Showing 361 - 370 of 5709 Items
The Current Hunt for Nitric Oxide's Effects on the Homarus americanus Cardiac Ganglion
Date: 2022-01-01
Creator: Joanna Lin
Access: Open access
- The crustacean heartbeat is produced and modulated by the cardiac ganglion (CG), a central pattern generator. In the American lobster, Homarus americanus, the CG consists of 4 small premotor cells (SCs) that electrically and chemically synapse onto 5 large motor cells (LCs). Rhythmic driver potentials in the SCs generate bursting in the LCs, which elicit downstream cardiac muscle contractions that are essential for physiological functions. Endogenous neuromodulators mediate changes in the CG to meet homeostatic demands caused by environmental stressors. Nitric oxide (NO), a gaseous neuromodulator, inhibits the lobster CG. Heart contractions release NO, which directly decreases the CG burst frequency and indirectly decreases the heartbeat amplitude, to mediate negative feedback. I investigated NO’s inhibitory effects on the CG to further understand the mechanisms underlying intrinsic feedback. Using extracellular recordings, I examined NO modulation of the SCs and LCs when coupled in the intact circuit and when firing independently in the ligatured preparation. Using two-electrode voltage clamp, I additionally analyzed the modulation of channel kinetics. Based on previous studies, I hypothesized that NO decreases the burst frequency of the LCs and SCs by modulating conductance properties of the voltage-gated A-type potassium current (IA). My data showed that NO decreased the burst frequency in the LCs and the burst duration in the SCs in a state-dependent manner. Furthermore, NO increased the IA inactivation time constant to decrease the LCs’ burst frequency. Thus, NO mediated inhibitory effects on cardiac output by differentially targeting both cell types and altering the IA current kinetics.
Music Streaming Services, Programming Culture, and the Politics of Listening
Date: 2015-05-01
Creator: Walker Kennedy
Access: Open access
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Predicting Anionic Pharmaceutical Sorption to Soils Using Probe Compounds Access to this record is restricted to members of the Bowdoin community. Log in here to view.
Date: 2022-01-01
Creator: Francesca Ann Cawley
Access: Access restricted to the Bowdoin Community
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The Photocatalytic Degradation of Ibuprofen and Three Beta-Blockers using BiOCl: An Investigation into the Mechanisms Responsible for Photocatalytic Activity Access to this record is restricted to members of the Bowdoin community. Log in here to view.
- Restriction End Date: 2027-06-01
Date: 2022-01-01
Creator: Jeffrey Charles Price
Access: Access restricted to the Bowdoin Community
Student Activism and Malaysian Politics, 1955-74: Revising the History of the Malay Language Society (PBMUM)
Date: 2023-01-01
Creator: Song Eraou
Access: Open access
- In the literature on student activism in Malaysia, the years from 1967 to 1974 are emphasized as vibrant years—students organized large-scale demonstrations, regularly asserted their opinions in the political arena, and even participated in electoral politics. This period was followed, however, with the imposition of strict laws in 1975 limiting freedom of speech and expression. Such laws were part of the broader containment policy pursued by the state after the May 13, 1969, racial riots, which allowed the state to stifle any form of political dissidence to ensure peace between different ethnic groups. One particularly active organization in this period was the Malay Language Society (PBMUM) of the University of Malaya. While PBMUM began with a dream of using language as a mode to foster national unity, after the riots it would be remembered as a race-based organization oriented toward Malays. This thesis offers a historical analysis and reinterpretation of the PBMUM, characterizing it as a platform for students at the University of Malaya to meet, discuss, and mobilize around the most important issues concerning Malaysian society. Importantly, members exhibited a continued devotion towards changing the fate of the rakyat (the people). In revising the history of PBMUM, this thesis also offers a deeper understanding of the Malaysian political landscape in the ‘60s and ‘70s, focusing on political discussions around nation-building in the lead up to the May 13 riots and its aftermath.