kDa protein, in the regulation of the processivity of axonal transport. BPAG1n4 has previously been shown to play an essential role in retrograde axonal transport by virtue of its interactions with the dynactin subunit p150Glued, and with endosomes via retrolinkin. Its ability to interact with the main components of the transport system make it ideally placed to coordinate retrograde transport. Here, I show that BPAG1n4 interacts with EB1 family proteins at the microtubule plus end. Using single molecule labeling coupled with live imaging, I found that expression of the isolated plus end binding domain results in a substantial impairment in the processivity of retrograde axonal transport in dorsal root ganglion (DRG) neurons. This suggests that the accessibility of the microtubule plus end to proteins such as BPAG1n4 is essential for maintaining the processive motility of endosomes along the axon. Interestingly, I have discovered an extremely rapid, calcium regulated switch between microtubule plus end interaction and lattice binding in the carboxyl terminus of BPAG1n4. This novel, calcium dependent regulatory mechanism is EF-hand dependent, and mutations of the EF-hands abolish this dynamic behavior. This study represents the first evidence of calcium signaling directly modulating the dynamic interaction of a protein with microtubules. Strikingly, I observed that disruption of the calcium responsiveness of BPAG1n4's association with the plus end severely impaired processive endosomal transport, suggesting the exciting possibility that calcium may play a role in regulating the traffic of endosomes along axons. This study thus provides exciting new insight into the molecular mechanisms that regulate the complex system of axonal transport. This domain of BPAG1n4 is conserved in other members of the spectraplakin family, suggesting that calcium regulation of microtubule plus end interaction may play a vital role in their functional activities as well. Addressing the potential role of this calcium switch may be crucial to fully understanding the diverse functional activities of spectraplakins in microtubule based cellular processes.

Advisor: Yang Yanmin
Kopito Ron Rieger
Reimer Richard J. advisor. Thesis advisor
Shen Kang
Investigation of optical and electrical properties of metal-insulator-metal devices [electronic resource]

Internal photoemission is a process where optically excited electrons transit from one medium to another before the electrons relax to their equilibrium energy. Demand for new ways of utilizing light, either for energy collection or signal transmission in all-optical-circuits, is driving reemerging interest in these "hot electrons", especially in metal-insulator-metal (MIM) structures due to their simple configuration and facile integration with optical systems. In this work, we investigate the electrical and optical properties of MIM devices used for energy collection and wavelength determination through hot carrier extraction. First, we develop a new method of electrical power generation based on optical absorption in MIM devices. This method takes advantage of internal photoemission at the metal-insulator interface to produce power through collection of high-energy hot carriers. Using a metal as the absorber is advantageous compared to traditional semiconductors as it can absorb over wider spectrum, though there are still significant challenges to making hot carrier devices practical. Second, we report a new method for electromagnetic wavelength determination using simple MIM devices. In addition to power generation applications, hot electrons from MIM devices create a unique monotonic dependence of open-circuit voltage on wavelength. We demonstrate this open circuit voltage is power-independent and use this characteristic to deconvolve multi-spectral signals by a single device, the first reported MIM device for wavelength detection. Third, we introduce nanogratings on the MIM device surface to excite surface plasmons by direct illumination. We are able to enhance the absorption from the intense field in the devices to boost the hot carrier collection efficiency. We present both theoretical and experimental results illustrating the possibility of broadband photocurrent enhancement. Fourth, we report an unusual photocurrent negative differential resistance (NDR) in the MIM device. Mid-gap states in the band gap of the insulator caused by low-temperature atomic layer deposition (ALD) lead to the abnormal photocurrent characteristics. We develop a model to interpret this unusual photocurrent NDR behavior.

Keywords: Materials Science and Engineering.
Advisor: Melosh Nicholas A. primary advisor. Thesis advisor
Brongersma Mark L. advisor. Thesis advisor
Dionne Jennifer Anne advisor. Thesis advisor
Janus [electronic resource] : media access in full-duplex wireless networks

Single-channel full-duplex wireless is a radio technology that transmits and receives at the same time and on the same frequency band. It is a nascent and exciting field of research that provides new opportunities to greatly improve wireless networks. Traditional wireless systems isolate transmission and reception in time, such as in timedivision duplex (TDD), or in frequency, as in frequency-division duplex (FDD). This is necessary because huge self-interference from the transmitting antenna is usually millions of times stronger than the signal at the receiving antenna and it saturates the receiver analog-to-digital converter (ADC). However, feasibility of full-duplex radios has been recently demonstrated at the physical layer with off-the-shelf components. Since then, there has been a lot of progress towards the goal of suppressing the huge self-interference signal with clever multi-stage cancellation schemes. Existing full-duplex work focuses on the physical layer and has not yet deeply studied its impact on the the MAC layer. There are several proposals that provide simple extensions from CSMA/CA popularly used in WiFi networks, but experiments show that these extensions poorly utilize the full-duplex channel, falling far short of the projected theoretical 2x throughput increase. In order to make the most out of the unique characteristics of a full-duplex physical layer, it is important to design a clean-slate MAC layer. This dissertation presents Janus, a media access protocol for full-duplex wireless local area networks. By allowing nodes to simultaneously transmit and receive on the same band, full-duplex by itself provides at most a 100% throughput improvement over half-duplex networks. Janus demonstrates that a media access control protocol designed especially for full-duplex can allow a network to achieve even greater gains: experimental results with WARP software radios show improvements of 150%. Janus achieves these gains through three mechanisms: inexpensively maintaining real-time interference topology information, centralizing scheduling at access points to use this information while reducing control overhead, and an intelligent scheduling algorithm that maximizes full-duplex cooperations while simultaneously minimizing bitrate reductions from inter-client interference. The effectiveness of such a centralized media access protocol design suggests that full-duplex may benefit from revisiting and rethinking many long-held assumptions about wireless protocol design.

Keywords: Electrical Engineering.
Advisor: Levis Philip primary advisor. Thesis advisor
Gill John T.
Poon Ada Shuk Yan
Job-Lock and Health Insurance Premiums: Evidence from the Massachusetts Health Care Reform

In this paper, I use the 2006 Massachusetts state health care reform to analyze the effect of a change in the price of individual market insurance on job-lock. I find that lower individual market insurance premiums do not reduce job-lock at levels significantly different from zero. Previous studies of job-lock have not explicitly quantified the relationship between premium prices and job-lock for the aggregate working population. My findings suggest that the Patient Protection and Affordable Care Act of 2010, which is largely modeled after the Massachusetts reform, may have a smaller effect on job-lock than originally anticipated.

Keywords:  Department of Economics
Stanford Department of Economics
Labor mobility
turnover
health insurance
government policy
Thesis
Advisor: Pencavel John