Showing 311 - 320 of 2039 Items
Critical Phenomena in the Gravitational Collapse of Electromagnetic Dipole and Quadrupole Waves
Date: 2021-01-01
Creator: Maria F. Perez Mendoza
Access: Open access
- We report on critical phenomena in the gravitational collapse of electromagnetic waves. Generalizing earlier results that focused on dipole electromagnetic waves, we here compare with quadrupole waves in axisymmetry. We perform numerical simulations of dipole and quadrupole wave initial data, fine-tuning both sets of data to the onset of black hole formation in order to study the critical solution and related critical phenomena. We observe that different multipole moments have different symmetries, indicating that the critical solution for electromagnetic waves cannot be unique, at least not globally. This is confirmed in our numerical simulations: while dipole data lead to a single center of collapse, at the center of symmetry, quadrupole data feature two separate centers of collapse on the symmetry axis, above and below the center of symmetry -- reminiscent of similar findings reported for critical collapse of vacuum gravitational waves. While the critical solution for neither the dipole nor the quadrupole data is exactly self-similar, we find that their approximate echoing periods appear to differ, as do the critical exponents. We discuss whether the centers of collapse found for dipole and quadrupole data might all have the same properties, which would suggest a ``local uniqueness" of the critical solution. Instead, we provide some evidence -- including the differing echoing periods and critical exponents -- suggesting that the critical solutions are distinct even locally. We speculate on the implications of our findings for critical phenomena in the collapse of vacuum gravitational waves, which share with electromagnetic waves the absence of a spherically symmetric critical solution.
"In Loving Virtue": Staging the Virgin Body in Early Modern Drama
Date: 2022-01-01
Creator: Miranda Viederman
Access: Open access
- The aim of this Honors project is to investigate representations of female virginity in Renaissance English dramatic works. I view the period as one in which the womb became the site of a unique renewal of cultural anxieties surrounding the stability of the patriarchy and the inaccessibility of female sexual desire. I am most interested in virginity as a “bodily narrative” dependent on the construction and maintenance of performance. I analyze representations of virginity in female characters from four works of drama originating in the Jacobean period of the English Renaissance, during and after the end of the reign of Elizabeth I, the Virgin Queen. Across four chapters, I examine the characters of Isabella from Shakespeare’s Measure for Measure (1604), Beatrice-Joanna from Thomas Middleton’s The Changeling (1622), the Jailer’s Daughter from Shakespeare and Fletcher’s The Two Noble Kinsmen (1634), and Helen from Shakespeare’s All’s Well That Ends Well (c. 1602-1605). To establish a framework for my readings, I situate each work in its contemporary cultural context, drawing upon Catholic and Protestant religious doctrines, period medical texts, and popular culture. I intend to explore the complex, often contradictory nature of the forms of virginity the plays depict. Still, I hope by uncovering the opportunities these four characters are provided by their virginity, that I can widen the confines of the category.
Evaluating Dam Relicensing and River Herring Habitat Restoration from a Broad, Multi-Ecosystem Perspective
Date: 2022-01-01
Creator: Matthew L. Thomas
Access: Open access
- This study investigates the potential benefits of using a broad, multi-ecosystem analysis in the licensing and relicensing of hydropower facilities. Specifically, it considers the impact of river herring restoration on coastal food webs and cod and other groundfish populations in the Gulf of Maine. The past two decades of research on fisheries management, ecosystem connectivity, and the connection between river herring and groundfish in the Gulf of Maine have resulted in a better understanding of the ways in which human activities, such as dam building, influence ecological processes. The paper analyzes two case studies of six Maine dams currently engaged in the Federal Energy Regulatory Commission’s (FERC) hydroelectric dam relicensing process. The analysis illustrates the shortcomings of the Federal Power Act’s provisions that address the balancing of ecological and power generation concerns. Following the case studies, a series of policy recommendations are presented to encourage a more transparent and predictable relicensing process that adequately values both ecological and power generation goals. Changes are suggested for both the FERC process itself and the process by which state and federal resource agencies may provide comments regarding how a proposed dam licensing or relicensing affects natural resources under their jurisdiction. The proposed policy recommendations will increase the resilience of natural systems as they adapt to climate impacts.
A Problem Best Put Off Until Tomorrow
Date: 2023-01-01
Creator: Evan Albers
Access: Open access
- Effective Altruism has led a recent renaissance for utilitarian theory. However, it seems that despite its surge in popularity, Effective Altruism is still vulnerable to many of the critiques that plague utilitarianism. The most significant amongst these is the utility monster. I use Longtermsim, a mode of thinking that has evolved from Effective Altruism and prioritizes the far-future over the present in decision-making processes, as an example of how the unborn millions of the future might constitute a utility monster as a corporate mass. I investigate three main avenues of resolving the utility monster objection to Effective Altruism: reconsidering the use of expected value, adopting temporal discounting, and adopting average utilitarianism. I demonstrate that at best there are significant problems with these responses, and at worst, they completely fail to resolve the utility monster objection. I then conclude that if situations do exist in which the costs to the present do not intuitively justify the benefits to the far future, we must reject utilitarianism altogether.
Sensitivity Analysis of Basins of Attraction for Nelder-Mead
Date: 2022-01-01
Creator: Sonia K. Shah
Access: Open access
- The Nelder-Mead optimization method is a numerical method used to find the minimum of an objective function in a multidimensional space. In this paper, we use this method to study functions - specifically functions with three-dimensional graphs - and create images of the basin of attraction of the function. Three different methods are used to create these images named the systematic point method, randomized centroid method, and systemized centroid method. This paper applies these methods to different functions. The first function has two minima with an equivalent function value. The second function has one global minimum and one local minimum. The last function studied has several minima of different function values. The systematic point method is a reliable method in particular scenarios but is extremely sensitive to changes in the initial simplex. The randomized centroid method was not found to be useful as the basin of attraction images are difficult to understand. This made it particularly troublesome to know when the method was working effectively and when it was not. The systemized centroid method appears to be the most precise and effective method at creating the basin of attraction in most cases. This method rarely fails to find a minimum and is particularly adept at finding global minima more effectively compared to local minima. It is important to remember that these conclusions are simply based off the results of the methods and functions studied and that more effective methods may exist.
Properties of Slicing Conditions for Charged Black Holes
Date: 2023-01-01
Creator: Sean E. Li
Access: Open access
- We consider an earlier analysis by Baumgarte and de Oliveira (2022) of static Bona-Massó slices of stationary, nonrotating, uncharged black holes, represented by Schwarzschild spacetimes, and generalize that approach to Reissner-Nordström (RN) spacetimes, representing stationary, nonrotating black holes that carry a nonzero charge. This charge is parametrized by the charge-to-mass ratio λ ≡ Q/M, where M is the black-hole mass and the charge Q may represent electrical charge or act as a placeholder for extensions of general relativity. We use a height-function approach to construct time-independent, spherically symmetric slices that satisfy a so-called Bona-Massó slicing condition. We compute quantities such as critical points and profiles of geometric quantities for several different versions of the Bona-Massó slicing condition. In some cases we do this analytically, while in others we use numerical root-finding to solve quartic equations. We conclude that in the extremal limit as λ → 1, all slices that we consider approach a unique slice that is independent of the chosen Bona-Massó condition. We then study dynamical, i.e. time-dependent, Bona-Massó slices by analytically predicting the qualitative behavior of the central lapse, i.e. the lapse at the black-hole puncture, for a particular slice that Alcubierre (1997) proposed to mitigate gauge shocks. These shock-avoiding slices are a viable alternative to the very common so-called 1 + log slices but exhibit different behavior in dynamical simulations. We use a perturbation of the radial coordinate at the location of the puncture to recover approximately harmonic late-time oscillations of the central lapse that Baumgarte and Hilditch (2022) observed in numerical simulations.
From “This Revolution is Neither Communist nor Capitalist!” to “Long Live the Socialist Revolution:” The Deterioration of U.S.-Cuban Relations from 1958-1961
Date: 2023-01-01
Creator: Julia Lyne
Access: Open access
- This thesis studies the deterioration of U.S.-Cuban relations from 1958-1961. Mainly drawing from primary sources from the National Archives, it seeks to answer and understand how and why relations deteriorated so rapidly. It pushes against the common belief that U.S.-Cuban relations were doomed from the start, instead highlighting in Chapter One Fidel Castro’s rise to power (and Fulgencio Batista’s fall from power) and revealing that the U.S. government was not entirely against Castro’s seizure of power. Chapter Two explores Castro’s first year in power and the (futile) attempts made by both governments to keep relations alive. Finally, it closes with the destruction of official and unofficial relations, suggesting that President Eisenhower’s covert approval of the invasion of the Bay of Pigs marked the covert ending to political relations as well as rising economic and political tensions due to an incompatibility of demand and interest in the sugar and oil industries. Ultimately, this thesis suggests that it was not just a matter of communism that led to the destruction of U.S.-Cuban relations at the time; instead, it was because of compounding effects of other various other economic and political factors and incompatibilities, such as the sugar and oil industries, public and political slandering and attacks from both sides, and an increasing acceptance of the Soviet Union and its supporters. This analysis does not seek to argue against the influence of communism in its entirety; rather, it aims to highlight and nuance the contributing factors to this deterioration.
Religious Negotiation and Identity Formation: Reading Material Religion in Oaxaca’s “Guelaguetza Oficial”
Date: 2023-01-01
Creator: Rene Sebastian Cisneros
Access: Open access
- The Oaxacan Guelaguetza Oficial is a folk-dance festival in the state of Oaxaca, Mexico which takes place on the last two Mondays of July each year. This state-sponsored celebration of Oaxacan identity is intertwined within histories of Indigenous religious belief and Catholic everyday practice. The Guelaguetza Oficial can be traced back to late 19thcentury celebrations venerating the Virgen del Carmen Alto. Oaxaqueños today predominantly practice an Indigenous-Catholic tradition whose rituals, festive scripts, pantheon of popular saints, and immanent understandings of heavenly power over earthly events can be traced back to negotiations between Indigenous forms of popular belief and institutionalized Catholic practice. Through historical and present-day religious tensions between existing modes of Indigenous religious belief and institutionalized Oaxacan Catholic practice, this thesis asserts that while Indigeneity often represented an obstacle to different structures of power in Mexican history, hegemonic institutions eventually came to accept the lasting presence of Indigenous identity and religious life to varying degrees within Mexican society and culture. This resulting reading of Guelaguetza demonstrates how religion is fundamentally implicated in the history of public festival and popular culture in Oaxaca. Furthermore, this thesis argues that Indigenous-Catholicism has not lost its prominence in public space in Oaxaca despite the reforms of post-1910 Oaxacan state and Mexican national politics and the effects of globalized neoliberal economies in the late 20th and early 21st centuries.
Deciphering Policymaking—The Enigma of the 2003 Iraq War
Date: 2024-01-01
Creator: Chengkai Gu
Access: Open access
- This thesis examines the forces shaping the United States’ decision to initiate the 2003 Iraq War. It argues that while the Bush administration had vested interests in disarming Iraq to eliminate Saddam Hussein’s military threat and to secure stable global oil supplies, the decision-making process leading to the Iraq War was heavily influenced by domestic politics, such as bureaucratic bargaining, CIA intelligence collections, and interest group competition. In addition, individual-level factors, such as top officials’ personal beliefs and psychologies, also shaped the decision to intervene in Iraq. By explaining how strategic, domestic, and personal factors interacted to shape the decision to launch the Iraq War, my study underscores the impact of less obvious micro-level dynamics on international politics and the multi-layered nature of foreign policymaking.
Una Comprensione Computazionale della Psiche Emotiva e Ordine nelle Ballate del Decameron: Stilometria e Elaborazione del Linguaggio Naturale
Date: 2023-01-01
Creator: Nothando Khumalo
Access: Open access
- The present thesis, written in Italian, explores the emotional psyche and narrative order embedded within the ballads of the Decameron, a renowned literary masterpiece by Giovanni Boccaccio. Leveraging the advancements in stylometry and natural language processing techniques, this research aims to convince medieval Italian literature scholars to produce more on scholarship of the ballads and uncover the intricate patterns of human emotions and narrative organization in the ballads. The study begins by establishing a comprehensive corpus of ballads from the Decameron, utilizing digital libraries and text repositories. Subsequently, using stylometric analysis, the research examines the linguistic and stylistic features that distinguish the brigata’s ballads, focusing on elements such as vocabulary, syntax, and rhyme scheme. These analyses enable the identification of authorial patterns, shedding light on the emotional expressions and narrative techniques employed by Boccaccio. A natural language processing model was used to predict authorship of the ballads using each of the brigata’s novelle as training data. The findings of this research contribute to a deeper understanding of the emotional and narrative purpose of the Decameron's ballads. Results of stylometric analysis allowed for new characterization of Panfilo’s ballad as sad and revealed how similarity in the emotional psyches of the brigata transcends gender. These novel perspectives allowed for unique literary analysis of the ballads. Accurate prediction of ballad authorship demonstrates that ballads fit into the narrative structure of the Decameron and restore order in each of the ten days.