Showing 1211 - 1220 of 4695 Items
Sensitivity Analysis of Basins of Attraction for Gradient-Based Optimization Methods
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.
The development of begging calls in Yellow Warblers
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.
Personally Relevant Indoor Nature Imagery’s Impact on Students’ Well-Being, Connection to Nature, and Eco-Conscious Behaviors
Date: 2019-05-01
Creator: Sarena Sabine
Access: Open access
- Previous research has shown that experiences in nature are predictive of increased connection to nature, well-being, and pro-environmental behavior. The current study investigated whether daily exposure to indoor nature imagery would also improve well-being and eco-conscious behaviors, and whether personally relevant images would enhance this hypothesized effect. Participants completed a test assessing baseline connection to nature and well-being, specifically satisfaction with life, positive and negative emotions, and stress. In the 2 (Nature vs. Built) X 2 (Familiar vs. Unfamiliar) study design, 125 participants either received a poster from a photo that they submitted (a personally-relevant nature scene or personally-relevant built scene) or a poster of an unfamiliar natural or built scene. After four weeks of daily exposure to this new poster in their home, participants completed a post-test which included the same measures of well-being and connection to nature, along with a novel eco-conscious behaviors measure involving environmental petitions. The nature intervention significantly improved participants’ satisfaction with life. The personal relevancy of images did not enhance well-being, either alone nor in interaction with image content. The finding that daily exposure could lead to improved well-being has implications for addressing mental health concerns.
Interview with Adriennie Hatten (Class of 1990) and Shelby Cogdell Knox (Class of 1991) by Marina Henke
Date: 2019-11-10
Creator: Adriennie Hatten
Shelby Cogdell Knox
Access: Open access
- Adriennie Hatten ('90) and Shelby Cogdell Knox ('91) both share their path to Bowdoin from East Cleveland. They describe the racism that they experienced on campus, especially in their first years at Bowdoin, and how they struggled to develop a sense of place in what was a campus with so few black students. Both Hatten and Knox were highly involved with the African American Society (AfAm) during their time at the College, and the two women share how central Russwurm was to their Bowdoin experience. They reminisce on various speakers that they brought to campus, including Toni Morrison. Finally, Hatten and Knox reflect on AF/AM/50, and share concerns about both the current state of Russwurm and the recent name change from the African-American Society to the Black Student Union. Finally both women criticize the ways that black alumni are treated by the College, and how they see that embodied in the offerings and verbage of their recent weekend on campus.
Interview with Marnita Eaddie (Class of 1990) by Marina Henke
Date: 2019-11-09
Creator: Marnita Eaddie
Access: Open access
- Marnita Eaddie ('90) reminisces about her time at Bowdoin, particularly the transition of moving from her predominantly black hometown of East Cleveland to Brunswick, Maine. She shares how variations in wealth between students showed during her time at Bowdoin, but also how students from a variety of backgrounds managed to come together. She recounts confronting racism on the predominantly white campus, and how she navigated being one of less than fifteen black students in her incoming class. She additionally describes her own commitment to academics during her four years at the College, and how she managed to balance a superb academic record along with holding various part-time jobs during all of her semesters. Eaddie brings up the impact of various tragedies on campus, including the death of student Pamela Herbert (‘90) in the Pan Am Flight 103 terrorist attack. Finally, she explores how her later work in the military contrasted and aligned with her Bowdoin experience.
Molly Kennedy '19 Interviews Jenna Scott '19
Date: 2015-01-01
Creator: Jenna Scott
Access: Open access
Interview with Justin Weathers (Class of 2018) by Aisha Rickford
Date: 2019-11-09
Creator: Justin Weathers
Access: Open access
- Justin Weathers ’18 grew up in Baltimore, Maryland. His track coach and AP Gov teacher, a graduate of Bowdoin, encouraged him to apply to Bowdoin. Weathers talks about transitioning from the mostly black population of Baltimore to the very white, very small town of Brunswick, ME. He reflects on how, while AfAm was a safe space at Bowdoin, the class, ethnic, and regional differences among black students at Bowdoin affected the black community at Bowdoin. He also reflects on several bias incidents happening at Bowdoin during his first year, which was also the rise of the Black Lives Matter movement. Weathers remembers how it was to experience the Baltimore riots of the mid 2010s while attending Bowdoin. Additionally, Weathers reflects on his lasting impact at Bowdoin, from making “More than Meets the Eye” a mandatory part of Bowdoin First-Year Orientation, to advocating for black students affected by Bowdoin’s zero tolerance violence policy, which neglects to account for racial and verbal violence, plus the difficulty of having conversations across difference at Bowdoin that feel productive. Overall, Weathers reflects on how Bowdoin shaped him into who he is today, and one of his favorite memories of Bowdoin: riding into Ivies on the Brunswick Quad with Bowdoin security on a golf cart.
"Chinese Final Project" by Caroline Glaser (Class of 2023)
Date: 2020-01-01
Creator: Caroline Glaser
Access: Open access
- For the final project, all students in Chinese 1104 created a short video about how COVID-19 impacted our lives. Author is class of 2023.
Reading & Teaching Chaucer: the "Good Wif"?
Date: 2020-01-01
Creator: Sophie Friedman
Access: Open access
- This two-chapter project applies formalist and feminist thinking to the thirty-line description of the Wife of Bath in Geoffrey Chaucer’s medieval, British work The Canterbury Tales. It is an interdisciplinary project; it studies how to read and teach Chaucer at the secondary level based off of these two approaches. In this formalist chapter, I study narrative voice, rhyme, irony, and ekphrasis, writing about the history and function of each of those tools and their role in the passage. I argue that the formalist close reading approach is an excellent teaching tool that generates thorough, rigorous, and joyful reading. In this feminist chapter, I compile a critical literary history of scholarly feminist and pre-feminist engagement with the passage over time. I read into an underlying genotype text, arguing that the Wife of Bath was a female entrepreneur who used textiles as a means of social, professional, and aesthetic expression and empowerment. Then I advocate for a feminist ethical teaching approach—one where we use the text as a non-ethical space in which to explore ethical questions surrounding gender. Ultimately, I argue that feminist and formalist approaches are interdependent and complementary; for both reading and teaching Chaucer, they stand stronger together.
Characterization of O-Linked Glycosylated Neuropeptides in the American Lobster (Homarus americanus): The Use of Peptide Labeling Following Beta Elimination
Date: 2020-01-01
Creator: Edward Myron Bull
Access: Open access
- Neuropeptides are a class of small peptides that govern various neurological functions, and the American lobster (Homarus americanus) provides a model system for their characterization. Neuropeptides are commonly post-translationally modified (PTM), and one common PTM is glycosylation. Past research in the Stemmler lab has found glycosylated neuropeptides in H. americanus; however, the extent and biological role of this modification has not been well characterized. This study was undertaken to determine the number of glycosylated peptides in the sinus glands of H. americanus and to develop an approach to tag the site of glycosylation using beta-elimination chemistry. LC-MS paired with high pH reverse phase fractionation was used to survey for glycosylated neuropeptides and beta elimination with an amine tag was used as an approach to characterize the site of glycosylation. Our results indicate that high pH fractionation is a useful approach to simplify complex mixtures of neuropeptides and improve glycopeptide detection. Efforts to use beta elimination and tagging to characterize glycosylated neuropeptides have been less successful. Beta elimination of full length peptides resulted in peptide degradation. An approach utilizing chymotrypsin to reduce peptide size coupled with beta elimination and labeling with 2-dimethylaminoethanethiol showed less evidence for degradation, and this approach yielded data isolating two potential serine residues for the site of glycosylation; however, the data was not sufficient to distinguish the two sites. Work to optimize reaction conditions using a glycopeptide standard showed that multiple isomeric products were formed during beta elimination. With the goal of optimizing reaction conditions, future work will further examine reaction kinetics to eventually apply the approach to the entire sinus gland