Showing 471 - 480 of 3500 Items

Investigating the role of eyes absent in photoreceptor axon targeting in Drosophila melanogaster

Date: 2021-01-01

Creator: Bethany J. Thach

Access: Open access

The eya gene is essential to development of the Drosophila visual system and eye-specific loss of function mutations in the gene commonly result in the missing eye phenotype. The eya2m35g mutation carries a deletion of exon 1B and adjacent regulatory sequences. Flies carrying the eya2m35g allele exhibit a photoreceptor axon phenotype that has not previously been associated with the eya gene. To determine a potential role for eya in photoreceptor axon targeting, I characterized various phenotypes of eya2m35g mutants and generated additional eya alleles consisting of smaller deletions within the eya2m35g mutation to locate the genetic source of axonal disruption. Using immunofluorescence staining to visualize Eya protein, I found a loss of eya expression in the optic lobe region of eya2m35g stage 9 embryos and third instar larvae. I also observed a loss of retinal basal glial (RBG) cells in the larval eye disc. Finally, I demonstrated that the disconnected axon phenotype is generated when a region of the intron immediately downstream of exon 1B is deleted. These findings suggest that a possible regulatory element for eya that is essential for photoreceptor axon targeting exists in this intronic region.


Caring like a state: The elaboration of a care ideology in Peru and Sri Lanka in the 20th century

Date: 2015-05-01

Creator: Katharine Herman

Access: Open access

This project compares the interaction between the government and the population in both Peru and Sri Lanka through the 20th century, focusing on the provision of care (services, benefits, and recognition as provided by the governing apparatus) as a locus for their most meaningful interaction. The provision of care can be seen as a form of communication established in certain practices, symbols, and discourses. Moreover, the provision of care works to reorient the subject population into a more beneficial relationship with the state–notably one of increased dependence and trust. Through the elaboration of what care is and how it functions, a care ideology is established creating a terrain through which the politics of the governed and the governing alike can be legitimized. Care ideology can then be considered a further articulation of the state idea, creating a dialogue about how governance can or should be affected within a certain context. These case studies then illustrate the terrain over which both of these governing bodies work. In Sri Lanka, the governing apparatus provides a means for citizens to live a symbolically meaningful life through paddy farming. In Peru, the governing apparatus provides access to the state through civil infrastructure like roads and education. Through care, material goods become invested with meaning and the state idea becomes materialized. Care is a then substantial project undertaken by the state to ensure its own reproduction and further widen the possibilities for the state project to be effected through its own citizens.


Accretion Onto a Black Hole at the Center of a Neutron Star: Nuclear Equations of State

Date: 2022-01-01

Creator: Sophia Christina Schnauck

Access: Open access

A recent re-examination of Bondi accretion (see Richards, Baumgarte and Shapiro (2021)) revealed that, for stiff equations of state (EOSs), steady-state accretion can only occur for accretion rates exceeding a certain minimum. To date, this result has been explored only for gamma-law equations of state. Instead, we consider accretion onto a small black hole residing at the center of a neutron star governed by a more realistic nuclear EOS. We generalize the relativistic Bondi solution for such EOSs, approximated by piecewise polytropes, and thereby obtain analytical expressions for the accretion rates which were reflected in our numerical simulations. After taking several different piecewise EOSs at different neutron star densities into account, the accretion rates of the different EOSs were only slightly larger than the previously observed minimum. In other words there appears to be evidence for a nearly universal accretion rate that depends only on the black hole mass. However, we also observed that for certain densities the fluid profiles of several EOSs exhibited superluminal sound speeds outside the horizon of the black hole, suggesting that the EOSs are not appropriate at these densities.


Jigs, Reels, and “Realness”: An Investigation of Ideas of Authenticity and Tradition in New England French Canadian Music

Date: 2021-01-01

Creator: Lowell Ruck

Access: Open access

Franco-American culture is increasingly recognized as an integral part of the heritage of Maine and New England, and has attracted growing academic attention in recent years. But while many scholars and cultural promoters focus on the French language in their work on this subject, few studies have considered the position of traditional music in Franco-American communities in the 21st century. This thesis examines French Canadian traditional music as it is played in New England and the ways in which musicians think about authenticity and tradition in their art. Using material from ethnographic interviews, it illuminates how musicians draw from individual, familial, and communal experiences and from past, present, and future conceptions of authentic tradition in their roles as cultural mediators. Ultimately, it suggests that players of French Canadian traditional music interact with this tradition in diverse ways, and that in doing so, they help to maintain the vibrancy of Franco-American cultural practices. La culture franco-américaine est reconnue de plus en plus comme partie intégrante de l’héritage du Maine et de la Nouvelle-Angleterre et attire maintenant l’attention académique. Mais même si beaucoup d’érudits et de promoteurs culturels ciblent la langue française dans leur travail sur ce sujet, peu d’études ont considéré la position de la musique traditionnelle dans les communautés franco-américaines du XXIe siècle. Cette thèse se concentre sur la musique traditionnelle canadienne-française de la Nouvelle-Angleterre et sur les façons dont les musiciens conceptualisent l’authenticité et la tradition dans leur art. En utilisant des entrevues ethnographiques, elle illumine comment les musiciens tirent des expériences individuelles, familiales et communautaires et des idées du passé, du présent et de l’avenir dans leurs rôles comme médiateurs culturels. Finalement, elle suggère que les joueurs de la musique traditionnelle canadienne-française interagissent avec cette tradition de plusieurs façons, et ce faisant, aident à maintenir la brillance des pratiques culturelles franco-américaines.


The Photocatalytic Degradation of Ibuprofen and Atenolol Using Bismuth Oxychloride and Titanium Dioxide

Date: 2021-01-01

Creator: Kamyron Anthony Speller

Access: Open access

Pharmaceuticals and personal care products (PPCPs) are contaminating natural bodies of water and are problematic for aquatic organisms and ecosystems. Generally, PPCPs are introduced to water systems due to incomplete removal by wastewater treatment plants (WWTPs). As such, it is vital to find ways to remediate these problematic contaminants before they are discharged into the environment. In this study, two photocatalysts¾titanium dioxide (TiO2) and bismuth oxychloride (BiOCl)¾were compared to determine their relative efficiencies (degradation rates) and dominant degradation mechanism (hydroxyl radical production or direct oxidation) with the goal of photocatalytically degrading two pharmaceuticals, atenolol and ibuprofen, using UV (254 nm) light. While TiO2 has been used extensively for photocatalytic degradation, BiOCl is a newer photocatalyst. The two pharmaceuticals selected for study represent two large classes of drugs (aryloxypropanolamine and propionic acid derivatives, respectively) that have been detected in the influent into and effluent from wastewater treatment plants and in the environment. When irradiated at 254 nm, BiOCl degrades ibuprofen with a rate constant 15 times greater than TiO2. On the other hand, TiO2 degrades atenolol with a rate constant 2.2 times greater than BiOCl. LCMS analysis of photodegradation products reveals different products produced by the two photocatalysts, providing evidence for the dominance of different degradation mechanisms for the two photocatalysts. In summary, this work suggests that BiOCl, potentially used in combination with TiO2, holds potential for degrading PPCPs in natural bodies of water.


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.