Showing 71 - 80 of 583 Items
Characterizing the influence of Atlantic water intrusion on water mass formation and primary production in Kongsfjorden, Svalbard
Date: 2015-05-01
Creator: Courtney Michelle Payne
Access: Open access
- With warming global temperatures and changes to large-scale ocean circulation patterns, warm water intrusion into Arctic fjords is increasingly affecting fragile polar ecosystems. This study investigated how warm Atlantic water intrusion and the tidewater glacial melting it causes impacted water mass formation and primary productivity in Kongsfjorden, Svalbard. Data were collected over a 2-week period during the height of the melt season in August near the Kronebreen/Kongsvegen glacier complex, the most rapidly retreating glacier in Spitsbergen. Since 1998, intruding waters have warmed between 4 and 5.5˚C, which has prevented sea ice formation and changed the characteristics of fjord bottom waters. Increased glacial melting in the last decade has changed the characteristics of surface waters in the fjord. Modeled light fields suggest that suspended sediment in this glacial meltwater has reduced the euphotic zone close to the ice face, preventing high primary production in both the consistent and intermittent sediment-laden meltwater plumes. However, measurements collected close to terrestrially terminating glaciers indicate that extremely high primary production can occur in conditions of low turbidity. The results of this study support a three-part model of the effects of warm-water intrusion on water mass formation and primary production, where changes in sea ice coverage and tidewater glacial dynamics affect the optical light field. This model allows for spatial predictions for the most likely impacts of warm water intrusion on primary production in Spitsbergen, and could be extrapolated out to explore potential phytoplankton response in other regions susceptible to warm-water intrusion.
The French Official Mistress: Fashioning Female Political Power in the Ancien Régime
Date: 2024-01-01
Creator: Samantha Brown
Access: Open access
- This thesis focuses on the French official mistress as a position of unofficial female political power under the French monarchy from the 16th to the 18th century. Centering on three case studies – Diane de Poitiers, Madame de Maintenon, and Madame de Pompadour – this thesis argues that the role of the official mistress extended beyond sexual companion to advisor, negotiator, diplomat, artistic patron, and cultural trendsetter. By taking a deep look at the epistolary and artistic record of these three official mistresses from across France’s modern history, the extent of their autonomy and political maneuvering becomes clear in the tactics they used to project and solidify their power. Diane de Poitiers, Madame de Maintenon, and Madame de Pompadour all existed in unique contexts of the French court and constructed their own methods of fulfilling the role of the official mistress, revealing both changes in the monarchy and their impacts upon it. Notably, the ways in which they projected identity through self-fashioning resulted in a reflection of this image back onto the monarch, expanding the extent of their impact on the monarchy. In striving to understand the political reality of women in France under Salic law and today, the position of maîtresse-en-titre is a crucial framework to recognize the significance of female power structures at court and in the monarchy, and the degree to which women were able to shape these structures themselves.
Semaphorin-Induced Plasticity in the Nervous System of the Cricket, Gryllus bimaculatus
Date: 2021-01-01
Creator: Alicia G. Edwards
Access: Open access
- The adult auditory system of the cricket, Gryllus bimaculatus, exhibits a rare example of neuronal plasticity. Upon deafferentation, we observe medial dendrites that normally respect the midline of the PTG in the central nervous system sprouting across the boundary and forming synaptic connections with the contralateral auditory afferents. The Horch Lab has investigated key molecular factors that might play a causal role in this paradigm. Specifically, the protein Sema1a.2 comes from a guidance molecule family and has a role in developmental neuronal plasticity in other organisms. In this study, I explored the role of Sema1a.2 in the neuronal plasticity of the adult auditory system of the cricket by conducting a series of dsRNA knockdown experiments targeting Sema1a.2 followed by backfill procedures in which we iontophoresed dye into the Ascending Neurons (ANs) to visualize the anatomical effects of the knockdown experiments using confocal microscopy. We found that there were no significant differences between animals injected with dsRNA against GFP and Sema1a.2 volume, with respect to qualitative and quantitative data. However, we believe with an increase in cohort size, the trends observed, particularly the effect of Sema1a.2 knockdowns on CWM and CBM volumes, will become more pronounced and significant. Potential future pathways could include conducting double knockdowns of Sema1a.2 and Sema2a to observe if these two proteins are working together to create a more obvious effect on midline crossing and branching. Other options also include looking into other protein families that might be the causing factor in this rare phenomenon (toll-like receptors).
Characterization of Yellow Family Proteins in Gryllus bimaculatus
Date: 2021-01-01
Creator: Alexandra W. Rubenstein
Access: Open access
- Neuronal plasticity occurs in developing nervous systems, with adult organisms rarely able to recover from neurological damage. The cricket, Gryllus bimaculatus, is useful to study neuronal plasticity due to its reorganization of the auditory system in response to injury beyond development. When a cricket ear is removed and auditory afferents severed, a rare phenomenon occurs: the dendrites of interneurons on the deafferented side cross the typically-respected midline of the prothoracic ganglion to form functional synapses with auditory afferents from the opposite side. To find proteins involved in this phenomenon, the Horch Lab assembled a de novo transcriptome from neurons in the prothoracic ganglion of G. bimaculatus. Differential gene expression analysis revealed upregulated protein yellows post-deafferentation, indicating these proteins could influence neuronal plasticity in the adult cricket CNS. I focused on characterizing the protein yellow family in the cricket. By relating protein yellows evolutionarily, mapping them onto the genome, and analyzing their sequences, I discovered the cricket has 10 yellow genes, including a newly identified yellow-r* and a block of yellows showing synteny with insect genomes. Additionally, yellow-e and -x in crickets are closely related to bacterial yellow, perhaps indicating a role for horizontal gene transfer in yellow gene evolution. The protein upregulated in the cricket CNS is closely related with yellow-f’s in other insects, indicating yellow-f is likely a secreted protein, highly expressed in the CNS, multifunctional, and conserved across insects. Characterizing yellow-f can give insight into how these upregulated proteins might be related to neuronal plasticity in G. bimaculatus.
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Palimpsestuous London: Spatial and Temporal Layering in Fin-de-Siècle Victorian Fiction Access to this record is restricted to members of the Bowdoin community. Log in here to view.
Date: 2015-05-01
Creator: Elisabeth A Strayer
Access: Access restricted to the Bowdoin Community
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From Homer to the Roman Empire: The Reception of Music in Antiquity Access to this record is restricted to members of the Bowdoin community. Log in here to view.
Date: 2023-01-01
Creator: Augustine Segger
Access: Access restricted to the Bowdoin Community
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Timing the Paleozoic Oxygenation of the Deep Ocean Using Thallium Isotopes This record is embargoed.
- Embargo End Date: 2028-05-17
Date: 2023-01-01
Creator: Jean Nikolas R. Clemente
Access: Embargoed
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Sex- and age-specific susceptibility of parvalbumin neurons to DNA methylation in a model of early life adversity This record is embargoed.
- Embargo End Date: 2025-05-19
Date: 2022-01-01
Creator: Alissa Chen
Access: Embargoed
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Antimicrobial Compounds in the Lobster, Homarus americanus: An Investigation of Lobster Shell Extracts This record is embargoed.
- Embargo End Date: 2027-05-19
Date: 2022-01-01
Creator: Usira Ahmed Ali
Access: Embargoed
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Illumination, Inspiration, and Inquisition: The 15th and 16th century reception and reaction of Dante’s Divina Commedia in Spain This record is embargoed.
- Embargo End Date: 2025-05-19
Date: 2022-01-01
Creator: Francesca Mauro
Access: Embargoed