Showing 111 - 120 of 298 Items
Reading & Teaching Chaucer: the "Good Wif"?
Date: 2020-01-01
Creator: Sophie Friedman
Access: Open access
- This two-chapter project applies formalist and feminist thinking to the thirty-line description of the Wife of Bath in Geoffrey Chaucer’s medieval, British work The Canterbury Tales. It is an interdisciplinary project; it studies how to read and teach Chaucer at the secondary level based off of these two approaches. In this formalist chapter, I study narrative voice, rhyme, irony, and ekphrasis, writing about the history and function of each of those tools and their role in the passage. I argue that the formalist close reading approach is an excellent teaching tool that generates thorough, rigorous, and joyful reading. In this feminist chapter, I compile a critical literary history of scholarly feminist and pre-feminist engagement with the passage over time. I read into an underlying genotype text, arguing that the Wife of Bath was a female entrepreneur who used textiles as a means of social, professional, and aesthetic expression and empowerment. Then I advocate for a feminist ethical teaching approach—one where we use the text as a non-ethical space in which to explore ethical questions surrounding gender. Ultimately, I argue that feminist and formalist approaches are interdependent and complementary; for both reading and teaching Chaucer, they stand stronger together.
Characterization of O-Linked Glycosylated Neuropeptides in the American Lobster (Homarus americanus): The Use of Peptide Labeling Following Beta Elimination
Date: 2020-01-01
Creator: Edward Myron Bull
Access: Open access
- Neuropeptides are a class of small peptides that govern various neurological functions, and the American lobster (Homarus americanus) provides a model system for their characterization. Neuropeptides are commonly post-translationally modified (PTM), and one common PTM is glycosylation. Past research in the Stemmler lab has found glycosylated neuropeptides in H. americanus; however, the extent and biological role of this modification has not been well characterized. This study was undertaken to determine the number of glycosylated peptides in the sinus glands of H. americanus and to develop an approach to tag the site of glycosylation using beta-elimination chemistry. LC-MS paired with high pH reverse phase fractionation was used to survey for glycosylated neuropeptides and beta elimination with an amine tag was used as an approach to characterize the site of glycosylation. Our results indicate that high pH fractionation is a useful approach to simplify complex mixtures of neuropeptides and improve glycopeptide detection. Efforts to use beta elimination and tagging to characterize glycosylated neuropeptides have been less successful. Beta elimination of full length peptides resulted in peptide degradation. An approach utilizing chymotrypsin to reduce peptide size coupled with beta elimination and labeling with 2-dimethylaminoethanethiol showed less evidence for degradation, and this approach yielded data isolating two potential serine residues for the site of glycosylation; however, the data was not sufficient to distinguish the two sites. Work to optimize reaction conditions using a glycopeptide standard showed that multiple isomeric products were formed during beta elimination. With the goal of optimizing reaction conditions, future work will further examine reaction kinetics to eventually apply the approach to the entire sinus gland
Determining the sites at which neuromodulators exert peripheral effects in the cardiac neuromuscular system of the American Lobster, Homarus americanus
Date: 2021-01-01
Creator: Audrey Elizabeth Jordan
Access: Open access
- Networks of neurons known as central pattern generators (CPGs) generate rhythmic patterns of output to drive behaviors like locomotion. CPGs are relatively fixed networks that produce consistent patterns in the absence of other inputs. The heart contractions of the Homarus americanus are neurogenic and controlled by the CPG known as the cardiac ganglion. Neuromodulators can enable flexibility in CPG motor output, and also on muscle contractions by acting on the neuromuscular junction and the muscle itself. A tissue-specific transcriptome gleaned from the cardiac ganglion and cardiac muscle of the American lobster was used to predict the sites and sources of a variety of crustacean neuromodulators. If corresponding receptors were predicted to be expressed in the cardiac muscle, then it was hypothesized that the neuropeptide had peripheral effects. One peptide for which a cardiac muscle receptor was identified is myosuppressin. Myosuppressin has been shown to have modulatory effects at the cardiac neuromuscular system of the American lobster. In previous research, myosuppressin had modulatory effects on the periphery of cardiac neuromuscular system alone. It remains an open question of whether myosuppressin acts on the cardiac muscle directly, if it is exerting its effects at the neuromuscular junction (NMJ), or both. To test this, I performed physiological experiments on the isolated NMJ. Myosuppressin did not modulate the amplitude of the excitatory junction potentials. Since no modulatory effects were seen at the NMJ, the cardiac muscle was isolated from the cardiac ganglion and then glutamate-evoked contractions were stimulated. I showed that myosuppressin increased glutamate-evoked contraction amplitude. These data suggest myosuppressin exerts its peripheral effects at the cardiac muscle and not the NMJ.
Down in arms: Marine climate stress inhibits growth and calcification of regenerating Asterias forbesi (Echinodermata: Asteroidea) arms
Date: 2021-01-01
Creator: Hannah L. Randazzo
Access: Open access
- Anthropogenic CO2 is changing the pCO2, temperature, and carbonate chemistry of seawater. These processes are termed ocean acidification (OA) and ocean warming. Previous studies suggest two opposing hypotheses for the way in which marine climate stress will influence echinoderm calcification, metabolic efficiency, and reproduction: either an additive or synergistic effect. Sea stars have a regenerative capacity, which may be particularly affected while rebuilding calcium carbonate arm structures, leading to changes in arm growth and calcification. In this study, Asterias forbesi were exposed to ocean water of either ambient, high temperature, high pCO2, or high temperature and high pCO2 for 60 days, and the regeneration length of the amputated arm was measured weekly. Ocean acidification conditions (pCO2 ~1180 μatm) had a negative impact on regenerated arm length, and an increase in temperature of +4°C above ambient conditions (Fall, Southern Gulf of Maine) had a positive effect on regenerated arm length, but the additive effects of these two factors resulted in smaller regenerated arms compared to ambient conditions. Sea stars regenerating under high pCO2 exhibited a lower proportion of calcified mass, which could be the result of a more energetically demanding calcification process associated with marine climate stress. These results indicate that A. forbesi calcification is sensitive to increasing pCO2, and that climate change will have an overall net negative effect on sea star arm regeneration. Such effects could translate into lower predation rates by a key consumer in the temperate rocky intertidal of North America.
An Analysis of Tidal Mixing Front Dynamics and Frontal Biophysical Interaction in the Harpswell Sound Shelf Sea
Date: 2023-01-01
Creator: Lemona Yingzhuo Niu
Access: Open access
- Tidal Mixing Fronts (TMFs) are prominent hydrographic features of tidally energetic shallow shelf seas, representing the transition from mixed to stratified waters. These frontal boundaries often host enhanced phytoplankton primary productivity, as complete vertical mixing exhumes nutrients from depth to the light-lit surface. Existing observational programs for locating TMFs include infra-red satellite imagery of sea surface temperature (SST) and vertical profiling of temperature and density. However, challenges in observationally distinguishing mixed from mixing using only conservatively mixed hydrographic properties persist. A novel approach based on phytoplankton in-situ oxygen production response to light is proposed in this paper to distinguish stable mixed from actively mixing regimes, and thus to identify remnant versus active TMFs. This project focuses on Harpswell Sound, a shallow (< 40m) coastal reverse estuary, as a case study of TMF dynamics. Our data unambiguously reveal the cross-shelf structure of active, mixed, and stratified regimes. Competition between wind mixing and buoyancy due to solar heating and river plumes were found to be the primary drivers of the active and remnant front locations, while tidal currents were a secondary driver. Such dynamism explains both the temporally variable and spatially patchy phytoplankton blooms observed in the shallow shelf sea environment of Harpswell Sound.
Peripheral modulation of cardiac contractions in the American lobster, Homarus americanus, by the peptide myosuppressin is mediated by effects on the cardiac muscle itself
Date: 2023-01-01
Creator: Isabel Stella Petropoulos
Access: Open access
- A substantial factor for behavioral flexibility is modulation — largely via neuropeptides — which occurs at multiple sites including neurons, muscles, and the neuromuscular junction (NMJ). Complex modulation distributed across multiple sites provides an interesting question: does modulation at multiple locations lead to greater dynamics than one receptor site alone? The cardiac neuromuscular system of the American lobster (Homarus americanus), driven by a central pattern generator called the cardiac ganglion (CG), is a model system for peptide modulation. The peptide myosuppressin (pQDLDHVFLRFamide) has been shown in the whole heart to decrease contraction frequency, largely due to its effects on the CG, as well as increase contraction amplitude by acting on periphery of the neuromuscular system, either at the cardiac muscle, the NMJ, or both. This set of experiments addresses the location(s) at which myosuppressin exerts its effects at the periphery. To elucidate myosuppressin’s effects on the cardiac muscle, the CG was removed, and muscle contractions were stimulated with L-glutamate while superfusing myosuppressin. Myosuppressin increased glutamate-evoked contraction amplitude in the isolated muscle, suggesting that myosuppressin exerts its peripheral effects directly on the cardiac muscle. To examine effects on the NMJ, excitatory junction potentials were evoked by stimulating of the motor nerve and intracellularly recording a single muscle fiber both in control saline and in the presence of myosuppressin. Myosuppressin did not modulate the amplitude of EJPs suggesting myosuppressin acts at the muscle and not at the NMJ, to cause an increase in contraction amplitude.
Host and symbiont-specific patterns of gene expression in response to cold stress in the temperate coral Astrangia poculata
Date: 2023-01-01
Creator: Kellie Navarro
Access: Open access
- The coral Astrangia poculata inhabits hard-bottom environments from the Gulf of Mexico to Massachusetts and withstands large seasonal variation in temperature (–2 to 26 °C). This thermal range and its ability to live in a facultative symbiosis makes this species an ideal model system for investigating stress responses to ocean temperature variation. Although it has been shown that aposymbiotic A. poculata upregulates more genes in response to cold stress than heat stress, the transcriptomic response of the holobiont (coral host and symbiotic algae) to stress is unknown. In this study, we characterize changes in gene expression in both the host and symbionts under cold stress (6ºC) and ambient (12ºC) seawater temperatures. We use RNAseq to visualize how patterns of global gene expression change in response to these temperatures within the transcriptomes of replicate corals (n=10, each temperature) and their symbiont partners. By filtering the holobiont assembly for known coral host and symbiont genes, we contrasted patterns of differential expression (DE) for each partner and the functional processes for each set of DE genes. Differential gene expression analyses revealed that the cnidarian coral host responds strongly to cold stress, while algal symbionts did not have a significant stress response. In the coral host, we found up-regulation of biological processes associated with DNA repair, immunity, and maintaining cellular homeostasis as well as downregulation of mechanisms associated with DNA repair and RNA splicing, indicating inhibition of necessary cellular processes due to environmental stress.
Site, Power, and Experience: Three Contemporary Installation Works on Global Mobility
Date: 2021-01-01
Creator: Xiyin Sabrina Lin
Access: Open access
- This Honors Project investigates the themes of immigration, space, and mobility through the lens of contemporary installation art. It addresses a brief history of global contemporary art, arguing that art of the past two decades has been shaped by preoccupations with and tensions surrounding space. Using the works of Yanagi Yukinori, Alfredo Jaar, and Doris Salcedo as case studies, the essay analyzes how artists use the medium of installation to address institutional history, contemporary geopolitics, as well as individual and collective experience. It interrogates the different aspects of installation art, including temporality, site-specificity, and the use of language, to demonstrate how the medium allows artists to use their own position in the system to critique its inherent limitations.
When is Change Possible? Presidential Power as Shaped by Political Context, Constitutional Tools, and Legislative Skills
Date: 2021-01-01
Creator: Ryan Telingator
Access: Open access
- Many Americans believe that the president is an omnipotent figure who can achieve any political or policy objective if they try hard enough. On the contrary, the presidency was intentionally crafted by the Framers of the Constitution to have limited legislative powers to mitigate the risk of despotism. Thus, this paper seeks to answer the question, when is change possible?, to try to bridge the gap between popular belief and Constitutional powers. Three questions guide this research: 1) What conditions are conducive for change? 2) What Constitutional tools help a president facilitate change? And 3) What skills can a president bring to office to help create change? This thesis seeks to answer these questions by reviewing the existing literature on political context, tools, and legislative skills. Case study analyses of the Lyndon Johnson and Ronald Reagan presidencies are then presented to assess their legislative successes and failures, and the factors behind them. Finally, the thesis concludes by evaluating President Joseph Biden’s first 100 days in office and uses the theory and findings from the cases to predict Biden’s ability to affect change. This research reveals that the political context is the most important factor in determining the possibility of change – successful change relies on open policy windows, resilient ideological commitments, and a mandate to stimulate congressional action. Within the constraints of the case studies, Constitutional tools were not important. Legislative skills helped to pass legislation, however, they were not potent enough to overcome a bad political context.
Reconsidering Operation Condor: Cross-border Military Cooperation and the Defeat of the Transnational Left in Chile and Argentina during the 1970s
Date: 2014-05-01
Creator: Georgia C Whitaker
Access: Open access
- In this study of the roots of Operation Condor, I track the development of this unusual military alliance forged by six Southern Cone governments (Chile, Argentina, Brazil, Bolivia, Uruguay, and Paraguay) during the 1970s, as well as the push-and-pull relationship between the transnational migration of political militants and the military’s impetus for collaboration. While most accounts of Condor focus on the United States as the operation’s primary orchestrator, I contend that initial motivation for the type of cooperation that Condor would later formalize was driven not by the U.S., but by the Southern Cone militaries’ perception that Marxism had to be excised from the entire region. In addition, while Condor scholars have either ignored or minimized the role of the left as political actors and placed the blame for violence exclusively on the militaries and the United States, I draw from unpublished Argentine police records, Argentine Embassy documents, and Chilean-Argentine solidarity group publications to argue that it is essential to broaden our understanding of what both sides in this ideological confrontation were attempting to accomplish. The transnational left, never a homogenous group, evolved to meet a variety of objectives. Many militants continued to be politically active while they were in exile, and many acted in solidarity with like-minded leftists in their midst.