Showing 1291 - 1300 of 3365 Items
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.
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.
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.
Stuck in Limbo: Temporary Protected Status, Climate Migrants and the Expanding Definition of Refugees in the United States
Date: 2021-01-01
Creator: Noelia Calcaño
Access: Open access
- There will be 1.2 billion climate refugees by 2050 as ecological disasters precipitate mass migrations around the world. The U.S. does not legally recognize climate migrants as refugees, instead adhering to the 1951 UN Refugee Convention that limits the definition of a refugee to individuals facing political persecution. Despite failing to expand the definition of a refugee, the U.S. has accommodated migrants displaced by natural disasters through a series of ad hoc fixes, most notably “Temporary Protected Status.” In Central American countries that were granted TPS, we encounter the paradox of the U.S. employing environmental disasters to justify continued extensions of this temporary protection, while addressing chronic conditions in the region. The central question of this thesis is, has employing the environment as a catch-all tool for Temporary Protected Status protection expanded the de facto definition of a “refugee,” for Central American migrants impacted by climate catastrophes and if so, how? Though TPS fills a gap in US law by providing de facto protections to migrants fleeing environmental disasters, the environment is being used as a catch-all tool for more systemic economic and political vulnerabilities in Central America. The environment is a catch-all tool for continued protection only insofar as it is not recognized as political, yet it is getting harder to employ the environment as an apolitical driver of migration. The precarious foundation of TPS threatens the hundreds of thousands of Central Americans that depend on this program to live and work legally in the United States.
Who We Are: Incarcerated Students and the New Prison Literature, 1995-2010
Date: 2013-05-01
Creator: Reilly Hannah N Lorastein
Access: Open access
- This project focuses on American prison writings from the late 1990s to the 2000s. Much has been written about American prison intellectuals such as Malcolm X, George Jackson, Eldridge Cleaver, and Angela Davis, who wrote as active participants in black and brown freedom movements in the United States. However the new prison literature that has emerged over the past two decades through higher education programs within prisons has received little to no attention. This study provides a more nuanced view of the steadily growing silent population in the United States through close readings of Openline, an inter-disciplinary journal featuring poetry, essays, fiction, and visual art created by incarcerated students enrolled in the College Program at San Quentin State Prison. By engaging the first person perspective of the incarcerated subject, this project will reveal how incarcerated individuals describe themselves, how they maintain and create intimate relationships from behind bars, and their critiques of the criminal justice system. From these readings, the project outlines conventions of “the incarcerated experience” as a subject position, with an eye toward further research analyzing the intersection of one's “incarcerated status” with one’s race, class, gender, and sexuality.
A Time for Every Purpose: Race, Medical Professionalism, and the Physicians’ Dilemma
Date: 2022-01-01
Creator: Reuben Mindlin Schafir
Access: Open access
- This thesis examines the intersection of race and professionalism in healthcare as they relate specifically to the debate over universal healthcare. It begins with the National Medical Association (NMA), a professional organization for Black physicians founded in 1895. The first two chapters follow the NMA as they attempt to navigate the two allegiances they have: one to be "race men," and work for racial equity in healthcare, and one to be professionals, and work towards affirming their professional sovereignty. The narrative begins in 1945, when President Harry Truman backed the first substantial proposal for a system of nationalized healthcare. Chapter two discusses the 1960s and how the confluence of the Great Society and the civil rights movement provided Black doctors with an opportunity to successfully serve both aspects of their identities. The third chapters explores the 1970s and the events following the passage of Medicare and Medicaid. The NMA began to align itself more closely with the American Medical Association (AMA), which had long-embodied the medical establishment. When this alignment occurred, the Black Panther party offered an alternative method of addressing racial health inequities that rejected not only the notion of healthcare as a commodity, but the entire national identity associated with the free market within which physicians sold care. This thesis considers how the interests of patients and the interests of doctors do and do not align, using race to bring this tension into high relief.
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.
Characterizing and Investigating the Electrophysiological Properties of the Plastic Cricket Auditory System in Response to Cooling
Date: 2022-01-01
Creator: Hannah Tess Scotch
Access: Open access
- The auditory system of the Mediterranean field cricket (Gryllus bimaculatus) is capable of profound compensatory plasticity. Following deafferentation due to the loss of an auditory organ, the dendrites of intermediate auditory neuron Ascending Neuron 2 (AN-2) grow across the midline and functionally connect to contralateral afferents. The loss of the auditory organ can be mimicked with reversible cold-deactivation, in which cooled Peltier elements silence the auditory organ and its afferents. Though this would presumably prevent AN-2 from firing, cooling instead induces a novel firing pattern called DOPE (delayed-onset, prolonged-excitation). In this study, intracellular physiological recordings were completed before, during, and after cooling in response to “chirp” and “pulse” sounds. Analysis was performed within and across crickets to characterize DOPE. Results revealed expected variability across individuals, as well as a wider spread of onset delay and a decrease in spike frequency and number of spikes per burst relative to baseline within individuals during cooling. Generally, subsequent warming only partially restored the neuronal responses to baseline as measured by all three parameters. This was particularly true in response to “pulse” stimuli. Future experiments will investigate if DOPE is caused by synaptic inputs or intrinsic properties of AN-2, as well as the role of inhibition in the circuit. Eventually, we hope to develop a complete model of the auditory circuit for future investigations of plasticity, with ramifications for treating human neuronal injury.
Interview with David Dickson (Class of 1976) by Aisha Rickford
Date: 2019-11-09
Creator: David Dickson
Access: Open access
- David Dickson '76 shares some remarks on his father, David W. D. Dickson, who graduated from Bowdoin in 1941, and his uncle who graduated in 1935. He talks about how the Bowdoin of their era had segregated fraternities that did not allow black students or Jewish students, and details his father’s experience with the emotional tax that such a reality posed. Dickson also talks about the importance of having the safe space of the African-American society that behaved as an “island on a lily-white campus.” He also talks about the former student organization, All Races United (ARU) and how students of marginalized backgrounds as well as “independent mainstream” students could come together in activism. Finally, Dickson shares how his experiences at Bowdoin affected the development of his racial identity.
Interview with Sandra Martinez (Class of 2013) by Marina Henke
Date: 2019-11-10
Creator: Sandra Martinez
Access: Open access
- Sandra Martinez ('13) recounts life at Bowdoin as a Latina woman. She describes Bowdoin as a space where she came more into her cultural identity, while also being where she felt the limitations and challenges of being a minority on campus. Additionally, Martinez discusses the simultaneous division and alliance between the African American Society and the Latin American Student Organization, and the various means students went to in bridging or instating this distance. As a math major, Martinez confronted the realities of a faculty lacking in diversity, and explored how this impacted her academic career and confidence in the classroom. Finally she speaks to the way that she learned to command her opinions, against at times people’s wishes, and gives advice to future Bowdoin women of color for how they can make space for themselves.