Physical Sciences and Mathematics Commons^™

Exchange Mechanisms In Macroscopic Ordered Organic Magnetic Semiconductors, Naveen Rawat

Graduate College Dissertations and Theses

Small molecule organic semiconductors such as phthalocyanines and their derivatives represent a very interesting alternative to inorganic semiconductor materials for the development of flexible electronic devices such as organic thin field effect transistors, organic Light Emitting Diodes and photo-voltaic cells. Phthalocyanine molecules can easily accommodate a variety of metal atoms as well in the central core of the molecule, resulting in wide range of magnetic properties. Exploration of optical properties of organic crystalline semiconductors thin films is challenging due to sub-micron grain sizes and the presence of numerous structural defects, disorder and grain boundaries. However, this can be overcome by …

New Insights For The Future Of Lake Champlain: Practical Approaches And Useful Tools For Grappling With Uncertainty And Weighing Trade-Offs In Watershed Management., Philip Halteman

Graduate College Dissertations and Theses

The effective management of non-point source nutrient pollution continues to prove elusive. Though the scientific literature is unequivocal that all anthropogenic land uses contribute to non-point source (NPS) pollution, variable levels of contribution over time and across location and complex relationships between cost and effect make finding technologically effective management solutions difficult. In addition, these solutions are implemented in a world of scarce resources, diverse and often competing concerns and values, and intense public scrutiny. Clearly, making the best possible decision about how to manage NPS pollution under these conditions is not simple. My overarching goal was to develop and …

How Wildlife Information, Recreation Involvement And Demographic Characteristics Influence Public Acceptability Of Development, Jessica Espenshade

Graduate College Dissertations and Theses

Increasing development like roads and houses will alter the future landscape of Vermont. Development provides important resources for people and society, but also results in consequences for wildlife and opportunities for recreation. Managing development requires information on the public's acceptability of development and how acceptability is shaped by information on various consequences. In this study, I examined three questions: 1) What is the public's acceptability of development? 2) Does wildlife information influence public acceptability of development and 3) Is the maximum amount of acceptable development influenced by views about wildlife, involvement in recreation, and demographic factors? I surveyed 9,000 households …

The Molecular Evolution Of Non-Coding Dna And Population Ecology Of The Spiny Softshell Turtle (Apalone Spinifera) In Lake Champlain, Lucas Edward Bernacki

Graduate College Dissertations and Theses

ABSTRACT

Spiny softshell turtles (Apalone spinifera) occur at the northwest limit of their range in Lake Champlain. This species, although widespread across North America, is listed as threatened in Vermont due to habitat destruction and disturbances of anthropogenic origin. The population of spiny softshell turtles in Lake Champlain is isolated from other North American populations and is considered as an independent management unit. Efforts to obtain information on the biology of spiny softshell turtles in Lake Champlain precede 1936 with conservation measures being initiated in 1987.

Methods of studying spiny softshell turtles in Lake Champlain have included direct …

Management By Crisis: Land Trust Conservation Engagement And Methods In Vermont, Louise Sopher Lintilhac

Graduate College Dissertations and Theses

Planning a future for the landscapes we live in can be a daunting challenge for many communities in Vermont. Conservation initiatives affect the quality of life for all community members and can be difficult if not impossible to change in the event of poor planning. Through examining stakeholder relationships with land trusts I have explored the complexities of planning processes used by land trusts in Vermont for conservation initiatives

The study involved one statewide land trust, the Vermont Land Trust, and two community land trusts, the Stowe Land Trust and the Duxbury Land Trust. I used qualitative methods including document …

Subsistence Under The Canopy: Agroecology, Livelihoods And Food Sovereignty Among Coffee Communities In Chiapas, Mexico, Margarita Fernandez

Graduate College Dissertations and Theses

One of the most pressing challenges facing the world today is how to sustainably feed a growing population while conserving the ecosystem services we depend on. Coffee landscapes are an important site for research on agrifood systems because they reflect global-scale dynamics surrounding conservation and livelihood development. Within them, we find both what is broken in our global agrifood system, as well as the grassroots struggles that strive to change the system by building socio-ecologically resilient, sustainable livelihoods. Research shows that smallholder shade coffee farmers steward high biodiversity and provide essential ecosystem services. At the same time, studies in the …

Grass-Based Dairy In Vermont: Benefits, Barriers, And Effective Public Policies, Serge William Wiltshire

Graduate College Dissertations and Theses

A comprehensive literature review was undertaken in order to define and assess the sustainability and resiliency characteristics associated with grass-based and confinement dairy farming. Primarily as a result of reduced input costs, grass-based dairy farming often enhances profitability over confinement systems, especially on small farms. Further, conversion of tilled soil to permanent pasture has been shown to significantly reduce harmful sediment and nutrient transport into waterways. Perennial forage also acts as a carbon sink, curtailing or even negating a grass-based farm's carbon footprint. Finally, social benefits derived from enhanced nutrition and higher quality of life are also associated with grass-based …

An Evaluation Of Vermicompost As A Fast-Acting Nitrogen Amendment To Mitigate Nitrogen Deficiencies In Organic Vegetable Production, Peter Dalton Austin

Graduate College Dissertations and Theses

For sustained production, organic agriculture depends on plant needs being synchronized with the release of nutrients from organic amendments during decomposition within the soil. Because decomposition is strongly dependent on soil moisture and temperature, nutrient needs may not always be met as planned or synchronous with plant need. Unlike conventional agriculture, fast acting amendments are not readily available. Much of the evidence that vermicompost benefits crop production comes from studies on seed germination and production of starts in greenhouses. Yet, there is a dearth of information derived from field studies. Soil, soil and water nitrogen, plant development, and marketable yield …

Numerical Simulations Of Reacting Flow In An Inductively Coupled Plasma Torch, Maximilian Dougherty

Graduate College Dissertations and Theses

In the design of a thermal protection system for atmospheric entry, aerothermal heating presents a major impediment to efficient heat shield design. Recombination of atomic species in the boundary layer results in highly exothermic surface-catalyzed recombination reactions and an increase in the heat flux experienced at the surface. The degree to which these reactions increase the surface heat flux is partly a function of the heat shield material. Characterization of the catalytic behavior of these materials takes place in experimental facilities, however there is a dearth of detailed computational models for the fluid dynamic and chemical behavior of such facilities. …

Gene Expression Noise In Stress Response As A Survival Strategy In Fluctuating Environments, Javier Garcia-Bernardo

Graduate College Dissertations and Theses

Populations of cells live in uncertain environments, where they encounter large variations in nutrients, oxygen and toxic compounds. In the fluctuating environment, cells can sense their surroundings and express proteins to protect themselves against harmful substances. However, if the stressor appears infrequently or abruptly, sensing can be too costly or too slow, and cells cannot rely solely on it. To hedge against the sudden appearance of a stressor, cell populations can also rely on phenotypic diversification through bet-hedging. In bet-hedging, cells exploit noise in gene expression or use multistable genetic networks to produce an heterogeneous distribution of resistance-conferring protein levels. …

Exploring The Google Books Corpus: An Information-Theoretic Approach To Linguistic Evolution, Eitan Pechenick

Graduate College Dissertations and Theses

The Google Books corpus contains millions of books in a variety of languages. Due to this incredible volume and its free availability, it is a treasure trove that has inspired a plethora of linguistic research.

It is tempting to treat frequency trends from Google Books data sets as indicators for the true popularity of various words and phrases. Doing so allows us to draw novel conclusions about the evolution of public perception of a given topic. However, sampling published works by availability and ease of digitization leads to several important effects, which have typically been overlooked in previous studies. One …

Spatiotemporally Periodic Driven System With Long-Range Interactions, Owen Dale Myers

Graduate College Dissertations and Theses

It is well known that some driven systems undergo transitions when a system parameter is changed adiabatically around a critical value. This transition can be the result of a fundamental change in the structure of the phase space, called a bifurcation. Most of these transitions are well classified in the theory of bifurcations. Among the driven systems, spatiotemporally periodic (STP) potentials are noteworthy due to the intimate coupling between their time and spatial components. A paradigmatic example of such a system is the Kapitza pendulum, which is a pendulum with an oscillating suspension point. The Kapitza pendulum has the strange …

Pedagogical Praxis Models In Sustainability Education: A Focus On Food Systems And Environment, Karen Lynn Nordstrom

Graduate College Dissertations and Theses

As societies embrace notions of sustainability, there is an increasing interest in how to best educate students about these concepts. The field of sustainability education (SE) is an approach that has been developed to address this concern. SE frameworks seek to integrate into curricular contents and formats within campus learning environments, in order to systematically improve upon approaches and services developed to support student learning and development. My research offers insight into the relationships between the philosophical principles and praxes of sustainability education, with the aim to inform educators on how best to prepare students to address complex sustainability issues. …

Lidar Remote Sensing Of Forest Canopy Structure: An Assessment Of The Accuracy Of Lidar And Its Relationship To Higher Trophic Levels, Christopher Felix Hansen

Graduate College Dissertations and Theses

Light detection and ranging (LiDAR) data can provide detailed information about three-dimensional forest horizontal and vertical structure that is important to forest productivity and wildlife habitat. Indeed, LiDAR data have been shown to provide accurate estimates to forest structural parameters and measures of higher trophic levels (e.g., avian abundance and diversity). However, links between forest structure and tree function have not been evaluated using LiDAR. This study was designed and scaled to assess the relationship of LiDAR to multiple aspects of forest structure and higher trophic levels (arthropod and bird populations), which included the ground-based collection of percent crown and …

Burst Pressure Properties And Ex Vivo Analysis Of Alginate-Based Hydrogels For Tissue Sealant Applications, Patrick Nelson Charron

Graduate College Dissertations and Theses

Lung diseases, cancers, and trauma can result in injury to the connective tissue lining the lung, i.e., the pleura. Pleural injuries lead to pneumothoraxes or pleural effusions, i.e., air or fluid leaking out of the lung respectively, and potential lung collapse - an immediately life threatening condition. While several bioengineered soft tissue sealants exist on the market, there is only one sealant FDA-approved for use in pulmonary surgery. In addition, very limited techniques are presented in the literature for characterizing the burst properties of hydrogel tissue sealants. For my thesis, I proposed to develop a protocol for characterizing the burst …

Promoting Time In Nature For Children: Investigating The Role Of Provider Nature Relatedness, Lindsey Gauderer

Graduate College Dissertations and Theses

Research has shown that time spent in and exposure to natural environments has numerous benefits for children, both physical and mental. At the same time, children face many barriers to obtaining time in the outdoors and today's youth spend less time outside than previous generations. Initiatives such as health care provider prescriptions for outdoor activity aim to encourage exposure to nature as a health intervention for children. In order to enhance the potential for success of programs such as these, factors influencing their implementation need to be assessed. This study aims to explore the impact that provider connectedness to nature, …

The Champlain Sea/Lake Champlain Transition Recorded In The Northeast Arm Of Lake Champlain, Usa-Canada, Ashliegh Theresa Belrose

Graduate College Dissertations and Theses

Sediment accumulated on a lakebed archives information about past climate and changes in the regional environment. Previous studies (Burgess, 2007; Koff, 2011; Palmer, 2012) in the Northeast Arm of Lake Champlain, specifically Missisquoi Bay and Saint Albans Bay, showed a period (~9,400 - 8,600 yBP) of elevated organic matter deposition in both bays, indicating a productive event that pre-dated any possible anthropogenic influence. However, the record was abruptly cut off and any documentation representing the span of time leading up to this event was not found. The elevated organic matter levels were explained as being the result of a warm, …

Experimental Investigation And Analysis Of High-Enthalpy Nitrogen Flow Over Graphite, Andrew Lutz

Graduate College Dissertations and Theses

The high-enthalpy flow generated by hypersonic vehicles traveling within the Earth's atmosphere inherently delivers an elevated heat flux to the vehicle surface. In addition to conductive heating, the liberated energy generated by various exothermic chemical reactions occurring at the vehicle surface further augment the total heat load. Quantifying the rates at which these reactions take place is imperative and remains a significant challenge as developers attempt to design the next generation of thermal protection systems.

This study focused on nitrogen recombination and carbon nitridation, as these reactions are ubiquitous to the most aggressive atmospheric re-entry trajectories in which carbon-based ablative …

Using Empirical Mode Decomposition To Study Periodicity And Trends In Extreme Precipitation, Noah Pfister

Graduate College Dissertations and Theses

Classically, we look at annual maximum precipitation series from the perspective of extreme value statistics, which provides a useful statistical distribution, but does not allow much flexibility in the context of climate change. Such distributions are usually assumed to be static, or else require some assumed information about possible trends within the data. For this study, we treat the maximum rainfall series as sums of underlying signals, upon which we perform a decomposition technique, Empirical Mode Decomposition. This not only allows the study of non-linear trends in the data, but could give us some idea of the periodic forces that …

Multi-Satellite Formation Trajectory Design With Topological Constraints Over A Region Of Interest Using Differential Evolution, David William Hinckley

Graduate College Dissertations and Theses

Satellite formation missions allow for scientific measurement opportunities that are only otherwise possible with the use of unrealistically large satellites. This work applies the Evolutionary Algorithm (EA), Differential Evolution (DE), to a 4-satellite mission design that borrows heavily from the mission specifications for Phase 1 of NASA's Magnetospheric Multi-Scale Mission (MMS). This mission specifies goals for formation "quality" and size over the arc when scientific measurements are to be taken known as the Region of Interest (ROI). To apply DE to this problem a novel definition of fitness is developed and tailored to trajectory problems of the parameter scales of …

Effects Of Landscape Change On Corsac Foxes In Mongolia, Myagmarjav Lkhagvasuren

Graduate College Dissertations and Theses

Landscape change affects the distribution of wildlife and represents a conservation concern, especially in Asia, which is experiencing rapid development. In Mongolia, mining, livestock grazing, infrastructure development and climate change represent major drivers of change that will impact habitats and few tools exist to predict how wildlife will respond. I examined the impacts of landscape change on the corsac fox (Vulpes corsac) in a steppe region of Mongolia. The corsac fox occurs widely throughout northern Asia, but has experienced declines in many regions and remains one the least studied canids. I addressed two questions: 1) how do common features of …

Catalytic Main Group Element Bond Formation Reactions Toward The Preparation Of Conjugated Materials, Neil Mucha

Graduate College Dissertations and Theses

Polymers incorporating main group elements offer different and interesting properties compared to their all carbon analogues. For example, π-conjugated polymers incorporating phosphorus in the main chain of the polymer have generated interest due to their unique thermal and electronic properties, which primarily result from delocalization of the phosphorous lone pair within aromatic units. Similarly, interest in polysilanes stems from conductivity resulting from σ electron delocalization, though current methods of preparation for both of these types of materials are lacking. In this dissertation, both early and late transition-metal compounds were used to dehydrocouple phosphine and silane substrates. The use of dehydrocoupling …

Density Functional Theory Study Of Dilute Transition Metal Phthalocyanines, Daniel Burrill

Graduate College Dissertations and Theses

Organometallic (OM) crystals are studied in fields ranging from spintronics to photovoltaics. This thesis focuses on studying a particular class of OM crystals known as transition metal-phthalocyanines (TM-Pc) - a molecular crystal composed of chains of planar OM molecules with a transition metal center and four coordinated pyrrole-aromatic rings joined by nitrogen atoms, similar to porphyrin. The structure resembles a dish rack pattern where the planar TM-Pcs of adjacent chains are oriented nearly perpendicular to each other. While TM-Pcs have been studied for decades due to their interesting optical properties and applications as dyes, there has been recent interest in …

Effects Of Pcb Contamination On The Environment And The Cultural Integrity Of The St. Regis Mohawk Tribe In The Mohawk Nation Of Akwesasne, Kim Ellen Mcrae

Graduate College Dissertations and Theses

The following research project examines the effects of polychlorinated biphenyls (PCBs) on the environment and the cultural integrity of the St. Regis Mohawk tribe in the Mohawk Nation of Akwesasne. This indigenous community has been subjected to widespread long-term industrial pollution from nearby toxic hazardous waste facilities and Superfund sites.

The Mohawk Nation of Akwesasne has the distinction of being the only tribe whose officially recognized territory straddles the border between the United States and Canada. Using qualitative methodologies, coupled with an interdisciplinary framework, this study successfully engages with Akwesasne community members to explore such issues as bottom-up approaches to …

Earthworm Presence In Northern Forests: Impact On Distribution Of Soil Carbon Within Aggregate Fractions, Meghan Elizabeth Knowles

Graduate College Dissertations and Theses

Growing concerns over climate change is driving research aimed at determining ways of retaining soil carbon (C) within managed northeastern forests. Earthworms are exotic to the state of Vermont and the current extent of earthworm community presence in the state's forests, as well as the long term impact these communities will have on soil C storage, is still unknown. Current research suggests that earthworms have conflicting effects on the C cycle of soils, simultaneously enhancing mineralization through soil mixing, while protecting C through the stabilization of microaggregate (mA) structures. The mA soil fraction represents a pool of physically stable structures …

Using Stable Isotope Analysis To Estimate Black Bear (Ursus Americanus) Diet In Vermont, Eliese Antona Dykstra

Graduate College Dissertations and Theses

The black bear (Ursus americanus) is an iconic species with cultural, economic and ecological importance in Vermont, USA. Bears exhibit a highly variable diet, and few studies have described bear diet in the state. Information on diet may provide insight into foraging behavior, thus allowing managers to better assess patterns of human-bear conflict. My objectives were to estimate the relative contribution of food items to bear diet and how factors including sex, habitat, food availability, and nuisance status describe patterns of consumption. I collected samples from bears and major food groups including C3 plants, white-tailed deer (Odocoileus virginianus), corn (Zea …

The Status Of Stonecats (Noturus Flavus) In The Laplatte And Missisquoi Rivers, Vermont, Elizabeth Puchala

Graduate College Dissertations and Theses

Stonecats (Noturus flavus, Rafinesque 1818) are designated as a Vermont state-listed endangered species because their known distribution is limited to two systems, the LaPlatte and Missisquoi rivers. The restricted distribution and lack of knowledge on abundance in either river is cause for concern in the continued survival of these populations. Based on the capture numbers and large size range of individuals, we predicted that the population in the LaPlatte River, which provides quality benthic habitat, is stable. However, the Missisquoi River population has the potential for increased intermittent mortalities from two sources, lampricide (3-trifluoromethyl-4-nitrophenol) treatment every four years and dewatering …

Biological Indicators Of Compost-Mediated Disease Suppression Against The Soilborne Plant Pathogen Rhizoctonia Solani, Lynn Fang

Graduate College Dissertations and Theses

Compost can suppress soilborne plant pathogens that cause significant damage on globally important food crops. However, reports of plant pathogen suppression are inconsistent likely because there are no established standards for feedstock material, application rate, and maturity age upon application. Excellent results can be achieved in greenhouse trials, but field applications are much less reliable. Disease suppression occurs through the activity of biocontrol organisms (direct antagonism), and general microbial competition. Biocontrol species are hypothesized to colonize the pile during the curing phase, but single species may not be as important as microbial consortia. Substrate composition during maturation may give rise …

The Interaction Mechanisms Of A Screw Dislocation With A Defective Coherent Twin Boundary In Copper, Qiongjiali Fang

Graduate College Dissertations and Theses

Σ3{111} coherent twin boundary (CTB) in face-centered-cubic (FCC) metals and alloys have been regarded as an efficient way to simultaneously increase strength and ductility at the nanoscale. Extensive study of dislocation-CTB interaction has been carried out by a combination of computer simulations, experiments and continuum theory. Most of them, however, are based on the perfect CTB assumption. A recent study [Wang YM, Sansoz F, LaGrange T, et al. Defective twin boundaries in nanotwinned metals. Nat Mater. 2013;12(8):697-702.] has revealed the existence of intrinsic kink-like defects in CTBs of nanotwinned copper through nanodiffraction mapping technique, and has confirmed the effect of …

Lake Trout Spawning Site Use In Lake Champlain & The Development Of The Binomial Rolling Residence Test, Victoria M. Pinheiro

Graduate College Dissertations and Theses

Lake trout populations were extirpated from the lower four Great Lakes by 1960 and from Lake Champlain by 1900. The decline of lake trout populations fueled a wave of restoration-based research that spanned the Great Lakes and filled in many of the gaps in our knowledge of lake trout behavior and ecology. However, remarkably little is known about lake trout spawning behavior, even less about sex-specific differences in spawning site use. Lake trout use specific spawning sites, and may return to the same site year after year. More males are caught on spawning sites than females and are present at …