Contributors: Li, Nannan, Panagiotopoulos, Athanassios Z., Chemical and Biological Engineering Department
... Structured nanoparticles are important for various scientific and industrial applications. For example, Janus particles can act as pigments in electronic paper, interfacial stabilizers, optical probes and catalysts; core-shell particles are useful in drug delivery; patchy particles can self-assemble into hierarchical structures. These applications require nanoparticles with a narrow size and morphology distribution, which needs to be addressed by the fabrication methods. In addition, a method which is simple and scalable is also desirable in order to achieve commercial applications of the nanoparticles. Flash Nanoprecipitation (FNP), which involves the rapid mixing of polymers in solution with a miscible non-solvent, is a continuous and scalable process that offers independent control over nanoparticle size, morphology, and composition. To understand the assembly mechanism of FNP and to make quantitative predictions for experiments, I performed molecular dynamics (MD) and kinetic Monte Carlo (KMC) simulations. On the nanoscale, the MD simulations studied the assembly mechanism and revealed how nanoparticles with a range of surface structures, including Janus, core-shell and patchy, arise from different processing conditions. The simulations also indicated that nanoparticle morphologies and other properties such as the composition and patchiness can be reliably tuned. To reach macroscopic length- and time-scales, I performed KMC simulations and studied how nanoparticle size and size distribution can be controlled by processing parameters specific to FNP, such as the mixing rate and the feed concentration. The model produced results in quantitative agreement with experiments and also provided insights on particle aggregation mechanism through the solvent displacement process. This multi-scale simulation approach allows predictions for the FNP process from a given set of feed polymers and processing parameters. The results demonstrate that the process is highly promising for the production of structured nanoparticles with various surface features in a scalable and controlled way. These results also provide guidelines for future design and preparation of polymeric nanoparticles with desired properties using FNP techniques, and thus facilitate their applications in various areas.
The Classical-Period Development Section: Compositional Strategies of Haydn, Mozart, Beethoven, and Schubert
Contributors: Matthay, Christopher, Agawu, Victor K, Music Department
... The development section has been described as the most characteristic feature of Classical-period sonata form, as that which distinguishes sonata form from related forms of the period. It has been called “the locus of variety and motion,” “the appointed field for the tournament of tonalities,” and, borrowing from dramatic theory, “the intrigue,” or “the knot.” Its function has been described variously as that of unfolding, elaboration, intensification, and digression. Of the three parts of sonata form, the development is, both tonally and in its treatment of thematic material, the least predictable and the most variable from work to work. This dissertation explores rhetorical and harmonic strategies of Haydn, Mozart, Beethoven, and Schubert for beginning and ending the development, and, in Mozart’s early sonata-form movements, for structuring the development as a whole. The project engages with the recent theories of Classical-Period form developed by William Caplin and by James Hepokoski and Warren Darcy; with the less schematic approaches to form of Charles Rosen, Leonard Ratner, and Donald Francis Tovey; and with eighteenth- and nineteenth-century theories of form and of harmony, including those of Riepel, Koch, Reicha, Marx, and Riemann. The approach taken attempts to balance taxonomy and interpretation, and is especially concerned to describe the effects produced by the given strategies in their various realizations in particular works. Chapter 1 describes a beginning strategy often used by Beethoven in his piano sonatas, that of opening the development with a transformed, “dissolving” statement of the work’s main theme. Chapter 2 explores a contrasting strategy used by Mozart in several of his middle- and late-period works, a strategy of beginning the development with a tight-knit new theme. Chapters 3 and 4 describe modulatory pathways used in High-Classical-period works to lead out of the key of the end of the exposition, and Chapters 5 and 6 describe retransitional strategies in sonata-form movements of the 1760s–1770s and 1780s–1810s, respectively. Chapter 7 describes three of Mozart’s strategies for structuring the development as a whole in his early sonata-form movements, and compares these with related strategies of Haydn and Johann Christian Bach.
Contributors: Chou, Winston, Dancygier, Rafaela M, Politics Department
... This dissertation collects four essays on transformative developments in contemporary European politics. These include the polarization of European party systems, exemplified by the rise of outsider parties at the fringes of the political spectrum; the loosening of traditional partisan bonds; the erosion of the political center; and social polarization, driven by the politicization of Europeanization, immigration, and national identity. The first essay, Bad Times or Bad Types?, examines the rise of the populist right in Europe through the prism of local politics in France. Examining a natural experiment involving wrongheaded financial decisions by local governments, it shows that populist voting can be a mechanism of elite accountability -- albeit one that is imperfect and conditioned by access to information. The second essay, The Distortionary Effects of Turnout Inequality, examines the implications of the political dealignment of working-class voters for electoral outcomes and party strategy in contemporary German politics. It questions the longstanding belief that turnout inequality -- the lower propensity for younger, less-educated, and lower-income respondents to vote -- systematically disadvantages Left parties. Drawing on an original survey and experiment, it shows that nonvoters in Germany are indeed poorer and less-educated than the electorate, but that they are also significantly more xenophobic than supporters of Left parties. Taking a broader view, the third essay, Party Strategy After Social Democracy, counterposes two explanations for the decline of Left parties in Western Europe. These include (1) steadily diverging preferences between the Left's two traditional constituencies, middle- and working-class voters; and (2) the strategic decision of many Left parties to moderate in order to pursue more middle-class voters. It amasses historical and contemporary survey evidence to show that the decline of Left parties is structural rather than strategic in nature. The dissertation closes with a fourth essay, Lying on Surveys. This essay is unique in that it is mainly a contribution to political methodology, albeit with an application to survey data from Europe. In this chapter, I develop new statistical tools for measuring misreporting on surveys and apply them to a survey experiment conducted among radical right voters in Germany.
Contributors: Reinhart, Wesley F, Panagiotopoulos, Athanassios Z, Chemical and Biological Engineering Department
... Colloidal crystals continue to draw attention for their applications in photonics, energy conversion, and biosensing, as well as for their usefulness in elucidating questions in fundamental physics and materials science. However, the wide range of applications for these particles is made possible by the equally wide range of possible self-assembled structures, which may be amorphous or crystalline, close-packed or open, and may include defects with varying morphology and concentration. Experiments, simulations, and theoretical treatments have all shown that this rich phase behavior is enabled by relatively weak interactions between the particles, which leads to small differences in free energy between competing equilibrium and non-equilibrium structures, presenting unique challenges in the fabrication and analysis of the resulting materials. This dissertation explores two complementary topics which both support the goal of engineering advanced materials through directed assembly of colloidal crystals. In the first half of this work, I explore the crystallization of triblock Janus colloids through a variety of simulation methods. I begin by calculating the equilibrium thermodynamic phase diagrams for these particles under a wide variety of conditions, quantifying the driving forces which stabilize each of the competing crystal polymorphs. I next evaluate the crystallization kinetics of several of these solid phases, finding that the different assembly mechanisms of each crystal lattice lead to surprising behaviors. Finally, I demonstrate how a patterned substrate biases the morphology of a crystal film toward large single crystals of a particularly useful polymorph. In the second half, I develop a novel framework for crystal characterization which infers relationships between observed structures automatically rather than relying on pre-programmed templates. I begin by establishing the mathematical basis for this method, showing how my Neighborhood Graph Analysis (NGA) can be used to identify crystal lattices from particle tracking data. Next I extend the framework to binary systems, demonstrating the first-ever automatic characterization of binary superlattices. Finally, I describe a streamlined version of the algorithm which reduces the computational cost by several orders of magnitude, allowing it to be implemented into a fully automated characterization and visualization workflow which is used to investigate a wide variety of crystal lattices.
Contributors: Enamorado, Ted, Imai, Kosuke, Politics Department
... This dissertation is a collection of three essays that deal with the challenges social scientists face when trying to integrate information from multiple sources. The first chapter focuses on technical aspects of data integration. Specifically, when a unique identifier that unambiguously links records is not available, merging datasets can be a difficult task. Probabilistic record linkage (PRL) aims to solve this problem by providing a principled framework. I propose an active learning algorithm for PRL, which incorporates human judgment. Using data where a unique identifier is available for validation, I find that the proposed method bolsters the accuracy of the merging process. In addition, I show that the proposed method can recover estimates that are indistinguishable from those obtained from a more extensive and time-consuming manual review. The second chapter uses data from multiple sources to study the impact of electoral rules on coalition building. To overcome endogeneity concerns, I exploit an arbitrary change in electoral rules across municipalities in Brazil and study its impact on pre-electoral coalitions (PECs). I find that in municipalities where elections are conducted using a dual-ballot system, the median number of parties in a given PEC is smaller than in those municipalities that use a single-ballot system. In addition, this reduction in the size of PECs is associated with an increase in the total number of candidates. These findings are consistent with theories that emphasize the opportunities for strategic behavior under a dual-ballot system. Finally, the third chapter (co-authored with Svetlana Kosterina) combines information from multiple sources to study ethnic voting. We show that local ethnic geography affects ethnic voting by incentivizing voters of an ethnicity that finds itself in the minority to misrepresent its preferences. We provide empirical evidence for our claim using the data from the Afrobarometer survey in Ghana to measure the voters' beliefs that they are likely to face adverse consequences for expressing their political preferences. Using geocoded data from Afrobarometer, as well as data from the Ghana Demographic and Health Survey, we find no evidence for local public goods provision as an alternative mechanism.
Contributors: Pearson, Heath, Biehl, João, Perry, Imani, Anthropology Department
... “The Carceral Outside” explores the evolution of a rural town in New Jersey that, over the course of two hundred years of capital accumulation, has transformed from an agricultural hub into a town with four prisons, a regional jail, and three police departments. It examines how the transformation of land over time was related to the search for and exploitation of laborers, and how that relationship between land and labor became racialized, paving the way for a rural “prison town.” The study is anchored by a detailed land history of each prison site, beginning in the late-eighteenth century and continuing to the present, and is bolstered by a chronicle of family and life histories based on more than two hundred ethnographic interviews. Additional data were supplied by newspaper archives in the library, local government archives, and published state and federal reports. U.S. “mass incarceration” and the “war on drugs” have been framed primarily as federal responses to deindustrialization driven by a racist backlash to expanded civil rights in the mid-twentieth century. This dissertation challenges that story, arguing instead that the long durée of carceral control and forced labor manifests as a core technique of market democracy. When land changes from “unused,” to agriculturally productive, to industrial, to punitive, the laborers change with it: from Indigenous genocide and African (American) slavery, to Japanese-American “internees” in labor camps during WWII, to prison labor and devalued laborers with felonies, to undocumented agricultural laborers from Central and South America. Laborers during these changing eras, in turn, signify and at times foment social divisions especially along lines of race/ethnicity. Historicizing this relationship between privatized land and racialized labor locates “mass incarceration” as only a current manifestation of market democracy’s continual re/production of a racialized division of laborers.
Contributors: Low, Ryan J., Tank, David W, Neuroscience Department
... Progress in systems neuroscience requires effective tools and techniques for probing neural circuits, and for analyzing the resulting data in ways that drive theoretical insight. This thesis consists of three parts, aimed broadly toward furthering the measurement and analysis of neural circuits. In the first part, we present methods for two-photon imaging of brain regions situated in deep fissures, enabling the use of cellular resolution optical tools for probing areas such as the medial prefrontal cortex (mPFC) and medial entorhinal cortex (MEC). We demonstrate recordings of population activity in the mPFC and grid cells in the MEC in behaving mice. In the second part, we present an optical approach for measuring dopaminergic input to the mPFC with high spatiotemporal resolution, which has not been feasible using traditional methods. We demonstrate recordings of mPFC dopamine signals in behaving mice, and present preliminary evidence for fine-scale heterogeneity across individual dopaminergic axons. In the third part, we present a new unsupervised learning algorithm for inferring underlying, nonlinear structure in neuronal population activity. We use this algorithm to characterize the geometric properties of hippocampal activity and their relationship to behavior. And, we propose a conceptual model explaining how neural coding and trial-to-trial variability both arise from movement along a low dimensional, nonlinear activity manifold, driven by internal cognitive processes.
Contributors: Smith, James Andrew, Tromp, Jeroen, Geosciences Department
... There are a variety of challenges when applying full-waveform inversion to underground tunnels in the near-surface. One challenge is in efficiently handling large amounts of seismic data on high-performance computing machines. Big data-sets allow for more measurements to be made that can resolve structures at unprecedented resolution. Utilizing these data-sets in seismic inversion work-flows requires developing new technologies that are fast, adaptable, and reproducible. The adaptable seismic data format (ASDF) is a modern data format that offers an organized, standards-based, and provenance-enhanced tool for earthquake seismology. A second challenge is generating accurate three-dimensional images of small subsurface voids near the surface. In advancing seismic imaging in the near-surface regime, three-dimensional elastic full-waveform inversion is applied to a known underground tunnel located in a desert geology at a depth of approximately 10 m. A set of successful experiments are presented that approximately image the underground tunnel in three-dimensions. A third challenge is in estimating the source time function from field data. Since the recorded data includes the effect of the source, the more accurate the estimate of the seismic source, the more accurate the model of the inverted subsurface velocity structure. A linear inversion method is applied for inverting for the source time signature from recorded sensor data. The inverted source is verified by comparing it with the measured accelerometer data from the field site. A fourth challenge is in incorporating anelastic attenuation into the inversion workflow. The range of possible parameter values for attenuation are constrained using the recorded data from the tunnel site. A set of 2D numerical experiments are presented that invert for attenuation directly in acoustic and elastic media.