VictorJuiz/thesis huggingface dataset:
Engineering of light emission devices for integration on silicon [electronic resource]

Silicon (Si) compatible lasers for applications in inter die and intra die optical interconnect systems and spectroscopy system have been an interesting topic for several years, but has yet to be practically demonstrated. One possible candidate material of a light source for inter die and intra die optical interconnect systems is germanium. Germanium (Ge) is compatible with Si and has a direct band gap of 0.8 eV, corresponding to the usual communication wavelength of 1550 nm. The small difference of 0.134 eV between the direct and indirect band gaps of Ge suggests the possibility of a radiative direct band gap transition. In the first part of this work, we focus on improving different aspects of Ge to reach the goal of lasing with a low threshold. The first aspect is the activated n-type dopant concentration and crystal quality, which we improve through a novel method of laser annealing, microwave annealing and co-implantation of dopants. The second aspect is the increase in the concentration of electron density in the active region through implementation of a unique electrical device design, known here as a gated microdisk resonator. The third aspect is the improvement in optical property by reducing the radiative recombination in the indirect valley through the fabrication of a photonic crystal. For spectroscopy applications, one candidate is thulium (Tm). We can dope the dielectrics with Tm3+ ions and pumped it at 1570nm taking advantage of light sources already used in telecommunications. This laser can be tuned to lase in the range from 1650nm to 2000nm depending on the matrix and the pump. This wavelength range can also be used in (light detection and ranging) LIDAR systems, gas sensing systems, spectroscopy on a chip and even to extend the range of wavelengths for telecommunications. In this second part of the work, we demonstrate photoluminescence with Tm-doped dielectrics and also show a method to optimize the microdisks for lasing with Tm.

Keywords: Electrical Engineering.
Advisor: Nishi Yoshio
Saraswat Krishna advisor. Thesis advisor
Vuckovic Jelena advisor. Thesis advisor
Engineering the NK1 Fragment of the Human Hepatocyte Growth Factor for Dual Use as a Potent Agonist and a Gene Therapy Delivery Vehicle

Regenerative medicine and wound healing are critically relevant topics in the current medical field. Estimates have placed the total number of patients impacted with chronic wounds in the US at 6.5 million, resulting in an annual expenditure of US$25 billion. Furthermore, the regenerative medicine industry has taken off, reaching over US$3 billion in both gross annual spending and sales. Growth factor-based therapies for use in regenerative medicine have shown initial promise in pre-clinical testing, but numerous obstacles to effective delivery and translation of expected activity have limited growth factors’ clinical potential. Accordingly, growth factor engineering techniques have been developed and employed to improve clinically relevant characteristics such as stability, circulation time, expression yield, and delivery methods. However, as is often the case in clinical applications, extremely potent therapeutics must be engineered to enable significant impact. This study integrates design and delivery methodologies from the fields of gene therapy and supercharged protein engineering to investigate the potential for the NK1 fragment of HGF to serve as a dual-use exogenous mitogen and plasmid delivery agent. Successful internalization was shown and characterized in mammalian cell systems. Additionally, rational engineering of covalent dimerization via the introduction of an N-terminal cysteine residue enhanced mitogenic activity in a number of NK1 variants. Finally, initial evidence is put forth for the ability of NK1 variants to complex with DNA, a critical step in preparing nonviral protein-based delivery vehicles for gene therapy applications.

Keywords: NK1
HGF
growth factor engineering
protein engineering
supercharged proteins
gene delivery
wound healing
regenerative medicine
bioengineering
Thesis
Advisor: Cochran Jennifer
Liphardt Jan
Enhanced thermionic energy conversion with a graphene anode [electronic resource]

Thermionic energy converters (TECs) are a direct heat-to-electricity conversion technology with the potential to outperform the current state-of-the-art solid-state energy conversion technologies in a wide range of working temperatures. TECs could not only be applied to large-scale power plants in a tandem cycle, but could also be deployed in distributed power generation systems at small scales. In a TEC, electrons evaporate from a hot electrode (the cathode) into a vacuum gap and are collected by a cooler electrode (the anode) to generate electric energy. However, the published TECs suffer from low output voltage as well as low output current because the work function of the anode is too high and the space charge barrier in the inter-electrode is too strong, which ultimately lead to low conversion efficiency. In this thesis, I will first present a phenomenological model to calculate a material's work function. This model shows that graphene has great potential to yield an ultra-low work function. I will then experimentally demonstrate such a graphene anode in an ultra-high vacuum system. The graphene is grown on a piece of copper foil by chemical vapor deposition. It is then transferred onto a 20 nm thick HfO2 layer prepared by atomic layer deposition on silicon. After in-situ deposition of a monolayer of Cs/O, the work function of the graphene anode is dramatically reduced from 4.62 eV to 1.25 eV. Furthermore, I will show that electrostatic gating graphene through the HfO¬2 dielectric layer can further reduce the work function of graphene. Due to the absence of surface Fermi level pinning and low surface state density according to graphene's linear dispersion relation, the Fermi level of graphene can by effectively raised through a DC bias with negligible energy consumption. I will show that combining Cs/O surface coating and electrostatic gating would lead to a world-record low work function for graphene of 1.0 eV. Finally, I will demonstrate a TEC prototype based on this graphene anode, together with a commercial dispenser cathode. At the cathode working temperature of 1000 ˚C, the work functions of both of the electrodes are reduced by Ba. In addition, this TEC prototype deploys a nano-manipulator system that can reduce the inter-electrode gap to 17 μm, leading to a much reduced space charge barrier. By addressing the two challenges simultaneously, a low work function anode and minimizing the space charge barrier, the overall conversion efficiency of this TEC prototype is improved by a factor of over 50, with an estimated maximum electronic conversion efficiency of 9.8 %, which is the highest reported by far at this relatively low working temperature.

Keywords: Physics.
Advisor: Pianetta Piero primary advisor. Thesis advisor
Howe Roger Thomas advisor. Thesis advisor
Shen Zhi-Xun advisor. Thesis advisor
Entity resolution and tracking on social networks [electronic resource]

In this thesis we study two interesting aspects of the problem of Entity Resolution (ER). The goal of ER is to identify and merge records that refer to the same underlying entity. The recent rise in adoption of social networks (Facebook, Google+, Twitter, and others) introduces new issues and twists to the traditional ER problem: crowdsourcing and limited information. We first study a hybrid human-machine approach to solving ER problems. Machine learning models can predict the probabilities of entity pairs referring to the same entity. However, machines make mistakes. Humans can help verify the equality of entity pairs, and social systems like Facebook allow users to help resolve entities on their platforms. We propose hybrid human-machine strategies with theoretical guarantees that leverage transitivity relations (e.g. a = c can be inferred given a = b and b = c). Next, we study the problem of ER with limited information. Social systems impose limits on API calls that constrain access to their full social graphs. We focus on the resolution of a single node g from one social graph G against a second social graph T. We want to find the best match for g in T, by dynamically probing T (using a public API), limited by the number of API calls that these social systems allow. We propose two ER strategies that are designed for limited information and can be adapted to different API limits. Finally, we study the problem of updating social graph snapshots when one has limited information. Effective social network ER requires up-to-date snapshots. Limited by the number of API calls that social systems allow, we seek to efficiently update a snapshot. We want to avoid re-crawling all of the nodes and minimize the number of API calls. We propose novel snapshot update strategies that are designed for limited information and can be adapted to different levels of staleness.

Advisor: Garcia-Molina Hector primary advisor. Thesis advisor
Paepcke Andreas
Ré Christopher advisor. Thesis advisor
Equal opportunity for political influence in democratic problem-solving [electronic resource]

How can democratic governance both incorporate high-quality outcomes and preserve equality of status and voice in decision-making? This dissertation contributes to liberal democratic theory by examining democracy's ability to solve collective problems. Solving a collective problem well through majority rule requires identifying and weighting competent input more heavily. Constructive political inequality (CPI) is what I call the unequal political influence that is necessary to solve collective problems well. CPI and the disagreement about the best means to a solution are beneficial parts to solving collective problems, yet neither are well-accommodated in contemporary liberal democratic theory. The democratic problem-solving framework I develop here presents itself as a hybrid of the two prevailing approaches in liberal democratic theory: the aggregative conception developed by Schumpeter ([1942] 1962) and Riker (1982) on one hand, and deliberative democracy developed by Cohen (1989) and others on the other hand. Equal opportunity is often relied upon to govern political influence through persuasion, but existing accounts of the principle do not sufficiently distinguish equal opportunity from equality of outcomes, the role of individual choice to be politically influential, and a statistically equal chance for influence. I show that equal opportunity is different from its colloquial use as merely a principle of non-discrimination. An appropriately specified conception of equal opportunity yields a basis for non-discrimination as well as a basis of explicit discrimination. To show how this new conception of equal opportunity for political influence can be applied to actual electoral reform proposals, I examine the use of vouchers to fund elections and the use of mini-publics to influence public opinion. Equal opportunity for political influence, appropriately specified, contributes to a better theoretical framework to motivate each of these reform proposals.

Keywords: Political Science.
Advisor: Ober Josiah primary advisor. Thesis advisor
Cohen Joshua
Reich Rob advisor. Thesis advisor
Essays in applied economics [electronic resource]

The first chapter is co-authored with Kevin Hoan Nguyen. Changes in the technology format of popular music distribution are nothing new. Vinyl records and cassette tapes disappeared in the 1990s, CDs faded out in the 2000s, and digital downloads began their decline in the 2010s to make way for streaming subscriptions and on-demand radio. We use data from Billboard's Hot 100, a weekly ranking of the most popular songs in the United States, to investigate the impact of technology format changes on the popularity characteristics of these songs. We find that the transition from CD to digital impacts popularity characteristics significantly. The digital technology format reduces the cost of releasing a single, which allows established artists to crowd out the Hot 100 by virtue of their reputation. Faster feedback mechanisms lead to the emergence of "one-week wonders" -- i.e., songs charting on the Hot 100 for only a week before disappearing. Once a song manages to survive the initial vetting process, the digital format facilitates discovery and allows the song to remain popular for longer than previously possible. The second chapter is co-authored with Kevin Hoan Nguyen. We investigate the effect of the Australian Youth Participation in Education and Training Reform, an unusual policy implemented from 2003 to 2010. The reform introduced a new phase of compulsory participation, where students must either stay in school, take approved vocational courses, attend an apprenticeship, work full-time, or any combination of the above. We find that almost half of the students -- who would have left school early absent the compulsory participation phase -- undertake training, employment, or other courses, suggesting that the policy induces a different set of compliers compared to traditional compulsory schooling laws. Although there is considerable heterogeneity in the effects on education attainment by socio-economic status and gender, the reform raises the total years of schooling by 0.14 years and the high school attainment level by 5.8 percent. The reform significantly raises wages and income for the treated cohorts. The third chapter is co-authored with Petra Moser. Policy changes in 1996 and 2012 retroactively placed thousands of foreign compositions, such as Sergei Prokofiev's Peter and the Wolf, under copyright in the United States. Critics argue that long-lived copyright terms limit access to important compositions for all but the most affluent U.S. orchestras, but there is little systematic evidence. This paper examines repertoire data for U.S. symphonies between 1842 and 2012 to investigate the impact of copyright on the diffusion of classical music. We find that copyright is a key determinant of the types of music that U.S. orchestras play, and that copyright disproportionately impacts orchestras that are more budget-constrained. Repertoire data also indicate that a lack of copyright protection helped popularize Russian music in the United States.

Keywords: Economics.
Advisor: Moser Petra primary advisor. Thesis advisor
Bresnahan Timothy F. advisor. Thesis advisor
Wright Gavin
Essays in empirical economics [electronic resource]

This thesis studies a range of economic issues that arise due to incomplete information when utilizing discrete choice models for estimation. First, I study the efficiency and profitability of a range of pricing plans, within the context of a market that offers subscription services. Second, I study the impact of unobserved quality in the trade of goods, showing with simulations and data how enriching a model of trade by allowing for unobserved heterogeneity (with parametric or non-parametric assumptions) can generate predictions more in line with the observed data.

Keywords: Business.
Advisor: Benkard C. Lanier primary advisor. Thesis advisor
Reiss Peter
Yurukoglu Ali advisor. Thesis advisor
Essays in finance and macroeconomics [electronic resource]

This dissertation explores various issues in finance and macroeconomics. The first two chapters deal with the workings of the prime brokerage and repo markets, with a special emphasis on the relationship between broker-dealers and hedge funds through collateral re-use in particular. The last chapter, co-authored with Daniel Garcia-Macia, deals with the impact of energy transitions on economic growth with a focus on the Industrial Revolution in the United Kingdom and has potential implications for the energy transitions in general. In the first chapter, I analyze the relationship between prime brokers and hedge funds. Prime brokers and hedge funds form relationships in a matching market. In particular, the research questions are: What are the determinants of these matches? How did they change after the financial crisis? I estimate a matching model in which part of the profits of prime brokers and hedge funds depends on variables that are defined at the level of the entire portfolio of clients that a prime broker serves. I show that prime brokers and their client hedge funds choose to have trading relationships with each other in a manner that reflects the benefits of specialization. Moreover, prime brokers preferred risky clients before the crisis, while they were averse to risky clients after the crisis. Identification follows from pairwise matching stability. I analyze the potential underlying economic mechanisms, mainly the cost advantages to a prime broker of collateral re-use between hedge fund clients. This is known as internalization. I estimate that the value of internalization for major prime brokers, such as Goldman Sachs, is around \

Keywords: Economics.
Advisor: Kurlat Pablo
Duffie Darrell advisor. Thesis advisor
Krishnamurthy Arvind advisor. Thesis advisor
Essays in financial economics [electronic resource]

This thesis studies how information affects trading and firm investment. In the first chapter I examine the conditions for the no-trade theorem to hold in multiperiod consumption settings and show it no longer holds in many reasonable scenarios. In situations where agents have different concerns for intertemporal substitution, information-based trade can be mutually acceptable because it enables agents to readjust their consumption profiles based on future consumption shocks. I show that the existing literature that finds no-trade results in various multiperiod consumption settings crucially depends on specific preference assumptions that lead to risk aversion dominating concerns for intertemporal substitution. The no-trade theorem fails to hold when a wider range of utility functions with a more important role for intertemporal substitution are considered. Chapter 2 presents quantitative analysis on the intertemporal substitution as a rational channel to generate trading. Intertemporal substitution bridges information-based trading and consumption-based asset pricing. Consumption-based asset pricing models are natural candidates to analyze information-based trading, and information-based trading affects the volatility of individual consumption processes. Quantitative analysis demonstrates that besides asset pricing implications, information-based trading related to intertemporal consumption smoothing can also explain a significant part of the trading volume observed in financial markets. Finally, Chapter 3 studies how a firm's growth is affected by the evolution of its external debt financing environment. Asymmetric information about the qualities of projects the firm can undertake makes external financing costly. Collateral can mitigate this problem, but its availability is limited by the size of the firm. As a firm grows, more collateral becomes available, broadening the firm's access to external debt financing channels and lowering its cost of capital. The firm's growth decision is affected by how effective additional collateral can be in lowering its cost of capital and the amount of assets it needs to accumulate to broaden its access to potential lending channels. A small firm may optimally choose to stay small when it is financially constrained and far from the size necessary to have access to formal lending. When the size of a small firm approaches the level needed to have access to formal lending there arises a strong incentive to expand, making the firm locally risk loving. The framework I study also raises some questions about the frequent use of a firm's growth rate as an empirical proxy for firm value. I show that a high growth rate is not necessarily associated with high firm value.

Keywords: Business.
Advisor: DeMarzo Peter M. primary advisor. Thesis advisor
Pfleiderer Paul primary advisor. Thesis advisor
Breon-Drish Bradyn
McQuade Tim
Essays in financial economics [electronic resource]

This thesis studies how credit market frictions affect debt pricing and the behavior of borrowers and lenders. In the first chapter, I study the matching of corporate borrowers with banks and the implications of endogenous matching for credit provision. I find that bank-dependent firms borrow from well capitalized banks, while firms with access to the bond market borrow from banks with less capital. This matching improves access to credit during a crisis by pairing bank-dependent firms with stable banks. During the 2008 Financial Crisis, bank-dependent borrowers faced significantly greater loan supply from their relationship banks than they would have without this matching. In the second chapter, I investigate the pricing of bonds issued by states and local governments. I use three distinct, complementary approaches to decompose municipal bond spreads into default and liquidity components, finding that default risk accounts for 74% to 84% of the average municipal bond spread after adjusting for tax-exempt status. The price of default risk is high given the rare incidence of municipal default and implies a high risk premium. In the third chapter, I explore the nature of corporate capital structure adjustments. The third chapter is coauthored with Arthur Korteweg, a professor at the University of Southern California, and Ilya A. Strebulaev, my principal adviser. We show that the frequency of capital structure adjustment varies significantly across firms. Using new hand-collected data from detailed corporate filings, we find that frequently refinancing firms tend to use lines of credit, which have minimal adjustment costs, to fund operating losses and working capital needs. In contrast, infrequently refinancing firms use long-term debt and equity, which have higher issuance costs, to fund investment and rebalance capital structure. Our findings suggest that adjustment costs are an important determinant of firms' financing choices.

Keywords: Business.
Advisor: Strebulaev I. A. (Ilʹi͡a Alekseevich) primary advisor. Thesis advisor
Bernstein Shai
Duffie Darrell advisor. Thesis advisor
Essays in microeconomics [electronic resource]

This dissertation theoretically analyzes how competition among firms affects their strategic choice of information provision, which is particularly important for internet businesses. The first chapter is motivated by crowd-sourced recommender platforms that organize social learning about ``experience goods'' by recommending items based on information collected from previous users. In order to balance making good recommendations and collecting information about new products, platforms ``experiment'' with products. This chapter studies how market structure affects experimentation over the life cycle of a product. Chapter two is inspired by targeting in internet advertising auctions, in which publishers decide how much information about user characteristics to reveal to advertisers. Revealing information increases efficiency, yet a monopolistic seller may prefer to hide information. When sellers are competing for potential bidders, a policy of providing more information can be a means of attracting bidders. This chapter investigates how the intensity of competition among sellers affects their incentives to reveal horizontal information.

Keywords: Business.
Advisor: Bulow Jeremy primary advisor. Thesis advisor
Skrzypacz Andrzej
Lambert Nicolas