Life Sciences Commons^™

The Influence Of Framing And Recent Experience On Farmer Choices In Experimental Games Depicting Risk-Reducing Agricultural Technologies, Ana Maria Ospina Tobar

Electronic Theses and Dissertations

Climate change is a major threat to food security, particularly in low and middle-income countries that are highly dependent on staple crops for subsistence. The vulnerability of staple crops, like maize, in the face of climate change, is increasing due to the increasing frequency of droughts. This thesis aims to evaluate two mechanisms through which farmers may be more willing to adopt new technologies that increase their resilience to climate change: First, I evaluate the effectiveness of a new virtual maize farming game as a learning tool to teach farmers about the outcomes they could obtain under different weather events …

Collaborative And Engaged Research To Strengthen Equity And Adaptive Governance In Co-Managed Fisheries, Gabrielle V. Hillyer

Electronic Theses and Dissertations

Small-scale, co-managed fisheries are found throughout the world and often represent intertwining cultures, societies, communities, economies, institutions, and governments. They face complex issues, derived from ecological and social sources. Solving these issues requires diverse expertise, often developed through engaged methodologies which can facilitate collaborative solution creation between researchers, community members, and others. In this dissertation, I demonstrate the benefits of these engaged methodologies and review how they, when coupled with anticolonial approaches to research, can create more equitable solutions to complex issues. This dissertation focuses on multiple projects within the wild clam fishery in Maine including: (1) the creation of …

Integrating Environmental Dna, Traditional Fisheries Techniques, And Species Distribution Modeling To Assess Bridle Shiner Status In Maine, Lara S. Katz

Electronic Theses and Dissertations

The bridle shiner (Notropis bifrenatus) is a small minnow species native to the eastern United States and southeastern Canada. The species is declining dramatically throughout most of its native range and has legal protection or concern status in thirteen states and two Canadian provinces. In Maine, the bridle shiner is listed as a Species of Special Concern and considered a Species of Greatest Conservation Need, partially because we lack a basic understanding of their status and distribution within the state. Bridle shiners have historically been found in southern and western Maine in densely vegetated, shallow habitats along the …

A Quantitative Visualization Tool For The Assessment Of Mammographic Risky Dense Tissue Types, Margaret R. Mccarthy

Electronic Theses and Dissertations

Breast cancer is the second most occurring cancer type and is ranked fifth in terms of mortality. X-ray mammography is the most common methodology of breast imaging and can show radiographic signs of cancer, such as masses and calcifcations. From these mammograms, radiologists can also assess breast density, which is a known cancer risk factor. However, since not all dense tissue is cancer-prone, we hypothesize that dense tissue can be segregated into healthy vs. risky subtypes. We propose that risky dense tissue is associated with tissue microenvironment disorganization, which can be quantified via a computational characterization of the whole breast …

Developing An Enhanced Forest Inventory In Maine Using Airborne Laser Scanning: The Role Of Calibration Plot Design And Data Quality, Stephanie Willsey

Electronic Theses and Dissertations

Forests provide essential ecosystem services such as carbon sequestration, clean water, lumber, and more. It is important that foresters be able to collect accurate forest inventories, especially in a changing climate. Foresters need to know what is in the forest not only to manage for the economic benefits, but also to manage for social acceptability and ecological soundness to prevent further degradation of these ecosystem services. One way to collect accurate and precise forest inventories is through the utilization of remote sensing products. These enhanced forest inventories (EFIs) can be done at varying resolutions that are contingent on the plot …

Factors Affecting Apothecia Production And Primary Infection By Monilinia Vaccinii-Corymbosi On Vaccinium Angustifolium, Ian Leonard

Electronic Theses and Dissertations

Mummy berry, caused by Monilinia vaccinii-corymbosi (MVC), is a prolific disease of Vaccinium angustifolium (wild blueberry) leading to decreased yield in wild blueberry fields throughout the Downeast (DE) and Midcoast (MC) regions of Maine (ME). This study aimed to identify factors affecting primary inoculum production and infection by MVC on wild blueberry, and what bud stages of wild blueberry are most susceptible to infection. Through common garden (CGE), field and incubation experiments conducted in 2021 and 2022, factors affecting carpogenic germination of MVC pseudosclerotia and relationships between susceptible wild blueberry buds and environmental factors were analyzed. The CGE conducted in …

Optimizing Strategies To Hydraulically Plant Atlantic Salmon Eggs Based On Fry Dispersal Patterns, Ernest J. Atkinson

Electronic Theses and Dissertations

The Gulf of Maine Distinct Population Segment of Atlantic Salmon has suffered from habitat loss and exploitation over the last century. Hatchery supplementation has prevented the extirpation of the species, but stocking methods represent tradeoffs between survival, domestication, and logistics. Egg planting, the use of eyed embryos, maximizes natural rearing opportunities which can be important for adaptation. This method, however, is logistically demanding and requires significant labor over large spatial, but short temporal, scales dictated by the ontogeny of the fish. However, the survival and dispersal behavior of Atlantic Salmon fry immediately after emergence from eggs planted in artificial nests …

Artificial Dendritic Neuron: A Model Of Computation And Learning Algorithm, Zachary Hutchinson

Electronic Theses and Dissertations

Dendrites are root-like extensions from the neuron cell body and have long been thought to serve as the predominant input structures of neurons. Since the early twentieth century, neuroscience research has attempted to define the dendrite’s contribution to neural computation and signal integration. This body of experimental and modeling research strongly indicates that dendrites are not just input structures but are crucial to neural processing. Dendritic processing consists of both active and passive elements that utilize the spatial, electrical and connective properties of the dendritic tree.

This work presents a neuron model based around the structure and properties of dendrites. …

Barriers To And Opportunities For Adoption In Maine’S Aquaculture Industry, Caitlin Cleaver

Electronic Theses and Dissertations

Aquaculture, or the farming of marine species, can diversify coastal economies, but development of this industry is hindered by negative perceptions or regulatory constraints. Commercial fishers are logical adopters of aquaculture, but can also mount opposition to its growth. This dissertation utilized innovation theory to understand fishers’ perceptions of and willingness to adopt aquaculture and drivers of and barriers to scallop aquaculture development in Maine (USA). Through a mail survey, lobster fishers’ perceptions of Maine’s aquaculture industry and their willingness to adopt aquaculture were assessed (Chapter 2). Individuals who were more satisfied with government management of aquaculture held more positive …

Understanding The Impacts Of Anthropogenic Effects An Habitat Variability Interactions On Maine's Rocky Intertidal Ecosystem, Laura Braun

Electronic Theses and Dissertations

The rocky intertidal ecosystem is an important ecological and cultural aspect of the picturesque Maine coast, playing a vital role in not only Maine’s coastal ecosystem, but also to Maine’s economy. It’s distinct community structure along the sharp elevational gradient and the presence of daily stressors (wave action, heat, and desiccation), make the rocky intertidal ecosystem an important model ecosystem to monitor for effects from anthropogenic impacts. In this thesis, I describe attempts to monitor and understand the impacts of two of these anthropogenic impacts on this system: climate change and industrial harvesting of Ascophyllum nodosum along Maine’s coast. For …

Carbon Dioxide Emissions From Deadwood In Forests Of The Northeastern United States, Zoe Read

Electronic Theses and Dissertations

As the climate changes, understanding the sources and sinks of greenhouse gases such as carbon dioxide (CO₂) is increasingly important. However, several components of the carbon cycle within forests remain poorly understood. For example, knowledge gaps exist in our understanding of CO₂ emissions from coarse woody material (CWM; logs and stumps), including how emissions change over time, how they are influenced by environmental variables, and how they compare to soil and ecosystem-level CO₂ emissions.

To fill these knowledge gaps, we examined CO₂ emissions from CWM at three sites. We sampled 18 red spruce (Picea …

3d Computer Modeling Offers New Insights Into Diatom Ecology, Joseph Mohan

Electronic Theses and Dissertations

Algae supply over half of the Earth’s global primary production and form the base of almost all aquatic food networks. Thus, changes in algal productivity or composition will induce profound shifts in many ecosystems. This research is guided by two questions. Herein I ask if 3D models of algae can be created accurately enough to use for research applications? If they can be accurately created, then how can these models be used to advance our understanding of functional trait evolution and paleoecology? Herein, I develop 3D computer models for estimating the volume of individual algae and their parts. I also …

Using Soil Testing Data To Examine Organic Carbon Changes During The Past 27 Years In Maine Agricultural Soils, Andrew Chase

Electronic Theses and Dissertations

Agricultural soils may act as a source or a sink for carbon (C) in the global C cycle. With rising atmospheric CO2 levels, C sequestration in soils may play an important role in climate change mitigation. Soil organic carbon (SOC) also contributes to key aspects of soil health and fertility, such as aggregation, water-holding capacity, microbial biomass, and nutrient mineralization. Although SOC may be calculated from estimates of soil organic matter (SOM) obtained by loss-on-ignition (LOI), factors such as sample clay concentration and combustion temperature introduce error into estimates of SOM. We explored the potential for an extensive collection of …

Quantifying Spatial Heterogeneity Of Wild Blueberries And Crop Water Stress Monitoring Using Remote Sensing Technologies, Kallol Barai

Electronic Theses and Dissertations

The wild blueberry is one of the major crops of Maine, with significant economic value and potential health benefits. Due to global climate change, drought impacts have been increasing significantly in recent years in the northeast region of the USA, causing significant economic losses in the agricultural sectors. It has been predicted to increase further in the future. Changing patterns of the elevated atmospheric temperatures, increased rainfall variabilities, and more frequent drought events have made the wild blueberry industry of Maine vulnerable, suggesting the adoption of novel approaches to mitigate the negative impacts of global climate changes. Also, wild blueberry …

Remotely Sensed Assessment Of The Preferred Habitat Of Alexandrium Catenella In The Gulf Of Maine And The Bay Of Fundy, Andre F. Bucci

Electronic Theses and Dissertations

Harmful Algal Blooms (HABs) of the toxic dinoflagellate Alexandrium catenella are an annually recurring problem in the Gulf of Maine (GoM), resulting in risks to human health and substantial economic losses due to shellfish harvesting closures. The monitoring approaches in the region are restricted to real-time identification of the HABs events, when they are clearly underway and already causing deleterious effects to the environment. To fully function as an early warning system rather than an immediate response, monitoring strategies need to be focused on environmental conditions preceding A. catenella HABs. However, the current understanding of the preferred habitat for A. …

The Effects Of Rising Ambient Temperatures On Thermoregulation And Range Shifts Of Northern Flying Squirrels, Elise K. Gudde

Electronic Theses and Dissertations

Climate change may potentially alter a species’ range distribution and thus the relationship between environmental temperatures and animal performance as a response to climate warming has become an important area of research. Two species of flying squirrel in North America, the southern flying squirrel (Glaucomys volans) and the northern flying squirrel (Glaucomys sabrinus) have undergone northward range shifts, with climate warming being the suspected driver. Because they are nocturnal and tree nesting, flying squirrels may be particularly susceptible to warmer temperatures, as they will experience the highest daily ambient temperatures during their resting phase. I used G. sabrinus as a …

Assessment Of Historical Climate Variability In Maine With Implications For Future Agricultural Productivity And Adaptation, Carly Frank

Electronic Theses and Dissertations

Climate change is a wicked problem with global impacts, one of which being the sustainability of the existing global food system. As temperatures and variability in precipitation are projected to increase, the challenges to agriculture are expected to intensify. This thesis examines the Maine historical climate record over the growing season, in combination with future projections, to assess how conditions have changed and will change with agricultural implications. In this analysis, relevant climatic variables are analyzed, and agriculture-significant measures are derived for Maine’s three climate divisions using four decades of daily and monthly gridded datasets. In addition, this thesis explores …

Age, Growth, Foraging, And Trophic Ecology Of Bigeye (Thunnus Obesus) And Yellowfin (Thunnus Albacares) Tuna In Continental Shelf And Slope Regions Of The Northeast U.S., Riley S. Austin

Electronic Theses and Dissertations

Traditional stock assessments require, in part, accurate knowledge of growth relationships to estimate a variety of aspects involved in population conservation management of exploited species. In addition, the local distribution and condition of top pelagic predators is driven by detection of abundant forage aggregations and along with traditional stock assessments, should be considered for effective management of marine populations. Empirical analyses of these data are severely lacking for bigeye (Thunnus obesus) and yellowfin (Thunnus albacares) tuna in the Atlantic Ocean, especially for the former. Given historical studies’ observations of these two top predators use as biological samplers due to their …

Evaluating Physical And Cultural Methods To Improve Weed Management In Organic Vegetables, Rebecca J. Champagne

Electronic Theses and Dissertations

Effectively managing weeds in organic vegetable production continues to be challenging and costly. Cultivation, often referred to as physical weed control (PWC), is foundational for organic farmers; however, efficacy tends to be low and highly variable. Additionally, some crops are slow to germinate, and thus have poor competitive ability against weeds and high mortality from cultivation. This can result in high costs for hand-weeding labor, abundant seed rain into the soil, and a recurring, often increasing, weed problem. These challenges may be addressed by “stacking” tools to increase weed control efficacy, integrating targeted seedbank management strategies to reduce the germinable …

Assessing The Long-Term Effects Of Natural Disturbance-Based Silvicultural On The Avian Assemblage At The Acadian Forest Ecosystem Research Program, Carl Pohlman

Electronic Theses and Dissertations

Active forest management alters the resources available to forest-obligate species. Large-scale intensive management practices where timber production is the primary objective can lead to notable ecological changes in forest ecosystems. A key concept of ecological forestry is to design forest management activities to emulate natural disturbance regimes as a way to maintain the ecological integrity of forests. The Acadian Forest Ecosystem Research Program (AFERP) was undertaken as an experimental demonstration of management reflective of the region’s disturbance regime, which typically produces small canopy gaps. AFERP includes nine research areas assigned to three silvicultural treatments: unharvested control, small gap (expanding-group selection …

Computationally Modeling Dynamic Biological Systems, Katherine Jarvis

Electronic Theses and Dissertations

Modeling biological systems furthers our understanding of dynamic relationships and helps us make predictions of the unknown properties of the system. The simple interplay between individual species in a dynamic environment over time can be modeled by equation-based modeling or agent- based modeling (ABM). Equation based modeling describes the change in species quantity using ordinary differential equations (ODE) and is dependent on the quantity of other species in the system as well as a predetermined rates of change. Unfortunately, this method of modeling does not model each individual agent in each species over time so individual dynamics are assumed to …

Biotic Interactions At Species’ Range Limits In A Changing Climate, Isaac Shepard

Electronic Theses and Dissertations

As the global climate changes, many species are shifting their geographic ranges, often towards the poles or upslope in elevation. The ubiquity of these observation has renewed discussions about the mechanisms that determine species’ range margins. Leading hypotheses state abiotic variables should be the most important factor for setting range limits in environmentally stressful habitats. However, I propose an alternative hypothesis that biotic interactions may still be critically important for setting range limits, even in abiotically stressful habitats. Using a model system of ponds in the Rocky Mountains of Colorado, I developed several field experiments to empirically test the role …

Forest Disturbance And Occupancy Patterns Of Carnivores: Results Of A Large-Scale Field Study In Maine, Usa, Bryn E. Evans

Electronic Theses and Dissertations

Understanding trends in the abundance and distribution of carnivores is important at global, regional and local scales due to their ecological role, their aesthetic and economic value, and the numerous threats to their populations. Carnivores in Maine range from the American black bear (Ursus americanus), to numerous native mesocarnivore species, such as American marten (Martes americana), fisher (Pekania pennanti), coyote (Canis latrans), red fox (Vulpes vulpes), bobcat (Lynx rufus), Canada lynx (Lynx canadensis) and to two small weasel species (Mustela erminea and Neogale frenata). …

Gradient Generating Microfluidic Coculture System For Disease Modeling And Neural Development, Phaneendra Chennampally

Electronic Theses and Dissertations

Cellular microenvironment or cell niche plays an important role in developmental biology and disease pathophysiology. Physical or chemical signals in microenvironment drive the cellular activity. These signaling molecules are generated from the surrounding cells/tissues as part of intercellular communication; a fundamental property of a cell. Dynamic profile of these signaling molecules in the microenvironment plays a pivotal role in transfer of molecular information from cell to cell in disease proliferation or fate determination. Recapitulating these signaling cues in an in vitro study is difficult to achieve using standard cell culture techniques. However microfluidic systems are capable of addressing these issues, …

Experimental Warming Effects On Growth, Yield, And Biotic Pressure Of Wild Blueberries In Maine, Yu-Ying Chen

Electronic Theses and Dissertations

As the global temperature rises, a need exists for understanding the potential impacts of warming on the wild blueberry industry in Maine. Warming can change the physiology, growth, and pest pressure of crops, and also accelerates the evapotranspiration rate, resulting in decreased soil moisture. The objectives of this study were: (1) To characterize the response of phenological, morphological, and physiological traits of the wild blueberries to warming; (2) To quantify the impacts of different temperature levels on yield and berry quality; (3) To determine the abiotic and biotic factors that may influence yield, such as winter damages, freezing temperatures, the …

To Know The Land With Hands And Minds: Negotiating Agricultural Knowledge In Late-Nineteenth-Century New England And Westphalia, Justus Hillebrand

Electronic Theses and Dissertations

Ever since the eighteenth century, experts have tried to tell farmers how to farm. The agricultural enlightenment in Europe marked the beginning of a long arc of new experts aiming to change agricultural knowledge and practice. This dissertation analyzes the pivotal period in the late nineteenth and early twentieth century in Germany and the United States when scientists, improvers, and market agents began to develop comprehensive ways to communicate agricultural innovation to farmers. In a functional approach to analyzing the negotiation of agricultural knowledge through its communication in things, words, and practices, this dissertation argues that the process of change …

Evaluating Methods For Research In Physical Weed Control And Farm Asset Tracking, Johnny J. Sanchez

Electronic Theses and Dissertations

Effective weed control has long been recognized as critical for agricultural production, yet weeds remain a major constraint to production and economic return in many agroecosystems. Moreover, improvements in physical weed control are necessary to address increasing problems of herbicide resistance in weeds of grain and fiber crops and the high cost of hand weeding in vegetables. From tractor-mounted cultivation tools to autonomous weeders, weeding implements are affected by weeds, crops, soil conditions, and actuator effectiveness. In order to address these complex and often interacting factors concerning weed control, new and innovative tools must be designed and evaluated. Chapter one …

Lexicographic Sensitivity Functions For Nonsmooth Models In Mathematical Biology, Matthew D. Ackley

Electronic Theses and Dissertations

Systems of ordinary differential equations (ODEs) may be used to model a wide variety of real-world phenomena in biology and engineering. Classical sensitivity theory is well-established and concerns itself with quantifying the responsiveness of such models to changes in parameter values. By performing a sensitivity analysis, a variety of insights can be gained into a model (and hence, the real-world system that it represents); in particular, the information gained can uncover a system's most important aspects, for use in design, control or optimization of the system. However, while the results of such analysis are desirable, the approach that classical theory …

Farmer Engagement Through Mental Modeling: Opportunities For Climate Change Outreach, Ruth S, Clements

Electronic Theses and Dissertations

Climate change poses a challenge to farming systems worldwide. Effective adaptation and mitigation may be facilitated by outreach that is locally tailored and framed in terms of farmers’ perceptions and values. However, existing research suggests that farmers and those providing outreach may have different climate change perspectives, and there is little understanding of how farmers consider and prioritize climate change in relation to other aspects of their farming system. Furthermore, the diverse agricultural, economic, social, and environmental challenges farmers face require agricultural research and engagement efforts that can identify and adapt to farmers’ dynamic priorities and perceptions. Mental modeling is …

Live Cell Super-Resolution Microscopy Quanitifies An Interaction Between Influenza Hemagglutinin And Phosphatidylinositol 4,5-Bisphosphate, Jaqulin N. Wallace

Electronic Theses and Dissertations

Influenza virus, colloquially known as the flu, is an acute respiratory disease that infects several millions of individuals each year in the U.S. and kills tens of thousands of those infected. Yearly viral vaccines are widely available, however, due to the virus’s high mutation rate, their efficacy varies greatly. Due to the variability in vaccine efficiency against seasonal influenza, and the potential for even more pathogenic versions of influenza to emerge at any time, there is a high demand for a universal treatment option.

Influenza virus hijacks a variety of host cell components in order to replicate. The glycoprotein hemagglutinin …