Contributors: Neilson, Christopher, Altmejd, Adam, Barrios-Fernandez, Andres, Drlje, Marin, Kovac, Dejan
... While it is a widely held belief that family and social networks can inﬂuence important life decisions, identifying causal effects is notoriously difficult. This paper presents causal evidence from three countries at different stages of economic development that the educational trajectories of older siblings can signiﬁcantly inﬂuence the college and major choice of younger siblings. We exploit institutional features of centralized college assignment systems in Chile, Croatia, and Sweden to generate quasi-random variation in the educational paths taken by older siblings. Using a regression discontinuity design, we show that younger siblings in each country are signiﬁcantly more likely to apply and enroll in the same college and major that their older sibling was assigned to. These results persist for siblings far apart in age who are unlikely to attend higher education at the same time. We propose three broad classes of mechanisms that can explain why the trajectory of an older sibling can causally affect the college and major choice of a younger sibling. We ﬁnd that spillovers are stronger when older siblings enroll and are successful in majors that on average have higher scoring peers, lower dropout rates and higher earnings from graduates. The evidence presented shows that the decisions, and even random luck, of your close family members and peer network, can have signiﬁcant effects on important life decisions such as the choice of specialization in higher education. The results also suggest that college access programs such as aﬃrmative action, may have important spillover effects through family and social networks.
Contributors: Reilly, John Patrick, Glisic, Branko, Civil and Environmental Engineering Department
... Structural Health Monitoring (SHM) is the process of equipping a structure with sensors in order to assess the condition of that system using a combination of structural and analytic techniques. In every application, SHM involves the comparison of an unknown structural state to a baseline of healthy behavior. SHM as a field has come to prominence as a solution to aging infrastructure but still lacks the ability to consistently monitor and assess different types of structures. One obstacle is that the uniqueness of bridges and buildings necessitates individualized monitoring strategies. Another challenge is the influence of environmental effects on structures, especially temperature. In bridges, daily temperature changes can influence the strain on the structure more than daily traffic loads. Many SHM techniques struggle to compare a baseline, healthy structural state to a new unknown state because of differences in the environmental conditions. Temperature Driven-Structural Health Monitoring (TD-SHM) considers temperature as the driving force in structural behavior and therefore the driving force in monitoring. TD-SHM compares an input temperature to an output strain and displacement to form three- dimensional signatures for the structure. These signatures describe the behavior for the structure across all monitored temperatures. Changes in these signatures indicate unusual behavior or damage in the structure. Two immediate benefits of this method are the universal nature of temperature effects on structures and the ability to measure temperature as an input on a structure for the formulation of a complete input-output model. This thesis develops TD-SHM using strain, temperature, and displacement data measured on the Streicker Bridge at Princeton University. The main conclusions are the following: 1) thermal gradients on structures can obscure the temperature-strain relationship, but it is possible to filter out time periods where these effects are present; 2) the coefficient of thermal expansion (CTE) of concrete structures varies throughout seasons and throughout structures but are consistent through the years, and 3) three-dimensional temperature signatures can provide insight into the thermal behavior of the structure and highlight unusual behavior based on changes to that signature.
Contributors: McKowen, Kelly, Greenhouse, Carol J, Biehl, João, Anthropology Department
... Following the 2007-2008 global financial crisis, international observers turned to the Nordic countries for a model of the “good society.” Their interest has revolved primarily around the region’s social democratic welfare model, wherein an extensive public sector provides comparatively generous cash transfers, social services, and healthcare “from cradle to grave.” While politicians wonder at the model’s replicability, social scientists and historians tease out its ideological and political origins, effects on material and psychological outcomes, and challenges in a post-industrial, migratory, and increasingly interconnected world. Where popular and scholarly concerns intersect is on the point of the “work ethic.” Skeptics worry that adopting a Nordic-style social safety net, whatever its merits, would imperil the economic incentives of work, fostering dependency and passivity. Based on 16 months of ethnographic fieldwork in Oslo, Norway between 2014 and 2017, this dissertation examines the relationship between the welfare system, the everyday lives of the unemployed, and the shared moral imagination of labor. The study’s principal finding is that the Norwegian welfare model is not morally corrosive. Rather, through the experience of life events like unemployment, it cultivates a distinctive “employment ethic” that affixes value to moderating one’s use of the welfare system and working in the formal sector. This suggests that the qualitative variation in welfare systems, documented by comparative scholars, is associated with qualitative variation in the moralities of work and worklessness. The Norway depicted in this dissertation is not static. The twilight of social democratic hegemony has unleashed new ideological currents and political actors. A strong petroleum sector has increased the material standard of living, revolutionizing leisure time and stimulating consumerism. Finally, immigration—of foreign workers, refugees, family members—has introduced greater ethnocultural diversity and thorny questions about identity, belonging, and integration. These changes have led to debates about the compatibility between the social democratic welfare model and the ethical commitments of for-profit welfare service providers, young people, and immigrants. This dissertation argues that of these three groups, only for-profit welfare service providers are motivated by a conception of “the good” that conflicts with that of Norway’s social democratic welfare model.
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ROBOTIC ASSEMBLY: A GENERATIVE ARCHITECTURAL DESIGN STRATEGY THROUGH COMPONENT ARRANGEMENTS IN HIGHLY-CONSTRAINED DESIGN SPACES
Contributors: Wu, Kaicong, Kilian, Axel, Meggers, Forrest, Architecture Department
... Architectural assembly has been a neglected research topic within the field of computational design. Instead, manual assembly and passive fabrication processes directed by top-down controlled geometric models have attracted more attentions. Such design-to-production model is problematic because it is difficult for designers to overcome the constraints of their empirical knowledge. Moreover, an extensive amount of resources can be wasted when architectural components are manually assembled. However, what has yet to be determined is whether the applications of advanced assembly machines, especially architectural robots, can reduce resource use and create new design principles. How can robotic assembly become a generative strategy to design architectural forms through component arrangements? Three design models were developed to study the sequence, fitting, and configuration of robotic assembly. In relation to the model of Robotic Equilibrium Assembly, scaffold-free constructions were examined through tooling innovations to recreate the design of compression-only arch structures. For the model of Material Outline Assembly, a scanning procedure was carried out to fit foam fragments into a shell by flexibly approximating a human-designed surface geometry. For the model of Stochastic Assembly, deep learning was applied to autonomously achieve higher assembly goals of natural wood log structures. These models were implemented using various computational and robotic approaches and tested in small-scale experiments. This research contributes to architectural design by redefining the role of assembly machines as generators that can free design space from the constraints of existing knowledge regarding geometries, fabrications, and structures. The experiment results indicate that, even with unfamiliar design problems, potential solutions can be identified using robotic assembly to arrange architectural components. The design control shifts from top-down, human-centered geometric modeling to bottom-up, machine-centered component assembly. This can stimulate human designers to recognize and overcome their cognitive barriers, challenge existing architectural design criteria, and discover unknown design principles. Future work can be done to develop autonomous assembly of raw materials, connect the learning processes of virtual and physical assembly machines, and apply large-scale robotic assembly in built environments.
Contributors: Langan, Andrew Blake, Mas, Alexandre, Boustan, Leah, Economics Department
... Despite decades of convergence, men and women's outcomes in the labor market remain highly unequal. This dissertation studies different aspects of gender inequality in the labor market, and policies that some firms have implemented that affect disparities between their male and female workers. I focus on tenure track academics in US research universities---a setting I argue generalizes in important respects to the broader high-skill, white-collar workforce, and which allows me to study individual outcomes in depth. I use newly-collected panel data, following faculty in four subjects---economics, political science, sociology, and accounting---from roughly five hundred departments across several decades, linked to their earnings at public universities and research output in top journals. In chapter 1, I measure how female managers affect gender disparities in their workplaces. Using the timing of transitions between department chairs, I find female chairs reduce gender gaps in publications and tenure for assistant professors, shrink the gender pay gap for faculty by a third, and raise the number of incoming female graduate students by ten percent. In chapter 2, co-authored with Leah Boustan, we study correlations between economics departments' characteristics like field concentrations and the prevalence of female faculty, and the relative performance of male and female graduates in their job placements and early careers. We conduct in-depth interviews with faculty and alumni from five departments, and synthesize their responses to make recommendations for departments seeking to improve gender equity among their graduates. In chapter 3, I study the impacts of policies that extend faculty tenure clocks following childbirth or adoption. Recent research on top economics programs finds that gender-neutral policies benefit men while hurting women's odds of earning tenure. Using the same difference-in-differences empirical approach and the same set of institutions as this prior work, but focusing on accounting, political science, and sociology departments, I find policy impacts that are more favorable to women. Subgroup analysis shows effects for women are more positive, and for men less so, in departments with more senior female faculty or for individuals working under female department chairs.
Contributors: George, Joppan, Prakash, Gyan, Thompson, Emily, History Department
... If the beginnings of aviation in India had the appearance of a public spectacle, what was merely a sideshow in Allahabad soon became the centerpiece of the tableau of late colonial politics. This dissertation traces that transformation. It forges a history of aviation away from the genius of aeronautical innovations in the West, and away from the foundries and factories, to situate its introduction and evolution in the field of everyday experiences of the colonial society. Airplanes in India were constitutive of the governing logic of the late colonial state and they produced a material reality quite different from that which it shaped elsewhere. The history of colonial aviation in the subcontinent deserves attention, not only because of the vastness of its circulation, but also because of the extent of its reach and the particularities of its use in the practice of aerial policing and surveillance of the frontier tribesmen. If the British sought to singularly propel the airplanes, in my dissertation, a cast of frontier tribesmen, legislators, writers, princes, an airhost, and peasants animated the colonial aviatic. To tell this story, my dissertation engages with two historical views. One view decenters the conventional British representations of the aviatic sense of the colonial natives and their assumed inadequacy in the reception of technological modernity. The colonial subjects on their part challenged the colonialist perspective to deliberately remodel it through their discursive, experiential, and material practices. The British empire’s interest in aerial vision that facilitated the formation of knowledge is the second view I explore. The privileged intimacy of the vertical perspective, I argue, enabled the territorialization of punitive, extractive, and epistemic powers of the colonial state.
Part I: On The Effects of Electron-Deficient Olefins in a Ni Catalyzed Csp3–Csp3 Cross Coupling Part II: Using Machine Learning to Predict Reaction Performance and Infer Mechanism in a Pd Catalyzed C–N Coupling
Contributors: Estrada, Jesus Gregorio, Doyle, Abigail G, Chemistry Department
... Chapter 1 outlines a mechanistic investigation into the Ni catalyzed Negishi cross-coupling reaction of 2,2-disubstituted aziridines in the presence of Fro-DO, an electron-deficient olefin ligand. The reaction proceeds through a Ni0/II catalytic cycle with a Ni azametallacyclobutane catalyst resting state. Turnover-limiting Csp3–Csp3 reductive elimination proceeds from a spectroscopically observable NiII-dialkyl intermediate. This investigation laid the foundation for performing ligand effect studies. Chapter 2 utilizes the key mechanistic findings of Chapter 1 to study ligand effects on the aziridine cross coupling. Using computational methods olefinic ligands were compared based on their impact on key catalytic steps. Fro-DO’s improved performance in the reaction is due to both its ability to lower the C–C reductive elimination barrier and to associate favorably to NiII, originating from a stabilizing secondary interaction between the ligand’s sulfonamide group and NiII. Design of new ligands to evaluate this proposal supports this model and led to the development of a tunable ligand framework. Chapter 3 describes the statistical analyses of a multi-dimensional dataset gathered using High-Throughput Experimentation for a Pd catalyzed C–N coupling reaction using isoxazole fragment additives. Various machine-learning regression algorithms were evaluated for prediction. A random forest (RF) model proved optimal (R2 = 0.92 and RMSE = 7.8%). We established model generalizability of the RF model along the additive dimension along with justification for use of chemical featurization. Interpretation of the RF model suggests that reaction poisoning by the additives is related to a Pd catalyzed isoxazole decomposition pathway. Experimental support for the ML derived hypothesis highlights the utility of ML as a tool to infer mechanisms.
Contributors: Ben, Rebecca, Da Costa Kaufmann, Thomas, Art and Archaeology Department
... This dissertation reassesses the relationships between Leonardo and the Borgias and the role of the family in the departure of the Leonardeschi from Italy to Spain. The correct identification of Pedro Luis Borgia as the patron of the Hernandos distinguishes both the Nativity with donor in the Museo del Prado and the doors of the high altarpiece of Valencia Cathedral as newly recognized instances of Borgia patronage. This allows for a reconsideration of the impact of Leonardo and his workshop on the family’s artistic patronage and a fresh look at the roles of both patron and artist in the diffusion of the Leonardesque. The first two chapters of the dissertation consider the artistic patronage of Pedro Luis Borgia in relation to that of his second cousin of Cesare Borgia, and great uncle, Rodrigo Borgia (Pope Alexander VI), demonstrating his connections to Leonardo and his role in the arrival of the Hernandos in Valencia. The third chapter clarifies the relationship between the Hernandos, Fernando Yáñez de la Almedina and Fernando Llanos, and argues that Yáñez was the Ferrando Spagnuolo documented assisting Leonardo on the Battle of Anghiari in 1505, thus distinguishing two relatively overlooked Leonardeschi. The final two chapters consider the works of the Hernandos after the deaths of their Borgia patrons, reassessing the reception of the Leonardesque in Valencia and the impact of the Hernandos’ relationships with both Leonardo and the Borgias on their late careers in Murcia and Cuenca. The significance of the dissertation lies in distinguishing Pedro Luis Borgia as a patron of the Leonardeschi, identifying the church at Piratello (Imola) and Valencia Cathedral as far more significant sites for Borgia artistic patronage than was previously understood, and revealing new aspects of Leonardo’s activity and reception on the quincentenary of his death.
Contributors: Lee, Victoria Elizabeth, Priestley, Rodney D, Prud'homme, Robert K, Chemical and Biological Engineering Department
... Polymer colloids with complex morphologies have shown great promise in applications ranging from drug delivery and biosensing to optics and enhanced oil recovery. In order to implement these materials on industrial scales, a processing platform which can generate kilograms of such colloids per day is highly desirable yet remains elusive. We have therefore developed Flash NanoPrecipitation (FNP) as a flexible and economical process to generate structured colloids in a scalable manner. This solvent-exchange process relies on the rapid mixing of a polymer solution with an antisolvent stream to produce supersaturated conditions for polymer chains. Upon exposure to these conditions, the polymer chains collapse and agglomerate to form monodisperse colloids which are electrostatically stabilized. Other mechanisms of stabilization are also explored in this work. In this dissertation, we have demonstrated the versatility of the FNP platform by exploiting the phase separation of chemically distinct polymers to produce colloids with structural complexity. The morphology of colloids prepared from homopolymer blends is dictated by the interfacial tensions of the various components. We manipulated these interactions through the addition of surfactant molecules and charged functional groups on the polymer chains, creating Janus, core-shell, and non-spherical colloids with precise and independent control over their size and composition. Similarly, the microphase separation of block copolymers was harnessed to create lamellar and micellar colloids with nanometer-scale internal domains. Hybrid polymer-inorganic colloids were prepared by taking advantage of electrostatic interactions between the polymers and inorganic nanoparticles. Precise control over the placement of the inorganic nanoparticles within the polymer support was achieved by simultaneously tuning the solvent conditions in the system. We also generated colloids with anisotropic surface functionality by using blends of hydrophobic homopolymers and an amphiphilic block copolymer. This resulted in amphiphilic Janus colloids which show promise as Pickering emulsion stabilizers. Using the low-cost, scalable, and flexible process of FNP, we have gained valuable insights into the mechanisms of colloid formation and are now able to predict and produce a wide range of polymer colloid morphologies.
Contributors: Wangensteen, Kjell Magne, Kaufmann, Thomas DaCosta, Art and Archaeology Department
... This dissertation examines the transformation of painting style and practice effected by the Swedish court painter David Klöcker Ehrenstrahl (1628–98). A native of Hamburg, Ehrenstrahl spent several years studying and working in various cities across Europe before rising to prominence in Sweden in the decades following the Thirty Years War. While much in demand by aristocratic clients, he primarily served two royal patrons during his long and distinguished career: Dowager Queen Hedwig Eleonora and her son, King Karl XI, who enlisted Ehrenstrahl’s talents for a series of ambitious cultural projects when the kingdom was at the height of its wealth and power. Though steeped in a variety of contemporary artistic models, ranging from Dutch still-life to English portraiture and High Roman Baroque allegory, Ehrenstrahl refused to confine himself to one particular genre or mode of painting following his arrival in Sweden. Rather, he self-consciously appropriated, adapted, and synthesized various motifs and styles to suit a variety of purposes, including his own advancement at court. Each of the dissertation’s four chapters highlights this process of "strategic synthesis" by focusing on a different part of Ehrenstrahl’s oeuvre. The first chapter examines the diverse artistic influences that Ehrenstrahl absorbed during his studies across Europe, demonstrated by a large group of his drawings. Chapter two examines Ehrenstrahl’s numerous portraits, in which he cleverly manipulated his painting style in order to outmaneuver his artistic rivals and cater to the tastes of his patrons. Chapter three examines Ehrenstrahl’s paintings of flora and fauna, which straddle the conceptual divide between Dutch and Flemish animal painting and proto-scientific illustration that flourished in late seventeenth-century Sweden. The final chapter considers Ehrenstrahl's allegories and history paintings in light of the shift towards absolutism under Karl XI. While this dissertation comprises a monograph on Ehrenstrahl, its fundamental argument is a methodological one that predicates artistic “style” as a set of conscious decisions often made in service to practical and political aims, not just aesthetic ones. The dissertation includes a comprehensive critical catalogue of Ehrenstrahl’s drawings and paintings, as well as eleven appendices containing archival documentation of Ehrenstrahl’s life and work.