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Articles 3751 - 3780 of 4194

Full-Text Articles in Physical Sciences and Mathematics

Factors In The Design And Development Of A Data Warehouse For Academic Data., Margaret C. Lester May 2003

Factors In The Design And Development Of A Data Warehouse For Academic Data., Margaret C. Lester

Electronic Theses and Dissertations

Data warehousing is a relatively new field in the realm of information technology, and current research centers primarily around data warehousing in business environments. As new as the field is in these environments, only recently have educational institutions begun to embark on data warehousing projects, and little research has been done regarding the special considerations and characteristics of academic data, and the complexity of analyzing such data. Educational institutions measure success very differently from business-oriented organizations, and the analyses that are meaningful in such environments pose very unique and intricate problems in data warehousing. This research describes the process of …

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The Use Of Acoustics To Resolve Nightly Excursions Of Hyperbenthos, Heather U. Abello May 2003

The Use Of Acoustics To Resolve Nightly Excursions Of Hyperbenthos, Heather U. Abello

Electronic Theses and Dissertations

Acoustic analysis of die1 vertical migration in the Darnariscotta River estuary, Maine, showed a fairly regular nightly increase in biovolume (mm3 m'3) of organisms in the water column, presumed to be due to emergence, the entry of hyperbenthic organisms into the water column. Timing of these events was significantly correlated with time of sunset and time of sunrise for more than 50% of the dates where emergence and re-entry could be identified, between June and October 2002. Emergence traps indicate that the mysid shrimp, Neomysis americana, is the predominant migrator. Daily fluctuations in irradiance influence the timing of emergence fiom …

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Scope For Activity, Specific Dynamic Action And Growth In Early Juvenile Stages Of Atlantic Cod, Gadus Morhua, Sorren Lund Hansen May 2003

Scope For Activity, Specific Dynamic Action And Growth In Early Juvenile Stages Of Atlantic Cod, Gadus Morhua, Sorren Lund Hansen

Electronic Theses and Dissertations

Growth rates of early life stages of Atlantic cod (Gadus morhua) are very high, but decline, as the fish grow larger. Little is know about the physiological processes that facilitate and regulate this growth pattern. In this study, feeding and swimming metabolism were measured in individual juvenile Atlantic cod (Gadus morhua) in order to investigate how energy are allocated to swimming and growth in fast growing stages of fishes. Metabolic rates were measured by the means of oxygen consumption using two "Brett-type" respirometers. The metabolic measurements were repeated several times in individual juvenile Atlantic cod with a wet body mass …

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Reactions Of Alcohols And Organophosphonates On Tungsten Trioxide Epitaxial Films, Shuguo Ma May 2003

Reactions Of Alcohols And Organophosphonates On Tungsten Trioxide Epitaxial Films, Shuguo Ma

Electronic Theses and Dissertations

The adsorption, diffusion, reactions, and desorption of water, alcohols, ethers, and an organophosphonate were studied using calibrated thermal desorption spectroscopy (CTDS) on thin film WO3(OOl) surfaces grown epitaxially on a single crystal α- Al2O3(li02) (sapphire) substrate. The studies were conducted on oxidized and reduced surfaces, which were characterized by x-ray photoelectron spectroscopy (XPS) and ultraviolet photoelectron spectroscopy (UPS). The desorption spectra for molecular desorption of all of these molecules shifted to lower temperature with increasing coverage, and had overlapping tails on the high temperature side. Monte Carlo simulations show that this typical desorption shape …

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Surface Interactions Of Mercury On Gold Foil Electrodes In Electrodeposition And Stripping And ; An Investigation Of Free Thiolate Ions From Metal-Thiolate Chalcogenides, Charles Martin Watson May 2003

Surface Interactions Of Mercury On Gold Foil Electrodes In Electrodeposition And Stripping And ; An Investigation Of Free Thiolate Ions From Metal-Thiolate Chalcogenides, Charles Martin Watson

Electronic Theses and Dissertations

Mercury, a highly toxic metal, whose environmental concentration magnifies with ascension of the food chain, is monitored in our waters, food and air. Monitoring mercury is generally done by sample collection, transport to the laboratory; followed by: digestion of the sample, separation of the mercury and detection of the mercury: mostly by cold vapor atomic absorption or, cold vapor atomic fluorescence. These monitoring methods, preclude, routine, in-the-field mercury determination. New analytical techniques have been proposed for in the field determination of mercury. They consist of mercury adsorption onto a sensor or electrode and measuring how much is there either as …

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Relationship Between Alkaline Pulp Yield And The Mass Fraction And Degree Of Polymerization Of Cellulose In Pulp, Mehmet Sefik Tunc May 2003

Relationship Between Alkaline Pulp Yield And The Mass Fraction And Degree Of Polymerization Of Cellulose In Pulp, Mehmet Sefik Tunc

Electronic Theses and Dissertations

Wood as a raw material is generally the dominant cost factor for the production of chemical pulp. Therefore, an increase in pulp yield has a major impact on the competitiveness of a mill. In order to optimize pulp yield, for example by changing operating conditions, a mill must be able to monitor the yield accurately. However, an accurate "real-time" pulp yield measurement method is not available at the present time. Pulping yield is presently measured from the amount of pulp produced from a given quantity of wood consumed over a 3 to 6 month time frame. This method is obviously …

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The Short And Long-Term Effects Of Herbicide Application In Maine Clearcuts On Ant Communities (Hymenoptera: Formicidae), Kerry Frances Lough May 2003

The Short And Long-Term Effects Of Herbicide Application In Maine Clearcuts On Ant Communities (Hymenoptera: Formicidae), Kerry Frances Lough

Electronic Theses and Dissertations

The short and long-term effects of glyphosate application on the diversity and abundance of ants in Maine clearcuts was assessed in a two-year study. Glyphosate is applied to release coniferous trees from suppression by competition with deciduous vegetation after a forest is clearcut. Previous research indicates glyphosate has limited immediate and long-term effects on non-target fauna, though specific species can be affected. Limited research on the effects of herbicides on insects indicates some initial decrease in insect populations. Beneficial insects, such as pollinators and predators, positively influence the forest ecosystem, but little research has examined the effects of herbicide application …

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Modeling Bird Species Occurrence In Current And Future Landscapes, Stephen Nicholas Matthews May 2003

Modeling Bird Species Occurrence In Current And Future Landscapes, Stephen Nicholas Matthews

Electronic Theses and Dissertations

With mounting evidence that global temperatures have increased significantly over the last century and the projections of greater changes in climate by the end of this century, understanding the potential consequences of these changes for species is essential to conservation efforts. Here I evaluate the potential response of birds to projected climate change by using regression tree analysis to create models of species distributions under current conditions from Breeding Bird Survey data and then project these models onto General Circulation Model (GCM) scenarios of global climate change. Before modeling species responses to climate change, I selected seventeen bird species to …

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The Integration Of Cadastral Base Mapping With Cadastral Parcel Attribution, Kurt B. Wurm May 2003

The Integration Of Cadastral Base Mapping With Cadastral Parcel Attribution, Kurt B. Wurm

Electronic Theses and Dissertations

A cadastre is a parcel-based, up-to-date land information system containing a record of interests in land. Creation and maintenance of a cadastre usually involves coordination between different public and private organizations that are responsible for the various data. The U.S. Bureau of Land Management (BLM) has built a Geographic Coordinate Data Base (GCDB) that currently provides cadastral base map data for more than 38,000 townships across the country, with many of the western states nearly complete. The GCDB strategy is that the coordinates can and do change as more recent and accurate information becomes available. The locational reliability of the …

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Population Dynamics And Spatial Analysis Of The Maine Green Sea Urchin (Strongylocentrotus Droebachiensis) Fishery, Robert C. Grabowski May 2003

Population Dynamics And Spatial Analysis Of The Maine Green Sea Urchin (Strongylocentrotus Droebachiensis) Fishery, Robert C. Grabowski

Electronic Theses and Dissertations

Fisheries research on the green sea urchin in Maine has been limited despite its importance to the state's fishing industry. The objective of this thesis was to generate critical information for the management and monitoring of the Maine green sea urchin fishery. In particular there are three main areas of interest: (1) an investigation of biological reference points; (2) spatial analysis and biomass estimation, and (3) the development of a simulation framework approach to determine an optimal sampling strategy for the fishery-independent survey program. Biological reference points are markers conlrnonly used to monitor and manage fisheries. For the Maine sea …

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Lipid Solubilization By Marine Benthic Invertebrates, Ian M. Voparil May 2003

Lipid Solubilization By Marine Benthic Invertebrates, Ian M. Voparil

Electronic Theses and Dissertations

This work characterized the size of lipoidal colloids in benthic invertebrates' guts, using contact angle dilutions and imaging the fluorescence of the hydrophobic probe Nile Red. Deposit feeders and Nereis virens ingesting sediment were found to have micelles rather than emulsions in the gut. Gut fluids from Arenicola manna (a deposit-feeding polychaete) readily formed emulsions when incubated with mussel meat (Mytilus edulis; 80 g-mussel L"-gut fluid), suggesting that micelles form due to a paucity of emulsifying lipids in the gut. Lipid tracer contained in emulsion droplets was twice as likely to be captured by sediment than was tracer in micelles. …

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Tidal Modulation Of Nocturnal Vertical Migration From The Benthos: A High-Resolution Acoustic Analysis, Leslie E. Taylor May 2003

Tidal Modulation Of Nocturnal Vertical Migration From The Benthos: A High-Resolution Acoustic Analysis, Leslie E. Taylor

Electronic Theses and Dissertations

Emergence-trap sampling has shown that several species living primarily on or in the sediment emerge nightly into the water column. This behavior was investigated using acoustic and traditional sampling methods. A TRACOR acoustic profiler, TAPS, was mounted on the sea bottom, looking upwards in approximately 10 m of water in the Damariscotta River estuary, Walpole, Maine. TAPS emits high-frequency (265-3000 kHz) sonar pulses and each minute measures backscatter from 12.5-cm range bins in the water column. TAPS data showed a distinct increase in backscatter in the water column most evenings, beginning around or after dusk and terminating before dawn. The …

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Extensions To Opengl For Cagd., Chunyan Ye May 2003

Extensions To Opengl For Cagd., Chunyan Ye

Electronic Theses and Dissertations

Many computer graphic API’s, including OpenGL, emphasize modeling with rectangular patches, which are especially useful in Computer Aided Geomeric Design (CAGD). However, not all shapes are rectangular; some are triangular or more complex. This paper extends the OpenGL library to support the modeling of triangular patches, Coons patches, and Box-splines patches. Compared with the triangular patch created from degenerate rectangular Bezier patch with the existing functions provided by OpenGL, the triangular Bezier patches can be used in certain design situations and allow designers to achieve high-quality results that are less CPU intense and require less storage space. The addition of …

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Oxygen Delignification Kinetics And Selectivity Improvement, Steven M. Violette May 2003

Oxygen Delignification Kinetics And Selectivity Improvement, Steven M. Violette

Electronic Theses and Dissertations

Pulp strength loss during oxygen delignification is caused by cellulose chain cleavage resulting fiom attack by oxygen-based radicals generated through reactions with lignin. The objective of this research was to improve the lignin-to-cellulose selectivity during oxygen delignification by using radical-scavenging polymeric additives that adsorb on the cellulose surfaces where protection fiom radicals is needed. Among the polymers evaluated were starch, carboxymethyl-cellulose, galactomannan, xylan, and glucomannan. Oxygen delignification experiments were conducted on Northeast softwood Kraft pulps at different temperatures, sodium hydroxide charges, reaction times, and pretreatments. The effect of polymer additives on the selectivity and kinetics was studied. Polymer adsorption on …

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Stable Sulfur Isotope Rations From West Antarctica And The Tien Shan Mountains: Sulfur Cycle Characteristics From Two Environmentally Distinct Areas, Lee Pruett Jan 2003

Stable Sulfur Isotope Rations From West Antarctica And The Tien Shan Mountains: Sulfur Cycle Characteristics From Two Environmentally Distinct Areas, Lee Pruett

Electronic Theses and Dissertations

Continuous snow pit and ice core samples from two distinct environments (West Antarctica and the Tien Shan mountains in central Asia) were analyzed for 6 3 4 ~ and used to assess different regional sulfur cycle characteristics. In West Antarctica, 18 continuous samples were obtained from the RIDSA ice core (78.73"S, 116.33"W, 1740 m asl), covering the years 1935 to 1976. Each sample represents from 2 to 3 years of snow deposition, and the combination of summer and winter seasons varies by sample. 6 3 4 ~ values range from 3.1 %O to 9.9%0, and reflect the overall isotopic composition …

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Knowledge-Based Task Structure Planning For An Information Gathering Agent, John Phelps Jan 2003

Knowledge-Based Task Structure Planning For An Information Gathering Agent, John Phelps

Electronic Theses and Dissertations

An effective solution to model and apply planning domain knowledge for deliberation and action in probabilistic, agent-oriented control is presented. Specifically, the addition of a task structure planning component and supporting components to an agent-oriented architecture and agent implementation is described. For agent control in risky or uncertain environments, an approach and method of goal reduction to task plan sets and schedules of action is presented. Additionally, some issues related to component-wise, situation-dependent control of a task planning agent that schedules its tasks separately from planning them are motivated and discussed.

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The Distribution Of The Irreducibles In An Algebraic Number Field, Rebecca Rozario Jan 2003

The Distribution Of The Irreducibles In An Algebraic Number Field, Rebecca Rozario

Electronic Theses and Dissertations

The objective of this thesis is to study the distribution of the number of principal ideals generated by an irreducible element in an algebraic number field, namely in the non-unique factorization ring of integers of such a field. In particular we are investigating the size of M(x), defined as M ( x ) =∑ (α) α irred.|N (α)|≤≠ 1, where x is any positive real number and N (α) is the norm of α. We finally obtain asymptotic results for hl(x).

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An Interhemispheric Comparison Of The Recession Of Mountain Glaciers In The Last 150 Years, Colby Smith Jan 2003

An Interhemispheric Comparison Of The Recession Of Mountain Glaciers In The Last 150 Years, Colby Smith

Electronic Theses and Dissertations

Historical records in the Northern Hemisphere show overall glacier retreat since about AD 1860-1890. A glacial retreat of similar timing and magnitude in the Southern Hemisphere is less well established. Comparison of the timing and magnitude of glacial recession in the two polar hemispheres over the past century can elucidate mechanisms driving global climatic change. In order to determine the recession patterns of Murchison, Hooker, and Tasman Glaciers in the Southern Alps of New Zealand, geomorphic maps were constructed and recent glacial deposits were dated using lichenometry. Since the mid-to-late nineteenth century, each glacier terminus has retreated about 1.5 km. …

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Relative Invertebrate Availability In Nebraska's Conservation Reserve Management Access Program, Ronald J. Leathers Jan 2003

Relative Invertebrate Availability In Nebraska's Conservation Reserve Management Access Program, Ronald J. Leathers

Electronic Theses and Dissertations

The Conservation Reserve Management Access Program (CRP-MAP) is a joint effort of the Nebraska Game and Parks Commission and Pheasants Forever of Nebraska that seeks to address brood habitat needs of pheasants (Phasianus colchicus) and other grassland birds by light disking and interseeding legumes into portions of aging CRP fields. The program has two specific goals - increasing the total invertebrate availability as a food source for pheasant chicks and increasing the structural complexity of vegetation. This study compares invertebrate biomass and structural complexity of vegetation in treated (disked and interseeded with legumes) and idle portions of CRP-MAP fields to …

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Soil Solution Dynamics In Response To Elevated Nitrogen And Sulfur Treatments At The Bear Brook Watershed In Maine, Johanna Szillery Jan 2003

Soil Solution Dynamics In Response To Elevated Nitrogen And Sulfur Treatments At The Bear Brook Watershed In Maine, Johanna Szillery

Electronic Theses and Dissertations

Base cation depletion in forest soils of northeastern North America is a continuing concern because of the ongoing elevated deposition of sulfur (S) and nitrogen (N), intensive-management practices, and the often poorly understood implications of land-use history on modem ecosystem function. At the Bear Brook Watershed in Maine (BBWM), one of two paired, forested watersheds has been subjected to experimental additions of S and N for over a decade. Treatments consist of 28.8 kg S ha-' yr-' and 25.2 kg N ha-' yr-' in the form of granular (NH&SO4 applied bimonthly by helicopter. Ceramic cup tension lysimeters were used to …

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12,000-Year Record Of Lake-Level And Vegetative Change At Mathews Pond, Piscataquis County, Maine, Usa, Andrea Masterman Nurse Jan 2003

12,000-Year Record Of Lake-Level And Vegetative Change At Mathews Pond, Piscataquis County, Maine, Usa, Andrea Masterman Nurse

Electronic Theses and Dissertations

This study of late-glacial and Holocene changes in lake-level and vegetation at Mathews Pond contributes new information about Holocene environments in northeastern North America. The research establishes a 12,000-year record of paleohydrology for the watershed adjacent to Big Reed Forest Reserve, the largest stand of old-growth forest in the northeastern United States. Mathews Pond is a 7.4 ha, closed-basin, groundwaterseepage lake located in an upland, forested region of the Aroostook River drainage system. Glacial meltwater briefly filled the basin - 13.0 ka (1 ka = 1000 I4C yr BP)). The lake existed as a shallow pool in the deep area …

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An Information Theoretic Study Of The Ising Antiferromagnet With Quenched Dilution On A Triangular Lattice, Matthew D. Robinson Jan 2003

An Information Theoretic Study Of The Ising Antiferromagnet With Quenched Dilution On A Triangular Lattice, Matthew D. Robinson

Electronic Theses and Dissertations

This investigation applies information theoretic techniques to study the ordering and structure of the Ising antiferromagnet with quenched disorder on a triangular lattice. The pure system shows no phase transition due to the high degree of frustration present. However, when quenched vacancies are introduced randomly into this geometrically frustrated system, a phase transition at finite temperature, to an ordered phase, can arise. If the vacancies are introduced on all three sublattices of the triangular lattice, then a two-dimensional spin-glass transition occurs. If dilution takes place on only one sublattice, then the other two sublattices develop magnetiza- tions below the critical …

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Crevassing And Calving Of Glacial Ice, James Patrick Kenneally Jan 2003

Crevassing And Calving Of Glacial Ice, James Patrick Kenneally

Electronic Theses and Dissertations

Calving of ice is a relatively new area of research in the still young field of glaciology. In the short time that calving has been studied, it has been mainly treated as an afterthought, with the predominant mode of thinking being that it will happen so to concern oneself with why is not important. Many studies dealt with observations of calving front positions over time vs. ice velocity in an attempt to quantify the calving rate as the difference between the two, while others have attempted to deduce some empirical relationship between calving rate and variables such as water depth …

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Performance Advantages Of Maximum Likelihood Methods In Prbs-Modulated Time-Of-Flight Energy Loss Spectroscopy, Zhongyu Yang Jan 2003

Performance Advantages Of Maximum Likelihood Methods In Prbs-Modulated Time-Of-Flight Energy Loss Spectroscopy, Zhongyu Yang

Electronic Theses and Dissertations

This thesis describes the design, experimental performance, and theoretical simulation of a novel time-of-flight analyzer that was integrated into a high resolution electron energy loss spectrometer (TOF-HREELS). First we examined the use of an interleaved comb chopper for chopping a continuous electron beam. Both static and dynamic behaviors were simulated theoretically and measured experimentally, with very good agreement. The finite penetration of the field beyond the plane of the chopper leads to non-ideal chopper response, which is characterized in terms of an "energy corruption" effect and a lead or lag in the time at which the beam responds to the …

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Design, Implementation And Assessment Of An Earth Systems Science Course For Secondary Teachers, Jeffery C. Owen Jan 2003

Design, Implementation And Assessment Of An Earth Systems Science Course For Secondary Teachers, Jeffery C. Owen

Electronic Theses and Dissertations

In the fall of 2002 the Department of Earth Sciences at the University of Maine piloted an innovative course developed as a core offering for the new Master of Science in Teaching program. A team of four instructors comprised of two Earth Sciences faculty and two science educators developed the course and implemented it with nine students- six in-service teachers and three pre-service teachers. The course addressed multiple needs of secondary teachers through the integration of instruction in curriculum design, pedagogy, assessment, and classroom-level educational research, and earth systems science content. The components of instruction taught in the course included: …

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Extracting Movement Patterns Using Fuzzy And Neuro-Fuzzy Approaches, Haci Mustafa Palancioglu Jan 2003

Extracting Movement Patterns Using Fuzzy And Neuro-Fuzzy Approaches, Haci Mustafa Palancioglu

Electronic Theses and Dissertations

Several applications generate large volumes of data on movements including vehicle navigation, fleet management, wildlife tracking and in the near future cell phone tracking. Such applications require support to manage the growing volumes of movement data. Understanding how an object moves in space and time is fundamental to the development of an appropriate movement model of the object. Many objects are dynamic and their positions change with time. The ability to reason about the changing positions of moving objects over time thus becomes crucial. Explanations on movements of an object require descriptions of the patterns they exhibit over space and …

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A Mathematical Model For Simplifying Representations Of Objects In A Geographic Information System, Gabriel Perrow Jan 2003

A Mathematical Model For Simplifying Representations Of Objects In A Geographic Information System, Gabriel Perrow

Electronic Theses and Dissertations

The study of operations on representations of objects is well documented in the realm of spatial engineering. However, the mathematical structure and formal proof of these operational phenomena are not thoroughly explored. Other works have often focused on query-based models that seek to order classes and instances of objects in the form of semantic hierarchies or graphs. In some models, nodes of graphs represent objects and are connected by edges that represent different types of coarsening operators. This work, however, studies how the coarsening operator "simplification" can manipulate partitions of finite sets, independent from objects and their attributes. Partitions that …

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Solar And Wind Energy Development In Maine: 1973-1997, Evan Rallis Jan 2003

Solar And Wind Energy Development In Maine: 1973-1997, Evan Rallis

Electronic Theses and Dissertations

Focusing on how Maine reflected, as well as stood out from national trends in the development of wind and solar energy, this study concentrates particularly on how Maine state government and environmental groups contributed to this development, as well as on the technological progress of these energy sources. It draws primarily on state government documents, newspapers, and periodicals for evidence. The 1973-74 energy crisis, combined with the rise of the environmental movement, led to an increased exploration of alternative energy sources, in particular those that were relatively friendly to the environment like solar and wind energy. Attempts to utilize these …

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Renormalization-Group Studies Of Three Model Systems Far From Equilibrium, Ivan T. Georgiev Jan 2003

Renormalization-Group Studies Of Three Model Systems Far From Equilibrium, Ivan T. Georgiev

Electronic Theses and Dissertations

This thesis describes the development of analytical and computational techniques for systems far from equilibrium and their application to three model systems. Each of the model systems reaches a non-equilibrium steady state and exhibits one or more phase transitions. We first introduce a new position-space renormalization-group approach and illustrate its application using the one-dimensional fully asymmetric exclusion process. We have constructed a recursion relation for the relevant dynamic parameters for this model and have reproduced all of the important critical features of the model, including the exact positions of the critical point and the first and second order phase boundaries. …

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People In Nature: Environmental History Of The Kennebec River, Maine, Daniel J. Michor Jan 2003

People In Nature: Environmental History Of The Kennebec River, Maine, Daniel J. Michor

Electronic Theses and Dissertations

The quality of a river affects the tributaries, lakes, and estuary it feeds; it affects the wildlife and vegetation that depend on the river for energy, nutrients, and habitat, and also affects the human community in the form of use, access, pride, and sustainability. In an age of mass consumerism and materialism, dwindling natural resources and wild spaces, and advanced technology, the ability to make a living and at the same time enjoy the benefits of rural living is increasingly difficult. Using the entire Kennebec River watershed as the scale of investigation with particular focus on the river corridor itself, …

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