Honors Projects
Showing 141 - 150 of 564 Items
Fall forward, spring back: Drivers of synchrony in the sea star crawl-bounce gait transition
Date: 2024-01-01
Creator: Brady R Nichols
Access: Open access
- The Froude number is the ratio of kinetic energy to gravitational potential energy used during locomotion and is often used to analyze gait transitions. Here, I compare and contrast the human walk-run gait transition, which occurs at a consistent Froude number of 1 because there exists a mechanical speed limit to walking, and the sea star crawl-bounce gait transition, which occurs around Froude numbers of 1*10^-3. In this thesis I investigate why sea stars exhibit two gaits despite lacking brains and moving at Froude numbers far below other known gait transitions, hypothesizing (1) that the crawl-bounce transition may be mechanical and thus still depends on the Froude number, and (2) that the crawl-bounce transition is best modeled gradually compared to the instantaneous human walk-run transition. Thirty sea stars were filmed and the resulting kinematic data is used here to inform thinking about the crawl-bounce transition. I first discuss damped driven harmonic motion of a single oscillator, but eventually turn to using coupled oscillators and deriving that a coupling constant between metronomes on a moving base is the Froude number, which is therefore relevant for the crawl-bounce transition. I lastly discuss a purely mathematical analogue of the crawl-bounce transition as a Hopf bifurcation in horizontal speed and vertical velocity phase space, which leads to a rough model with results qualitatively similar to observed kinematic data from films, and indicates that a gradual transition is in fact a good fit for the crawl-bounce transition.
DS-PSO: Particle Swarm Optimization with Dynamic and Static Topologies
Date: 2017-05-01
Creator: Dominick Sanchez
Access: Open access
- Particle Swarm Optimization (PSO) is often used for optimization problems due to its speed and relative simplicity. Unfortunately, like many optimization algorithms, PSO may potentially converge too early on local optima. Using multiple neighborhoods alleviates this problem to a certain extent, although premature convergence is still a concern. Using dynamic topologies, as opposed to static neighborhoods, can encourage exploration of the search space at the cost of exploitation. We propose a new version of PSO, Dynamic-Static PSO (DS-PSO) that assigns multiple neighborhoods to each particle. By using both dynamic and static topologies, DS-PSO encourages exploration, while also exploiting existing knowledge about the search space. While DS-PSO does not outperform other PSO variants on all benchmark functions we tested, its performance on several functions is substantially better than other variants.
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.
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.
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Urban Modernity and Turbulent Water: Toward a Transnational History of Expansion in Northern Japan, 1866-1882 Access to this record is restricted to members of the Bowdoin community. Log in here to view.
Date: 2018-05-01
Creator: Ethan Barkalow
Access: Access restricted to the Bowdoin Community
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Investigating the Effect of Side Chains with Hydrogen Bonding Capabilities on Peptoid Catalysts for Enantioselective Trifluoromethylation of 4-Chlorobenzaldehyde Access to this record is restricted to members of the Bowdoin community. Log in here to view.
- Restriction End Date: 2025-06-01
Date: 2020-01-01
Creator: Rebecca Londoner
Access: Access restricted to the Bowdoin Community
The combinatorial effects of temperature and salinity on the nervous system of the American lobster, Homarus americanus
Date: 2024-01-01
Creator: Katrina Carrier
Access: Open access
- The ability of nervous systems to maintain function when exposed to global perturbations in temperature and salinity is a non-trivial task. The nervous system of the American lobster (H. americanus), a marine osmoconformer and poikilotherm, must be robust to these stressors, as they frequently experience fluctuations in both. I characterized the effects of temperature on the output of the pyloric circuit, a central pattern generator in the stomatogastric nervous system (STNS) that controls food filtration and established the maximum temperature that neurons in this circuit can withstand without “crashing” (ceasing to function but recovering when returned to normal conditions). I established a range of saline concentrations that did not cause the system to crash, and then determined whether combinatorial changes in temperature and salinity concentrations alter the maximum temperature the system tolerated. Even as burst frequency increased as temperature increased, phase constancy was observed. Interestingly, the system crashed at higher temperatures upon exposure to lower saline concentrations and lower temperatures in higher saline concentrations. I also established the range of saline concentrations that the lobster’s whole heart and cardiac ganglion (CG), the nervous system that controls the lobster’s heartbeat, can withstand. Then, I examined whether exposure to altered salinity and elevated temperature alters the crash temperature of the whole heart and CG. The CG crashed at higher temperatures than the whole heart in each saline concentration. Like the STNS, the whole heart and CG both crashed at higher temperatures in lower saline concentrations and higher temperatures in lower saline concentrations.
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Beyond Religion: Reframing Liberal Democracy’s Treatment of Exemptions Within the Public-Private Separation This record is embargoed.
- Embargo End Date: 2027-05-16
Date: 2024-01-01
Creator: Julianna Brown
Access: Embargoed
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Group-theory constraints on color-ordered four-point amplitudes in SO(N) gauge-theories Access to this record is restricted to members of the Bowdoin community. Log in here to view.
Date: 2024-01-01
Creator: Athis Osathapan
Access: Access restricted to the Bowdoin Community
Real-Time Object Recognition using a Multi-Framed Temporal Approach
Date: 2018-05-01
Creator: Corinne Alini
Access: Open access
- Computer Vision involves the extraction of data from images that are analyzed in order to provide information crucial to many modern technologies. Object recognition has proven to be a difficult task and programming reliable object recognition remains elusive. Image processing is computationally intensive and this issue is amplified on mobile platforms with processor restrictions. The real-time constraints demanded by robotic soccer in RoboCup competition serve as an ideal format to test programming that seeks to overcome these challenges. This paper presents a method for ball recognition by analyzing the movement of the ball. Major findings include enhanced ball discrimination by replacing the analysis of static images with absolute change in brightness in conjunction with the classification of apparent motion change.