VictorJuiz/thesis huggingface dataset:
Energy cost minimization and network management for data centers [electronic resource]
Keywords: Electrical Engineering.

Cloud-computing services are becoming integral part of our daily life. These services are supported by a type of computer system known as data center. As the demand for cloud-computing services soars, data centers are growing into massive-scale infrastructure of computational power, storage, and applications. Nowadays moderate-sized production data centers for enterprises typically comprise hundreds of thousands of servers, and consume tens of mega-watts of power to run and cool the equipment. Operating ever-growing data centers incurs soaring energy cost. Moreover, the sheer number of servers and networking devices in data centers presents a serious challenge to data-center network management. In this thesis, we are interested in problems on energy cost minimization and network management for data centers. The first part of the thesis concerns energy cost minimization for data centers. We present two workload scheduling methods for data-center energy cost minimization. The first is the temporal workload scheduling method for one data center. This method exploits the temporal variety of electricity price, and dynamically schedules user requests to execute in the time domain while guaranteeing a strict service delay bound for user requests. The second is the spatio-temporal workload scheduling method for distributed data centers in geographically separate regions. This method exploits both the spatial and temporal variety of electricity price, and dynamically schedules user requests to execute in both the space and time domain while guaranteeing a strict service delay bound for user requests. Evaluation experiments demonstrate that these two methods significantly reduce energy cost for one data center and distributed data centers respectively. The second part of the thesis concerns network management for data centers. An architecture named Ethane was recently proposed to manage enterprise networks, and data-center networks in particular. Ethane requires flow-based Ethane switches. One premise is that Ethane switches can be much simpler than conventional switches and routers. We build Ethane switches on the NetFPGA platform and install them as part of the Ethane-controlled prototype network deployed at Stanford University. Our experiments demonstrate that simple Ethane switches are sufficient to support the Ethane architecture for network management. In Ethane and other network management frameworks, statistics components are indispensable. An architecture named Counter Braids was recently proposed for network statistics. One premise of Counter Braids is that the hardware implementation of Counter Braids consumes little circuitry and supports fast counter-updating. We build a Counter Braids prototype on the NetFPGA platform and perform comprehensive tests. Our experiments demonstrate that Counter Braids uses a modest amount of resource; and the NetFPGA-based Counter Braids prototype easily gathers network statistics for an aggregate network throughput of 4 Gbps.
Energy stable high-order methods for simulating unsteady, viscous, compressible flows on unstructured grids [electronic resource]
Keywords: Aeronautics and Astronautics.

High-order methods have the potential to dramatically improve the accuracy and efficiency of flow simulations in the field of computational fluid dynamics (CFD). However, there remain questions regarding the stability and robustness of high-order methods for practical problems on unstructured triangular and tetrahedral grids. In this work, a new class of 'energy stable' high-order methods is identified. This class of schemes (referred to as the 'Energy Stable Flux Reconstruction' class of schemes) is proven to be stable for linear advection-diffusion problems, for all orders of accuracy on unstructured triangular grids in 2D and unstructured tetrahedral grids in 3D. Furthermore, this class of schemes is shown to be capable of recovering the well-known collocation-based nodal discontinuous Galerkin scheme, along with new schemes that possess explicit time-step limits which are (in some cases) more than 2x larger than those of the discontinuous Galerkin scheme. In addition, the stability of the Energy Stable Flux Reconstruction schemes is examined for nonlinear problems, and it is shown that stability depends on the degree of nonlinearity in the flux and on the placement of solution and flux points in each element. In particular, it is shown that choosing the solution and flux point locations to coincide with the locations of quadrature points promotes nonlinear stability by minimizing (or eliminating) nonlinear aliasing errors. A new class of symmetric quadrature points is identified on triangles and tetrahedra for this purpose. Finally, the Energy Stable Flux Reconstruction schemes and the new quadrature points are applied to several nonlinear problems with the aim of assessing how well the schemes perform in practice.
Engineering bacterial populations via DNA messaging [electronic resource]
Keywords: Bioengineering.

Evolution has selected for organisms that benefit from genetically encoded cell-cell communication. We observe cell-cell communication throughout every scale in nature, from simple single-celled bacteria to complex multicellular mammals. Engineers have begun to repurpose elements of natural communication systems to coordinate their own population-level behaviors, including oscillations and programmed pattern formation. Existing engineered systems, however, rely on small, system-specific biomolecules to send messages among cells. However, such molecules are capable of sending only a single message, typically ``regulate transcription.'' Thus, the information transmission capacity of such biological communication systems is fundamentally limited. Through this thesis, I demonstrated the decoupling of messages from a common communication channel via the autonomous transmission of numerous arbitrary genetic messages. To do so, I engineered a cell-cell communication platform using bacteriophage M13 gene products to autonomously package and deliver heterologous DNA messages of varying lengths and encoded functions. Further, I increased the range of engineered DNA messaging across semisolid media by coupling message transmission or receipt to active cellular chemotaxis. Through this coupling, I demonstrated that our system is adaptable to different contexts by creating simple patterns. Finally, using recombinase-mediated logic gates developed within the Endy laboratory, I demonstrated the ability to program bacteria by transmitting logic gates to surrounding cells. Overall, this work significantly enhances the suite of cell-cell communication tools available to engineers. I have shown that a variety of DNA messages can be transmitted among cells and have moved the field of synthetic biology closer to designing synthetic ecologies with more complex communication schemes and varied behaviors.
Engineering quantum systems with coherent feedback control [electronic resource]
Keywords: Applied Physics.

The control of quantum dynamics in which feedback is accomplished via coherent, all-optical signal processing suggests the possibility of mature, engineered quantum systems that are technologically homogeneous and in which both plant and controller are quantum systems. In this thesis, I give a focused case study of several systems in which feedback control of the system dynamics is accomplished entirely through field-mediated, coherent signal processing. I describe some recently developed theoretical tools for modeling individual and networks of open quantum systems, and analyze the applications of coherent quantum feedback to squeezed-light generation and quantum error correction.
Entropy, stress, and collapse [electronic resource] : mechanics of the gram-positive bacterial cell envelope
Keywords: Microbiology and Immunology.

This thesis examines three topics that are related to the Gram-positive bacterial cell envelope. First, I examine how transmembrane proteins navigate through the thick, heavily cross-linked Gram-positive cell wall while remaining anchored to the bacterial membrane. I develop a theoretical model that predicts that entropic confinement of a disordered protein can drive translocation through the cell wall. I experimentally test important predictions of the model to demonstrate that translocation depends on the length of the translocating protein and the geometry of the bacterial surface, while demonstrating that entropy-driven translocation occurs in a variety of Gram-positive species. Second, I study how the antimicrobial peptide nisin causes cell death in Gram-positive bacteria. I demonstrate that nisin treatment triggers membrane collapse in multiple Gram-positive species, and provide evidence that collapse is initiated by an increase in compressive stress in the membrane. Finally, I examine the process of cell division in the Gram-positive coccus Staphylococcus aureus. Contrary to the current view of S. aureus division, cell volume increases monotonically during the cell cycle, as opposed to occurring entirely during cell separation. I observed a dramatic millisecond hemisphere-to-sphere transition during cell separation that was accompanied by a decrease in surface area, suggesting that separation is associated with a redistribution of cell wall stress.
Epigenetic and transcriptional control of the Caulobacter cell cycle [electronic resource]
Keywords: Chemistry.

In order for a cell to propagate, numerous events must be coordinated spatially and temporally within the cell. Caulobacter crescentus, an [alpha]-proteobacterium that divides asymmetrically, employs many layers of control such as phospho-relay systems, protein localization, targeted proteolysis, epigenetic regulation, and transcriptional regulation to achieve this spatial and temporal coordination over its cell cycle. This work focuses on two of these layers: the epigenetic role of the CcrM DNA methyltransferase and the regulatory roles of the GcrA and SciP transcription factors. The timing of transcriptional activation of at least four essential Caulobacter genes is affected by the methylation state of GANTC sites in their promoters. To explore the global scope of this regulatory mechanism, we determined the methylation state of the entire genome over the cell cycle (Chapter 2). This led to the identification of four novel methylation motifs in addition to the previously characterized CcrM methyltransferase motif. Only the GANTC motif which is methylated by CcrM exhibited a dynamic methylation pattern, shifting from fully methylated to hemi-methylated concomitant with replication fork passage. Using these cell cycle-dependent methylation profiles of GANTC sites as well as gene expression data from synchronized cell populations, we identified candidate genes whose transcription might be affected by the methylation state of their promoters. In addition, 27 GANTC sites were found to be unmethylated throughout the cell cycle. In Chapter 3, we used DNA footprinting to show that the GcrA transcription factor contains an N-terminal helix-turn-helix domain that binds DNA between the -10 and -35 promoter elements of three genes: podJ, parE, and ctrA. Each of the three footprinted regions contains a GANTC methylation site. Furthermore, we demonstrated through ChIP-qPCR that GcrA binds these sites in vivo. Mutations in these GcrA-binding regions reduced promoter activity, indicating that GcrA binding at these sites is important for activity. Finally, in Chapter 4, we identified a novel set of signaling pathways in the cell cycle network established by the SciP transcription factor, and we show that SciP binds DNA and identified its binding motif. At least 58 genes are in the SciP regulon, including many flagellar and chemotaxis genes. The SciP transcription factor functions to repress ctrA and CtrA target genes, restricting the expression of these genes to a precise time in the cell cycle when CtrA is available but SciP is not, and thus enhances the robustness of the Caulobacter cell cycle. This work expands our understanding of the master regulatory network that is involved in controlling the Caulobacter cell cycle. In addition, it describes the global methylation state of each base in the chromosome as a function of the cell cycle which will facilitate the discovery of novel methylation-mediated regulatory mechanisms in Caulobacter.
Escaping the double bind [electronic resource] : self-reliance is a distinct and positive form of agency for women in organizations
Keywords: Business.

Four experiments test the idea that self-reliance is a functional form of agency for women in organizations. Drawing on theories of interpersonal perception and group based stereotypes, this paper suggests that women face backlash for displaying agency related to competition and hierarchy (e.g., dominance), but not for displaying agency unrelated to competition and hierarchy (e.g., self-reliance). This is because only displays of the former evoke negative assessments of women's trustworthiness. Participants judged male and female targets to be similarly competent when they displayed high levels of either self-reliance or dominance (Studies 1-4). But, whereas they judged male targets to be similarly trustworthy regardless of the type of agency they displayed, they judged female targets to be more trustworthy when they displayed self-reliance than when they displayed dominance (Studies 1-4). Consequently, participants were more likely to hire (Study 2), to vote for (Study 3), and to invest in the company of (Study 4) a woman when she displayed self-reliance than they were when she displayed dominance. Participants made no such distinctions between men that displayed self-reliance and men that displayed dominance. Moreover, whereas there was evidence of backlash against women that displayed dominance in three of the four studies, there was no evidence of backlash against women that displayed self-reliance in any of the studies. These findings suggest that by framing agency as self-reliance female leaders may be able to demonstrate competence without a cost.
Essays in applied microeconometrics [electronic resource]
Keywords: Economics.

This subject of this dissertation is applied microeconometrics. Chapter 1 estimates the effect of physician incentives on treatment choices in heart attack management. Our results suggest that if physicians received bundled payments instead of fee-for-service incentives, heart attack management would become considerably more conservative, and about 20 percent of patients would receive different treatments. Chapter 2 studies the effect of Medicaid on health expenditures. At age 19, some enrollees lose Medicaid eligibility. We find that this quasi-experimental loss of coverage causes substantial changes to the level and composition of health care use. Average health expenditure falls by around 60 percent. Chapter 3 compares set-asides and subsidies in government procurement auctions. Restricting entry appears to substantially reduces efficiency and revenue, although it increases participation of favored bidders.
Essays in behavioral finance and online markets [electronic resource]
Keywords: Economics.

In this dissertation I study a number of questions in behaviroal finance and online markets. In the first chapter, I empirically analyze why people hold expensive credit card balances, often over substantial time horizons. Specifically, I test whether hyperbolic discounting can explain why many consumers are not able to reduce their credit card debt. In the second chapter, I analyze the effect of potential market misvaluation for corporate acquisitions when some managers are overoptimistic. I focus on the implications for the method of payment and the implications for subsequent returns depending on the method of payment chosen. In the third chapter, joint work with Liran Einav, Jonathan Levin and Neel Sundaresan, we study seller experiments in online markets. We document the prevalence of pricing and auction design variation for listings on eBay. We show how this variation can be used to learn about questions of consumer behavior and market outcomes, while leveraging the scale and heterogeneity of online markets.
Essays in energy resource economics [electronic resource]
Keywords: Economics.

This dissertation consists of three chapters whose common theme is innovation and tax policies as they concern emerging energy technologies and resources in the United States and Canada. The first chapter investigates whether there is econometric evidence of learning-related externalities in the U.S. wind development business that might substantiate learning-by-doing as a basis for costly policies to support wind energy. I develop a modeling framework that: (i) disentangles firms' experience installing wind capacity from other determinants of wind power projects' costs -- in particular, input prices, scale economies, and exogenous technical change; and (ii) allows for alternative measures of experience and multiple channels through which experience can accumulate. For a variety of specifications, I find evidence of firm-specific learning-by-doing but no evidence of knowledge spillovers across firms, which calls into question the need for policies to support U.S. wind on the grounds that there are learning-related externalities. The second chapter develops a model of production and investment in the upstream natural gas business in an effort to characterize and evaluate an efficient and government revenue-maximizing royalty regime for shale gas in Canada. The model suggests that efficient production, investment, and royalty revenue outcomes can be achieved via a royalty on shale gas producers' operating profits, with royalty rates sensitive to gas wells' locations and market prices for gas. Simulation results based on this model suggest that the royalty regime currently in place in British Columbia -- the province with the best shale gas resources in Canada -- over-taxes shale gas producers at low prices, and under-taxes shale gas producers at high prices, compared to the proposed alternative royalty regime. The third chapter revisits the issue of identifying and estimating learning-by-doing in U.S. wind (and renewable energy technologies more generally). I explain why statistical inference based on learning curves -- a class of regression models employed in much existing empirical research on learning-by-doing in renewables -- is suspect and should not inform policy. Specifically, I show that popular learning curve models make strong assumptions that: (i) preclude the ability to distinguish between inter-firm knowledge spillovers and firm-specific learning-by-doing (i.e. learning that does and does not entail externalities); and (ii) disregard factors besides learning in explaining the evolution of firms' costs over time.
Essays in financial economics [electronic resource]
Keywords: Business.

This dissertation consists of three essays in which I study dynamic incentive problems in corporate finance. In particular, I use methods from dynamic contracts, dynamic games, and stochastic control to study agency and asymmetric information problems in finance and economics. In Chapter 1, ``Contracting Timely Delivery with Hard to Verify Quality, '' I analyze the optimal long-term contract in a setting with an extreme problem of multi-tasking in which one task is value destroying. I study this problem in a stylized continuous-time optimal contract model with hidden effort and imperfect monitoring about project quality. I consider a situation with imperfect performance measures in which the agent can manipulate output as to improve observed performance at the expense of project quality. The optimal contract balances the provision of incentives to exert effort and the cost of monitoring quality. The optimal contract has the following features: 1) termination is unpredictable as otherwise the agent would manipulate performance when he is close to being fired; 2) monitoring is contingent on the agent's past performance -- agents with a weak performance are monitored more thoroughly; 3) cash compensation is deferred longer and the optimal contract has longer duration and lower turnover than in a setup without manipulation. In Chapter 2, ``Trading Dynamics in the Market for Lemons, '' I analyze dynamic trading in a market with a divisible asset and asymmetric information, as in the market for lemons. I characterize an equilibrium in which the seller signals high value by both delay of trade and by retaining a larger fraction of the asset. Due to the lack of commitment not to trade again in the future, separation is only partial and improves over time. In equilibrium, these two signaling mechanisms are related, and delay is an increasing function of cumulative sales. The equilibrium expected surplus is the same as in a static market for lemons in which only low-quality assets are traded. In the dynamic setting, even though there is an efficiency gain because high-quality assets are eventually traded; this gain is offset by the delay in trade of low-quality assets. Finally, Chapter 3, ``Optimal Capital Structure with Contingent Capital Requirements'' study the impact of contingent capital requirements on the optimal capital structure and dividend decisions of a regulated bank.
Essays in international trade [electronic resource]
Keywords: Economics.

This dissertation consists of three chapters, studying causes and effects of trade policy. The first two chapters study a policy that was imposed on an economy from the outside - a blockade, while the third deals with policies which are self imposed. In the first chapter, I use detailed household expenditure and price data to study the welfare consequences of the blockade imposed on the Gaza Strip between 2007 and 2010. Using the West Bank as a counterfactual, I find that being removed from world markets reduced welfare by 17%-28% on average. Moreover, households with larger pre-blockade expenditure levels experienced disproportionally larger welfare losses. The second chapter uses firm level data to study the effects of the blockade on domestic production in Gaza. I find that the blockade triggered reallocation of workers across firms and sectors, especially from manufacturing to services, and from industries that use imported inputs intensively, or export. In addition, labor productivity fell sharply by 24%. This decline was however significantly higher in manufacturing (39%) than in services (5%). These findings suggest that access to world markets did not only determine the location of the Gaza economy on a given Production Possibility Frontier, but also determined the shape of this PPF. The third and last chapter deals with the the effects of Preferential Trade Agreements (PTAs) on the level of protectionism that member countries use against non members of their PTA. Using data on the use of Anti-dumping Duties by the U.S. before and after the implementation of the North American Free Trade Agreement (NAFTA), I find that American industries that were exposed to imports from Mexico became much more likely to receive protection in the form of AD duties relative to industries that were not exposed to imports from Mexico. I interpret these findings as evidence supporting the "protection diversion" hypothesis, according to which countries that enter PTAs will become more aggressive in using protection measures against non-members.