Showing 1561 - 1570 of 2039 Items
Modeling the Development & Expression of Political Opinion: A Zallerian Approach
Date: 2024-01-01
Creator: Avery C Ellis
Access: Open access
- Research focused on John Zaller's famous RAS model of political opinion formation and change from "The Nature and Origins of Mass Opinion" (1992). Analyzed the mathematical and psychological underpinnings of the model, the first paper to do so in over fifteen years and the first to do so through an analysis of motivated reasoning and Bayesian reasoning. Synthesized existing critiques of Zaller's model and other literature to suggest ways to build on Zaller, utilizing fundamental reunderstandings of opinions and messages from political and mathematical perspectives. Found verification for Zaller's model, confirming its value, but also found support for the proposed RAIS model, which suggests foundational changes in the way citizens interact with information in the current political environment. Confirmed the utility of a Zallerian framework for analyzing shifts in mass opinion over time and suggested ways to improve the creation of surveys and polls for understanding elections and reported opinions on issues.
New Institutional Economics: Political Institutions and Divergent Development in Costa Rica and Honduras
Date: 2022-01-01
Creator: Maynor Alberto Loaisiga Bojorge
Access: Open access
- For most of their histories, Costa Rica and Honduras were primarily agricultural societies with little economic diversification. However, around 1990, after the implementation of Washington Consensus reforms, the economies of both nations began to diverge. Costa Rica’s economy rapidly expanded for the following 30 years, while Honduras remained stagnant. Through a New Institutional Economics approach, I argue that institutional differences between Costa Rica and Honduras are responsible for the impressive economic growth Costa Rica has been able to achieve in the past few decades. Specifically, early political developments in Costa Rica have deeply imbedded relatively egalitarian values into the population, helping shape formal and informal inclusive political institutions. Meanwhile, Honduras experienced the development of extractive political institutions, as political and economic power was heavily concentrated in the hands of a select few. These political institutions were crucial during the implementation stages of Washington Consensus reforms, as strong and inclusive political institutions attracted Foreign Direct Investment that helped propel the Costa Rican economy and materialize its position as an outlier in the region. In contrast, lack of institutional guarantees discouraged foreign investors from investing money into the Honduran economy. Through a deep dive into the political histories of both nations, from European discovery to modernity, I conclude that the political institutions of these Central American nations have determined their economic growth paths.
Empire of Horror: Race, Animality, and Monstrosity in the Victorian Gothic
Date: 2022-01-01
Creator: Grace Monaghan
Access: Open access
- This project examines Victorian England through the analysis of three Victorian gothic novels: Bram Stoker’s Dracula (1897) and The Jewel of Seven Stars (1903/1912), and Richard Marsh’s The Beetle (1897). The end of the nineteenth century and the final years of the Victorian era brought with them fears and uncertainties about England’s role in the world and its future, fears that the Victorian gothic sought to grapple with, but inevitably failed to contain. In examining this genre, I draw on “Undisciplining Victorian Studies” (Chatterjee et al, 2020), which calls for the field of Victorian studies to center racial theory. As such, I foreground race and whiteness in these novels, in conjunction with animality, empire, and sexuality, all of which were crucial tools in the imperial gothic’s project of constructing the monstrous Other. The British empire relied on the establishment of a physical and moral boundary between itself and the colonized Other, in order to justify its imperialism and maintain its own perceived superiority. Yet, ultimately, this project demonstrates that the boundaries between the self and the Other, between morality and monstrosity, and between mainland England and its empire, were dangerously porous.
Diatom blooms in Harpswell Sound: seasonality, succession, and origin
Date: 2023-01-01
Creator: Charlie Francis O'Brien
Access: Open access
- Harpswell Sound (HS) is an inlet in northeastern Casco Bay that exerts control on Gulf of Maine ecosystem health, yet its complex phytoplankton community dynamics have not been characterized with sufficiently detailed analyses. In this research, high-resolution automated microscopy and current velocity observations were used to test the seasonality, ecological succession, bloom origin location, and potential toxicity of populations in HS between 2020 and 2022. Winter months could exhibit slow accumulation of diatom biovolume. Cold, salty surface water has net outflow in winter as nutrients from depth are replenished during net upwelling conditions, and populations could be exported from the inlet at the surface. Extreme current velocity variability in spring due to the Kennebec River plume in HS destabilizes spatially uniform populations. Warm, low-salinity surface water with net inflow in summer (net downwelling which retains populations at the head of the sound) corresponds with temporally separate dinoflagellate and diatom blooms. Large, multi-peaked spring and fall diatom blooms are recurrent, contrasting small, short-lived blooms in summer. A successional pattern from diatoms to dinoflagellates is confirmed for summer but refuted for other seasons. The hypothesis that diatom succession during all blooms in HS is characterized by large centric cells preceding small cells or pennate cells was explored but no clear pattern in decreasing cell size was observed. Observed tidal effects on biovolume concentration could mask that blooms develop at coherent times but spatially separated. A diverse community of toxic phytoplankton, including dinoflagellates and Pseudonitzschia, are observed throughout the year.
The Role of ELMO5 in Arabidopsis thaliana Cell Adhesion
Date: 2022-01-01
Creator: Isabel Kristina Ball
Access: Open access
- Plant cell growth and development relies on proper cellular adhesion. As the extracellular matrix serves as the area of connection between two cells, its synthesis and maintenance are essential for cellular adhesion. The middle lamella region, the layer of the extracellular matrix between two adjacent cell walls, is diffuse with the polysaccharide pectin due to its delivery by Golgi vesicles early during cell division. A Ruthenium Red screen for cellular adhesion mutants identified the family of 5 ELMO proteins that are critical for proper cellular adhesion. To further our understanding of plant cellular adhesion and pathways of pectin synthesis and modification, this work investigates ELMO5. Plants homozygous for a T-DNA insertion in ELMO5 and a new deletion mutant allele generated using CRSPR do not have a cellular adhesion phenotype, suggesting it is either not critical for cellular adhesion or is redundant with another gene. Redundancy within the ELMO family is identified through the analysis of double mutants of elmo5 and each of the other four elmo genes. Both elmo1-/- elmo5-/-and elmo4-/- elmo5-/-mutants have a visibly worse cellular adhesion defect phenotype, suggesting partial redundancy through the ELMO family. The mutants are also rescued by growth on agar, pointing to the importance of turgor pressure and osmotic potential in modulating cellular adhesion. Both ELMO4 and ELMO5 were found to localize to the Golgi using a GFP fusion, consistent with a role for ELMOs as scaffold for pectin biosynthesis.
The role of modulation on the pyloric neurons and the neuromuscular junction in a pattern generator-effector system
Date: 2023-01-01
Creator: Jackie Seddon
Access: Open access
- Neuromodulation, the process of altering the electrical outputs of a neuron or neural circuit, allows an organism to control its physiological processes to meet the needs of both its internal and external environments. Previous work shows that the pyloric pattern of the kelp crab (Pugettia producta) stomatogastric nervous system (STNS) neurons responded to fewer neuromodulators than the Jonah crab (Cancer borealis). Since the kelp crab diet primarily eats kelp, it is possible that the movements of the foregut that control digestion may require less flexibility in functional output compared to an opportunistic feeder. To determine whether a reduced flexibility is correlated with diet, this study compared the modulatory responses in Pugettia to two other species of majoid crabs: Chionoecetes opilio and Libinia emarginata, which are both opportunistic feeders. Pooled data for this study found that Libinia and Chionoecetes responded to all twelve modulators tested. When considering the effect of modulators on stomatogastric ganglion (STG) motor outputs, we must consider whether these modulators also alter the excitatory junction potentials (EJPs) at the neuromuscular junction (NMJ), and whether there are differences in responses across species. To test this, the dorsal gastric nerve (dgn) was stimulated while recording intracellularly from the muscle fibers of the associated gm4 muscles. The NMJ of the gm4 in Cancer borealis did not appear to be broadly modulated, as only RPCH and CabTRP showed increases in amplitude, and RPCH decreased facilitation at 5 Hz.
Eroding the Bedrock: The Future of Public Administration Without Chevron Deference
Date: 2024-01-01
Creator: Rose Keller
Access: Open access
- When Congress passes a bill, it produces words on a page. Who decides what those words mean? Historically, the onus of a statute’s interpretation has rested with the federal agencies charged with its implementation. The Chevron doctrine, a two-step standard that affords federal agencies significant latitude in interpreting their own enabling legislation, has been the applicable deference regime in statutory interpretation cases since 1984. Contrary to this tradition, recent Supreme Court jurisprudence has reasserted the primacy of the judiciary in statutory interpretation cases, often ignoring Chevron entirely. In 2023, the Court granted certiorari to Loper Bright Enterprises v. Raimondo, a case that explicitly asked the Court to consider overruling Chevron vs. NRDC, a foundational case in the field of administrative law. This thesis explores the implications of eroding deference to federal agencies through a case study of the Food and Drug Administration and two of its responsibilities. Ultimately, there are potentially negative consequences to limiting agency jurisdiction via eviscerating judicial deference that counsel a more discerning approach.
An AGN as a Counterpart for Neutrino Event IceCube-220303A
Date: 2024-01-01
Creator: Nur Schettino
Access: Open access
- Cosmic rays have been detected for over a century. While some sources have been confirmed, they cannot explain the high energy of the particles (> 10^15 eV), so it remains unclear where and how they are accelerated to extreme energies. The study of astrophysical high-energy neutrinos may help solve the puzzle. These neutrinos are produced by cosmic rays interacting with other charged particles or photons. Moreover, while cosmic rays do not reveal their sources of origin because they can be deflected by magnetic fields, cosmic neutrinos detected by the IceCube Observatory can be traced back to their sources of origin. We will consider an active galactic nucleus (AGN) as a candidate source for a high-energy neutrino.This thesis examines the AGN WISEA J175051.31+105645.3 as a potential source for IceCube-220303A, a high-energy neutrino with a 78% probability of being astrophysical in origin. Using follow-up NuSTAR and Swift/XRT observations, WISEA J175051.31+105645.3 was the only viable source we found in IceCube-220303A’s uncertainty region. We used follow-up X-ray data to construct a multi-wavelength spectral energy distribution (SED) through which we calculated the AGN’s neutrino energy flux. This calculation yields the number of neutrinos we would expect to detect from the AGN in a given time period. We used this number to calculate the probability that IceCube-220303A was emitted by WISEA J175051.31+105645.3. Finding a statistically significant link between IceCube-220303A and WISEA J175051.31+105645.3 may help us better understand what processes can accelerate particles like cosmic rays to extreme energies and learn more about AGN.
Modulation of the stretch feedback pathway in the cardiac neuromuscular system of the American lobster, Homarus americanus
Date: 2024-01-01
Creator: Karin van Hassel
Access: Open access
- The cardiac ganglion (CG) is a central pattern generator, a neural network that, when activated, produces patterned motor outputs such as breathing and walking. The CG induces the heart contractions of the American lobster, Homarus americanus, making the lobster heart neurogenic. In the American lobster, the CG is made up of nine neurons: four premotor pacemaker neurons that send signals to five motor neurons, causing bursts of action potentials from the motor neurons. These bursts cause cardiac muscle contractions that vary in strength based on the burst duration, frequency, and pattern. The activity of the CG is modulated by feedback pathways and neuromodulators, allowing for flexibility in the CG’s motor output and appropriate responses to changes in the animal’s environment. Two feedback pathways modulate the CG motor output, the excitatory cardiac muscle stretch and inhibitory nitric oxide feedback pathways. Despite our knowledge of the modulation of the CG by feedback pathways and neuromodulators separately, little is known about how neuromodulators influence the sensory feedback response to cardiac muscle stretch. I found one neuromodulator to modulate each phase of the stretch response differently, one neuromodulator to generally not affect the stretch response, and three neuromodulators to suppress the stretch response. These results suggest neuromodulators can act to produce flexibility in a CPG’s motor output, allowing the system to respond appropriately to changes in an organism’s environment, and allow for variation in CPG responses to different stimuli.
Activation of Hydrogen by Sterically Modulated Coinage Metal Catalysts via Mutual Quenching of Hard/Soft Acid/Base Mismatches
Date: 2024-01-01
Creator: Zach Leibowitz
Access: Open access
- To mitigate the devastating environmental impacts of climate change in the coming decades, it is imperative that we replace the use of fossil fuels with renewable energy sources such as wind, solar, and hydroelectric. As these renewable energy sources are inherently intermittent, there exists a need for sustainable mechanisms to store renewable energy for later use. While the direct use of dihydrogen (H2) as a combustible fuel would allow for energy storage without the harmful release of carbon dioxide (CO2) upon combustion, the practicality of H2 as a synthetic fuel is limited by its low volumetric energy density. Combining sustainable H2 production (e.g. electrolysis using energy from renewable sources) with subsequent carbon fixation (e.g. the hydrogenation of CO2) represents a promising pathway to the sustainable production of high-density synthetic fuels. We hypothesize that such a process could be catalyzed by an IPr**-supported catalyst containing a hard/soft acid/base (HSAB) mismatch, with a polarizable coinage metal acting as a soft acid. As such, the aim of our project is the construction of a catalogue of IPr**-supported copper, silver, and gold catalysts that we anticipate will facilitate the heterolysis of dihydrogen and subsequent hydrogenation of CO2. In the present paper, we report the synthesis and characterization of an IPr**-silver complex which will serve as a precursor to many of our proposed HSAB mismatch catalysts and discuss next steps as we construct our catalogue of catalysts.