Honors Projects
Showing 211 - 220 of 564 Items
Exploring Random Walks on Graphs for Protein Function Prediction
Date: 2018-05-01
Creator: Angela M Dahl
Access: Open access
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as political actors and placed the blame for violence exclusively on the militaries and the United States, I draw from unpublished Argentine police records, Argentine Embassy documents, and Chilean-Argentine solidarity group publications to argue that it is essential to broaden our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.
Bubbles & Bought-Ins: Reevaluating Price Movements in the Art Market
Date: 2020-01-01
Creator: Silas Wuerth
Access: Open access
- Employs two tests for bubbles in the art market. First, a right-hand forward recursive augmented Dickey-Fuller test to identify explosive price movements. Second, a test for the statistical significance of hedonic regression price index coefficients after controlling for equity market performance. Finds strong evidence for a speculative bubble in the pre-Great Recession "Post-War & Contemporary" market. Evidence for this bubble diminishes but does not dissipate after accounting for the effect of failed sales on index returns.
Natural variation in chromatin conformation among populations of Drosophila melanogaster
Date: 2021-01-01
Creator: Utku Ferah
Access: Open access
- The role of polymorphisms in protein-coding and non-coding regions of the genome during adaptive evolution has been a long-debated subject in evolutionary biology. Although the importance of coding-sequence polymorphisms during evolution has been well-documented, the influence of non-coding regions of the genome on phenotypic diversity and adaptive evolution remains less clear. Enhancers are cis-regulatory elements that dictate gene transcription rates, times, and locations; enhancers are located in noncoding regions and, when active, exhibit an open-chromatin conformation. In the current study, we identified putative enhancers that differ in chromatin conformation among three natural isolates of Drosophila melanogaster from different parts of the world. The genome-wide numbers of enhancers active in some natural isolates—but inactive in others—will provide insight into the amount of raw material available for evolution due to transcriptional regulatory variation.
Extreme Value Theory and Backtest Overfitting in Finance
Date: 2015-05-01
Creator: Daniel C Byrnes
Access: Open access
- In order to identify potentially profitable investment strategies, hedge funds and asset managers can use historical market data to simulate a strategy's performance, a process known as backtesting. While the abundance of historical stock price data and powerful computing technologies has made it feasible to run millions of simulations in a short period of time, this process may produce statistically insignificant results in the form of false positives. As the number of configurations of a strategy increases, it becomes more likely that some of the configurations will perform well by chance alone. The phenomenon of backtest overfitting occurs when a model interprets market idiosyncrasies as signal rather than noise, and is often not taken into account in the strategy selection process. As a result, the finance industry and academic literature are rife with skill-less strategies that have no capability of beating the market. This paper explores the development of a minimum criterion that managers and investors can use during the backtesting process in order to increase confidence that a strategy's performance is not the result of pure chance. To do this we will use extreme value theory to determine the probability of observing a specific result, or something more extreme than this result, given that multiple configurations of a strategy were tested.
Aortic pressure and heart rate in the lobster Homarus americanus are modulated by mechanical feedback and neuropeptides
Date: 2021-01-01
Creator: Grace Marie Hambelton
Access: Open access
- Baroreceptors are stretch receptors located in the aorta of mammals; in response to increased afterload, they elicit a decrease in heart rate, creating a negative feedback loop that lowers blood pressure. Although lobsters (Homarus americanus) do not have baroreceptors like mammals, closely related land crabs have been shown to have baroreceptor-like responses. Heart contraction is also regulated by the Frank-Starling response, where increasing stretch or preload increases the contractile force of the heart. In addition to these types of biomechanical modulations, lobsters use a central pattern generator, the cardiac ganglion, to maintain synchronicity of the heartbeat. The heart is also controlled by the central nervous system via neuromodulators, such as myosuppressin, which has been shown to increase active force and decrease frequency in isolated lobster hearts. We performed experiments on a lobster heart with the main arteries still intact, and varied the preload by stretching anterior arteries, and the afterload by elevating the dorsal abdominal artery. We added myosuppressin to modulate the cardiac ganglion output and muscle contraction. We found that the baroreceptor-like response is most directly modulated by active force, whereas frequency could be a secondary control. Increasing preload does increase active force, but that does not correlate to a higher cardiac output, which shows that how hard the heart pumps is not what determines how effectively it is pumping. Additionally, we found that myosuppressin has a much stronger effect on frequency than active force, and so with myosuppressin, frequency becomes the main determinant of cardiac output.
Alexander the Great and the Rise of Christianity
Date: 2021-01-01
Creator: Stephen M. Girard
Access: Open access
- Alexander the Great and the Rise of Christianity focuses on the political, mythical, and philosophical connection between Alexander the Great's life and the beginnings of early Christianity. The first chapter of the text focuses on an analysis of mythical conceptions of Alexander the Great as “Son of God” as well as cultural perceptions of him as “Philosopher King” and cosmopolitan, and how these portraits of Alexander were influential for Christianity. The second chapter analyzes Alexander’s relationship with the Jewish people, and his appearances in the Old Testament apocalyptic Book of Daniel. The last chapter discusses Alexander’s relationship with Christianity itself, seen through a study of the life of Jesus, Alexandrian Judaism, and the early Christian apologists.
The Effects of Temperature on the Cardiac System of the American Lobster, Homarus americanus
Date: 2014-05-01
Creator: Elizabeth A Owens
Access: Open access
- The American lobster, Homarus americanus, inhabits a large oceanic range spanning from Labrador, Canada to North Carolina, USA. This geographic range varies in temperature by as much as 25ºC, and daily temperature fluctuations of up to 12ºC may occur at a single location depending on season, water depth, and tides. The cardiac system of the lobster is sensitive to these temperature changes, and has been shown to adjust its functioning over a large temperature range. A previous study showed that various functional parameters respond differently to temperature changes, but a stable cardiac output can be maintained over the range of 2-20ºC. The current study showed that the effects of temperature were exerted primarily through changes in the lobster heart central pattern generator, the cardiac ganglion. Similar patterns of change were seen in both semi-intact hearts and isolated cardiac ganglion preparations in response to increasing temperature. Specifically, with increasing temperature, the burst frequency showed a biphasic pattern in which frequency initially increased, then decreased rapidly at high temperatures. The burst duration, duty cycle, and number of spikes per burst generally decreased with increasing temperature, and spike frequency increased over the entire temperature range. Semi-intact hearts and isolated cardiac ganglia showed similar “crash” patterns, characterized by complete loss of function at high temperatures and complete recovery of function when temperature was returned to baseline. Feedback in the semi-intact heart provided some stabilization of bursting activity, but it did not provide the expected protection from high temperatures. The isolated CG had a significantly higher crash temperature than did the semi-intact system. This discrepancy in crash temperatures may be explained by considering factors at the level of the muscle and neuromuscular junction (NMJ), such as stretch and nitric oxide (NO) feedback and the balance of facilitation and depression at the NMJ. Stimulated preparations showed defacilitation of contraction amplitude at high temperatures despite the maintenance of constant burst parameters of stimulation. Therefore, several factors contributing to the relatively low crash temperature of the intact system may be a shift in the balance of facilitation and depression at the NMJ, a depression in ganglion function due to the release of NO by the muscle, or a combination of the two mechanisms.
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The Photodegradation of Endocrine Disrupting Compounds in Aqueous Solutions Access to this record is restricted to members of the Bowdoin community. Log in here to view.
Date: 2014-05-01
Creator: Peyton C Morss
Access: Access restricted to the Bowdoin Community
A Moderated-Mediation Model of Emerging Adult and Parent Religiosity, Externalizing Behavior, and Parenting Style
Date: 2021-01-01
Creator: Benjamin M. Simonds
Access: Open access
- The present study investigated whether emerging adult religiosity mediated the relationship between high parental religiosity and low levels of offspring externalizing, and whether these pathways are moderated by aspects of authoritative parenting (i.e., acceptance, firm control, and psychological autonomy). Surveys were completed by 275 emerging adults aged 18-25, including scales assessing their religiosity, the religiosity of their parents, the style of parenting in which they were raised, and their own engagement in externalizing behaviors. Results indicated a correlation between high levels of parental and emerging adult religiosity, and a marginal relationship between high parental religiosity and reduced offspring externalizing. However, emerging adult religiosity was not related to externalizing, such that no mediation model could be tested. Psychological autonomy granting moderated the relationship between parental religiosity and emerging adult externalizing: low parental religiosity was associated with high levels of emerging adult externalizing only in parents who exhibited low levels of psychological autonomy granting, while high parental religiosity was related to low emerging adult externalizing regardless of psychological autonomy granting. The results indicate a complex relationship between parenting, externalizing, and religiosity.