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Missing Data in Complex Sample Surveys: Impact of Deletion and Imputation Treatments on Point and Interval Parameter EstimatesKellermann, Anh Pham 15 January 2018 (has links)
The purpose of this simulation study was to evaluate the relative performance of five missing data treatments (MDTs) for handling missing data in complex sample surveys. The five missing data methods included in this study were listwise deletion (LW), single hot-deck imputation (HS), single regression imputation (RS), hot-deck-based multiple imputation (HM), and regression-based multiple imputation (RM). These MDTs were assessed in the context of regression weight estimates in multiple regression analysis in complex sample data with two data levels. In this study, the multiple regression equation had six regressors without missing data and two regressors with missing data. The four performance measures used in this study were statistical bias, RMSE, CI width, and coverage probability (i.e., 95%) of the confidence interval.
The five MDTs were evaluated separately for three types of missingness: MCAR, MAR, and MNAR. For each type of missingness, the studied MDTs were evaluated at four levels of missingness (10%, 30%, 50%, and 70%) along with complete sample conditions as a reference point for interpretation of results. In addition, ICC levels (.0, .25, .50) and high and low density population were also manipulated as studied factors.
The study’s findings revealed that the performance of each individual MDT varied across missing data types, but their relative performance was quite similar for all missing data types except for LW’s performance in MNAR. RS produced the most inaccurate estimates considering bias, RMSE, and coverage of confidence interval; RM and HM were the second poorest performers. LW as well as HS procedure outperformed the rest on the measures of accuracy and precision in MCAR; however LW’s measures of precision decreased in MAR and MNAR, and LW’s CI width was the widest in MNAR data. In addition, in all three missing data types, those poor performers were less accurate and less precise on variables with missing data than they were on variables without missing data; and the degree of accuracy and precision of these poor performers depended mostly on the level of data ICC. The proportion of missing data only noticeably affected the performance of HM such that in higher missing data levels, HM yielded worse performance measures. Population density factor had negligible effects on most of the measures produced by all studied MDTs except for RMSE, CI width, and CI coverage produced by LW which were modestly influenced by population density.
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The Study of Hyper-Rayleigh Scattering of Organic Materials at 1907nmKuo, Tz-Yuan 24 July 2002 (has links)
The technique of hyper-Rayleigh scattering is employed to measure the first molecular hyperpolarizabilities£]of nonlinear optical chromophores provided by Industrial Technology Research Institute.
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In the thesis, the effect of the molecular structure and the solvent on the hyperpolarizabilities will be discussed further.
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Blunder or Plunder? Donor, Recipient, and Aid Attributes for the Successful Use of Bilateral Aid as a Foreign Policy ToolBezerra, Paul Anthony, Bezerra, Paul Anthony January 2017 (has links)
Since the 1970s, the number and variety of states providing bilateral aid has grown. In 1973, 16 states provided aid; in 2013, 31 provided aid. This growth may not appear substantial, but it greatly outstrips growth in the number of states in the international system over the same time period (~46% versus 94%). Given states commit aid for a variety of reasons – prominently, including their own geopolitical self-interests – this growth in the bilateral aid donor community suggests donors are likely to encounter increased competition for any given recipient’s foreign policy cooperation. In the face of this increased competition, this dissertation asks: under what conditions will some bilateral aid donors experience greater foreign policy cooperation as a result of their aid efforts than other donors? To answer this question, this dissertation develops and contributes a framework for better understanding when bilateral donors – in the context of a competitive aid-for-policy "marketplace" – will experience greater geopolitical gain.
The donor-recipient aid and cooperation framework suggests each component of the aid-for-policy exchange – the donor, the recipient, and the aid itself – is likely to influence the success any given donor experiences utilizing aid to promote foreign policy cooperation. At its core, the framework argues any given donor’s ability to use aid to promote foreign policy cooperation is a function of their own decision-making and policy process; in particular, their abilities to interpret information and adjust policies. This function, however, is likely to be conditioned by the recipient’s set of donor relationships, the donor's ability to overcome friction and resistance in their policy process, and the on-the-ground experience of the aid’s consumers. In developing this argument, the donor-recipient aid and cooperation framework draws upon a variety of theories from international relations, foreign policy decision-making, public policy, and organization theory.
Overall, I find elements related to the donor and the recipient condition the success any given donor experiences utilizing aid to promote foreign policy cooperation. The results indicate that donors who possess dependence-based power advantages, or higher levels of mutual dependence, with their recipients are likely to experience improved foreign policy cooperation, but this experience substantively varies across different levels of aid giving. Additionally, some donors – due to their power status, regime type, or organizational memberships and normative adherences – are likely to experience more cooperation than others as a result of lower decision costs and institutional costs in their policy processes. The third element of the donor-recipient aid and cooperation framework, the aid itself, remains untested and is left for analysis in future work.
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A Two-Level Galerkin Reduced Order Model for the Steady Navier-Stokes EquationsPark, Dylan 15 May 2023 (has links)
In this thesis we propose, analyze, and investigate numerically a novel two-level Galerkin reduced order model (2L-ROM) for the efficient and accurate numerical simulation of the steady Navier-Stokes equations. In the first step of the 2L-ROM, a relatively low-dimensional nonlinear system is solved. In the second step, the Navier-Stokes equations are linearized around the solution found in the first step, and a higher-dimensional system for the linearized problem is solved. We prove an error bound for the new 2L-ROM and compare it to the standard Galerkin ROM, or one-level ROM (1L-ROM), in the numerical simulation of the steady Burgers equation. The 2L-ROM significantly decreases (by a factor of 2 and even 3) the 1L-ROM computational cost, without compromising its numerical accuracy. / Master of Science / In this thesis we introduce a new method for efficiently and accurately simulating fluid flow, the Navier-Stokes equations, called the two-level Galerkin reduced order model (2L-ROM). The 2L-ROM involves solving a relatively low-dimensional nonlinear system in the first step, followed by a higher-dimensional linearized system in the second step. We show that this method produces highly accurate results while significantly reducing computational costs compared to previous methods. We provide a comparison between the 2L-ROM and the standard Galerkin ROM, or one-level ROM (1L-ROM), by modeling the steady Burgers equation, as an example. Our results demonstrate that the 2L-ROM reduces the computational cost of the 1L-ROM by a factor of 2 to 3 without sacrificing accuracy.
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Energy dissipation in oxide glasses / Dissipation d'énergie dans les verres d'oxydesDamart, Tanguy 28 September 2017 (has links)
L'atténuation d'ondes à basse et haute fréquences dans les verres n'est pas encore bien comprise en grande partie car les phénomènes à l'origine de cette dissipation varient grandement en fonction de la fréquence. L’existence de structures complexes et organisation multi échelle dans les verres favorise l'apparition de temps de relaxation allant de la seconde à la femtoseconde et de corrélation prenant place de l’Angström à la centaine de nanomètre. A basse fréquence, une meilleur compréhension de ces phénomènes de dissipation serait bénéfique à de nombreux domaines. Par exemple, les multi-couches recouvrants les miroirs des interféromètres servant à détecter les ondes gravitationnelles sont réalisées à partir de verres d'oxyde (SiO2 et Ta2O5) qui sont une source majeur de dissipation. A haute fréquence, l'étude de la dissipation pose des questions théoriques sur le lien entre asymétrie locale et atténuation acoustique.Durant cette étude, nous avons réalisé une analyse approfondie de l'interaction entre ondes mécaniques et structure des verres en utilisant des techniques de simulations telle que la dynamique moléculaire. En partant de la synthèse de verres de SiO2 et Ta2O5, nous nous sommes appliqués à trouver l'origine structurelle de la dissipation aux différentes échelles de fréquence. A basse fréquence nous avons été capable de catégoriser les déplacements atomiques à l'origine de la dissipation en utilisant la théorie des états à deux niveaux. A haute fréquence, nous avons utilisé une technique de spectroscopie mécanique appuyé par un développement analytique pour montrer l'importance du désordre local dans l’existence de dissipation / The origin of sound attenuation at low and high frequency in glasses stays elusive mainly because of the complex temperature and frequency dependence of the phenomena at its root. Indeed, the presence of complex structures and multi-scale organizations in glasses induce the existence of relaxation time ranging from the second to the femto-second and of spatial correlation ranging from the Angström to a hundred nanometers. At low-frequency, a better understanding of the phenomena at the origin of dissipation would be beneficial to several applications. For example, the multi-layers coating the mirrors of gravitational waves detectors consists of a superposition of two oxide glasses: silicate (SiO2) and tantalum pentoxide (Ta2O5), are an important source of dissipation. At high frequency, the study of dissipation raises theoretical questions about the link between attenuation and dissipation as well as between loclt asymmetry and dissipation. In the present study, we conducted an analysis of the interaction between mechanical waves and the structure of two oxide glasses using simulation techniques such as non-equilibrium molecular dynamics. At high-frequencies, we implemented and used mechanical spectroscopy to measure dissipation numerically and performed in parallel an analytical development based on the projection of the atomic motion on the vibrational eigenmodes. At low-frequencies, we used molecular dynamics to gather sets of thermally activated events that we classed in three categories based on topologically distinct atomic motions and from which we predicted dissipation numerically using a refreshed TLS model
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Three is a Crowd : A Critical Analysis of Third Party Actor Influence Regarding the Nuclear Negotiations Between P5+1 and IranPucher, Isabelle, Dahlbeck, Kim January 2015 (has links)
This thesis examines third-party actor influence on the domestic level in the ongoing diplomatic negotiations between P5+1 and Iran, with the research question being; What demands, arguments and strategies does the Congress and AIPAC use to influence the negotiation process between the U.S. and Iran? Secondly, what are their goals for doing so? Furthermore, the combined theoretical framework has been applied onto the material using a critical method in order to answer the questions. Legislative bills from the Congress, regarding congressional insight to the agreement, have been approved. In this pressured negotiation process with high stakes it is astounding that these actions are allowed. Due to this behavior from Congress, amongst others, it becomes interesting to study the negotiation process and its salient third-party actor influence. The results suggests that legislative actions combined with various demands and arguments, focused on mistrust of Iran, history and the security of Israel, are their main strategies to gain influence. An additional new, third, level has also been discovered by the authors of this thesis in regards to these complicated negotiations.
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Regime Type and Trade Policy : Has Increased Democratization Contributed to Lower Trade Barriers Among Autocratic States?Olsson, David January 2009 (has links)
<p> </p><p> </p><p> </p><p> </p><p> </p><p><h1>Abstract</h1><h2>C-Level Paper in Political Science, by David Olsson, Autumn 2008. Supervisor: Malin Stegman McCallion. “Regime Type and Trade Policy: Has Increased Democratization Contributed to Lower Trade Barriers Among Autocratic States?”</h2><p> </p><p>In this paper a new two-level game theory, based on previous research and deductive reasoning, is constructed and tested empirically. The purpose is to examine if developing new democracies, trading with developing autocracies, is an explanatory factor of trade liberalization among the latter. The research questions are: 1) Have tariff rates in developing autocratic countries followed the pattern of reduced tariffs among their developing new democratic trading partners? And; 2) If this is the case, is there a relative shift in trade flows that confirms this change to be an effect of the new democracies’ presumed influence?</p><p> In order to sufficiently carry out an empirical scrutiny, seven other determinants found to have effects on trade policies in previous research, are accounted for using a “most similar systems design”. For reasons of delimitation, six autocracies and their fifteen most important trading partners, observed 1980-1999, have been paired and analyzed. Each pair consists of one autocracy that trades with new democracies and one that does not; regarding the other determinants they are as similar as possible. The used material is the World Development Indicators, the Polity IV Dataset, the Yearbook of International Trade Statistics, the World Economic Outlook Database, the Database of Political Institutions, statistics from the World Trade Organization, the Dataset of Armed Conflicts, and the Unweighted Average Tariffs Measurement. </p><p> The conclusion is that there are no indicators that affirm the theory and research questions. However, the theory is not unambiguously falsified. Hence, studies on more countries and time spans are needed. </p><p> </p><p> </p></p><p> </p><p><p> </p></p><p> </p>
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A host-parasite multilevel interacting process and continuous approximationsMéléard, Sylvie, Roelly, Sylvie January 2011 (has links)
We are interested in modeling some two-level population dynamics, resulting from the interplay of ecological interactions and phenotypic variation of individuals (or hosts) and the evolution of cells (or parasites) of two types living in these individuals. The ecological parameters of the individual dynamics depend on the number of cells of each type contained by the individual and the cell dynamics depends on the trait of the invaded individual. Our models are rooted in the microscopic description of a random (discrete) population of individuals characterized by one or several adaptive traits and cells characterized by their type. The population is modeled as a stochastic point process whose generator captures the probabilistic dynamics over continuous time of birth, mutation and death for individuals and birth and death for cells. The interaction between individuals (resp. between cells) is described by a competition between individual traits (resp. between cell types). We look for tractable large population approximations. By combining various scalings on population size, birth and death rates and mutation step, the single microscopic model is shown to lead to contrasting nonlinear macroscopic limits of different nature: deterministic approximations, in the form of ordinary, integro- or partial differential equations, or probabilistic ones, like stochastic partial differential equations or superprocesses. The study of the long time behavior of these processes seems very hard and we only develop some simple cases enlightening the difficulties involved.
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Evolutive two-level population process and large population approximationsMéléard, Sylvie, Roelly, Sylvie January 2013 (has links)
We are interested in modeling the Darwinian evolution of a population described by two levels of biological parameters: individuals characterized by an heritable phenotypic trait submitted to mutation and natural selection and cells in these individuals influencing their ability to consume resources and to reproduce. Our models are rooted in the microscopic description of a random (discrete) population of individuals characterized by one or several adaptive traits and cells characterized by their type. The population is modeled as a stochastic point process whose generator captures the probabilistic dynamics over continuous time of birth, mutation and death for individuals and birth and death for cells. The interaction between individuals (resp. between cells) is described by a competition between individual traits (resp. between cell types). We are looking for tractable large population approximations. By combining various scalings on population size, birth and death rates and mutation step, the single microscopic model is shown to lead to contrasting nonlinear macroscopic limits of different nature: deterministic approximations, in the form of ordinary, integro- or partial differential equations, or probabilistic ones, like stochastic partial differential equations or superprocesses.
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U.S.,ISRAEL, PALESTINE : - A REFLECTION OVER THE IMPORTANCE OF NEGOTIATION -Varga, Kristina January 2012 (has links)
The purpose of this study is to examine the U.S. relations to Israel and the affect the relationship has had on Palestine from the viewpoint of Robert D. Putnam’s `two level-game´ theory. The core of the theory is that representatives have been placed between two tables; where one represents domestic negotiations while the other represents foreign negotiations. The bargains made at the foreign table affects the state’s domestic politics and vice versa. Applying the theory on U.S. relations to Israel it is possible to see that the U.S. is leading an unsuccessful negotiation at both tables. The relationship between the U.S. and Israel has existed since U.S. decided to recognize the state in 1948. Events such as the Holocaust and 9/11 have let Israel keep its underdog status as well as its sympathy from the American population. Israel also has a very powerful lobby group which have tried to steer U.S. policies towards its goal, the continuation of the Israeli state. The U.S. government have different interests in the region, besides the peace between Israel and Palestine. This leads to the government’s most difficult mission, being able to both satisfy their own people as well as proceeding with its plans and agendas for the region.
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