VictorJuiz/thesis huggingface dataset:
Insights into NF-[kappa] B signaling from single-cell dynamics [electronic resource]
Keywords: Bioengineering.

The mammalian immune response is a striking example of many cells working in concert to produce a coherent, complex behavior. The first steps in the immune response are orchestrated by the innate immune system, and one particularly important protein is the transcription factor nuclear factor (NF)-[kappa] B. To better characterize the signaling events of innate immunity at the level at which they start, we have developed a platform to monitor the dynamics of NF-[kappa] B signaling in live, individual cells. This thesis presents three studies that use live-cell imaging, quantitative analysis, and computational modeling to reveal novel insights into how the NF-[kappa] B network functions. In the first study, we investigate how single mammalian cells respond to different concentrations of the signaling molecule tumor necrosis factor (TNF), and how they relay information to the gene expression programs by means of NF-[kappa] B. We find, in contrast to population-level studies, that the activation is heterogeneous and is a digital process at the single-cell level. Next, we focus on lipopolysaccharide (LPS), a molecule found in the outer membrane of gram-negative bacteria that strongly activates NF-[kappa] B. We find that different sources and preparations of LPS induce markedly different dynamics of NF-[kappa] B. Finally, studies of signal transduction often focus on how responses to stimuli differ, and yet the network's most essential dynamic features are probably invariant across stimuli. To identify invariant dynamic features in the NF-[kappa] B network, we treated cells with a broad panel of stimuli. Most properties of the dynamics varied with stimulus type or concentration, but one property had an invariant distribution: the period of NF-[kappa] B's oscillations between cytoplasm and nucleus. Contrary to existing theory of NF-[kappa] B dynamics, this invariance is only observed in the population; individual cells vary significantly. Overall, this work underscores the dynamic nature of biological systems, and highlights how quantitative measurements in single cells can advance our understanding of such systems.
Institutional change and entrepreneurship [electronic resource]
Keywords: Management Science and Engineering.

This dissertation examines the role that changes to the institutional environment play in the life cycle and performance of new ventures. I do so by taking advantage of three natural experiments that relate to key events in the life of a venture: founding, success, and failure. The first study, examines lowering the "barriers to success" of IPO reform. Then, the second study focuses on the "barriers to failure" with an examination of bankruptcy law reform. Finally, the third study analyzes the effects of changes to "barriers to entry" caused by a reduction of the capital requirements for founding a firm. Each study uses the empirical context of Japan in an era of reform. By developing new institutional theory constructs, I demonstrate that changes to the institutional environment have important effects on the types of firms that form, the individuals who start firms, and on new venture performance. In particular, the studies demonstrate important effects such that institutional changes that make success easier can have a negative effect on new firm performance but changes that ease bankruptcy can improve new venture performance. In addition, changes that lower the cost of starting a venture are resisted by technology firms and new firms with novel founders, but adopted by new firms in other industries. Importantly, the studies indicate that institutional changes have a heterogeneous effect on different types of individuals with important performance consequences. Thus, this work has implications for scholars and policymakers by demonstrating that policies for entrepreneurship should give more import to the quality rather than the quantity of entrepreneurs, to social mechanisms such as conformity and legitimacy that go beyond economic incentives, and to the second order effects of reforms not just their direct effects.
Instruments of religion and empire [electronic resource] : Spanish science in the age of the Jesuits, 1628-1756
Keywords: History.

Dissertation Abstract This dissertation explores the role of Jesuit mathematicians in the seventeenth century Spanish Monarchy through a series of case studies. From 1625 to 1750, the Society of Jesus acted as the primary source of mathematical pedagogy in the Spanish Monarchy through its network of missions and schools in Europe, the Americas and Asia. Jesuit teachers in Spain taught cosmography, navigation and military engineering to Spanish military and naval officers, while Jesuit missionaries led expeditions and established missions in the frontier areas of Spanish America. The title of this dissertation, "Instruments of Religion and Empire" refers to the dual role that the Jesuits played in the Spanish Monarchy during this period. This dissertation links scientific actors in the Spanish Monarchy to trends and ideas circulating elsewhere in Europe, therby undermining the idea that Spain was an intellectually isolated backwater. Additionally, it demonstrates the continuities between Jesuit mathematicians and missionaries and the subsequent Spanish Enlightenment.
Integration and deployment of thick film piezoelectric actuators/sensors on organic stretch[a]ble substrates [electronic resource]
Keywords: Aeronautics and Astronautics.

Ultrasonic sensing systems are widely used in various applications including inspection for structural safety and material characterization. Networks of micro scale ultrasonic actuators and sensors that could be deployed and integrated into structures conforming to complex shapes could potentially revolutionize how inspections are performed. Such systems could be used to interrogate the state of the host structure on demand and in real time. These systems could also enable a new class of multi-functional materials for various new applications, such as high performance flight of unmanned aerial vehicles or tactile sensing in prosthetic devices. This thesis presents a method to integrate networks of screen printed piezoceramic actuators/sensors with organic substrates enabling the networks to be stretched and deployed over areas an order of magnitude greater than the original coverage area and conform to complex shapes. This work required integration of screen printing with non-standard MEMS and C-MOS fabrication techniques to create complete systems consisting of screen printed piezoceramics, micro-scale wires, electrodes, spin coated organic films, etc. Many limitations were overcome in the process. For example, screen printed piezoceramics require high temperature processing, on the order of 1000 °C, and are attached to the substrates they are printed upon. This prevents direct fabrication of piezoceramics on organic substrates or transfer from a temporary substrate. The method presented here overcame these limitations by creating and processing the piezoelectric devices with electrodes and wiring on a high temperature substrate. Then, in a reversal of typical fabrication methods, the target organic substrate was deposited onto the piezoelectric devices. Finally, multiple layers were used to protect the system while the high temperature substrate was etched off, releasing the complete network of piezoceramics and wiring onto an organic film. This process also enabled the micro-fabrication of multiple layers of independent sensor systems on opposite sides of the same organic film. Prototypes of the devices were fabricated and tested to verify the functionality of the network both on contiguous organic films and on stretched networks covering large areas. The capabilities demonstrated in this work provide a foundation that can be adapted to create and deploy other ultrasonic devices, MEMS, and sensor systems on organic stretchable networks.
Interaction via limited feedback and coding [electronic resource]
Keywords: Electrical Engineering.

The integration of communication and control in modern networked systems calls for study of the connection between the two fields. In this thesis, we investigate two aspects of this connection: the use of feedback in communication systems and the notion of coding in decentralized control. While feedback is an essential part of most control systems, the use of feedback in communication systems is poorly understood; in theory the study of feedback is mostly limited to channels with ideal feedback, and in practice feedback is limited to sending channel state information or a few bits for acknowledgments. We will show how sending more feedback bits drastically reduces the error probability of a point-to-point communication system. Given an AWGN channel with rate-limited feedback, we show that the error exponent can jump from a finite value, in the absence of feedback, to infinity if and only if the feedback rate is not less than the data rate. Coding is an integral part of most communication systems. However, little is understood about the role of coding in decentralized control. We present a class of networked decision problems where agents use a simple coding mechanism to reach an optimal collective decision. The agent with the most information embeds its coded information in its action that is observed by other agents. This communication via action helps other agents improve their individual decisions and leads to an optimal total cost. We conclude the thesis by arguing that feedback and coding play key roles in networked systems as they enable interactive decision-making among agents. Such interaction allows agents (controllers, sensors, actuators, communicators) to optimally adapt to fundamental network/device/environmental limitations such as loss, delay and constrained energy.
Interactions and high dimensional data [electronic resource]
Keywords: Statistics.

To date, testing interactions in high dimensions has been a challenging task. In this manuscript we attack the problem of estimating and testing marginal interactions for binary response in high dimensions. We give a simple approach to testing using permutations that we show to be more robust, more parsimonious, and more powerful than existing alternatives. We also give a framework for classification that we show, in some cases, can significantly outperform more classical methods.
Interface electronics for emerging sensor systems [electronic resource]
Keywords: Electrical Engineering.

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.
Interframe compression of visual feature descriptors for mobile augmented reality [electronic resource]
Keywords: Electrical Engineering.

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.
The interpersonal costs of indulgence [electronic resource]
Keywords: Psychology.

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.
Intracortical neural interface systems [electronic resource]
Keywords: Electrical Engineering.

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.
Investigating the bachelor's degree pipeline [electronic resource] : three papers on college access and student success
Keywords: Education.

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.
Investigation of optical and electrical properties of metal-insulator-metal devices [electronic resource]
Keywords: Materials Science and Engineering.

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.