Showing 111 - 120 of 583 Items

The role of behavioral diversity in determining the extent to which the cardiac ganglion is modulated in three species of crab

Date: 2020-01-01

Creator: Grace Bukowski-Thall

Access: Open access

Central pattern generators (CPGs) are neural networks that generate the rhythmic outputs that control behaviors such as locomotion, respiration, and chewing. The stomatogastric nervous system (STNS), which contains the CPGs that control foregut movement, and the cardiac ganglion (CG), which is a CPG that controls heartbeat, are two commonly studied systems in decapod crustaceans. Neuromodulators are locally or hormonally released neuropeptides and amines that change the output patterns of CPGs like the STNS and CG to allow behavioral flexibility. We have hypothesized that neuromodulation provides a substrate for the evolution of behavioral flexibility, and as a result, systems exhibiting more behavioral flexibility are modulated to a greater degree. To examine this hypothesis, we evaluated the extent to which the STNS and the CG are modulated in the majoid crab species Chionoecetes opilio, Libinia emarginata, and Pugettia producta. C. opilio and L. emarginata are opportunistic feeders, whereas P. producta has a highly specialized kelp diet. We predicted that opportunistic feeding crabs that chew and process a wide variety of food types would exhibit greater STNS neuromodulatory capacity than those with a specialized diet. The STNS of L. emarginata and C. opilio responded to the seven endogenous neuromodulators oxotremorine, dopamine, CabTrp Ia, CCAP, myosuppressin, proctolin, and RPCH, whereas the STNS of P. producta only responded to proctolin, oxotremorine, myosuppressin, RPCH (25% of the time), variably to dopamine, and not at all to CabTrp and CCAP. Because P. producta, L. emarginata, and C. opilio all belong to the Majoidea superfamily, their primary distinctions are their feeding habits. For this reason, we further predicted that there would be no relationship between diet and modulatory capacity in the cardiac ganglion (CG) of the neurogenic heart. This would suggest that a lack of STNS modulatory capacity in P. producta relative to L. emarginata and C. opilio is specific to evolved foregut function. Whole-heart recordings from P. producta indicated that, unlike the STNS, the CG responds to CabTrp and CCAP. P. producta hearts also responded to oxotremorine and inconsistently to dopamine and proctolin. The CG of C. opilio was modulated by CabTrp, CCAP, dopamine, proctolin, myosuppressin, and oxotremorine, but not RPCH. The CG of L. emarginata responded to CCAP, and inconsistently to CabTrp, dopamine, and proctolin, but not to myosuppressin, RPCH, and surprisingly oxotremorine. Although cardiac responses were not identical between species, opportunistic and specialist feeders responded more similarly to the modulators tested in the heart than in the STNS. Notably, P. producta responded to each modulator in a similar manner to C. opilio and/or L. emarginata. However, L. emarginata’s surprising lack of cardiac response to oxotremorine suggests that phylogenetic closeness may not control for differences in CG and STNS function between species. Nevertheless, sample sizes of all three species were quite small, and individual differences lead to inconsistencies in the data. As a result, sample size must be enlarged to draw firm conclusions.


Spatially variable syn- and post-orogenic exhumation of the Appalachian Mountains from apatite and zircon (U-Th)/He thermochronology

Date: 2020-01-01

Creator: Luke Coughtry Basler

Access: Open access

We present zircon and apatite (U-Th)/He (ZHe, closure temperature = 150-200ºC; AHe, closure temperature = 45-80ºC) results from two study regions in the Appalachians Mountains to investigate the timing, rates, and spatial trends of exhumation during Alleghanian orogenesis, Atlantic rifting, and post-rift passive margin conditions. Within West Virginia and Virginia, 10 ZHe dates along an across-orogen transect display an eastward younging trend, from ~425 million years (Ma) in the western Appalachian Plateau province, to ~250-300 Ma in the central Valley-Ridge fold-thrust belt, and 163 ± 29 Ma in the eastern Piedmont. Inverse thermal modeling of ZHe data using external geologic constraints indicates: (1) Pre-depositional cooling signatures within Pennsylvanian Appalachian Plateau rocks, suggesting provenance from recycled Taconic or Acadian basin strata, (2) Rapid Alleghanian (250-300 Ma) cooling in the Valley and Ridge province, indicating syn-orogenic uplift and exhumation, followed by a protracted period of stable syn-rift thermal conditions from ~250-150 Ma, and (3) Rapid rift-induced cooling in the Piedmont province, likely caused by rift-flank uplift and the post-rift lessening of the geothermal gradient. Within the Northern Appalachians of Vermont, four metamorphic samples yield averaged AHe dates of 100-120 Ma. Inverse thermal modeling indicates stable thermal conditions from 90 Ma to the present, limiting cooling driven by the recently recognized Northern Appalachian lithospheric thermal anomaly to < 20ºC. Modeling also indicates steady mid-Cretaceous (120-90 Ma) cooling (70 to 30ºC) coeval with passage over the Great Meteor Hotspot, although cooling rates are slower than would be expected during hotspot-induced thermal doming.


Miniature of They Used to Be Castles
They Used to Be Castles
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      Date: 2021-01-01

      Creator: Lily Anna Fullam

      Access: Access restricted to the Bowdoin Community



        Miniature of Protein Transition: Alternative Proteins and Policy Pathways to a More Sustainable Diet in the United States
        Protein Transition: Alternative Proteins and Policy Pathways to a More Sustainable Diet in the United States
        This record is embargoed.
          • Embargo End Date: 2025-05-14

          Date: 2020-01-01

          Creator: Anna Barnes

          Access: Embargoed



            Miniature of Differential modulation of the <i>Homarus americanus</i> cardiac neuromuscular system across cell types and among neuropeptide isoforms
            Differential modulation of the Homarus americanus cardiac neuromuscular system across cell types and among neuropeptide isoforms
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                Date: 2020-01-01

                Creator: Emily R Oleisky

                Access: Access restricted to the Bowdoin Community



                  Una Comprensione Computazionale della Psiche Emotiva e Ordine nelle Ballate del Decameron: Stilometria e Elaborazione del Linguaggio Naturale

                  Date: 2023-01-01

                  Creator: Nothando Khumalo

                  Access: Open access

                  The present thesis, written in Italian, explores the emotional psyche and narrative order embedded within the ballads of the Decameron, a renowned literary masterpiece by Giovanni Boccaccio. Leveraging the advancements in stylometry and natural language processing techniques, this research aims to convince medieval Italian literature scholars to produce more on scholarship of the ballads and uncover the intricate patterns of human emotions and narrative organization in the ballads. The study begins by establishing a comprehensive corpus of ballads from the Decameron, utilizing digital libraries and text repositories. Subsequently, using stylometric analysis, the research examines the linguistic and stylistic features that distinguish the brigata’s ballads, focusing on elements such as vocabulary, syntax, and rhyme scheme. These analyses enable the identification of authorial patterns, shedding light on the emotional expressions and narrative techniques employed by Boccaccio. A natural language processing model was used to predict authorship of the ballads using each of the brigata’s novelle as training data. The findings of this research contribute to a deeper understanding of the emotional and narrative purpose of the Decameron's ballads. Results of stylometric analysis allowed for new characterization of Panfilo’s ballad as sad and revealed how similarity in the emotional psyches of the brigata transcends gender. These novel perspectives allowed for unique literary analysis of the ballads. Accurate prediction of ballad authorship demonstrates that ballads fit into the narrative structure of the Decameron and restore order in each of the ten days.


                  Miniature of A Quadtree-Based, Multi-Resolution Algorithm for Computing Viewsheds on Grid Terrains
                  A Quadtree-Based, Multi-Resolution Algorithm for Computing Viewsheds on Grid Terrains
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                      Date: 2023-01-01

                      Creator: Lily Caroline Smith

                      Access: Access restricted to the Bowdoin Community



                        #IVFgotyou: Instagram IVF Influencers as Social (Media) Support Systems

                        Date: 2023-01-01

                        Creator: Susu Gharib

                        Access: Open access

                        This paper details the ways in which IVF and infertility influencers on Instagram use their platforms to resist the silence surrounding reproductive difficulties. The analysis draws upon a thematic analysis of posts tagged with IVF-related hashtags and a semi-structured ethnographic interview with one influencer. Through these methods, I found that influencers build intimate publics through their platforms by sharing their journeys, interacting with followers, and reciprocal support. Within the context of the intimate publics, influencers are able to connect with others who understand their experiences, allowing them to break through the silence they may feel in their offline social groups.


                        Miniature of Structural and methodological factors influencing the sorption of alkylpyridiniums to aluminosilicates
                        Structural and methodological factors influencing the sorption of alkylpyridiniums to aluminosilicates
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                            Date: 2023-01-01

                            Creator: Seamus Frey

                            Access: Access restricted to the Bowdoin Community



                              Miniature of The Influence of Polymers on the Solubility of Flufenamic Acid and Mefenamic Acid Cocrystals
                              The Influence of Polymers on the Solubility of Flufenamic Acid and Mefenamic Acid Cocrystals
                              This record is embargoed.
                                • Embargo End Date: 2027-05-16

                                Date: 2024-01-01

                                Creator: Morgan Adams

                                Access: Embargoed