Honors Projects

Showing 31 - 40 of 564 Items

Dendrites of Cardiac Ganglion Regulate Heartbeat of American Lobster, Homarus americanus, Through Stretch Feedback

Date: 2014-05-01

Creator: Mara R Chin-Purcell

Access: Open access

Central pattern generators are neuronal networks that produce reliable rhythmic motor output. A simple pattern generator, known as the cardiac ganglion (CG), controls the heart of the American lobster, Homarus americanus. Previous studies have suggested that stretch feedback relays information to the cardiac ganglion about the degree of filling in the heart, and that this feedback is mediated by stretch-sensitive dendrites extending from CG neurons. I sought to determine the mechanisms behind this stretch feedback pathway. One hundred second extension pyramids were applied to each heart while amplitude and frequency of contractions were recorded; 87% of hearts responded to stretch with a significant increase in frequency of contractions. To ascertain the role of dendrites in this feedback pathway, the accessible branches along the trunk of the CG were severed, de-afferenting the CG. In de-afferented hearts, stretch sensitivity was significantly less than in intact hearts, suggesting that the dendrites extending from the CG are essential for carrying stretch feedback information. To separate the effects of active and passive forces of heart contraction on stretch sensitivity, the CG was de-efferented by severing the motor nerves that induce muscle contraction. Hearts with only anterolateral nerves cut or with all four efferents cut were significantly less stretch sensitive than controls. These results indicate that the CG is sensitive to active stretch of each contraction. Hearts with reduced stretch feedback had more irregular frequency of contractions, indicating that a role of stretch feedback in the cardiac system may be to maintain a regular heart rate.


Leadership from Within: Founders, advocates, and organizational networks operating in Maine's immigrant community

Date: 2019-05-01

Creator: Samuel Robert Kenney

Access: Open access

Much of the discourse surrounding African immigration to Maine has centered on the provision of public services that facilitate community development and integration. This project investigates different types of leadership strategies employed by African individuals in Maine that advance community objectives. When African immigrant leaders are empowered to affect public policy, they re-frame traditional conceptions of aid-dependency and vulnerability commonly applied to African immigrants in media and popular culture. Through leadership in nonprofit and civic spheres, African immigrant community leaders translate grassroots connectivity with informal networks into meaningful influence in the realm of public policy. This project focuses on the evolution of community leadership in Maine’s Somali community, the network of immigrant-serving organizations that provide specialized public services across the state, and the capacity of one organization in particular, the Maine Immigrants’ Rights Coalition (MIRC) to ensure accurate representation of policy initiatives to civic officials for individuals unable to participate in the electoral process. This project evaluates the political utility of ‘lived experience’ as a component of diversity in the realm of public policy.


Mechanisms underlying variable responses to isoforms of the neuropeptide C-type allatostatin (AST-C) in the cardiac neuromuscular system of the American lobster, Homarus americanus

Date: 2019-01-01

Creator: Evalyn Mackenzie

Access: Open access

Central Pattern Generators (CPGs) are neural networks that produce steady, rhythmic patterned outputs that activate particular muscles and consequently create recurrent rhythmic movements. The cardiac ganglion (CG) of the American lobster (Homarus americanus) is a useful model system for the study of CPGs. Neuropeptides modulate cardiac contractions driven by the CG in H. americanus and accordingly elicit a range of effects. Post-translational modifications such as amidation can impact function of a peptide neuromodulator. C-type allatostatins (AST-Cs) are a group of neuropeptides that modulate the cardiac neuromuscular system of H. americanus. The objective of this study was to determine what structural aspects of the peptides were responsible for the similarity in responses elicited by AST-C I and AST-C III and the difference in responses evoked by AST-C II in comparison. AST-C I and AST-C III are not C-terminally amidated, whereas AST-C II is C-terminally amidated. We first hypothesized that amidated AST-C peptides would evoke similar responses to one another in contraction amplitude and frequency. Our second hypothesis was that exchanging the amino acids alanine and tyrosine at a specific location in AST-C II and AST-C III would affect the conformation of the peptide, and consequently impact peptide binding and elicit different effects. In contrast to our predictions, we did not see similar responses evoked by all amidated or all non-amidated peptides among lobsters. In support of our second hypothesis, there was a significant difference in percent change in contraction amplitude elicited among AST-C II Y, AST-C II and AST-C III.


Miniature of Experiments in Gender: A Comparative Analysis on the Literary Representation of Women in Medicine and Science during the Weimar Republic
Experiments in Gender: A Comparative Analysis on the Literary Representation of Women in Medicine and Science during the Weimar Republic
Access to this record is restricted to members of the Bowdoin community. Log in here to view.

      Date: 2021-01-01

      Creator: Rachel Bercovitch

      Access: Access restricted to the Bowdoin Community



        Miniature of Modulation of ionic currents by nitric oxide negative feedback in the lobster cardiac ganglion
        Modulation of ionic currents by nitric oxide negative feedback in the lobster cardiac ganglion
        Access to this record is restricted to members of the Bowdoin community. Log in here to view.
        • Restriction End Date: 2026-06-01

          Date: 2021-01-01

          Creator: Emily Renee King

          Access: Access restricted to the Bowdoin Community




            Three-Year-Old Agents of Social Change: How aeioTU Educators Build on Children’s Agency

            Date: 2024-01-01

            Creator: Andrea Rodriguez

            Access: Open access

            aeioTU is a Colombian organization that works to enact social change through the field of early childhood education. In collaboration with the Colombian government, aeioTU oversees several public centers located in socioeconomically vulnerable municipalities in Colombia. This thesis analyzes the aeioTU curriculum and the practices of several aeioTU teachers through the theoretical lens of Freire’s critical pedagogy. This thesis argues that by fostering critical awareness of the world from an early age, as well as by collaborating closely with mothers and the communities at large, aeioTU teachers equip children with the tools to become social agents who can challenge and positively change their lived realities. The research presented in this thesis affirms the potential of aeioTU teachers to enact social change in socioeconomically vulnerable communities by building on young children’s social agency.


            Liberty and Its Legacy An Analysis of Freedom and Liberty in American Political Rhetoric

            Date: 2023-01-01

            Creator: Ryan S. Kovarovics

            Access: Open access

            The concept of freedom has always been central to the American identity, but its meaning has never been agreed on by all and has long been the subject of debate. An abridged explanation of the evolution of liberty’s meaning in political thought and American history is presented in the first chapter of this project. It demonstrates the long-standing importance of individual freedom in America and highlights some historical moments when liberty has come into conflict with other societal values. When used in American political rhetoric today, “freedom” and “liberty” typically take on a “negative” meaning that is focused mostly on individual freedom from government intervention. This is especially clear with regard to issues each party claims to “own” in the context of freedom, including abortion for the Democrats and the covid-19 pandemic response for the Republicans. To verify this partisan ownership of freedom and compare how each party uses freedom in political rhetoric, an empirical analysis was conducted of the uses of “freedom” and “liberty” in candidate tweets and campaign ads from the 2022 midterm elections. The analysis found some support for partisan ownership of freedom rhetoric surrounding these and other issues, but the most interesting finding was that Democrats and Republicans invoked “freedom” and “liberty” in their rhetoric at virtually identical rates. This shows that neither party can lay an exclusive claim to be the “party of freedom.”


            Love is Real & I Just Had Some for Dessert: Legacies of Communal Care & Compassion in Asian Diasporic Women's Food Writing

            Date: 2023-01-01

            Creator: Miki Rierson

            Access: Open access

            In this project I work to recover influential yet often erased Asian American female immigrant chefs and food authors from the mid-twentieth century to the present, situating their contributions in a deep-rooted tradition of diasporic women who used cooking as a means of communal agency and care. Immigrant Asian cookbook authors and chefs have long faced internal criticisms from their own diasporic communities of either inauthenticity or engaging in “food pornography,” to use writer Frank Chin’s term—a line of criticism that Lisa Lau has elaborated on as “re-Orientalism.”Though these criticisms should not eclipse the works themselves, I discuss and counter them in my project because they reflect broader challenges faced particularly by Asian female diasporic authors even today. , I seek to address a broader scholarly gap through my project. Presently, much important work exists on the legacies of historical trauma and violence on marginalized communities, work that highlights the insidious ways violence manifests in academia, pop culture, and everyday lives. This project is a personal pursuit to focus on the healing and beautiful aspects of diasporic community and identity, an ode to the parts of us that are not defined by the pain and suffering but that seek self-affirmation beyond them.


            Miniature of Written in the Body: Embodiments of Gender, Asexuality, Queerness, and Disability
            Written in the Body: Embodiments of Gender, Asexuality, Queerness, and Disability
            Access to this record is restricted to members of the Bowdoin community. Log in here to view.

                Date: 2023-01-01

                Creator: Corey Schmolka

                Access: Access restricted to the Bowdoin Community