Physical Sciences and Mathematics Commons^™

Effects Of Increasing Temperature And Acidification On The Growth And Competitive Success Of Alexandrium Catenella From The Gulf Of Maine, Drajad Seto

Electronic Theses and Dissertations

The increases in ocean temperature and pCO2 due to climate change are projected to affect the growth and future prevalence of Harmful Algal Blooms (HABs) in nearshore waters, but systematic studies on the effects these climate drivers have on harmful algal species are lacking. In particular, little is known about how future climate scenarios will affect the growth of the toxic dinoflagellate Alexandrium catenella, which produces the toxins responsible for paralytic shellfish poisoning (PSP) that threaten the health and economy of coastal communities in the Gulf of Maine. I examined growth responses of A. catenella and two other naturally co-occurring …

Considering The Non-Programming Geographer's Perspective When Designing Extracurricular Introductory Computer Programming Workshops, Thomas R Etherington

Journal of Spatial Information Science

Computer programming is becoming an increasingly important scientific skill, but geographers are not necessarily receiving this training as part of their formal education. While there are efforts to promote and support extracurricular introductory computer programming workshops, there remain questions about how best to deliver these workshops. Therefore, as part of a recent introductory programming extracurricular workshop I organized for non-programing geographers, I tried to understand more about their perceptions of computer programming. I identify that one of the most important aspects for geographers to learn to computer program is to have training that is domain specific to ensure that the …

Towards Harmonizing Property Measurement Standards, Abdullah Kara, Volkan Çağdaş, Ümit Işıkdağ, Bülent Onur Turan

Journal of Spatial Information Science

Area and volume values of buildings and building parts have been used in many applications including taxation, valuation and land use planning. Many countries maintain a national standard for representing the measurements of floor areas in buildings. The national standards generally use similar basis for measuring building floor areas, in fact, areas specified in national standards often have semantic differences. Therefore, a number of international standards have been developed for harmonizing floor area measurements; however, they also have differences. This study aims at harmonizing the floor areas defined in the international property measurement standards by revealing the semantic relations between …

Bridging Space, Time, And Semantics In Giscience, Margarita Kokla, Eric Guilbert, Mir Abolfazl Mostafavi

Journal of Spatial Information Science

No abstract provided.

Hyper-Local Geographically Weighted Regression: Extending Gwr Through Local Model Selection And Local Bandwidth Optimization, Alexis Comber, Yunqiang Wang, Yihe Lü, Xingchang Zhang, Paul Harris

Journal of Spatial Information Science

Geographically weighted regression (GWR) is an inherently exploratory technique for examining process non-stationarity in data relationships. This paper develops and applies a hyper-local GWR which extends such investigations further. The hyper-local GWR simultaneously optimizes both local model selection (which covariates to include in each local regression) and local kernel bandwidth specification (how much data should be included locally). These are evaluated using a measure of model fit. The hyper-local GWR approach evaluates different kernel bandwidths at each location and selects the most parsimonious local regression model. By allowing models and bandwidths to vary locally, this approach extends and refines the …

Georeferencing Places From Collective Human Descriptions Using Place Graphs, Hao Chen, Stephan Winter, Maria Vasardani

Journal of Spatial Information Science

Place descriptions in everyday communication or in online text provide a rich source of spatial knowledge about places. Such descriptions typically consist of references to places and spatial relationships between them. An important step to utilize such knowledge in information systems is georeferencing the referred places. Beside place name disambiguation, another challenge is that a significant proportion of place references in such descriptions are not official place names indexed by gazetteers, thus cannot be resolved easily. This paper presents a novel approach for georeferencing places from collective descriptions using place graphs, regardless of whether they are referred to by gazetteered …

Towards Place-Based Exploration Of Instagram: Using Co-Design To Develop An Interdisciplinary Geovisualization Prototype, Catherine Emma Jones, Daniele Guido, Marta Severo

Journal of Spatial Information Science

An abundance of geographic information is hidden within texts and multimedia objects that has the potential to enrich our knowledge about the relationship between people and places. One such example is the geographic information embedded within user-generated content collected and curated by the social media giants. Such geographic data can be encoded either explicitly as geotags or implicitly as geographical references expressed as texts that comprise part of a title or image caption. To use such data for knowledge building there is a need for new mapping interfaces. These interfaces should support both data integration and visualization, and geographical exploration …

Investigations Into The Advancement Of Cryptotephra Geochemical Fingerprinting, Laura Hartman

Electronic Theses and Dissertations

The primary purpose of this work is to advance new sample preparation and analytical methods for ice core tephrochronology. When a volcanic source can be accurately identified using volcanic glass particle geochemistry, it may provide a robust time reference for the ice core’s timescale. The presence of an identifiable tephra layer may also suggest atmospheric pathways at the time of deposition, or assist in reconstructing volcanic forcing of climactic state for a specific event. One of the perpetual challenges in ice core based tephrochronological work is measuring the geochemical composition of ultra-fine particles (<10 >μm). Not only is it difficult …

Controls On Phosphorus Export From An Agricultural Watershed: Amsden Brook, Fort Fairfield, Maine Usa., Gregory J. Mcdonald

Electronic Theses and Dissertations

This study explores the sources and mechanisms of phosphorus (P) mobilization during base flow within the Amsden Brook watershed, Fort Fairfield, Maine, USA. Amsden Brook is an agriculturally dominated watershed drained by a spring-fed and perennial first- to second-order stream. We characterized the P concentrations within the watershed to investigate connections between soils, stream sediment, surface water, and groundwater. Waters were monitored monthly during the 2017 snow-free period for temperature, pH, dissolved oxygen, conductivity, soluble reactive P (SRP), total P, strong acid anions, strong base cations, dissolved organic carbon (DOC), Al, Fe, and Mn. Phosphorus speciation within soils and sediment …

Remote Sensing Of Icebergs In Greenland's Fjords And Coastal Waters, Jessica Scheick

Electronic Theses and Dissertations

Increases in ocean water temperature are implicated in driving recent accelerated rates of mass loss from the Greenland Ice Sheet. Icebergs provide a key tool for gaining insight into ice-ocean interactions and until recently have been relatively understudied. Here we develop several methods that exploit icebergs visible in optical satellite imagery to provide insight on the ice--ocean environment and explore how iceberg datasets can be used to examine the physics of iceberg decay and parent glacier properties. First, a semi-automated algorithm, which includes a machine learning-based cloud mask, is applied to six years (2000-2002 and 2013-2015) of the Landsat archive …

Stream Dynamics In The Headwaters Of Post-Glacial Watershed Systems, Brett Gerard

Electronic Theses and Dissertations

This dissertation summarizes research examining watershed processes across Northern New England, with an emphasis on the Central and Coastal regions of Maine. The research presented here focuses on the linkages between watershed geomorphic conditions, climate, and surface flow regimes driving stream channel hydraulic conditions and bed dynamics governing channel geometry. The geologic and human history of the landscape provides the context in which earth surface processes are examined within the dominant physiographic settings in Maine to describe vulnerabilities to climate change. Results are summarized to support the development of sustainability solutions for forecasted watershed management problems by natural resource management …

Advantages And Limitations To The Use Of Optical Measurements To Study Sediment Properties, Emmanuel Boss, Christopher R. Sherwood, Paul Hill, Tim Milligan

Marine Sciences Faculty Scholarship

Measurements of optical properties have been used for decades to study particle distributions in the ocean. They are useful for estimating suspended mass concentration as well as particle-related properties such as size, composition, packing (particle porosity or density), and settling velocity. Measurements of optical properties are, however, biased, as certain particles, because of their size, composition, shape, or packing, contribute to a specific property more than others. Here, we study this issue both theoretically and practically, and we examine different optical properties collected simultaneously in a bottom boundary layer to highlight the utility of such measurements. We show that the …

Climatic Range Filling Of North American Trees, Benjamin Seliger

Electronic Theses and Dissertations

Understanding the degree to which species distributions are controlled by climate is crucial for forecasting biodiversity responses to climate change. Climatic equilibrium, when species are found in all places which are climatically suitable, is a fundamental assumption of species distribution models, but there is evidence in support of climate disequilibria in species ranges. Long-lived, sessile organisms such as trees may be especially vulnerable to being outpaced by climate change, and thus prone to disequilibrium. In this dissertation, I tested the degree to which North American trees are in equilibrium with their potential climatic ranges using the ‘range filling’ metric, which …

Multispectral Classification Of Gulf Of Maine Surface Waters: Seasonal And Interannual Variability, Brianna M. King

Electronic Theses and Dissertations

Bio-optically, surface waters of the northeastern US continental shelf are strongly heterogeneous, exhibiting highly variable distributions in both time and space of suspended sediment, colored dissolved organic matter (CDOM), and phytoplankton concentration and community structure. These render the standard global NASA satellite chlorophyll algorithm suspect. However, spectral signatures of the water are well quantified by the actual satellite-based multispectral reflectance (Rrs) measurements. Here, we use 6 bands of Rrs measurements from 19 years (1998-2016) of monthly composite SeaWiFS and MODIS data to identify the spectral signatures of dominant water types present over the northeast shelf. A merged multivariate clustering approach …

Minerva 2018, The Honors College

Minerva

This issue of Minerva includes an article on the Honors Endeavor by recently retired faculty member, David Gross; an adaptation of Isaac Record's 2018 Distinguished Honors Graduate lecture; an article on 2018 Honors Read Just Mercy; and a wonderful farewell to beloved Honors College Administrative Specialist, Deb Small. Other highlights include a reflection by CLAS-Honors preceptor of philosophy, Hao Hong; and a look into 2018-2019 student thesis research.

Three-Dimensional Bedrock Channel Evolution With Smoothed Particle Hydrodynamics, Nick Richmond

Electronic Theses and Dissertations

Bedrock channels are responsible for balancing and communicating tectonic and climatic signals across landscapes, but it is difficult and dangerous to observe and measure the flows responsible for removing weakly-attached blocks of bedrock from the channel boundary. Consequently, quantitative descriptions of the dynamics of bedrock removal are scarce. Detailed numerical simulation of violent flows in three dimensions has been historically challenging due to technological limitations, but advances in computational fluid dynamics aided by high-performance computing have made it practical to generate approximate solutions to the governing equations of fluid dynamics. From these numerical solutions we gain detailed knowledge of the …

The Effects Of Seasonal Variations In Chemistry And Hydrology On The Microbial Community And Its Sulfide Oxidation Potential In A Naturally Acidic Maine Stream, Raymond C. Kahler Iii

Electronic Theses and Dissertations

Sulfide minerals oxidize through interaction with water and oxygen, releasing hydrogen ions. The process often occurs naturally near metal sulfide deposits, and can be accelerated through mining. Microorganisms accelerate the rate of sulfide oxidation. Acidified streams typically contain high metal concentrations (e.g. aluminum) and microbes in these systems may develop resistances to metal toxicity. Stream flow can affect sulfide oxidation and microbial community structure. Baseflow can influence stream chemistry from interactions with the surrounding bedrock, while stormflow affects stream chemistry and the local microbial community through dilution and addition of microbes transported by runoff. Microbial community composition is affected by …

Application Of Silicon Nanohair Textured P-N Junctions In A Photovoltaic Device, Michael Small

Electronic Theses and Dissertations

The goal of this project is to design and develop a fabrication process for a silicon photovoltaic device which incorporates a nanohair textured p-n junction. The silicon nanowires are etched into a silicon wafer, comprising an epitaxial p-layer on n-substrate, via metal-assisted chemical etching (MACE). The resulting nanowires contain p-n junctions that lie along the length of the vertical nanowires. This construct has the potential to increase the optical bandwidth of a silicon photovoltaic device by allowing a greater amount of short wavelength light to reach the junction. In addition, the MACE method of nanofabrication has the potential for decreasing …

Modern And Paleoecological Perspectives On A Terrestrial-Marine Linkage In The Falkland Islands, Dulcinea V. Groff

Electronic Theses and Dissertations

The Falkland Islands are a biodiversity hotspot in the South Atlantic Ocean, with some of the world’s most important populations of seabirds and seals. The impact of climate change on these marine populations and their coastal breeding habitat in the Falklands is unknown. Coastal grasslands of Poa flabellata (tussac grass) form critical breeding habitat for wildlife, but have been heavily degraded by the introduction of livestock in the 17^th century. This dissertation investigates the impacts of global change (climate change, grazing) on P. flabellata and its sensitivity to the fecal nutrient subsidies provided by marine wildlife. Chapter 1 provides …

Ums Data Governance Annual Report 2018, University Of Maine System Data Advisory Committee

General University of Maine Publications

The newly formed University of Maine System Data Governance program was launched to improve the System's capacity to collect information and deploy resources in service to the students and in response to Maine's dire demographic and workforce challenges.

The UMS campuses and administrative units make up a complex system that requires a strategic approach to data collection and analysis. From understanding the intricacies of distance education and online programs, to aligning human resource and financial department codes, unified data governance is essential to ensuring the integrity and reliability of the University of Maine System's data.

Improved Correction For Non-Photochemical Quenching Of In Situ Chlorophyll Fluorescence Based On A Synchronous Irradiance Profile, Xiaogang Xing, Nathan Briggs, Emmanuel Boss, Hervé Claustre

Marine Sciences Faculty Scholarship

In situ chlorophyll fluorometers have been used to quantify the distribution of chlorophyll concentration in natural waters for decades. However, chlorophyll fluorescence is depressed during daylight hours due to non-photochemical quenching (NPQ). Corrections attempted to date have provided improvement but still remain unsatisfactory, often overestimating the expected value. In this study, we examine the relationship between NPQ and instantaneous Photosynthetically Active Radiation (iPAR) using field data from BGC-Argo floats equipped with Chlorophyll-a fluorometers and radiometers. This analysis leads to an improved NPQ correction that incorporates both iPAR and mixed layer depth (MLD) and is validated against data collected at sunrise …

Physical And Chemical Response Of Small, North Temperate Lakes To Recovery From Acidification And Climate Change, Amanda Gavin

Electronic Theses and Dissertations

As the rate of sulfate (SO42-) deposition continues to decline and climate is trending towards warmer and wetter conditions, the biogeochemical and physical response of small, north temperate lakes is variable. In this study, we observed long-term chemical trends combined with seasonal water temperature patterns in the context of climate change and recovery from acidification in two remote lake populations in Maine: 29 high elevation lakes and eight low elevation lakes. Small, temperate lakes are the most abundant type of lake, making them a widely representative study sample to consider. Maine’s high elevation lakes (>600m) could potentially provide unique …

Thermochemical Conversion Of Guaiacol Over Unsupported Tungsten Oxide And Nickel Supported Catalysts, Pamela Ruiz Martinez

Electronic Theses and Dissertations

Interest in conversion of biomass into renewable fuels has motivated development of thermochemical methods for production of bio-oil and development of hydrodeoxygenation catalysts for upgrading the oil. Two types of catalysts were investigated. The catalytic activity of unsupported tungsten oxide bronze catalysts for the conversion of guaiacol was explored as a representative compound from bio-oil. The reactions were carried out in a trickle bed reactor at various concentrations of the reactant and hydrogen pressure, as well as varying catalyst activation and reaction temperatures. The reaction pathway from guaiacol to phenol by demethoxylation, followed by hydrogenation to cyclohexanol, and finally dehydration …

Three Examples Of Mondoromy Groups, Alice A. Wise

Electronic Theses and Dissertations

This thesis illustrates the notion of the Monodromy group of a global analytic function through three examples. One is a relatively simple finite example; the others are more complicated infinite cases, one abelian and one non-abelian, which show connections to other parts of mathematics.

Retreat Of The Antarctic Ice Sheet In The Southern Ross Embayment From Records At Amundsen And Liv Glaciers, Southern Transantarctic Mountains, Jillian Pelto

Electronic Theses and Dissertations

The Antarctic Ice Sheet contains ~58 m of global sea-level equivalent and thus its future behavior under global warming is of pressing concern. Examination of past ice-sheet behavior during periods of warming climate can afford insight useful for predicting future sea-level rise. This study focuses on a major unanswered question - namely, the cause of Antarctic Ice Sheet retreat following the last glaciation. Documenting the timing and nature of this deglaciation is crucial to understand the mechanisms behind ice-sheet behavior. Here, I examine how the marine portions of the ice sheet responded to the major warming that occurred at the …

Towards An Efficient, Scalable Stream Query Operator Framework For Representing And Analyzing Continuous Fields, John Whittier

Electronic Theses and Dissertations

Advancements in sensor technology have made it less expensive to deploy massive numbers of sensors to observe continuous geographic phenomena at high sample rates and stream live sensor observations. This fact has raised new challenges since sensor streams have pushed the limits of traditional geo-sensor data management technology. Data Stream Engines (DSEs) provide facilities for near real-time processing of streams, however, algorithms supporting representing and analyzing Spatio-Temporal (ST) phenomena are limited.

This dissertation investigates near real-time representation and analysis of continuous ST phenomena, observed by large numbers of mobile, asynchronously sampling sensors, using a DSE and proposes two novel stream …

Nitrogen Cycling During A Period Of Environmental Change, Kaizad Patel

Electronic Theses and Dissertations

Natural and anthropogenic disturbances have altered the N cycle on the regional to global scale. Although numerous studies have examined the effects of chronic atmospheric N deposition on ecosystem processes, less is known about intra-annual variability of these processes, or how these responses might be altered under conditions of changing climate. The work described in this dissertation focuses on the effects of a changing chemical and physical climate, particularly terrestrial N processes (a) during Maine’s changing winters, and (b) in response to chronic elevated N additions.

Subnivean winter soil processes were examined at the Dwight B. DeMerritt Forest (DBDF) and …

Principles And Guidelines For Advancement Of Touchscreen-Based Non-Visual Access To 2d Spatial Information, Hari Prasath Palani

Electronic Theses and Dissertations

Graphical materials such as graphs and maps are often inaccessible to millions of blind and visually-impaired (BVI) people, which negatively impacts their educational prospects, ability to travel, and vocational opportunities. To address this longstanding issue, a three-phase research program was conducted that builds on and extends previous work establishing touchscreen-based haptic cuing as a viable alternative for conveying digital graphics to BVI users. Although promising, this approach poses unique challenges that can only be addressed by schematizing the underlying graphical information based on perceptual and spatio-cognitive characteristics pertinent to touchscreen-based haptic access. Towards this end, this dissertation empirically identified a …

Understanding Student Development Of Science Literacy Skills In An Undergraduate Environmental Science Course, Molly Picillo

Electronic Theses and Dissertations

Educators are expected to instill a variety of skills in their students that are necessary to be competent citizens of society. One such set of skills, science literacy skills, broadly encompass the ability of an individual to evaluate reliability of data and information and critically analyze and interpret them (Gormally Brickman, Hallar, & Armstrong, 2009). These skills are utilized in everyday decision-making and given their pertinence, there is a need for citizens to be scientifically literate. Thus, educators need tools and assessments to help students develop these skills and analyze their science literacy. The aim of this study was to …

The Hilbert-Huang Transform: A Theoretical Framework And Applications To Leak Identification In Pressurized Space Modules, Kenneth R. Bundy

Electronic Theses and Dissertations

Any manned space mission must provide breathable air to its crew. For this reason, air leaks in spacecraft pose a danger to the mission and any astronauts on board. The purpose of this work is twofold: the first is to address the issue of air pressure loss from leaks in spacecraft. Air leaks present a danger to spacecraft crew, and so a method of finding air leaks when they occur is needed. Most leak detection systems localize the leak in some way. Instead, we address the identification of air leaks in a pressurized space module, we aim to determine the …