Showing 201 - 250 of 681 Items
Date: 2022-01-01
Creator: Levi McAtee
Access: Open access
- Do minimum wage increases serve as stepping-stones to higher-paying jobs for low-pay workers? This paper analyzes the impact of state minimum wage policy on the one-year wage growth rates of individuals across the wage distribution and whether that impact changes for individuals in highly monopsonistic industries. I review the recent literature on the disemployment effect, the impact of the minimum wage on wage growth rates, the nature of monopsonistic industries, and the relationship between the minimum wage and monopsony power. I offer theoretical reasons why the minimum wage may impact the wage growth rates of individuals in monopsonistic industries differently than it impacts those of individuals in competitive industries. I then re-estimate Lopresti’s and Mumford’s (2016) panel fixed effects model to determine how the effect of a minimum wage increase depends nonlinearly on the size of the increase. Using data from 2005-2008, Lopresti and Mumford found that small minimum wage increases have a significant negative impact on wage growth rates, while large minimum wage increases have a significant positive impact. Using data from 2016-2019, I find similar results. As my primary empirical contribution, I test whether individuals in highly monopsonistic industries experience minimum wage changes differently than individuals in more competitive industries. I find monopsony power in the form of high labor immobility primarily impacts the wage growth rates of high-pay workers and does not influence how low-pay workers experience minimum wage changes. Finally, I recommend policymakers impose larger minimum wage increases to avoid impeding the wage-growth of low-pay workers.
Date: 2015-05-01
Creator: Andrew J Pryhuber
Access: Open access
Date: 2023-01-01
Creator: Philip Carl Bonanno
Access: Open access
- This project explores fiction from white authors in the Southern Renaissance, specifically William Faulkner, Flannery O’Connor, and Carson McCullers. By examining their work alongside some of the performers that appeared historically in freak shows of the South, chapter one investigates how physically enfreaked individuals (usually phenotypically white) have access to power and the powers of whiteness. Chapter 2 interrogates how the South pathologizes promiscuity as mental illness with words such as moronic or feeble-mindedness, and the ramifications it has for the stratification on class divides among Southern elites and “White Trash.” The chapter seeks to answer the question of why, for a short period in the 1940s, white women were more likely to be punished with forced sterilization than Black women. Chapter 3 uncovers the rhetorical agency used by Benjy in Faulkner’s The Sound and the Fury, looking at how he resists the powers of whiteness through crip time and his trauma responses to his family that seeks to reinsert the Antebellum South. Using an intersectional approach of critical whiteness studies, disability studies, crip theory, and queer theory, relies on a variety of scholars including, but not limited to; David Mitchell and Sharon Snyder, Rosemarie Garland-Thompson, Richard Dyer, Matt Wray, Jasbir Puar, Ellen Samuels, and Allison Kafer. The primary works examined include promotional materials of historical freaks, McCullers’ The Ballad of a Sad Café, William Faulkner’s The Hamlet and The Sound and the Fury, and Flannery O’Connor short stories “Good Country People” and “A Temple of the Holy Ghost.”

- Embargo End Date: 2027-05-19
Date: 2022-01-01
Creator: Katherine Aiello McKee
Access: Embargoed
Date: 2015-05-01
Creator: Jackson F Bloch
Access: Open access
- Nestling birds use begging calls to solicit resources from adults. Efficient transmission of calls is necessary for motivating parental feeding and outcompeting siblings. However, ambient acoustic masking and costs such as predation may influence the structure of the calls. While many interspecific comparisons of begging behavior have been made, the ontogeny of calls is understudied. In this study, Yellow Warbler (Setophaga petechia) begging calls were recorded and analyzed at different stages of nestling development to document changes in acoustic structure and gain insight into the selective forces that influence call development. Begging calls increased in peak frequency, frequency range, and amplitude during the 5-day recording period. Call duration did not change with age. Call structure did not differ between nestlings living in distinct acoustic environments. As begging calls increase in amplitude with age, perhaps due to increased food needs and competition from nestmates, nestlings may compensate for increased predation risk by increasing the peak frequency of the calls. Higher frequency calls attenuate more quickly than do low frequency calls and fall outside the frequency range of maximum hearing sensitivity for some potential predators. Previous studies on warbler begging have shown that nestlings of ground-nesting warblers, which are subject to higher rates of predation, beg at higher frequencies than do nestlings of tree-nesting warblers. This study supports the hypothesis that changes to begging call structure during development mirror the differences in call structure of species under different predation risks.

- Embargo End Date: 2028-05-18
Date: 2023-01-01
Creator: Olivia Bronzo-Munich
Access: Embargoed
Date: 2022-01-01
Creator: Jacqueline Boben
Access: Open access
- Extreme sports, like skateboarding, whitewater kayaking, and skiing, have historically been male-dominated. As women’s participation in these sports grows, my research asks: how do women navigate sports spaces and cultures that have for so long been defined by men? To answer this question, I draw on ethnographic research on communities of skateboarders, whitewater kayakers and skiers conducted during the summer of 2021 in Bozeman, Montana. I found that the specific landscapes where these extreme sports take place are often conceptualized by participants as more masculine spaces. Within these spaces and communities, women participants often leverage gender performances associated with masculinity to gain entry into these male-dominated communities. Performing in more masculine ways mitigates feelings of hypervisibility, while also helping to build connections to established members of the community. More than simply fitting in, women find that these gendered performances also help them to build competence in the sport. At the same time, women are transforming skateboarding, whitewater kayaking, and skiing through their participation by creating opportunities for more dynamic and fluid gender performances.

- Embargo End Date: 2027-05-19
Date: 2022-01-01
Creator: Clayton James Wackerman
Access: Embargoed
Date: 2023-01-01
Creator: Salina Chin
Access: Open access
- In popular discourse, understandings of queerness and religiosity as antithetical proliferate. However, the political involvement of Portland, Maine’s First Parish Unitarian-Universalist Church in Maine’s queer political movement points to a more complex relationship between the LGBTQ+ community and progressive religious institutions. Through participant observation, archival research, and semi-structured interviews with nine LGBTQ+ community members and informants, I reveal the crucial role of Portland’s First Parish Unitarian-Universalist Church in Maine’s queer political movement from the late 1980s into the present day. On the one hand, progressive faith-based spaces across Maine provide safe spaces for queer political organizing. On the other hand, “ephemeral placemaking” in progressive faith-based spaces represents an assimilationist political strategy that stresses LGBTQ+ respectability. Thus, I argue that queer placemaking in progressive faith-based spaces reflects both subversive and assimilationist politics. LGBTQ+ activists utilize ephemeral placemaking strategies within progressive faith-based spaces to challenge political opposition from the religious Right while also reinforcing what Mikulak (2019) terms “godly homonormativity”: the normalization of LGBTQ+ identity and the upholding of heteronormativity by emphasizing respectability and monogamy. My analysis of queer political organizing within progressive faith-based spaces “queers” religion and LGBTQ+ politics, disrupting dominant narratives of religion as homophobic and LGBTQ+ politics as radical.

- Restriction End Date: 2028-06-01
Date: 2023-01-01
Creator: Kevin Jairre Fleshman
Access: Access restricted to the Bowdoin Community
Date: 2016-05-01
Creator: Katelyn J Suchyta
Access: Open access
Date: 2024-01-01
Creator: Matthew Cesar Audi
Access: Open access
- Since the late 1800s, people have immigrated to the United states from Lebanon and Syria, and the community’s racial and ethnic position within the United States has been contested ever since. Previous research emphasizes that while people from the Middle East and North Africa (MENA) are legally classified as “white” on the U.S. Census. However, many people from the region do not identify as white, and they often face discrimination or threats of violence. For people of Arab and Christian backgrounds this is further complicated because they are a part of the majority through their religion, but part of a minority through their ethnic background. In addition, media depictions of MENAs tend to be homogenizing and stereotypical. This thesis attempts to fill a gap in literature on Christian Lebanese American identities by conducting ethnographic interviews with Lebanese-Americans from a variety of generations. It pulls from theories of diaspora and race, emphasizing the importance of context and migration trajectories when understanding Lebanese American identities. My findings demonstrate wide-ranging diversity in how Christian Lebanese-Americans understand and articulate identity due to three major factors: divergent migrant pathways in multiple countries, generational difference given changing racial politics in the U.S., and generational difference given the impacts of U.S. foreign policy in the Middle East upon young Lebanese-Americans.
Date: 2023-01-01
Creator: Angus Zuklie
Access: Open access
- In economic circles, there is an idea that the increasing prevalence of algorithmic trading is improving the information efficiency of electronic stock markets. This project sought to test the above theory computationally. If an algorithm can accurately forecast near-term equity prices using historical data, there must be predictive information present in the data. Changes in the predictive accuracy of such algorithms should correlate with increasing or decreasing market efficiency. By using advanced machine learning approaches, including dense neural networks, LSTM, and CNN models, I modified intra day predictive precision to act as a proxy for market efficiency. Allowing for the basic comparisons of the weak form efficiency of four sectors over the same time period: utilities, healthcare, technology and energy. Finally, Within these sectors, I was able to detect inefficiencies in the stock market up to four years closer to modern day than previous studies.
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.

- Restriction End Date: 2026-06-01
Date: 2023-01-01
Creator: Eliza M. Rhee
Access: Access restricted to the Bowdoin Community
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.
Date: 2024-01-01
Creator: Mei Bock
Access: Open access
- A collection of poems exploring threads including the Lower East Side, immigration, stray animals, art, and Chinese-American identity.

Date: 2023-01-01
Creator: Nuoya (Laura) Yang
Access: Access restricted to the Bowdoin Community
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.
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.

- Embargo End Date: 2027-05-16
Date: 2024-01-01
Creator: Julianna Brown
Access: Embargoed
Date: 2023-01-01
Creator: Lorenzo Hess
Access: Open access
- Reuse of N95 FFRs helps mitigate the effects of shortages. UV-C exposure is an ideal method for the decontamination necessary for FFR reuse. Recent research quantifies the transmittance of UV-C through the 3M1870+ and 3M9210+ FFRs [1]. Other research measures the reduction in viral load in relation to UV-C exposure time [11]. We design and program a ray tracing simulator in MATLAB to characterize the distribution of scattered photons in N95 FFRs. We implement an object-oriented FFR with configurable physical characteristics. We use the simulator to record the number of photons available for decontamination in each sub-layer of the filtering layers of the 3M1870+ and 3M9210+ for a given number of photons incident to the layers. We make assumptions about the photon absorption and viral deactivation in each sub-layer to derive a relation between the number of incident photons and the number of viruses remaining. The transmittance computed by our simulator matches the experimentally measured transmittance. The diameter of the simulated scattered beam also matches the experimentally measured scattered beam diameters. Our data, combined with our assumptions about absorption and deactivation, however, fail to account for the dropoff in viral load observed at about 25 seconds of exposure time in the 3M1870+.

Date: 2023-01-01
Creator: Emma Straw Noel
Access: Access restricted to the Bowdoin Community
Date: 2023-01-01
Creator: Luke Bartol
Access: Open access
- With the impacts of climate change becoming more and more apparent every day, finding means of effective action to mitigate its effects become increasingly critical. While localized work can play an important role, federal action is necessary to have the most widespread and effective impact, especially on interconnected issues such as clean energy. Congressional action is the avenue of change at this level, however in an increasingly partisan and divided environment, progress on this front is far short of what is needed. Looking to the president is logical here, both as a single actor more insulated from partisan fights, but also as head of the branch in charge of implementing the nation’s laws. This paper looks to explore what means of influence the president has on the action taken by federal agencies and how such methods can be made more effective. Through a principal-agent framework, the role of regulatory and appointment powers are examined with a variety of historical and contemporary case studies. While only a subset of the powers afforded to a president, the areas explored offer wide latitude for action, in areas that are particularly important for energy development. The paper concludes with some reflections for the future, suggesting how these considerations can be practically applied.

- Embargo End Date: 2029-05-16
Date: 2024-01-01
Creator: Katie Draeger
Access: Embargoed
Date: 2021-01-01
Creator: Ruby Chimereucheya Ahaiwe
Access: Open access
- The American lobster Homarus americanus uses its innate immune system for protection against foreign bodies and diseases. Hemocytes in the innate immune system are responsible for the rapid and effective cellular response against pathogens and infections observed in lobsters. These hemocytes, particularly semi-granulocytes and granulocytes, store antimicrobial peptides (AMPs) which specifically target and destroy microbes. Hemocyte samples from the American lobster Homarus americanus hemolymph or circulatory fluid, mixed and fractionated into separated semi-granular and granular cell samples, were analyzed for possible AMP presence. A defensin AMP, Hoa-D1, (SYVRSCSSNGGDCVYRCYGNIINGACSGSRVCCRSGGGYamide; with C representing a cysteine participating in a disulfide bond) was successfully isolated and identified by mass using reversed-phase high-performance liquid chromatography (HPLC) and liquid chromatography-mass spectrometry (LC-MS/MS). Preliminary results also show the defensin AMP to be concentrated in the semi-granulocytes and granulocytes.Hoa-D1 was isolated via HPLC fractionation. Isolated Hoa-D1 and semi-granular and granular hemocyte extracts were tested for bioactivity against the gram-negative bacteria, Escherichia coli, using the Kirby-Bauer disk diffusion assay. The assay did not show any activity, an outcome attributed to concentrations of the AMP that were too low to have any antimicrobial effect on E. coli. Subsequent work on this study should involve increasing the concentration of Hoa-D1 in test samples. Studying function of AMPs in the American lobster can provide more information on the depth of their cellular immune responses in other crustaceans, and possibly contribute to the development of novel antibiotics for treating diseases in humans.
Date: 2015-05-01
Creator: Emily C. Weinberger
Access: Open access
- Selective attention and justice sensitivity (JS), a personality trait reflecting individual differences in perceptions of injustice, have been shown to affect how people assign punishments. In the present study peoples’ decision-making processes were investigated to better understand the inconsistencies in legal punishment decisions, particularly when using retributive versus restorative justice. Subjects participated in three phases of the experiment. First, subjects completed a justice sensitivity scale and then rated the appropriateness of punishment options to handle a criminal scenario. Second, participants’ selective attention was indicated by their recall of pertinent features from three ambiguous criminal scenarios. Finally, participants were primed with either restorative justice or neutral control words, and rated the appropriateness of punishment options to handle a new criminal scenario. Results revealed no significant associations between JS and ratings of punishment options, although patterns suggested negative relationships between observer JS and retributive justice ratings, and victim JS and restorative justice ratings. Results did show a significant effect of JS in predicting the facts remembered, such that as observer JS increased, more restorative justice facts were recalled, and as victim JS increased, fewer restorative justice facts were recalled. No significant effect of the restorative justice prime was observed. These results may contribute to better understanding of criminal justice policy in the United States.
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.
Date: 2022-01-01
Creator: Gillian King
Access: Open access
- This project is an analysis of the effectiveness of five distinct optimization methods in their ability in producing clear images of the basins of attraction, which is the set of initial points that approach the same minimum for a given function. Basin images are similar to contour plots, except that they depict the distinct regions of points--in unique colors--that approach the same minimum. Though distinct in goal, contour plots are useful to basin research in that idealized basin images can be inferred from the steepness levels and location of extrema they depict. Effectiveness of the method changes slightly depending on the function, but is generally defined as how closely the basin image models contour information on where the true minima are located, and by the clarity of the resulting image in depicting well-defined regions. The methods are tested on four distinct functions which were chosen to assess how each method performs in the presence of various challenges. This project ranks the five methods for their overall effectiveness and consistency across the four functions, and also analyzes the sensitivity of the methods when small changes are made to the function. In general, less sensitive and consistently effective methods are more applicable and reliable in applied optimization research.
Date: 2017-05-01
Creator: Walter Chacon
Access: Open access

Date: 2024-01-01
Creator: Foje-Geh Robert Tendoh
Access: Access restricted to the Bowdoin Community
Date: 2018-01-01
Creator: Tessa Westfall
Access: Open access

Date: 2024-01-01
Creator: Brielle Martin
Access: Access restricted to the Bowdoin Community
Date: 2017-05-01
Creator: Marisa O'Toole
Access: Open access
- Fifteen years into its operation as the preeminent international institution charged with the prosecution of the most serious international crimes, the International Criminal Court (ICC) has faced and continues to face intense backlash from the African continent. Once the Court’s most fervent advocates, many African leaders now lambast the ICC. In recent months, three African countries and the African Union en masse have attempted withdrawal from the Court, thus pushing the ICC-Africa relationship into the international spotlight as a topic of acute global interest. This paper seeks to explore the critiques behind this backlash through both a historical and present-day lens, as well as from the perspectives of African leaders, victims-locals, and civil society actors. In doing so, it investigates historical critiques of the ICTY and ICTR, concerns raised during the Rome Statute negotiations, current African leader perspectives as viewed through the case studies of Darfur, Kenya, Uganda, and the AU-ICC relationship, and present African victim-local and civil society opinions of the Court. By understanding the current and multi-faceted African opposition to the ICC and such criticisms’ historical roots, as well as the pockets of hope for the Court within Africa, this analysis reveals the ICC’s main challenges in its relationship with the African continent. With such hurdles unveiled, the ICC can pursue several strategies, located primarily on the state and individual levels, in its endeavor to address these important critiques and regain African support.
Date: 2018-01-01
Creator: Margaret Marie Conley
Access: Open access
- The O2:CO2 exchange ratio of the terrestrial biosphere (αb) is an important parameter in carbon sink calculations, but its value is not well constrained. We investigate the stoichiometry of O2 and CO2 at Harvard Forest in Petersham, Massachusetts over a span of six years, considering the covariation of O2 and CO2 in forest air during 6-hour periods to determine an average value for the O2:CO2 exchange ratio. This approach provides a way to determine the value of αb averaged across seasonal cycles and species assemblages. Our analysis produces an overall average exchange ratio of -1.06 ± 0.01. Comparing measurements within and above the canopy and during nighttime and daytime periods, we observe that atmospheric dynamics and canopy effects produce lower exchange ratios indicative of an enhanced forest signal at the low intake and for daytime periods. We also see an increase in the exchange ratio in the winter compared to the summer that may reflect changes in plant physiological processes or contamination by a fossil fuel signal. To determine whether our observed ratio is truly representative of αb, we use a simple model to estimate the range of variability in CO2 and O2 mixing ratios expected from local influence alone and use this as a criterion to isolate periods dominated by local exchange, yielding an average summer forest exchange ratio of -1.00 ± 0.02. Our analysis provides insight into the average value and variability of αb for temperate forests for use in calculation of the land carbon sink.
Date: 2018-05-01
Creator: Sarah Claudia Bonanno
Access: Open access
Date: 2024-01-01
Creator: Grant Griesman
Access: Open access
- Central pattern generators (CPGs) are neuronal networks that produce rhythmic motor output in the absence of sensory stimuli. Invertebrate CPGs are valuable models of neural circuit dynamics and neuromodulation because they continue to generate fictive activity in vitro. For example, the cardiac ganglion (CG) of the Jonah crab (Cancer borealis) and American lobster (Homarus americanus) contains nine electrochemically coupled neurons that fire bursts of action potentials to trigger a heartbeat. The CG is modulated by neuropeptides, amines, small molecule transmitters, gases, and mechanosensory feedback pathways that enable flexibility and constrain output. One such modulator, the SLY neuropeptide family, was previously shown to be expressed in hormonal release sites and within the CG itself and has unusual processing features. However, its physiological effect was unknown. Here, I performed dose-response experiments in the crab and lobster whole heart and isolated CG to determine the threshold concentration of SLY neuropeptides to which these systems respond. The crab isoform had strong, excitatory effects in the crab whole heart and weakly modulated the crab CG. The lobster isoform weakly modulated the lobster whole heart and CG. Surprisingly, the crab isoform exerted large, variable effects on the lobster system, which suggests that SLY neuropeptides, their receptors, and their signaling pathways may be evolutionarily conserved across these two species. This research contributes to our understanding of how neural circuits can generate flexible output in response to modulation. It may also offer insight into processes influenced by peptidergic neurotransmission in the nervous systems of other animals, including mammals.

Date: 2024-01-01
Creator: Athis Osathapan
Access: Access restricted to the Bowdoin Community
Date: 2015-05-01
Creator: Stephen Ligtenberg
Access: Open access
Date: 2024-01-01
Creator: David Ma
Access: Open access
- Particle swarm optimization (PSO) is a metaheuristic optimization method that finds near- optima by spawning particles which explore within a given search space while exploiting the best candidate solutions of the swarm. PSO algorithms emulate the behavior of, say, a flock of birds or a school of fish, and encapsulate the randomness that is present in natural processes. In this paper, we discuss different initialization schemes and meta-optimizations for PSO, its performances on various multi-minima functions, and the unique intricacies and obstacles that the method faces when attempting to produce images for basins of attraction, which are the sets of initial points that are mapped to the same minima by the method. This project compares the relative strengths and weaknesses of the Particle Swarm with other optimization methods, namely gradient-descent, in the context of basin mapping and other metrics. It was found that with proper parameterization, PSO can amply explore the search space regardless of initialization. For all functions, the swarm was capable of finding, within some tolerance, the global minimum or minima in fewer than 60 iterations by having sufficiently well chosen parameters and parameterization schemes. The shortcomings of the Particle Swarm method, however, are that its parameters often require fine-tuning for different search spaces to most efficiently optimize and that the swarm cannot produce the analytical minimum. Overall, the PSO is a highly adaptive and computationally efficient method with few initial restraints that can be readily used as the first step of any optimization task.
Date: 2018-05-01
Creator: Angela M Dahl
Access: Open access
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.

Date: 2025-01-01
Creator: Jiahn Son
Access: Access restricted to the Bowdoin Community
Date: 2025-01-01
Creator: Jonathan Gordon Lerdau
Access: Open access
- Libyan Jewry and Jews of the Italian peninsula have engaged in near-constant interaction at least as far back as the time of the Roman empire. This project seeks to add to the history of those interactions by discussing Italian Jewish colonial impacts on the Libyan Jewish population. Using ideas of Orientalism and the imagined nation, this project demonstrates how Libyan Jewish identity was shaped by interaction with Italy and how Italian Jews worked colonially to subjugate, define, and change Libyan Jewry. Through analyzing–among other things–newspapers, scholarship, and general Italian Jewish discussion of and interaction with Libyan Jews, I show how Italian Jews (and elite Libyan Jews) worked to Italianize and later ‘Hebraicize’ the Libyan Jewish community..
Date: 2025-01-01
Creator: Alexander Richardson
Access: Open access
- The primary goal of this thesis is to bridge two powerful learning paradigms—kernel methods and deep learning—to design novel neural architectures. Kernel methods offer a strong theoretical foundation, in contrast to deep learning, which often operates as a black-box despite its widespread success in real-world applications. In an era where such opaque models increasingly shape the economy and daily life, it is crucial to develop architectures that combine the theoretical clarity of kernel methods with the empirical effectiveness of deep learning. At present, computer scientists largely lead the charge in advancing state-of-the-art models, while many mathematicians work retrospectively to understand why these methods are so successful. A key motivation for this thesis—admittedly a personal one—is the hope that mathematical theory can not only explain existing architectures, but also inspire the development of better ones from the outset.

Date: 2025-01-01
Creator: Matthew Joseph Morales
Access: Access restricted to the Bowdoin Community

Date: 2025-01-01
Creator: Yanevith A. Peña
Access: Access restricted to the Bowdoin Community
Date: 2025-01-01
Creator: Yasemin Altug
Access: Open access
- In order to maintain circuit stability through environmental perturbations, such as increases in temperature, neural circuits are able to adjust their output via modulatory and ion channel regulation. For instance, peptide modulators enable the lobster cardiac neuromuscular system to sustain physiological function at temperatures that surpass the crash temperature of the organ in the absence of modulation. Crash temperature is defined as the temperature at which neural activity ceases. For a crash, this temperature induced loss of activity is recovered when temperature is returned within the permissible range. Thus, it is hypothesized that there are underlying physiological mechanisms employed by the nervous system that compensates for changes in temperature and provides stability within acute temperature fluctuations. Neuromodulatory mechanisms have been proposed as one hypothesis that provide this temperature compensation. In accordance with previously collected data (Lemus 2022), I hypothesized that myosuppressin, a crustacean neuropeptide, provides stability during acute temperature variations. Because myosuppressin acts on the cardiac neurons and muscles separately, we hypothesized that the myosuppressin-induced increase in heart contraction amplitude, and decrease in contraction period can offset each other to provide system stability as temperature is increased. To test whether or not myosuppressin stabilizes circuit output as temperature is increased, myosuppressin was applied to the lobster whole heart at 7ºC, 10ºC, 13ºC and 16ºC, for 20 minutes. Changes in cardiac output in response to temperature and modulation were assessed by measuring the contraction force, heart beat frequency, and minimum contraction force. Interestingly, and contrary to previous results, in this data set, the cardiac neuromuscular system was temperature compensated in saline alone (control), and was not temperature compensated when perfused with myosuppressin (10-6 M). These findings seemed to differ from Lemus’ data (2023), where the cardiac neuromuscular system was not temperature compensated in control conditions and became temperature compensated when perfused with myosuppressin. The seasons at which each data set was collected (June-August vs November-March) could underlie these observed discrepancies.

Date: 2025-01-01
Creator: Jasmine Jia
Access: Access restricted to the Bowdoin Community

Date: 2025-01-01
Creator: Elisabeth C. Chan
Access: Access restricted to the Bowdoin Community