Browsing by Subject "Experiment"

This dissertation explores the aeroelastic stability of a folding wing using both theoretical and experimental methods. The theoretical model is based on the existing clamped-wing aeroelastic model that uses beam theory structural dynamics and strip theory aerodynamics. A higher-fidelity theoretical model was created by adding several improvements to the existing model, namely a structural model that uses ANSYS for individual wing segment modes and an unsteady vortex lattice aerodynamic model. The comparison with the lower-fidelity model shows that the higher-fidelity model typical provides better agreement between theory and experiment, but the predicted system behavior in general does not change, reinforcing the effectiveness of the low-fidelity model for preliminary design of folding wings. The present work also conducted more detailed aeroelastic analyses of three-segment folding wings, and in particular considers the Lockheed-type configurations to understand the existence of sudden changes in predicted aeroelastic behavior with varying fold angle for certain configurations. These phenomena were observed in carefully conducted experiments, and nonlinearities - structural and geometry - were shown to suppress the phenomena. Next, new experimental models with better manufacturing tolerances are designed to be tested in the Duke University Wind Tunnel. The testing focused on various configurations of three-segment folding wings in order to obtain higher quality data. Next, the theoretical model was further improved by adding aircraft longitudinal degrees of freedom such that the aeroelastic model may predict the instabilities for the entire aircraft and not just a clamped wing. The theoretical results show that the flutter instabilities typically occur at a higher air speed due to greater frequency separation between modes for the aircraft system than a clamped wing system, but the divergence instabilities occur at a lower air speed. Lastly, additional experimental models were designed such that the wing segments may be rotated while the system is in the wind tunnel. The fold angles were changed during wind tunnel testing, and new test data on wing response during those transients were collected during these experiments.

In a democratic society, does the electorate approve of truth and disapprove of deception, do opinion patterns exclusively mimic partisan elite views, or do opinion patterns react exclusively to successful or failed outcomes? Do citizens hold leaders accountable for the perceived truthfulness of foreign policy claims or do they only evaluate whether or not the policies were successful? The existing literature on public opinion and foreign policy calls the accountability role for the public "audience costs," and specifies that concerns about audience costs constrain leaders. However, the literature is not clear on what role normative issues may play in generating audience costs. This gap in the literature is notable because so much of the debate surrounding significant policy issues, especially war-making and military action, is couched in retrospective, normative, moralizing language. These debates make no sense if the pragmatic, forward-looking dimensions of audience costs - reliability and success - are all that exist. Through a survey experiment and four historical case studies developed with primary and secondary historical sources, news articles, and polling data, I find that there is a complex dynamic at work between the public's desire for successful outcomes and the high value placed upon truth-telling and transparency within a democracy. Studying justifications for military action and war, I find that the public will be motivated to punish leaders perceived as deceptive, but that imposition of audience costs will be moderated by factors including partisanship, degree of elite unity, and the leader's damage control strategy in response to disapproval.

What is the utility and relative efficacy of positive inducements and sanctions in international politics? Are inducements and sanctions actually different or just the two sides of the same coin? How have inducements and sanctions been used and how effective have they been? My dissertation examines the effect of carrot and stick-like foreign policies in international relations. Dominant works on risk-taking and decision-making—like loss aversion – have shown that people are more sensitive to potential losses than gains, which would suggest that sanctions should be utilized more in order to achieve preferred outcomes. I find, however, that inducement policies that require concessions from the target state can be framed to gain the target state’s public support and allow target state leaders to “save face.” In contrast, I find that sanctions provoke nationalism, creating a rally around the flag effect, resulting in negative consequences for the sender state. Using a presence-absence framework of positive and negative outcomes, utilizing experimental methods to study the micro-foundations of inducement and sanction perceptions, as well as a case study of the Six-Party Talks based on field work consisting of archival work and interviews, my dissertation aims to bridge the policy-academy gap by translating a perennial policy-level problem of “carrots vs. sticks” to an academic question assessing the utility and relative efficacy of positive inducements versus sanctions.

The effect of Mindfulness Based Stress Reduction (MBSR) training on experimental measures of attention and emotion regulation was assessed. Two laboratory based measures of attention and emotion regulation were employed. Amongst a number of hypotheses, the effect of MBSR on return to emotional baseline was assessed. Analyses indicated that MBSR training had no effect on physiological indices of emotion regulation. Self-report measures indicated that MBSR training led to faster return to baseline negative emotional experience following a stressor. Implications and future directions are discussed.

We test the validity of using the Quasiparticle Random Phase Approximation incalculating the nuclear matrix elements for neutrinoless double beta decay of 136Xe. The approximation is tested by measuring the transition strengths to the ground state and to excited 0` states in the residual nucleus via the (3He, n) two proton dropoff reaction. In this thesis, we describe the experimental techniques and data analysis methods developed and used to perform cross-section measurements of the (3He, n) reaction on 134Xe and 136Xe. We report our cross-section results as a differential cross section at a 3He lab energy of 26 MeV and a neutron scattering angle of 0 degrees. The cross section for the reaction on 134Xe was measured to be 355 ̆ 33 μb/sr, and the cross section for the reaction on 136Xe was measured to be 205 ̆ 19 μb/sr. In both reactions, strong transitions to 0` excited states were observed, though these transitions were much stronger for 136Xe. These results indicate a failure of the BCS approximation (commonly used as part of the QRPA) to describe the ground state of the 136Xe isotope and a possible failure for the 134Xe isotope as well.

The Global South, and particularly Latin America, experienced a remarkable expansion in conditional cash transfer (CCT) programs in the last fifteen years. Although a large literature examines the effects of CCTs on human development, the political behavioral consequences remain underexplored. In the dissertation, I address this gap by analyzing the effects of CCTs on political participation and policy. I also explore the implications of these effects for human development.

My central argument is that CCTs increase political participation among beneficiaries, and both program transfers and conditionalities contribute to these positive effects. More specifically, CCTs provide beneficiaries with politically relevant resources, including civic skills and access to state officials and community leaders. These resources reduce the costs of political participation and facilitate more involvement in political activities, particularly in more demanding forms of participation. In addition, I argue that CCTs increase the private provision of local services and influence the outcomes of some non-national elections.

To test this argument, I use four main sources of data: (1) existing survey data from Latin America in 2012; (2) original survey data from Mexico in 2014; (3) experimental data from Mexico in 1998-2000; and (4) in-depth interviews and focus groups from Mexico in 2012. Multilevel models and linear regression models are used to estimate the effects of CCTs on political behavior and service provision. The in-depth interviews and focus groups help to unravel more of the causal mechanism that connects CCTs to political participation.

The evidence largely supports my argument. I find that CCTs increase participation in a wide variety of political activities, including electoral and non-electoral activities. In addition, the pathways to increased participation include improved civic skills and increased access to state officials and local leaders. Moreover, CCTs increase the private provision of sewerage services.

I conclude that CCTs have both desirable and undesirable consequences. On the one hand, CCTs increase democratic political participation, improve civic skills, reduce the distance between beneficiaries and government officials, and increase access to local services. The increased access to sewerage services creates an indirect pathway to improved human development outcomes. On the other hand, CCTs reduce the pressure on local officials to provide local services, and in some contexts contribute to electoral rewards for undeserving incumbent parties.

My dissertation explores literature’s participation in these cross-disciplinary debates over nothingness; I argue that literary forms create the possibilities of scientific discourse later in the century. To fully understand the complex network of relationships that formed early modern science as well as, in consequence, our own experimental philosophy requires examining the challenges that literature issues to science. To demonstrate the mutually productive relationship between the literature and science of the period, my dissertation charts the seventeenth century's different literary conceptions of nothingness, and the contribution of writers such as John Donne, William Shakespeare, John Milton, and Margaret Cavendish to these debates over both the nature of nothingness and, more broadly, how we come to know anything at all. Literary texts – in the form of sonnets, tragicomedies, and even proto-science fiction – produce knowledge in ways that anticipate and subtly revise scientific processes.

The first chapter, “Encompassing Nothingness in Donne’s Poetry” evaluates two of John Donne’s poems from Songs and Sonnets alongside the introduction of the symbol of zero into Western systems of calculation and the invention of the microscope. I argue for a re-reading of poems such as “A Valediction: Forbidding Mourning” and “The Flea” that accounts for their seemingly paradoxical representation of absence and presence by considering Donne’s thought in terms of mathematical developments as well as developing literary technologies. The culmination in the poem’s well-known image of the compass, drawing a circle centered on a point inscribes the Arabic symbol for zero; the poem thus participates in the broader project of transforming nothingness into an appropriate object for scientific inquiry. Donne’s poetry also anticipates scientific method by forming imagined communities of observers whom he addresses and leads through a process of witnessing nothingness, thus revealing its status as an object of scientific inquiry, and consequently, as something after all.

Chapter 2, “Playing at Nothing in The Winter’s Tale,” looks at the treatment of nothingness in this play as a model for literature’s production of experimental science in the seventeenth century. In The Winter’s Tale, Leontes’s solipsistic assurance of his wife’s infidelity and the infallibility of his own senses gives way to knowledge formed collectively by a performance that reforms and reconciles the community. This performance suggests that the community, rather than the solitary individual, is the basis for building knowledge. Through analyzing Leontes’s method of knowledge production versus the communal models that close the play, I argue that The Winter’s Tale preemptively figures the shift from a patronage-based court philosophy to an experimental philosophy. In doing so, The Winter’s Tale helps to revise the dominant narrative about when the idea of communal witnessing begins by emphasizing the importance of literary contributions to conceptualizing the history of science.

Chapter 3, “Experience in Paradise Lost” pays particular attention to the shift from observation to experience as represented in Milton’s poetry. Engaging with critical debates over Milton’s materialism, I read Milton’s epic as it rejects the idea of creation ex nihilo and instead focuses on creation out of Chaos. Just as Boyle justified his explorations into atomistic philosophy and rejected the idea of a universe created by random atomic interactions, Milton’s universe, too, is established and ordered by a divine Creator. Unlike Boyle, however, Milton rejects the experiment, which he identifies with a fallen world, in favor of experience – described in Paradise Lost as wisely used, individually mediated reason.

Chapter 4, “‘To Make Your World of Nothing’: Nothingness in Margaret Cavendish’s The Blazing World” examines Cavendish’s 1666 utopian proto-science fiction romance in conjunction with Robert Hooke’s 1665 Micrographia, a text that explores the minute worlds opened to human observation with the microscope’s invention. Cavendish’s text envisions a world-building that is entirely the result of individual human invention – in her words, one made of “Nothing but Wit.” Cavendish focuses on the imaginative possibilities opened by a creation focused on seeming nothingness; her text fantasizes about a world in which this act of creation forces multiple boundaries to break down (human / animal, scientist / experiment). The Blazing World challenges the rules for scientific practice enshrined by the Royal Society by imagining experiments that create hybrids that challenge the seemingly objective stance of the scientific observer as well as the facts produced in the laboratory itself.

Political persuasion research has long focused on the various factors of persuasion – source, message, audience, and medium – with partisan identity inevitably being considered the dominant predictor of whether persuasion occurs. However, in studying these factors of persuasion, the existing literature has considered them in isolation from each other rather than in interaction. Ignoring the ways in which these factors may interact – and the implications these interactions may have for how persuasion occurs – results in an incomplete and inaccurate picture of the ways in which individuals receive and process political information. Through a series of original survey experiments conducted on various survey platforms, this dissertation develops an interactive framework of political persuasion, using the communication strategy of unexpected messaging as an example. The results illustrate (1) unexpected messaging can lead to a significant increase in the evaluations of perceived trustworthiness and expertise of political speakers and sources of political information, and that these evaluations can even lead to shifts in policy opinions, a particularly critical finding in today’s polarized political environment; (2) unexpected messaging breaks through the partisanship barrier, causing respondents of both political parties to more positively evaluate speakers, and to vote across party lines; and (3) when partisan and policy cues are salient, the partisanship of the audience receiving an unexpected message determines how the message will be interpreted.