Showing 331 - 340 of 583 Items

How do long-term above-ground biomass dynamics vary between different forest stand types at Harvard Forest?

Date: 2023-01-01

Creator: Maya Y. Chandar-Kouba

Access: Open access

Monitoring forest carbon storage is necessary in accurately modelling the global carbon cycle. In the Northeast, terrestrial forests represent a major carbon sink with above-ground biomass (AGB) accounting for 40% of stored forest carbon. Therefore, understanding how AGB varies spatiotemporally is essential in predicting future carbon storage. Repeated measurements in permanent, long-term plots provide an opportunity to examine how carbon stored in AGB is changing over time. I used 29 years of data from the Harvard Forest Environmental Monitoring Systems (HF EMS) Site to determine how stand composition, intrinsic factors, and extrinsic environmental factors influenced rates of carbon storage in AGB over time. Using a partition around medoids (PAM) clustering method, I separated the 34 ground plots at the EMS stand into their respective stand types. I found that each stand type at the HF EMS plots accumulates carbon at consistent rates throughout the study period, although rates of carbon accumulation between stands were significantly different. Red Pine stands experience a rapid decline in biomass in 2018 due to the introduction of the Southern Pine Beetle. Across all stand types, sporadic mortality events determine variations in yearly rates of carbon accumulation, although this has little significant influence on total AGB accumulation. Leaf area index (LAI) and foliar N contents have no effect on growth increments. Extrinsic environmental variables had mixed effects on growth and mortality, highlighting the complexities of predicting forest carbon storage under changing climate conditions.


Rhythmic behaviors: Understanding neuromodulation at the neuromuscular level

Date: 2023-01-01

Creator: Kenneth Garcia

Access: Open access

Neuromodulation allows for the flexibility of neural circuit dynamics and the outputs they produce. Studies of the stomatogastric nervous system (STNS) have expanded our knowledge on the actions of neuromodulators, small molecules that most often activate G-protein coupled receptors and reconfigure circuit activity and composition. In these systems, modulation has been found to occur at every level, from sensory-motor coupling to neuromuscular transmission (Harris-Warrick and Marder 1991). Neuromodulators have complex effects on motor output; they can alter the firing of individual neurons while also modulating muscle properties, neuromuscular transmission, and sensory neuron response to muscle activity (Fort et al. 2004). We investigated this further by recording the motor output produced by the gastric mill rhythm of the lobster STNS under neuromodulator conditions. How is this neuromuscular system as a whole modulated to produce motor flexibility? We hypothesized that these neuromodulators act on individual receptors of component neurons of central pattern generator (CPG)-effector system themselves and at the periphery, coordinately altering muscle contraction by altering all levels of the crustacean neuromuscular system. Application of NRNFLRFamide, RPCH, oxotremorine, and proctolin to the gastric mill 4 (gm4) muscles of the Cancer crab showed that neuromodulators that have been found to have variable, yet significant effects on the activity of the neurons of the STNS directly alter the activity of the gm4 muscles as well, suggesting that coordination of peripheral actions and direct neuronal modulation regulates patterned motor output.


Miniature of Neptune City
Neptune City
This record is embargoed.
    • Embargo End Date: 2026-05-18

    Date: 2023-01-01

    Creator: Lily Randall

    Access: Embargoed



      Miniature of A multifaceted analysis of Semaphorin-induced neuroplasticity in the nervous system of <i>Gryllus bimaculatus</i>
      A multifaceted analysis of Semaphorin-induced neuroplasticity in the nervous system of Gryllus bimaculatus
      Access to this record is restricted to members of the Bowdoin community. Log in here to view.
      • Restriction End Date: 2028-06-01

        Date: 2023-01-01

        Creator: Ean Lev Small

        Access: Access restricted to the Bowdoin Community



          Invisible Ailments: A Collection

          Date: 2023-01-01

          Creator: Jane L. Godiner

          Access: Open access

          "Invisible Ailments" is a collection of short stories that trace the depth, breath, and sweeping range of lived experiences of people struggling with mental illness. While it is a work of fiction, the people in these stories might feel eerily familiar — to your friends, your family members, your loved ones, or, if you're brave enough to admit it, yourself.


          Miniature of Live imaging of somatic homolog pairing in <i>Drosophila</i> supports a button-based mechanism for pairing facilitated by the genetic insulator <i>gypsy</i>
          Live imaging of somatic homolog pairing in Drosophila supports a button-based mechanism for pairing facilitated by the genetic insulator gypsy
          This record is embargoed.
            • Embargo End Date: 2026-05-18

            Date: 2023-01-01

            Creator: Holden D. Hadfield

            Access: Embargoed



              Miniature of The Impact of Toll 6-1 Function on the Maintenance and Plasticity of the <i>Gryllus bimaculatus</i> Auditory System
              The Impact of Toll 6-1 Function on the Maintenance and Plasticity of the Gryllus bimaculatus Auditory System
              Access to this record is restricted to members of the Bowdoin community. Log in here to view.
              • Restriction End Date: 2028-06-01

                Date: 2023-01-01

                Creator: Jada Scotland

                Access: Access restricted to the Bowdoin Community



                  Characterizing the Roles of Toll7 in the Gryllus Bimaculatus Peripheral Nervous System Development

                  Date: 2023-01-01

                  Creator: Rowland Luo

                  Access: Open access

                  The study of neuronal development could provide foundational information on neurogenesis and neuroplasticity. The small size and relatively simple nervous system of Orthoptera make them ideal models for neurodevelopmental studies. The peripheral nervous system development is an intricate and precise process that each sensory neurons are able to reach their central nervous system partners in a relatively short amount of time. Although the peripheral nervous system in limb buds and their genetic regulations are well understood in grasshopper embryos, few studies have explored the developing nervous system in a cricket model. Therefore, the first goal of the current experiment is to characterize the normal peripheral nervous system development in cricket embryos. Previous studies in Drosophila have suggested Toll6 and Toll7 receptors could serve as important targets for the neurotrophic-like factors Spaetzle2 and 5. Malfunctioning neurotrophic pathways could lead to abnormal nervous system development. Therefore, the second goal of the current study is to explore the roles of Toll7 in the development of the cricket peripheral nervous system. Immunohistochemical staining using anti-horseradish peroxidase (Anti-HRP) was used to illustrate crickets' embryonic developing peripheral nervous system in the limb buds from developmental stage 7.0 to 11.0. Cricket eggs were injected with Toll7 double stranded RNA (dsRNA) and rhodamine dye to suppress the Toll7 mRNA level. The control eggs were injected with GFP dsRNA and rhodamine dye. The peripheral nervous system development in cricket embryos is largely homologous to that observed in grasshopper embryos. All later-emerged sensory neurons followed the pathway established by the first pioneer neuron Ti1. Ti1 made stereotypical turns following the steering signals on epithelial and guidepost cell surfaces and eventually fasciculate with lateral motor axons from the central nervous system. When examining the peripheral nervous system development with Toll7 knockdown, a decrease in limb bud volume was observed at stage 7.7 and stage 8.0, suggesting Toll7’s potential roles in aiding cell-cell intercalation processes in Orthoptera embryos. Furthermore, a delay in Ti1 pioneer neuron development was observed with Toll7 knockdown at early developmental stages, providing evidence for Toll-Spaetzle pathway’s neurotrophic-like functions. The results of the current experiment provide the first description of the peripheral nervous system development in the cricket limb buds and further evidence of Toll-Spaetzle pathway’s neurotrophic properties.


                  Miniature of Mathematically Modeling a Nonlinear, Passive Acoustic Filter
                  Mathematically Modeling a Nonlinear, Passive Acoustic Filter
                  This record is embargoed.
                    • Embargo End Date: 2026-05-18

                    Date: 2023-01-01

                    Creator: Bjorn Ludwig

                    Access: Embargoed



                      Playing the Fool: Analyzing the Phenomena of Iurodstvo In Contemporary Russian Cinema and Civil Society.

                      Date: 2023-01-01

                      Creator: Colby Silva Santana

                      Access: Open access

                      Of Russia's cultural and religious icons, the holy fool (iurodivy) is quite possibly the most significant one of contemporary times. The holy fool – a historical and cultural character that feigns insanity to produce moral and spiritual reflections and hide the purity of their souls – has left its traces over a significant portion of Russia's literary history, postmodern tradition, and socio-political thought. In its uniquely positioned role as a powerful form of institutional critique, today taking shape in modern-day political protest performance culture, the holy fool has often been utilized to interrogate the intertwined relationship of the Russian state and the Orthodox Church. This analysis reviews the scholarship on holy foolery and how it has manifested in various fields of study. Although scholarship on this subject is significant, there exists a lack of research into representation of the holy fool in contemporary Russian cinema. Cinema is uniquely positioned to portray holy foolery, thanks to the unique form of spectatorship the film camera allows. This thesis analyzes several case studies of 21st-century Russian cinema that feature characters representing qualities of iurodstvo and its related models. In doing so, this work traces the history and development of iurodstvo through the lens of cinema and suggests new ways of understanding holy foolery's manifestation as a political tool.