Showing 521 - 530 of 681 Items
Characterizing the exhumation path of the first ultrahigh-pressure terrane in North America Access to this record is restricted to members of the Bowdoin community. Log in here to view.
Date: 2015-05-01
Creator: Zachary FM Burton
Access: Access restricted to the Bowdoin Community
An AGN as a Counterpart for Neutrino Event IceCube-220303A
Date: 2024-01-01
Creator: Nur Schettino
Access: Open access
- Cosmic rays have been detected for over a century. While some sources have been confirmed, they cannot explain the high energy of the particles (> 10^15 eV), so it remains unclear where and how they are accelerated to extreme energies. The study of astrophysical high-energy neutrinos may help solve the puzzle. These neutrinos are produced by cosmic rays interacting with other charged particles or photons. Moreover, while cosmic rays do not reveal their sources of origin because they can be deflected by magnetic fields, cosmic neutrinos detected by the IceCube Observatory can be traced back to their sources of origin. We will consider an active galactic nucleus (AGN) as a candidate source for a high-energy neutrino.This thesis examines the AGN WISEA J175051.31+105645.3 as a potential source for IceCube-220303A, a high-energy neutrino with a 78% probability of being astrophysical in origin. Using follow-up NuSTAR and Swift/XRT observations, WISEA J175051.31+105645.3 was the only viable source we found in IceCube-220303A’s uncertainty region. We used follow-up X-ray data to construct a multi-wavelength spectral energy distribution (SED) through which we calculated the AGN’s neutrino energy flux. This calculation yields the number of neutrinos we would expect to detect from the AGN in a given time period. We used this number to calculate the probability that IceCube-220303A was emitted by WISEA J175051.31+105645.3. Finding a statistically significant link between IceCube-220303A and WISEA J175051.31+105645.3 may help us better understand what processes can accelerate particles like cosmic rays to extreme energies and learn more about AGN.
Modulation of the stretch feedback pathway in the cardiac neuromuscular system of the American lobster, Homarus americanus
Date: 2024-01-01
Creator: Karin van Hassel
Access: Open access
- The cardiac ganglion (CG) is a central pattern generator, a neural network that, when activated, produces patterned motor outputs such as breathing and walking. The CG induces the heart contractions of the American lobster, Homarus americanus, making the lobster heart neurogenic. In the American lobster, the CG is made up of nine neurons: four premotor pacemaker neurons that send signals to five motor neurons, causing bursts of action potentials from the motor neurons. These bursts cause cardiac muscle contractions that vary in strength based on the burst duration, frequency, and pattern. The activity of the CG is modulated by feedback pathways and neuromodulators, allowing for flexibility in the CG’s motor output and appropriate responses to changes in the animal’s environment. Two feedback pathways modulate the CG motor output, the excitatory cardiac muscle stretch and inhibitory nitric oxide feedback pathways. Despite our knowledge of the modulation of the CG by feedback pathways and neuromodulators separately, little is known about how neuromodulators influence the sensory feedback response to cardiac muscle stretch. I found one neuromodulator to modulate each phase of the stretch response differently, one neuromodulator to generally not affect the stretch response, and three neuromodulators to suppress the stretch response. These results suggest neuromodulators can act to produce flexibility in a CPG’s motor output, allowing the system to respond appropriately to changes in an organism’s environment, and allow for variation in CPG responses to different stimuli.
Sexual Knowledge in Late-Colonial Bombay: Contested Authority, Politicized Sciences
Date: 2022-01-01
Creator: Rahul Prabhu
Access: Open access
- Sexuality was at the fulcrum of various issues facing late-colonial India from social reform projects such as child marriage, women’s rights and birth control to concerns of socioeconomic, physical and sexual weakening. The question of sexual modernity became implicated in imaginations of the modern post-colonial nation, setting the stage for a period of energized, linguistically plural projects of sexual knowledge production. While science was used to authorize such projects in the West, where could authority be located in a context where science held plural meaning and authority itself was highly contested? This paper asks how scientific authority was understood, deployed and shaped by the eugenics project of Narayan Sitaram Phadke (1894-1978) and the sexology project of A.P. Pillay (1890-1956). This thesis argues that the mechanics of each figures’ utilization of science captures how the interaction between scientific authority and society was understood by Phadke and Pillay in different ways. While both figures subscribed to the idea that science was universally authoritative in the making of sexual modernity, Phadke’s and Pillay’s projects show the plurality in how science was understood by social reformers. Furthermore, the thesis presents the differences between Phadke’s and Pillay’s projects as a product of the larger movements – British-era birth control advocacy, Hindu nationalism, upper-caste marriage reform and global sexology – that Phadke and Pillay were distinctly invested in or separated from. Scientific authority and the mechanics of its use is proposed as a vivid lens into the complex dynamics of modernization in late-colonial India.
From Bleeding to Breathing: Embodying Violence and Healing in the Performances of Ana Mendieta, Regina José Galindo and Ruby Rumié Access to this record is restricted to members of the Bowdoin community. Log in here to view.
Date: 2021-01-01
Creator: Norell Sherman
Access: Access restricted to the Bowdoin Community
Art of the Profile: Profile Journalism in Theory and Practice This record is embargoed.
- Embargo End Date: 2028-05-18
Date: 2023-01-01
Creator: Halina E. Bennet
Access: Embargoed
Narration, Nation et Nationalisme dans les récits d’enfance de Mouloud Feraoun et Mohammed Dib
Date: 2022-01-01
Creator: Reed Foehl
Access: Open access
- During the mid-20th century, a new form of Algerian literature emerged, thematically detached yet linguistically tied to France. Novelists aligned with this littérature algérienne de langue française used their narrative power to expose the atrocities of the colonial period, while emphasizing the rising nationalist spirit throughout the country. A peculiar aspect of this national literature is the presence of a child protagonist. Many of Algeria’s most prominent authors centered their first novels on a young boy. This leads to my central question: does the récit d’enfance (childhood narrative) possess certain qualities that lend it useful for representing ubiquitous suffering, as well as an imminent national awakening. My research focuses on two Algerian novelists, Mouloud Feraoun and Mohammed Dib, who employ the récit d’enfance for different aims. In this paper, I first define the récit d’enfance and show how Feraoun and Dib implement this literary style. Secondly, I argue that Mohammed Dib’s trilogy is distinctly political. Employing the critical theories of Frantz Fanon and Benedict Anderson, I contend that Dib’s trilogy, published between 1952-1957, is a littérature de combat (combat literature). Although Feraoun’s publication of Le Fils du Pauvre in 1950 inaugurated Franco-Algerian literature, his work is more reflective than political. Comparing Feraoun and Dib’s early work, allows me to expose the disparate narratives arising in the decade prior to Algerian independence. Their portrayal of colonial oppression, as well as the courage and ambition of an exploited people, remains useful when studying models of colonial and post-colonial nationalism and nation-state.
Testing conservation of an mRNA transport pathway in yeast Access to this record is restricted to members of the Bowdoin community. Log in here to view.
Date: 2021-01-01
Creator: Kyu Young "Kevin" Chi
Access: Access restricted to the Bowdoin Community
Investigating the photoacidic properties of 8-benzylideneamino-2-naphthol This record is embargoed.
- Embargo End Date: 2027-05-19
Date: 2022-01-01
Creator: Oliver M. Nix
Access: Embargoed
The Role of ELMO5 in Arabidopsis thaliana Cell Adhesion
Date: 2022-01-01
Creator: Isabel Kristina Ball
Access: Open access
- Plant cell growth and development relies on proper cellular adhesion. As the extracellular matrix serves as the area of connection between two cells, its synthesis and maintenance are essential for cellular adhesion. The middle lamella region, the layer of the extracellular matrix between two adjacent cell walls, is diffuse with the polysaccharide pectin due to its delivery by Golgi vesicles early during cell division. A Ruthenium Red screen for cellular adhesion mutants identified the family of 5 ELMO proteins that are critical for proper cellular adhesion. To further our understanding of plant cellular adhesion and pathways of pectin synthesis and modification, this work investigates ELMO5. Plants homozygous for a T-DNA insertion in ELMO5 and a new deletion mutant allele generated using CRSPR do not have a cellular adhesion phenotype, suggesting it is either not critical for cellular adhesion or is redundant with another gene. Redundancy within the ELMO family is identified through the analysis of double mutants of elmo5 and each of the other four elmo genes. Both elmo1-/- elmo5-/-and elmo4-/- elmo5-/-mutants have a visibly worse cellular adhesion defect phenotype, suggesting partial redundancy through the ELMO family. The mutants are also rescued by growth on agar, pointing to the importance of turgor pressure and osmotic potential in modulating cellular adhesion. Both ELMO4 and ELMO5 were found to localize to the Golgi using a GFP fusion, consistent with a role for ELMOs as scaffold for pectin biosynthesis.