Showing 201 - 210 of 317 Items
The Shah Bano Case: An English-Language Democratic Practice in Post-Colonial India
Date: 2023-01-01
Creator: Hafsa Hossain
Access: Open access
- In 1985, Mohd. Ahmad Khan v. Shah Bano Begum, known commonly as the Shah Bano Case, became a flashpoint for Indian democracy. The Shah Bano case revolved around the maintenance of a divorced woman, not the first of its kind by any means. A case that sparked major social and political upheaval during a broader period of political turmoil, the Shah Bano case has long been interpreted as an expression of the crisis and contradictions between the democratic rights of women as citizens and the democratic rights of Muslims as a religious minority in the Indian nation-state. In the immediate aftermath of the case, critical feminist and post-colonial scholarship grappled with the dilemmas it involved, but to some extent remained caught up in those dilemmas. This thesis builds upon the important work of these and later scholars, but it also draws new attention to the specific role of the English-language public sphere in shaping the terms of debate that surrounded the case in the 1980s. This paper argues against the binary understanding of the landmark Shah Bano Case as either a failure or success of Indian secularism. I argue that the case and its aftermath demonstrate the continual nature of Indian secularism and democratic practice, especially laden in the post-Emergency era.
On L-functions and the 1-Level Density
Date: 2023-01-01
Creator: Arav Agarwal
Access: Open access
- We begin with the classical study of the Riemann zeta function and Dirichlet L-functions. This includes a full exposition on one of the most useful ways of exploiting their connection with primes, namely, explicit formulae. We then proceed to introduce statistics of low-lying zeros of Dirichlet L-functions, discussing prior results of Fiorilli and Miller (2015) on the 1-level density of Dirichlet L-functions and their achievement in surpassing the prediction of the powerful Ratios Conjecture. Finally, we present our original work partially generalizing these results to the case of Hecke L-functions over imaginary quadratic fields.
Using data from the LISST-100 to recreate phytoplankton size distribution and processes in Harpswell Sound, Maine
Date: 2014-08-01
Creator: Schuyler Nardelli
Access: Open access
- Phytoplankton are the simple single-celled photosynthesizers that live in the ocean and form the base of the food chain. Cell size is a basic proxy for physiological rates as well as ecosystem structure. Thus, cell size can be used in a model framework to track changing environmental conditions that could potentially lead to harmful algal blooms (HABs, aka “red tides”)—events that can be detrimental to human health, marine life, and fisheries. HABs occur when a single algae (phytoplankton) species either grows unconstrained to a concentration such that it becomes toxic or causes low oxygen concentration in the water. In typical estuaries, less dense freshwater flows towards the ocean, and denser salty seawater flows into the estuary in the subsurface. However, Harpswell Sound is a reverse estuary that receives its freshwater input at its mouth from the upstream Kennebec River. This yields upstream surface low salinity flow and downstream deep high salinity flow. This rare dynamic allows phytoplankton located in the surface of seawater to be retained in the sound in conditions conducive to high growth and HABs, and can be used as a warning for conditions throughout the Gulf of Maine. To study the temporal and spatial dynamics of phytoplankton in the sound, we used the LISST-100, which uses light scattering properties to collect continuous in-situ water column observations of particle concentrations and size distributions. Although the LISST-100 was built to measure sediment size with a spherical shape, studies have been conducted that show it can accurately describe a diverse range of phytoplankton shapes and sizes, provided the population has sufficient size differences and is fairly concentrated, conditions found in Harpswell Sound. Weekly profiles of the water column were collected at the Bowdoin Buoy from 5/21/14-6/18/14, as well as a 20-day continuous time series collected at Bowdoin’s Coastal Studies Center dock from 5/30/14-6/18/14 along with supplementary oceanographic data. We determined that semi-diurnal tidal fluctuations are sufficient to move water masses past the buoy and dock with each tide, thereby connecting them. Phytoplankton were found to be in the 3-50 micron size range, with a peak diameter of approximately 7 microns. Additionally, three independent phytoplankton blooms were observed over the course of the 20-day time series as different water masses flowed through the sound. They were sourced in the oceanic water masses found under the freshened surface layer. Over the five-week period the populations gradually surfaced with their water mass as the overlying freshwater dissipated in the absence of rainfall. The LISST-100 served as a useful tool for determining phytoplankton distribution and dynamics within Harpswell Sound, and with further research there is great potential to continue to increase proficiency with the instrument in order to better understand phytoplankton dynamics and harmful algal blooms. Final Report of research funded by the Rusack Coastal Studies Fellowship.
Vulnerability of eelgrass (Zostera marina) to green crab (Carcinus maenas) invasion
Date: 2014-08-01
Creator: Sabine Y Berzins
Access: Open access
- Eelgrass (Zostera marina) is a perennial seagrass that is widely distributed among the shallow subtidal and intertidal Atlantic coastline of the United States and Canada. A highly productive keystone species, eelgrass helps maintain healthy estuarine and ecosystem functions by stabilizing sediments, regulating water flow, absorbing nutrients, and providing critical habitat for animals including commercially important species like soft-shell clams, blue mussels, and migrating waterfowl. Loss of eelgrass beds can therefore result in degraded water quality, shoreline erosion, and reduced fish and wildlife populations. Historically, the Maine coast supported extensive eelgrass beds. However, between 2010 and 2013, eelgrass distribution in Casco Bay declined in area by over 55%. This decline in eelgrass distribution coincides with a regional population explosion of green crabs (Carcinus maenas), an invasive species that physically disturbs eelgrass while foraging for prey. This summer, I collaborated with several Casco Bay Eelgrass Partners including individuals from the Fish and Wildlife Service, Maine Department of Environmental Protection, and the Friends of Casco Bay. Led by U.S. Geological Survey biologist Dr. Hilary Neckles, this project identifies factors that make eelgrass more or less resilient to invasion by green crabs. In June, we established permanent eelgrass survey transects at five locations spanning eastern Casco Bay. Where possible, two transects were established in different types of sediment (fine or coarse/sandy). Most of the eelgrass loss observed over the past decade has been in fine sediments. The question remains; is eelgrass in coarse sediments prone to similar levels of damage? In addition to differences in substrate type, each site also exhibited varying degrees of eelgrass density, shoot height, green crab density and population structure, and other environmental stressors including light availability, temperature, nutrient availability, and natural physical disturbance. I made biweekly measurements of green crab densities at one site, Widgeon Cove in Harpswell. Crap trapping indicated few green crabs occurred near the Widgeon Cove transect, but traps at the other four Casco Bay sites collected as many as 300 crabs within a 24-hour period. Final measurements in the eelgrass transects will be taken in September and data collection will be completed in October. Data gathered this summer will provide information to help move forward with a plan to protect and potentially restore eelgrass in Casco Bay. Additionally, I identified patches of eelgrass in the Kennebec Estuary that might be viable sites for replanting next summer. I hope to continue working on this project next year, thinking about ways to restore eelgrass to the system while identifying ways to increase trapping pressure on green crabs such that their numbers might be reduced. Final Report of research funded by the Rusack Coastal Studies fellowship.
This is What You Want: Stories
Date: 2017-05-01
Creator: Savannah Blake Horton
Access: Open access
- This is What You Want: Stories is a collection of nine stories exploring the role of humor in dark situations. It is a work of fiction.
Effects of Alkalinity and Ocean Acidification on Clam Shell Development in Phippsburg, ME
Date: 2014-08-01
Creator: Bailey Moritz
Access: Open access
- With increased CO2 in the atmosphere from the burning of fossil fuels, more is absorbed into the surface ocean, causing a reaction that leads to lower pH. This process is known as ocean acidification, which has raised global concern. Over the past decade, the clam flat near Head Beach in Phippsburg has been reduced to approximately a sixth of its former productive area. The town of Phippsburg allots money every spring to seed the clam flat with juvenile soft-shell clams (Mya arenaria) in order to support the local clamming economy, but the clams are no longer growing in much of the mud flat. A possible explanation for this loss is acidification. In order to understand if ocean acidification is the cause, I collected water samples from the mud to test for alkalinity along a transect of 5 sites spanning productive and non-productive areas of the flat. Alkalinity is a measurement of the waters ability to buffer pH changes. Lower alkalinity could mean that clams would have more difficulty forming their calcium carbonate shells due to dissolution in low pH waters. Combined with the pH measurements gathered by my peer, Lloyd Anderson ‘16, we were able to calculate aragonite saturation state. Water with a saturation state below 1 is capable of dissolving calcium carbonate (aragonite) shells. A large portion of this research project was figuring out the best methodology to use for collecting data on the clam flat. The tested water needs to represent that which the clams are actually using while they are embedded in the mud. Additionally, juvenile clams only live in the upper centimeter or so of sediment. We followed methodologies used in past studies in Maine (Green et al 2013). Three pore water samples from each site were extracted and brought back to the lab to be filtered on 7 separate days throughout July. We began sampling 2 hours prior to low tide. I determined alkalinity using an automated titration system. Average alkalinity ranged from 2200-2500 μeq/kg. The results indicated that there was not a significant difference or pattern in alkalinity or saturation state between productive and unproductive areas of the clam flat (Fig. 1). Error bars in the figure represent variability at each site over the entire study period, while analytical reproducibility was ± 9.04 μeq/L. Large changes were observed merely from one day to another. Coastal ecosystems are complex and variations such as time of day, temperature, or productivity may have influences on the porewater characteristics (Duarte 2013). While ocean acidification does not appear to be the primary driving force behind the clams’ decline at this location, the saturation state was consistently quite low ( Final Report of research funded by the Rusack Coastal Studies Fellowship.
Investigating the Effects of Climatic Change and Fire Dynamics on Peatland Carbon Accumulation in Coastal Labrador, Canada
Date: 2014-08-01
Creator: Anna Hall
Access: Open access
- High-latitude peatlands store a large stock of carbon in accumulated belowground biomass, estimated at 500 ± 100 Gt C (Yu 2012). For comparison, the atmospheric C pool is estimated at about 775 Gt (IPCC 2007) making the peatland carbon pool a potentially significant player in the global carbon cycle. Peatland carbon storage is controlled by a balance between plant productivity and decomposition, with plant matter produced during the summer months accumulating from year to year rather than fully decomposing. Peatlands are sensitive to changes in climatic regime and have the potential to shift from a net sink of atmospheric C to a net source of C with future disturbance by climate warming (Yu 2012).There are two major predictions as to how climate change could affect peatland C accumulation. Warmer temperatures could cause faster decomposition of plant biomass and lead to C release to the atmosphere and a positive feedback effect on climate change (Schuur et al. 2008). If this is the case, current warming trends suggest that peatlands could release up to 100 Gt C to the atmosphere by the year 2100 (Davidson and Janssens 2006). Alternatively, warmer summer temperatures and a longer growing season could lead to faster peat production and therefore CO2 drawdown from the atmosphere, somewhat mitigating the effects of climate change (Schuur et al. 2008). A detailed study of past C accumulation rates over a known historical warm period gives insight into how peatlands may respond to future climate warming. This project focuses on C accumulation in peatlands in Labrador, Canada, over the past 8,000 years. Because Canadian peatlands store approximately 150 Gt C, approximately 1/3 of the global peatland carbon pool, it is important to understand how the dynamics of these peatlands could be affected by present and future climate warming (Tarnocai 2006). However, the majority of research has focused on central Canada, leaving significant knowledge gaps surrounding coastal Eastern Canada (vanBellen et al. 2012). Particular emphasis in this study was given to the Holocene Thermal Maximum (HTM) which occurred from 4-6 thousand years ago in Labrador, when summer temperatures were 0.5 – 1°C warmer than at present (Kerwin et al. 2004). This study also attempts to determine the effect of fires on rates of C storage in these peatlands. Lightning-ignited peat fires have the potential to consume stored biomass and release significant CO2 to the atmosphere (Tarnocai 2006). Six peat cores (out of a total of 14 collected in Labrador in 2013) were used for this study. Throughout the following year, calibrated radiocarbon dates, bulk density, and percent carbon were used to calculate carbon accumulation rates. This summer, areal charcoal concentration (a measure of macroscopic charcoal used as a proxy for fire severity) was used to determine the influence of fires in this region. From 8,000 years ago to the present, rates of C accumulation averaged 23.1 ± 6.7 gC m-2 yr-1. Accumulation rates were highest during the HTM, averaging 29.6 ± 2.4 g C m-2 yr-1. Samples containing macroscopic charcoal had an average concentration of 0.62 mm2 cm-3 with a maximum concentration found of 3.51 mm2 cm-3. These consistently low charcoal concentrations indicate that fire was neither common nor severe in Labrador peatlands. While Kuhry (1994) and Payette et al. (2012) found that fires in Canada occurred twice as frequently during the HTM than at present, no trends in fire severity were found in these cores, and there was no evidence that fires had a significant influence on C accumulation. Therefore, the C accumulation trend we see in Labrador is not controlled by fire and is likely either a direct result of temperature variation or of vegetational and hydrological shifts caused by changes in climate. This work supports a growing body of evidence from high latitude peatlands suggesting that future warming conditions could lead to increased soil C sequestration. Final Report of research funded by the Freedman Coastal Studies Fellowship.
The Relationship between Nitrate Concentration and Phytoplankton Blooms in Harpswell Sound
Date: 2014-08-01
Creator: Sasha Kramer
Access: Open access
- Phytoplankton require certain essential nutrients for growth. The Redfield ratio (Redfield, 1934) dictates an ideal element proportion of 106 carbon: 16 nitrogen: 1 phosphorus in order to maintain balanced phytoplankton growth through photosynthesis (Li et al., 2008). Under typical conditions, the concentration of nutrients present in the water directly controls the attainable phytoplankton yield (i.e. one inorganic nitrogen from nitrate yields one organic nitrogen in cellular form). While plankton that are starved of nutrients tend to die off quickly, plankton that are simply nutrient limited can adjust to constant but low levels of nutrient concentration (Cullen et al., 1992), often by adjusting their Redfield ratio. As an essential nutrient, nitrogen is a limiting factor for phytoplankton growth in the ocean (Dugdale, 1967). In oceanic and coastal ecosystems, dissolved nitrate (NO3-) is the most commonly available form of nitrogen (Zielinski et al., 2011). The formation of nutrients through microbial processes such as denitrification in deep water creates a source of nitrogen in the deep ocean (Arrigo, 2005). Phytoplankton growth is limited by both light and nutrients: therefore, the transport of nitrate into the euphotic zone controls the rate of primary production. In the Gulf of Maine, nitrate concentration varies with depth and season. Water density is determined by temperature and salinity; these qualities in turn control the depth of mixing and stratification, and thus the depth of the nitracline, the depth at which the high-nutrient deep waters are found (Townsend, 1998). An instrument known as the In Situ Ultraviolet Spectrophotometer (ISUS by Satlantic, Inc.) offers the ability to quantify nitrate concentrations based on optical properties. The instrument specifically measures the magnitude of absorption of ultraviolet light by dissolved nitrate molecules in the water. The concentration is determined from the ratio of the measured absorption coefficient to the molar absorption coefficient of nitrate. The ISUS is placed directly into the water at a site of specific interest—it measures the absorption and computes the nitrate concentration at this site every hour. This method of analysis gives superior stability, precision, and accuracy in data compared to a typical water sample analysis in a laboratory setting (Johnson & Coletti, 2002). For the past 4 years, an ISUS sensor has been deployed on the Bowdoin Buoy in Harpswell Sound collecting hourly observations of nitrate concentration concurrent with hourly observations of chlorophyll fluorescence (which can be used as a proxy for phytoplankton biomass). Once per week between May 21, 2014 and June 18, 2014, measurements of the depth distribution of salinity, temperature, density, chlorophyll fluorescence, and dissolved oxygen content were taken at the Bowdoin Buoy. Water samples were collected at five discrete depths each week, and were returned to the lab for analysis of chlorophyll concentration on the Turner fluorometer and nutrient concentration on the SmartChem. These laboratory analyses were used to calibrate and validate the buoy- and boat-based optical observations. The analysis of nitrate observations was performed in two phases. First, the variability in nitrate measured on the buoy since 2007 along with co-located discrete water samples was compared to a published historical dataset in order to place Harpswell Sound in the broader context of the Gulf of Maine. Second, the timeseries buoy observations of nitrate and chlorophyll were analyzed to determine temporal covariability. The historical nutrient and water quality data for the Gulf of Maine gathered by Rebuck et al. 2009 for 1990-2009 (in addition to unpublished data from 2010-2012) provided a broader spatial and temporal range for comparison with data from the Bowdoin Buoy in Harpswell Sound, Maine from 2007-2012. The historical nutrient data for the Gulf of Maine were measured in the lab; the nutrient data for Harpswell Sound was measured by the ISUS. There are relatively few match-ups for validation, but these points did show the correlation between the two methods. However, the similarity of the distribution of measured nitrate from water samples in lab and the in situ temperature and salinity characteristics of the sampled waters were very coherent with those measured by the ISUS, providing some quantitative validation. Future analysis of the ISUS data from summer 2014, in comparison to nutrient data from the water samples taken over the course of this summer, will further justify the validity of the ISUS data. A clear relationship between nitrate concentration and water temperature and nitrate concentration and salinity for both the Gulf of Maine and Harpswell Sound emerged (Figure 1). The highest concentrations of nitrate are found in the saltiest water (between 30-34 psu) and coldest water (between 3 and 12 degrees Celsius). This pattern was observed both generally in the Gulf of Maine and more specifically in Harpswell Sound, indicating that processes observed in Harpswell Sound are connected to broader scale oceanographic processes. These results also indicate that nutrients generated by deep ocean processes are dominant and river sources are negligible, a result that is not found in most areas. For both chlorophyll data and ISUS nitrate data, 2010 proved to be a model year with a clear and thorough timeseries from early February to late November. After analysis, the relationship between nitrate and chlorophyll showed a strong preliminary correlation of chlorophyll concentration (once again, as a proxy for phytoplankton biomass) increasing as nitrate concentration decreases (Figure 2). The low levels of phytoplankton consume the high levels of nitrate and therefore, as the bloom grows, the concentration of nitrate decreases proportionally. The expected dependence of chlorophyll concentration on nitrate concentration becomes incredibly clear through these results, similar to the results presented in Li et al., 2010. The ISUS data from 2007-2012 requires further processing in order to fully explore the relationship between chlorophyll and nitrate concentration on a pertinent timescale to bloom growth dynamics. While it is possible to construct a full time-series from the newly manipulated ISUS dataset after this summer work, it would be important and interesting to further examine the relationship between chlorophyll concentration and nitrate concentration in Harpswell Sound on daily, weekly, seasonal, and yearly timescales. This next step of investigation will require more time for data processing, but the work done this summer to validate the ISUS data and show the correlation between Harpswell Sound and the Gulf of Maine is incredibly promising for future work. Final report of research funded by the Doherty Coastal Studies Research Fellowship.
Genetic Analysis of Adhesion Protein ELMO3 in Arabidopsis thaliana
Date: 2022-01-01
Creator: Garrison Asper
Access: Open access
- The Extracellular Matrix (ECM) between plant cells is vital for structure, development, and intercellular adhesion. A pectin rich layer in between cells, the middle lamella, is largely responsible for regulating the adhesive properties of adjacent plant cells. Homogalacturonan (HG) pectin, the most common, is synthesized in the Golgi and secreted into the ECM where it undergoes calcium crosslinking, increasing its adhesive properties. Mutations in proteins essential for HG synthesis can reveal a severe adhesion defective phenotype, where the hypocotyls of dark grown Arabidopsis exhibit cell sloughing, curling, and general disorganization. A family of five ELMO proteins are suspected to act as scaffolds for pectin biosynthesis enzymes. ELMO1 and ELMO4 mutants exhibit an adhesion deficient phenotype, and a double mutant provides evidence of redundancy in function between ELMO1 and ELMO2. ELMO1-GFP co-immunoprecipitated with enzymes required for HG synthesis indicating its role as a scaffold protein. Double mutants of the other ELMO homologues were created to determine if they exhibit functional redundancy, and ELMO1 and ELMO3 appear partially redundant. A gene deletion of ELMO3 was also created using the CRSPR/Cas9 system, resulting in two distinct elmo3 deletion alleles, which were phenotypically identical to the original elmo3-/- mutant. All adhesion defective phenotypes can be partially suppressed by altering the osmoticum and hence turgor that provides pressure on adhesive cells. Lastly, ELMO3-GFP was localized to the Golgi, the site of pectin biosynthesis, further supporting a common role of the ELMOs in pectin biosynthesis.
Effects of myosuppressin, a peptide neuromodulator, on membrane currents in the crustacean cardiac ganglion
Date: 2022-01-01
Creator: Anthony Yanez
Access: Open access
- Central pattern generators are neural circuits that can independently produce rhythmic patterns of electrical activity without central or periphery inputs. They control rhythmic behaviors like breathing in humans and cardiac activity in crustaceans. Rhythmic behaviors must be flexible to respond appropriately to a changing environment; this flexibility is achieved through the action of neuromodulators. The cardiac ganglion of Homarus americanus, the American lobster, is a central pattern generator made up of four premotor neurons and five motor neurons. Membrane currents in each cell type, which can be targeted for modulation by various molecules, generate rhythmic bursts of action potentials. Myosuppressin, a FMRFamide-like peptide, is one such neuromodulator. The currents targeted for neuromodulation by myosuppressin are unknown. I investigated the molecular and physiological underpinnings of the modulatory effect of myosuppressin on motor neurons in the cardiac ganglion. First, using single cell RT-qPCR, I determined that across animals, motor neurons express myosuppressin receptor subtype II at equal levels relative to each other. Using sharp intracellular recordings, I showed that myosuppressin decreased burst frequency and the rate of depolarization during the inter-burst interval. I predicted that this effect resulted from the modulation of either A-type potassium current or calcium-dependent potassium current. Using two-electrode voltage clamp, I found that total outward current did not substantially change after treatment with myosuppressin. This result was surprising and provides grounds for explorations of subtle forms of neuromodulation in simple neural circuits.