VictorJuiz/thesis huggingface dataset:
Network effects in alternative fuel adoption [electronic resource] : empirical analysis of the market for ethanol

This paper investigates the importance of network effects in the demand for ethanol-compatible vehicles and the supply of ethanol fuel retailers. An indirect network effect, or positive feedback loop, arises in this context due to spatially-dependent complementarities in the availability of ethanol fuel and the installed base of ethanol-compatible vehicles. Marketers and social planners are interested in whether these effects exist, and if so, how policy might accelerate adoption of the ethanol fuel standard within a targeted population. To measure these feedback effects, I develop an econometric framework that considers the simultaneous determination of ethanol-compatible vehicle demand and ethanol fuel supply in local markets. The demand-side of the model considers the automobile purchase decisions of consumers and fleet operators, and the supply-side model considers the ethanol market entry decisions of competing fuel retailers. I propose new estimators that address the endogeneity induced by the co-determination of alternative fuel vehicle demand and alternative fuel supply. I estimate the model using zip code level panel data from six states over a six year period. I find the network effect to be highly significant, both statistically and economically. Under typical market conditions, entry of an additional ethanol fuel retailer leads to a 12% increase in consumer demand for ethanol-compatible vehicles. The entry model estimates imply that a monopolist requires a local installed base of at least 204 ethanol-compatible vehicles to be profitable. As an application, I demonstrate how the model estimates can inform the promotional strategy of a vehicle manufacturer. Counterfactual simulations indicate that subsidizing fuel retailers to offer ethanol can be an effective policy to indirectly increase ethanol-compatible vehicle sales.

Keywords: Business.
Advisor: Hartmann Wesley R. (Wesley Robert)
Nair Harikesh S. (Harikesh Sasikumar)
Hong Han advisor. Thesis advisor
Reiss Peter C. (Peter Clemens) advisor. Thesis advisor
Network effects in alternative fuel adoption [electronic resource] : empirical analysis of the market for ethanol

This paper investigates the importance of network effects in the demand for ethanol-compatible vehicles and the supply of ethanol fuel retailers. An indirect network effect, or positive feedback loop, arises in this context due to spatially-dependent complementarities in the availability of ethanol fuel and the installed base of ethanol-compatible vehicles. Marketers and social planners are interested in whether these effects exist, and if so, how policy might accelerate adoption of the ethanol fuel standard within a targeted population. To measure these feedback effects, I develop an econometric framework that considers the simultaneous determination of ethanol-compatible vehicle demand and ethanol fuel supply in local markets. The demand-side of the model considers the automobile purchase decisions of consumers and fleet operators, and the supply-side model considers the ethanol market entry decisions of competing fuel retailers. I propose new estimators that address the endogeneity induced by the co-determination of alternative fuel vehicle demand and alternative fuel supply. I estimate the model using zip code level panel data from six states over a six year period. I find the network effect to be highly significant, both statistically and economically. Under typical market conditions, entry of an additional ethanol fuel retailer leads to a 12% increase in consumer demand for ethanol-compatible vehicles. The entry model estimates imply that a monopolist requires a local installed base of at least 204 ethanol-compatible vehicles to be profitable. As an application, I demonstrate how the model estimates can inform the promotional strategy of a vehicle manufacturer. Counterfactual simulations indicate that subsidizing fuel retailers to offer ethanol can be an effective policy to indirectly increase ethanol-compatible vehicle sales.

Advisor: Hartmann Wesley R. (Wesley Robert)
Nair Harikesh S. (Harikesh Sasikumar)
Hong Han advisor. Thesis advisor
Reiss Peter advisor. Thesis advisor
Network services [electronic resource] : congestion, investment, and contracting

This thesis addresses aspects of a problem at the core of information technology: how does congestion management influence the outcome of interactions between providers of services on networks and users of those services? The mitigation and management of congestion, whether through an application of or investment in technology, is an essential task for any large or growing service provider. The particular way in which congestion is managed can have surprising effects both on the health of a network and the economics of service provision. We make two main contributions. First, we explore the interaction between content distribution and traffic engineering. We use a game-theoretic framework in which users of a network select the source of content, and the traffic engineer decides how the traffic will route through the network. Second, we analyze the impact of contractual structure on market outcomes in service industries. Our results highlight how different contractual agreements change the intensity of price competition in service industries; broadly speaking, we show that competition is intensified when firms choose to offer congestion level guarantees.

Keywords: Management Science and Engineering
Advisor: Johari Ramesh
Saberi Amin advisor. Thesis advisor
Van Roy Benjamin advisor. Thesis advisor
The network structures of corrupt innovations [electronic resource] : the case of Enron

The focus of this dissertation is the interplay of information and social network structure. I investigate how different types of information influence how individuals choose to communicate, and the implications of these choices on the entire social system. In particular, I look at how both overt and covert information is shared across an organization's communication network over a four-year period. The contrast between overt and covert activities affords the opportunity to examine whether different content types change the way individuals mobilize to accomplish goals within an organization. First, I analyze how different social network positions allow individuals to obtain different types of information within an organization's network. I demonstrate that individuals are more likely to participate in an overt communication network when they have large but sparse networks of informal ties through which to acquire information. This finding is contrasted with covert network involvement, where greater closeness centrality or shorter distances to other organizational members predicts participation. Second, the examination of individuals who participated in both covert and overt information networks highlights the divergent behaviors associated with the two activities. When sharing overt information, individuals are more likely to encourage network cohesion, practice structural egalitarianism, and engage in reciprocal communication. In contrast, when actors share covert information, they attempt to reduce network cohesion and reciprocity and foster a power structure. Finally, I present results that show the aggregate network effects of individual strategies for sharing either overt or covert information. I find that communication within overt networks is far more reciprocal than communication in covert networks, where information flow is asymmetrical. This study uses longitudinal email data taken from Enron Corporation between 1998 and 2002; these data provide a unique opportunity to study the communication network of the firm's employees and analyze the messages shared between employees. In contrast to previous studies, which assume transmission of information along network ties, this dataset allows for actual observation of information transfer between organizational members. I couple social network analysis and qualitative coding to explore how the content of information affects both communication patterns and the spread of information.

Keywords: Sociology.
Advisor: Powell Walter W. primary advisor. Thesis advisor
Cook Karen S. advisor. Thesis advisor
Granovetter Mark S. advisor. Thesis advisor
Neural mechanisms of visual and auditory attention [electronic resource]

Attention involves selecting the most relevant information from the abundance of information available in the sensory environment. When we attend to an object, neurons in the brain become more selective to processing information about the attended object at the expense of processing information about other, irrelevant objects. While the phenomenology of attention is well characterized, little is known about the mechanisms by which attention modulates neural responses to influence perception. In this thesis, I explore neural mechanisms of attention with a combination of approaches at several levels: 1) whole-brain functional imaging to characterize the spatiotemporal dynamics of forebrain networks that are engaged during attention, 2) extracellular electrophysiology in the midbrain of tranquilized barn owls to measure and characterize gamma oscillations, a prominent neural signature of attention, and 3) pharmacological techniques in a chick midbrain slice preparation to understand the cellular and circuit mechanisms involved in generating and regulating the structure of these oscillations. I conclude by describing ongoing work on developing neuromorphic (hardware) models of putative mechanisms of attention, as well as the development of a novel behavioral paradigm for rapidly and reliably measuring attention in birds. This work highlights the power of integrative and multi-level approaches for exploring the neural basis of cognitive functions, such as attention.

Advisor: Knudsen Eric I.
Boahen Kwabena (Kwabena Adu) advisor. Thesis advisor
Shenoy Krishna V. (Krishna Vaughn) advisor. Thesis advisor
Wandell Brian A. advisor. Thesis advisor
NMR spectroscopy for structural and dynamic studies of the beta2-adrenergic receptor [electronic resource]

G protein coupled receptors (GPCRs) are seven transmembrane proteins that are expressed in all eukaryotic cells and tissues. These receptors play key roles in human physiology and disease. The goal of my work is to understand the molecular detail of ligand recognition by GPCRs, and how this process leads to conformational changes that manifest as cellular signaling. Meeting this goal will advance our knowledge of membrane protein biology. It will also reveal structural targets and physicochemical logic to aid pharmaceutical design. The age of GPCR structural biology recently arrived with the first x-ray structures of rhodopsin and the beta2 adrenergic receptor (beta2AR). However, membrane proteins are constantly fluctuating entities. Dynamic behavior is intrinsic to their function. As such, static x-ray structures alone are inadequate. Herein, I develop biophysical techniques to study these dynamic receptors. Using NMR spectroscopy, I characterize conformational changes in the extracellular region of the beta2AR, a surface rich with potential for drug design. I also explore the signaling properties of monomeric GPCRs and conformational changes of other macromolecules using single-molecule fluorescence. While many questions about GPCRs remain, I hope this work is a small step towards understanding these important, fascinating, and beautiful molecules.

Keywords: Biophysics.
Advisor: Kobilka Brian K. primary advisor. Thesis advisor
Maduke Merritt C.
Puglisi Joseph D. advisor. Thesis advisor
Weis William I. advisor. Thesis advisor
Nonlocal modulation and dispersion [electronic resource]

Quantum entanglement has been the subject of a growing field in quantum optics that aims to study the physical properties of entangled systems and find new applications for their use. Entangled photons have been proposed as a means to achieve long distance quantum communications and cryptography, perform computational tasks beyond the capabilities of classical computers, image beyond the classical limit, and provide measurement sensitivities unobtainable with analogous classical light sources. At the heart of these applications is the fact that entangled photons behave strikingly different from classical light or even pairs of independent single photons. This thesis reviews an interference effect known as nonlocal cancellation of dispersion and proposes and demonstrates a new, analogous effect which we term as nonlocal modulation. These techniques allow one to undo the effect of one dispersive medium or phase modulator with a similar system at a distant point in space, as observed by correlations between entangled photons. We explore the use of nonlocal dispersion compensation, combined with chirped quasi-phase-matched nonlinear crystals, to generate ultrashort entangled photons with high generation rates. To aid in the measurement of ultrashort entangled photons, we propose and demonstrate a resonance technique to increase the sensitivity of ultrafast sum-frequency-generation correlators. Principal accomplishments of this work include: the first observation of nonlocal modulation, the first observation of the radar-like "chirp and compress" technique with entangled photons, and the first experimental demonstration of resonant sum frequency generation using broadband biphotons.

Keywords: Electrical Engineering
Advisor: Fejer Martin M. (Martin Michael) primary advisor. Thesis advisor
Harris S. E. (Stephen Ernest)
Vuckovic Jelena advisor. Thesis advisor
A non-negative framework for joint modeling of spectral structure and temporal dynamics in sound mixtures [electronic resource]

Statistical modeling of audio is an ongoing pursuit. There is a great deal of structure in audio and good models need to make use of this structure. Audio is non-stationary but the statistics of the spectral structure are quite consistent over segments of time. Moreover, there is a structure to the non-stationarity itself in the form of temporal dynamics. Sound mixtures are commonly encountered in practice. Polyphonic music, multiple concurrent speakers, and most environmental sounds are mixtures. Moreover, most real world sound sources are actually a mixture of the source and noise. When dealing with mixtures, the structure of the individual sources becomes particularly important if we wish deal with the sources separately. In recent years, non-negative spectrogram factorization methods have become quite popular for modeling audio as they provide a rich representation of audio spectra and are amenable to high quality reconstructions. However, they disregard non-stationarity as they use a single dictionary to characterize the statistics of the spectral structure of an entire source. On the other hand, hidden Markov models (HMMs) cater well to non-stationarity and have been used successfully to model temporal dynamics. They can be powerful for audio analysis, as shown by their application to speech recognition. They can also be used for the reconstruction of sources but have certain limitations due to a rigid observation model. This can be an issue for high quality reconstructions. We propose a new model of single sound sources, the non-negative hidden Markov model (N-HMM), that jointly models the spectral structure and temporal dynamics of a given source. In the proposed model, rather than learning a single dictionary, we learn several small dictionaries that characterize the spectral structure of the source, catering well to non-stationarity. Moreover, we jointly learn a Markov chain that characterizes the temporal dynamics of the source. This is done with a flexible observation model that allows high quality reconstructions. We demonstrate this model on content-aware audio processing. We then propose a new model of sound mixtures, the non-negative factorial hidden Markov model (N-FHMM), that combines models of individual sources. This model incorporates the spectral structure and temporal dynamics of each individual source. We demonstrate the model on single channel source separation and show that it yields superior performance to non-negative spectrogram factorization. Although it is demonstrated on source separation, the N-FHMM is a general model of sound mixtures and can be used for various applications.

Keywords: Music
Advisor: Smith Julius O. (Julius Orion) primary advisor. Thesis advisor
Slaney Malcolm advisor. Thesis advisor
Smaragdis Paris advisor. Thesis advisor
Tibshirani Robert advisor. Thesis advisor
Novel capacitorless single-transistor DRAM technologies [electronic resource]

The dynamic random access memory (DRAM) industry has achieved miracles packing more and more memory bits onto ever smaller silicon die. But, the scaling of the conventional 1Transistor/1Capacitor (1T/1C) DRAM is becoming increasingly difficult, in particular due to the capacitor which has become harder to scale, as device geometries shrink. Recently the capacitorless single-transistor (1T) DRAMs have attracted attention, due to its ability to achieve higher memory cell density and to solve the problems associated with the scaling of the capacitor. The information is stored as different charge levels at a capacitor in conventional 1T/1C DRAM, whereas the 1T DRAM employs floating body effects within the transistor to store the information without the need of the capacitor. The absence of the capacitor is advantageous in terms of scalability, process and fabrication complexity, and compatibility with the logic processing steps, device density, yield and cost. Due to all these advantages of the capacitorless DRAM, and to solve the scaling problem of conventional 1T/1C DRAM, this work is focused on creating novel single transistor DRAM technologies. . The first device that is studied is vertical double-gate (DG) capacitorless single-transistor DRAM. This device has advantages of being vertical with a small footprint, it can be integrated on bulk Si and being a double-gate device allows better electrostatic control of the channel and higher intrinsic device retention. The second device that is investigated is a novel DRAM device: capacitorless single-transistor quantum well DRAM, which employs energy-band engineering approach within the body of the transistor in order to create a "hole storage pocket" and "carrier distribution control layer" which results in superior device characteristics in terms of scalability and memory sensing window. The third and the final device that is studied is also a novel DRAM device: capacitorless single-transistor charge trap DRAM. The body of this device is engineered with the intentional charge traps so as to obtain a memory effect. This novel DRAM relies on the existence and absence of electrons within its body and uses a charge-trapping mechanism in its memory operation, unlike conventional 1T DRAMs that rely on holes and employ floating-body effects in their memory operation.

Keywords: Electrical Engineering
Advisor: Saraswat Krishna primary advisor. Thesis advisor
Nishi Yoshio
Wong Hon-Sum Philip
On ion probes and traps, barium tagging for the EXO double beta decay detector [electronic resource]

The Enriched Xenon Observatory seeks to measure neutrino mass through observation of neutrinoless double beta decay. A new generation of ton-scale experiments are being developed, which aim to probe neutrinoless double beta decay half-lives on the order of 10^27 - 10^28 years. The keys to reaching these sensitivities are large source mass and reduction of radioactive backgrounds; this thesis details efforts to develop a system for tagging the 136-Ba+ daughter of the double beta decay of 136-Xe, for the purposes of background elimination in a large experiment.

Keywords: Physics
Advisor: Gratta Giorgio primary advisor. Thesis advisor
DeVoe Ralph advisor. Thesis advisor
Kasevich Mark A. advisor. Thesis advisor
On the emission of gamma rays by young pulsars [electronic resource]

The gamma-ray emission from young rotation-powered pulsars has been studied in detail. The antenna patterns of emission are calculated for a variety of geometric emission models. These antenna patterns vary with magnetic inclination and spindown power; correspondingly, libraries of emission patterns are calculated across the phase space of possible parameter combinations. These libraries allow one to explore the possible gamma-ray light curves under a given model, for a given set of input parameters. A method of quantitative comparison was developed to allow the determination of a goodness-of-fit between an observed pulsar light curve and all of the possible simulated light curves for a given model. This method can localize the region of input parameter space that produces a model's best fit to an observed light curve. This can then be compared to external constraints on input parameters, often supplied by observations at other wavelengths (i.e., radio polarization and x-ray morphology). Finally, a simulation is run to reproduce the Galactic young pulsar population as faithfully as possible. Onto this population we apply the antenna patterns of various models in order to study the properties of the young gamma-ray pulsar population as a whole, constraining properties of the objects and evaluating the ability of the geometric gamma-ray models to reproduce the population-wide distributions of observables.

Keywords: Physics
Advisor: Romani Roger W. (Roger William) primary advisor. Thesis advisor
Kuo Chao-Lin (Physics professor) advisor. Thesis advisor
Michelson Peter F. advisor. Thesis advisor
Optical microendoscopy for imaging cells lying deep within live tissue [electronic resource]

Optical microendoscopy is an emerging modality for imaging in live subjects. Using gradient refractive index (GRIN) microlenses, microendoscopy enables subcellular-resolution imaging in deep tissues that are inaccessible by traditional imaging techniques. We present a platform of methods and technologies that build upon GRIN microendoscopy: 1) miniaturized microscopes for imaging in awake, behaving animals, 2) methods for imaging contractile dynamics in the muscles of animal and human subjects, 3) chronic brain preparations that allow for longitudinal examinations of subcellular neuronal features and disease progression, and 4) novel microendoscope probes whose imaging capabilities approach that of standard water-immersion microscope objectives. When combined with the broad sets of available fluorescent reporters, and minimally invasive surgical preparations, the work described in this dissertation enables sophisticated experimental designs for probing how cellular char- acteristics may underlie or explain behavior, in models of both healthy and diseased states.

Keywords: Biophysics.
Advisor: Schnitzer Mark Jacob
Deisseroth Karl
Delp Scott
Smith Stephen J.