The Relationship Between Participation, Social Networks and Cooperation: How Social Networks Influence Voter Turnout through Mobilization and how both Networks and Turnout are Related to Cooperation.

This dissertation is organized around three papers that illustrate the codependence of cooperation, political participation and social networks. It takes advantage of a unique project, the 2010 Rural Social Network Study that comprehensively mapped the social relationships of residents in 32 small Honduran communities. These data are paired with survey questions and behavioral observations of subsamples in incentivized settings. The first paper, ``Cooperation and Popularity,'' reinforces the claim that cooperation and friendship share a strong positive relationship. Friendship and social networks may have evolutionary roots in cooperation, but this work is the first to demonstrate a relationship between the number of friends one has and the propensity to cooperate. Number of friendships predicts cooperation in a public goods game. Specifically, I find that individuals with more friends are more likely to cooperate in earlier rounds, and that a group's total amount of money earned increases with the aggregate number of friends of its members. The second paper, ``Habituated Cooperation and Voter Turnout,'' provides empirical support for the claim that voting is a cooperative act. Prior theoretical work argues for a link between cooperation and voter turnout. I demonstrate that there is a robust empirical relationship been those who cooperate in public goods games and self-reported voting. The final paper, ``Social Networks and Mobilization,'' demonstrates that mobilization occurs more commonly when strong affective relationships are present. This study is the first to demonstrate how one’s position within a social network can affect the ability to mobilize others for participation in a community meeting. Specifically, the greater the number of connections a person is away from a mobilizer, the less likely she is to attend a community meeting. I also show that as mobilizers are more central to the network, the percentage of those who attend the community meeting grows. Together these papers illustrate that cooperation, social networks, and participation are linked to one another thereby contributing to the understanding of the interrelationship between social, political, and economic dynamics in the political process. These findings could be used to augment political participation and community cooperation through social networks.PhDPolitical ScienceUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/133345/1/dstaff_1.pd

Hustle and Flow: A Social Network Analysis of the American Federal Judiciary

Scholars have long asserted that social structure is an important feature of a variety of societal institutions. As part of a larger effort to develop a fully integrated model of judicial decision making, we argue that social structure—operationalized as the professional and social connections between judicial actors—partially directs outcomes in the hierarchical federal judiciary. Since different social structures impose dissimilar consequences upon outputs, the precursor to evaluating the doctrinal consequences that a given social structure imposes is a descriptive effort to characterize its nature. Given the difficulty associated with obtaining appropriate data for federal judges, it is necessary to rely upon a proxy measure to paint a picture of the social landscape. In the aggregate, we believe the flow of law clerks reflects a proxy for social and professional linkages between jurists. Having collected available information for all federal judicial law clerks employed by an Article III judge during the “natural” Rehnquist Court (1995-2004), we use these nearly 20,000 clerk events to craft a series of network based visualizations. Using network analysis, our visualizations and subsequent analytics provide insight into the path of peer effects in the federal judiciary. For example, we find the distribution of “degrees” is consistent with the power law distribution implying the social structure is dictated by a small number of socially prominent actors. Drawing from the complex systems literature, our findings suggest federal judicial actors self-organize at positions of criticality, possibly through Yule’s Law. In sum, if social structure “matters” then our results have significant implications for doctrinal phase transition and the “evolution” of the law

Hustle and Flow: A Social Network Analysis of the American Federal Judiciary

Scholars have long asserted that social structure is an important feature of a variety of societal institutions. As part of a larger effort to develop a fully integrated model of judicial decision making, we argue that social structure—operationalized as the professional and social connections between judicial actors—partially directs outcomes in the hierarchical federal judiciary. Since different social structures impose dissimilar consequences upon outputs, the precursor to evaluating the doctrinal consequences that a given social structure imposes is a descriptive effort to characterize its nature. Given the difficulty associated with obtaining appropriate data for federal judges, it is necessary to rely upon a proxy measure to paint a picture of the social landscape. In the aggregate, we believe the flow of law clerks reflects a proxy for social and professional linkages between jurists. Having collected available information for all federal judicial law clerks employed by an Article III judge during the “natural” Rehnquist Court (1995-2004), we use these nearly 20,000 clerk events to craft a series of network based visualizations. Using network analysis, our visualizations and subsequent analytics provide insight into the path of peer effects in the federal judiciary. For example, we find the distribution of “degrees” is consistent with the power law distribution implying the social structure is dictated by a small number of socially prominent actors. Drawing from the complex systems literature, our findings suggest federal judicial actors self-organize at positions of criticality, possibly through Yule’s Law. In sum, if social structure “matters” then our results have significant implications for doctrinal phase transition and the “evolution” of the law

Social Architecture, Judicial Peer Effects and the Evolution of the Law: Toward a Positive Theory of Judicial Social Structure

Building upon the themes of this symposium, as well as a growing extant literature demonstrating the common law displays properties of a complex system, we believe existing theories of judicial decision-making and legal change would benefit from the concepts and techniques typically reserved for the study of complexity. Among possible approaches, network analysis offers one manner of representing the interactions between various entities across a complex system. Specifically, as applied to the path of the common law as well as theories of judicial decision-making, the networks paradigm helps evaluate the manner in which individual level judge choice maps to the judiciary\u27s aggregate doctrinal outputs. Of course, to the extent individual decision-making is driven by factors entirely intrinsic to a given case and a given jurist, the study of interactions is arguably trivial as the description of aggregate would reflect little more than the summation of individual preferences in a manner consistent with the institution\u27s aggregation rule. It is far more likely, however, that judicial choice is, at least in part, impacted by a combination of jurists who are socially prominent and socially proximate. While in some forms of network structure such peer effects are limited, in many states of the social world, they are supremely consequential. The precursor to evaluating potential doctrinal consequences is a classificatory effort designed to determine the micro implications of a given observed macro landscape. Section I provides a brief overview of complexity theory while simultaneously reviewing existing theories of judicial decision-making and legal change. Section II considers a series of classic network structures. Among the possibilities considered herein are random graphs, clustered graphs, as well models built upon processes of preferential attachment. Drawing from the larger complexity literature, Section II also describes the processes of self-organization likely responsible for generating each of these network structures. With an understanding of these possible states of the world in mind, Section III concludes with a consideration of judicial decision making, arguing the path of the law - from emergence to convergence - is conditioned, in part, upon the nature of self-organized social architecture that relevant decisional actors confront. In all, we believe architecture matters. Thus, our broad sweep of the possibility frontier should help identify the conditions under which network effects are present in the development of the common law

Exposure, hazard, and survival analysis of diffusion on social networks

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/144676/1/sim7658_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/144676/2/sim7658.pd

Measuring the Economic Impact of Recurrent Flooding on Workforce Productivity and Property

From the Executive Summary: This research draws upon expertise across multiple disciplines and fields. Leveraged are natural systems data and social-behavioral data. The high-level objective is to advance our understanding of how very recent recurrent flooding has impacted residents within the City of Portsmouth, and then forecast these impacts under projections of sea level rise. While this research draws upon data for the City of Portsmouth, the findings may be generalized to the broader Hampton Roads region

Flexibility within the Heads of Muscle Myosin-2 Molecules

We show that negative-stain electron microscopy and image processing of nucleotide-free (apo) striated muscle myosin-2 subfragment-1 (S1), possessing one light chain or both light chains, is capable of resolving significant amounts of structural detail. The overall appearance of the motor and the lever is similar in rabbit, scallop and chicken S1. Projection matching of class averages of the different S1 types to projection views of two different crystal structures of apo S1 shows that all types most commonly closely resemble the appearance of the scallop S1 structure rather than the methylated chicken S1 structure. Methylation of chicken S1 has no effect on the structure of the molecule at this resolution: it too resembles the scallop S1 crystal structure. The lever is found to vary in its angle of attachment to the motor domain, with a hinge point located in the so-called pliant region between the converter and the essential light chain. The chicken S1 crystal structure lies near one end of the range of flexion observed. The Gaussian spread of angles of flexion suggests that flexibility is driven thermally, from which a torsional spring constant of ~ 23 pN·nm/rad2 is estimated on average for all S1 types, similar to myosin-5. This translates to apparent cantilever-type stiffness at the tip of the lever of 0.37 pN/nm. Because this stiffness is lower than recent estimates from myosin-2 heads attached to actin, we suggest that binding to actin leads to an allosteric stiffening of the motor–lever junction