A biosystematic study was made in seven populations of Mimulus
nanus Hook. & Arn. and M. cusickii (Greene) Piper (Scrophulariaceae)
in central Oregon, and a taxonomic revision was made of the four
species of section Eunanus reported from Oregon--M. nanus, M.
cusickii, M. clivicola Greenm. and M. jepsonii Grant. Mimulus...
Selenoprotein W (SeW) is a protein whose function is unknown, but potentially plays a vital role in calcium metabolism, as an indirect link has been established with white muscle disease (WMD). White muscle disease occurs in selenium deficient animals, and is characterized by the precipitation of calcium in muscle, leading...
The study of preschool children's peer relations has
primarily employed sociometric interviews and observations
of children's social participation during free-play
situations as methods of assessment. These assessments of
peer relations have traditionally demonstrated lack of fit
between attitude (as measured by sociometry) and behavior
(observation of social participation). Often, sociometric...
There has been much interest generated recently
regarding the nature and cause of dating violence. The
purpose of this study was to determine what factors affected
individuals' attitudes toward dating violence. A sample of
403 college volunteers completed questionnaires which were
designed to assess their attitudes toward abuse as it...
Species declines and extinctions have been recorded across taxa as evidence of an ongoing global biodiversity crisis. Amphibians are at the forefront of these declines with nearly one third of amphibian species estimated to be at risk of extinction. While many factors contribute to population declines and extinctions, the role...
The ongoing worldwide loss of biodiversity has been described as a "biodiversity crisis," "the Anthropocene defaunation," and alternatively "an extinction spasm." More recently, many scientists have come to the conclusion that we are witnesses to Earth's sixth major mass extinction event, which has the potential to fundamentally alter basic ecological...
Mat-forming ectomycorrhizal (EcM) fungi represent a prevalent constituent of many temperate forest ecosystems and create dramatic changes in soil structure and chemistry. EcM mat soil have been shown to have increased microbial respiration rates and have been hypothesized to harbor unique assemblages of fungi and bacteria. The objectives of this...
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Joseph W. Spatafora
Mat-forming ectomycorrhizal (EcM) fungi represent a prevalent
Twenty sites of uniform topography and soil were select ed in the
montane forest found on the East flank of the Central Oregon Cascades.
These sites were located along a vegetational gradient composed of
five plant communities: Abies/Pachistima, Pinus/Ceanothus, Pinus
Arctostaphylos-Purshia, Pinus/Purshia/Festuca, and Juniperus
Festuca. An attempt was made to...
Population trends and patterns in species distributions are the major currencies used to examine responses by biodiversity to changing environments. Effective conservation recommendations require that models of both distribution dynamics and population trends accurately reflect reality. However, identification of the appropriate temporal and spatial scales of animal response, and then...
The orb web is a multipurpose structure---serving as a home for its inhabitant spider, as a prey capture device, and as a physical extension of the spider’s sensing abilities. Biologists are particularly interested in the spider’s ability to locate prey trapped in its web by sensing the vibrations induced from...
Numerous investigations demonstrate that mantle convective processes such as upwelling affect the surface topography of the overriding plate. The surface expression of mantle flow has been coined ‘transient topography’. Transient topography in the North American plate is thought to result from a mantle thermal anomaly beneath the Yellowstone volcanic center,...
Despite more than two centuries of exploration, including more than six million deep wellbores with depths exceeding 40,000 feet in some parts of the world, our ability to constrain subsurface processes and properties remains limited. Characteristics of the subsurface vary and can be analyzed on a variety of spatial scales....
Perspective-taking has been defined as the tendency
to take the point of view of another, to put oneself in
the psychological shoes of another. This ability has
been argued to be an important component of social
interaction. This research examined three components of
perspective-taking: a general measure of perspective
taking...
This study examined the relationships among authoritarian
parental attitudes, home environments, parental attitudes
toward the children's freedom, and the cognitive performances
of kindergarten children. Socioeconomic status of the family
and sex of child and parent differences were also examined.
Subjects consisted of 73 pairs of Korean parents and their
children....
The implementation and construction of Mechanically Stabilized Earth (MSE) walls has undergone substantial expansions in recent years, owing to its relatively low cost, ease of construction, and high efficiency compared to conventional retaining methods. As a result, MSE walls are being constructed to greater heights with complex features (e.g. multiple...
Oregon's land use planning system is often recognized as having been successful in its goals of limiting urban sprawl and protecting resource lands from development. However, it is difficult to quantify the impact of these regulations, because we cannot observe what would have happened in the absence of land use...
A growing body of literature exists on how human population growth and changes in climatic factors influence the availability of water (Elliot et al. 2014, Prudhomme et al. 2014). These studies typically conclude that climate change is expected to have negative consequences on water availability, an effect that is magnified...
This dissertation consists of three papers on land use economics and regulation. The
first paper reviews numerous past literatures on how land-use regulation, agricultural
subsidies, and use-value assessment method affect land values. The second paper uses a
theoretical model to analyze how imposing minimum-lot-size zoning and different
designs of minimum-lot-size...
The importance of role-taking skills in the social development of
children has been well documented. Further, it has been shown that
children's development of role-taking skills is dependent upon the
quantity and quality of social interactions which require the
consideration of alternative perspectives. Given recent evidence of
the importance of...
The earth is undergoing a “biodiversity crisis” characterized by loss of populations, species, genetic diversity, and ecosystem services. Part of this crisis consists of population declines, extinctions, and increased incidence of deformities in amphibians. It is unknown whether deformities contribute to these declines. Many cases of population declines in amphibians...
Infectious diseases are a growing concern for both humans and wildlife. The negative effects of infectious disease have been exemplified by the recent global amphibian population declines associated with disease outbreaks. Although multiple pathogens and factors play a role in these declines, the aquatic fungal pathogen, Batrachochytrium dendrobatidis (Bd), has...
Robotic limbs have been shown to enable mobility in unstructured, real-world terrain; they allow robots to step around cluttered environments, scramble up hills, carry heavy loads, and even perform acrobatics. However, mechanical limbs cannot operate as a means for such dynamic locomotion if they are simply treated as general articulated...
Montane meadows in the western Cascades of Oregon occupy approximately 5% of the landscape, but contribute greatly to the region's biodiversity. Western Cascades meadows are dynamic parts of the landscape and have contracted by over 50% in the past two hundred years in the HJ Andrews Experimental Forest (hereafter Andrews...
Transition metal oxides are an important class of materials for the wide variety optical, electrical, dielectric, magnetic, and thermal properties observed. Their unique structure-property relationships allow for property tuning and often provide insight into the fundamentals of chemistry. The work in this thesis was focused on the design, synthesis and...
Attachment, as described by Bowlby (1969), is an emotional bond between two people. It is an invisible internal characteristic which is assumed to exist because of behaviors exhibited by the attached individual. These proximity seeking behaviors are critical for survival of the infant. Sensitivity of the mother to the infant's...
Environmental concerns about urban air quality, global climate change, energy
security and economic considerations motivate a growing interest in alternative fuels for
the transportation sector. Ethanol, a fermentation-derived fuel, can be produced by
bioconversion of renewable materials, such as wood, grass, and waste. Combustion of
ethanol fuel, in both neat...
The main result of this paper is a proof of the existence of a solution
generated by a method for the variational assimilation of observational data
into the two-dimensional, incompressible Euler equations. The data are
assumed to be given by linear (measurement) functionals acting on the space
of functions representing...
The links between forests, streamflow, and climate are poorly understood. Despite hundreds of studies over the past 60 years, fundamental questions of forests' effects on the hydrologic cycle remain unanswered. The hydrological cycle involves mutually-dependent biological and physical processes that operate at multiple scales of time and space, and this...
A comprehensive tribal-level classification for the world's subfamilies of Hesperiidae, the skipper butterflies, is proposed for the first time. Phylogenetic relationships between tribes and subfamilies are inferred using DNA sequence data from three gene regions: 943 bp of cytochrome oxidase subunit I (COI) (in the mitochondrial genome), 739 bp of...
Life on Earth intimately depends on the function of countless proteins. For the majority of studied proteins, function absolutely depends on conformation (i.e. 3-dimensional shape in solution). The exact nature of how a protein goes from an unfolded linear polypeptide chain to an organized folded molecule is still not known,...
Plant-pollinator mutualisms are one of the most prevalent and economically important mutualisms in nature. Like many other ecological systems, plant-pollinator communities are threatened by anthropogenic activity, both directly (e.g., habitat conversion and fragmentation) and indirectly (e.g., climate change). While we are aware of many of the activities that adversely impact...
The word orogenesis is derived from the Greek words oros meaning mountains and genesis meaning creation and refers to the study of the complex processes involved in the growth and evolution of mountain ranges (orogens). Orogens develop where crustal deformation builds topography and forms landscapes. This dissertation explores the role...
This dissertation uses manipulative experiments to explore amphibian-Bd infection dynamics. Although there has been almost two decades research since the discovery of Bd, many questions still remain regarding what conditions mediate chytridiomycosis virulence. My research shows how certain host and pathogen factors can influence disease virulence. Identifying how host and...
A rotating, flat plate condensation experiment has been developed to
investigate the heat of the Rotating Bubble Membrane Radiator (RBMR). The
RBMR is a proposed heat rejection system for space applications which uses
working fluid condensation on the inside surface of a rotating sphere to
reject heat to space. The...
The time-averaged velocity field in the North Pacific was estimated in two
sets of inverse calculations. The planetary geostrophic equations were the basis for
dynamical models of the flow in each case. The inverse estimates of the circulation
were obtained by minimizing a positive-definite cost function, which measured the
inconsistency...
Active tectonics of a deformation front constrains the kinematic evolution and structural interaction between the fold-thrust belt and the most-recently accreted foreland basin. At the Himalayan deformation front, the thrust front is blind, characterized by a broad fold (the Suruin-Mastgarh anticline (SMA)), and displays no emergent faults cutting the southern...
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Andrew J. Meigs
ABSTRACT
Active tectonics of a deformation front constrains the
A model has been developed to predict the long-term
oxidation rate of Zircaloy-4 for ex-reactor (autoclave) and
in-reactor (PWR) environments and operating conditions. A
computer program has been written to solve the oxygen
diffusion equation by employing a fully implicit finite
difference method for a one dimensional cylindrical
geometry. The...
The major components of wheat flour are keys to its functionality in processing and product quality. The major components, other than the lipids, are polymers: starch, protein, and non-starchy polysaccharides (NSP). In wheat NSP are primarily arabinoxylans (AX). These components are compartmentalized in the grain but are forced into close...
Some parasites may modify the behavior of their
hosts. Altered behaviors may: 1) benefit the host in
that they defend against the pathogen, 2) benefit the
pathogen and represent manipulations of the host
response, and 3) benefit neither the host or the
pathogen and simply be a product of the...
Two separate studies on the distribution of gammarid amphipods in the bathyal and abyssal benthic environments demonstrated that different assemblages could be found at a single depth over distances on the order of 100 kilometers. These studies evaluated changes in the species composition and relative abundance of the amphipod assemblage...
Headwater streams and their riparian zones are a common, yet poorly understood,
component of Pacific Northwest landscapes. I sought to describe the ecological significance of
headwater stream riparian zones as habitat for forest-floor invertebrate communities, and to
assess how alternative management strategies for riparian zones may impact these communities.
I...
Tan spot of wheat is an economically significant disease caused by the fungal pathogen, Pyrenophora tritici-repentis. Certain races of the fungus secrete Ptr ToxA (ToxA), a 13.2 kDa proteinaceous host-selective toxin that is responsible and sufficient to cause disease in susceptible wheat varieties. Disease symptoms develop only when the ToxA...
Peroxiredoxins (Prxs) are dominant peroxide-reducing enzymes with two important roles: they protect all organisms from oxidative damage induced by peroxides, and in eukaryotes, they participate in hydrogen peroxide signaling pathways. This dissertation presents studies aimed at the biophysical characterization of select Prxs and a Prx reductase to elucidate their structure-function...
The shallow, wave-swept sea floor off the central Oregon coast
is used by 0-age flatfishes as a nursery ground. This dissertation
is based on a series of projects designed to: 1) identify the dominant
meiobenthic nematodes present in a coastal nursery area; 2)
describe the important temporal and spatial scales...
A multidisciplinary western Beaufort Sea Ecological Cruise
(WEBSEC) was conducted from August 15 to September 20, 1971.
During the cruise, one hundred ninety-nine 0.1 m² Smith-McIntyre
grabs samples were taken at forty stations located on the continental
shelf and slope of the western Beaufort Sea. The Gammaridean
Amphipoda and Cumacea...
Sulfur is one of the six elements required during the early stages of the evolution of life, and enzymes involved in sulfur transfer and oxidation are increasingly being recognized as potential drug targets for antimicrobials as well as for therapies for cancer, neurodegenerative and inflammatory diseases. Bacteria are able to...
The function of a protein is defined by its three-dimensional structure, and in understanding the three-dimensional structure of a protein, we gain an understanding of its function and mechanism. Protein structures, especially at high resolution, can provide detailed insights into many elements of enzyme function and catalysis – identifying residues...
Ultraviolet-B radiation (UVB) is an abiotic stressor in both terrestrial and aquatic systems. The stratospheric ozone layer, depleted due to anthropogenic activities and the cause of elevated UVB at earth's surface over the last four decades, is predicted to recover by 2065. However, UVB levels in aquatic systems may continue...
Peroxiredoxin (Prx) enzymes catalyze the reduction of hydrogen peroxide, peroxynitrous acid, and organic peroxides, and are extremely efficient peroxidases, with k[subscript cat]/K[subscript M] on the order of 10⁷ - 10⁸ M⁻¹ s⁻¹. Besides their role in oxidative stress defense, evidence has accumulated that some eukaryotes, including humans, use Prxs as...
Biogeochemical mechanisms employed by key organisms, or symbiotic associations of organisms, transform the function and structure of their environment through processes recognized as ecosystem engineering. This dissertation seeks to investigate organism-ecosystem interactions that serve globally significant ecological functions in marine systems and impact how systems respond to environmental change. Using...
A transient code (TFETC) for calculating the temperature
distribution throughout the radial and axial positions of a
thermionic fuel element (TFE) has been successfully developed.
It accommodates the variations of temperatures, thermal power,
electrical power, voltage, and current density throughout the
TFE as a function of time as well as...
Pollution by pesticides is a ubiquitous concern for wildlife. The effects of
pesticides are especially concerning in aquatic environments, which are particularly
vulnerable as they have several exposure routes for the influx of chemicals. These
effects are of particular concern as biodiversity loss reaches unprecedented rates. This
includes recent declines...
Wheat is a globally traded staple crop. Wheat is important in human diets because of its agronomic adaptability, physical characteristics, functionality for the production of leavened products and nutritional value. Two significant characteristics make wheat an important staple food-crop. First, the proteins present in wheat endosperm have attributes that enable...
This dissertation explores two economic phenomena involving forest-dependent areas: wage distribution and migration pattern of individuals. Are forest-dependent rural areas less desirable for workers from the standpoint of labor market returns? Are different skills (e.g. education, experience) rewarded differently in these areas? If there are interregional wage differences, would that...
The DNA mismatch repair (MMR) pathway maintains genomic stability and
reduces cancer risk (colorectal and other internal cancers) by correcting polymerase
errors and activating cell cycle checkpoints and apoptosis in response to DNA damage.
Few studies have examined the influence of commonly encountered environmental
mutagens/carcinogens on the etiology of MMR-deficient...
This dissertation's three essays explore the effects of climate change on land use
changes in the U.S., how future land areas in all major land uses change by projecting
land use at the regional scale under two IPCC climate change scenarios. Investigate how
and what role should carbon sequestration plays...
Contemporary environmental change encompasses massive biodiversity loss and
increasing numbers of emerging diseases worldwide. As part of a global biodiversity
crisis, amphibians are disappearing at unprecedented rates. Batrachochytrium
dendrobatidis is an emerging infectious pathogen prominently associated with many
declines. Chapter 1 reviews the past decade of research on this system...
The Run-Ahead Predictive Simulation Software (RAPSS) is an architecture designed for faster-than-real-time decision support for operators of complex networks. To enable further development of the RAPSS methodology, the necessary proof of principle is illustrated in two applications: decision support for shift technical advisors in nuclear power plant control rooms (RAPSS-STA),...
The purpose of the study was to: (1) test a client-outcome
evaluation methodology in a community mental health clinic, (2)
relate a measure of clients' recent life change to client outcomes,
(3) relate functions staff perform for clients to staff mental health
profession and to client outcomes, and (4) suggest...
The need for cheap reliable energy, while simultaneously avoiding uranium supply constraints makes uranium carbide (UC) fueled Gas Fast Reactors offer an attractive nuclear reactor design. In order to qualify the fuel, an enhanced understanding of the behavior of uranium carbide during operation is paramount. Due to a reduced re-solution...
Advancing the understanding of natural resource management is an important step in mitigating the effects of human activity on the environment, and ensuring efficient outcomes for many sectors of the economy. As humanity’s role in the natural world becomes better understood, the importance of interdisciplinary modeling has grown in leaps...
I examined two amphibian communities to assess factors
that may impact amphibian biodiversity. The results suggest
that the potential factors which influence the maintenance
of amphibian biodiversity are multi-faceted and thus,
attempts to understand these factors must reflect these
complexities.
I investigated factors that influenced the susceptibility
of western toad...
The causes of the global biodiversity crisis are varied and complex. Anthropogenic threats may act in isolation, or interact additively or synergistically with each other or with natural stressors to affect sensitive taxa. The recent emergence of many infectious diseases in wildlife has brought attention to the role of disease...
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Andrew R. Blaustein
The causes of the global biodiversity crisis are varied and complex
My thesis explored the effects of and potential mediating mechanisms for an important environmental stressor, ultraviolet-B (UVB) radiation. UVB radiation has negative effects on organisms in both terrestrial and aquatic systems. I used meta-analysis to quantify the effects of UVB radiation on a diversity of aquatic organisms (Chapter 2). UVB...
Critical Heat Flux (CHF) is an important safety parameter for the design of nuclear reactors. The most commonly used predictive tool for determination of CHF is a look-up table developed using tube data with an average hydraulic test diameter of 8 mm. There exist in the world today nuclear reactors...
In the past decade, declines in amphibian populations have captured scientific and popular interest. The causes of the declines are likely to be complex and involve interactions between several environmental stressors. Using multifactorial experiments, I investigated the combined effects of several anthropogenic stressors on developing amphibians in Oregon, USA. In...
Emerging infectious diseases impact both human and wildlife populations. Infectious agents, in particular the aquatic fungus Batrachochytrium dendrobatidis (chytrid), have an influential role in driving global amphibian population declines. The emergence of the chytrid fungus has aspects of both geographic spread as well as climate shifts altering environmental conditions and...
This thesis includes three studies involving different aspects of modeling protein structure. The first study illustrates the levels of insight available from atomic-resolution protein structures. The second study derives general trends of protein geometry from atomic-resolution structures and shows their implications for modeling. The third study creates a model of...
Biodiversity loss is of global concern, and is due in part to deforestation and high consumer demand for wood and wood products. The neotropical tree species Cedrela odorata (“Spanish cedar” or “cedro”) is economically valuable for its wood and faces threats of overexploitation. Due to strong similarities in wood features...
Predator-prey interactions have historically been studied to explain patterns of organization observed in populations and communities. They have also been important in understanding the evolution of antipredator responses in prey and counterstrategies in predators. Despite the breadth of knowledge that exists for heterospecific interactions, relatively few studies have investigated the...
Emerging infectious diseases are increasing globally and are a threat to human, wildlife, and ecosystem health. The emerging fungal pathogen, Batrachochytrium dendrobatidis (Bd), or amphibian chytrid fungus, is associated with worldwide amphibian population declines and extinctions. Bd has been found on every continent where amphibians exist and has been documented...
To assess the context dependence of kin discriminating
behavior, I examined kin-biased aggregation behavior in tadpoles
of R. cascadae in different ecological conditions. I manipulated food
distribution, predator presence, thermal heterogeneity, and
relatedness in a multifactorial mesocosm experiment. All four
factors interacted to influence tadpole dispersion. My results
suggest that...
The goal of this project was to pave the way for more data-driven decision making when considering safety within Nuclear Engineering by proving the concept of new and innovative accident scenario modeling techniques for the analysis of the economics of nuclear safety margins. To do this, a simple, if extremely...
Habitat fragmentation has been widely studied in the biological literature and
is considered a primary threat to biodiversity. However, there has been little research
on land-use policies to reduce fragmentation. This dissertation focuses on two major
research issues related to fragmentation policies. First, I develop an analytical model
to analyze...
The link between aboveground net primary productivity (ANPP) and resource gradients generated by complex terrain (solar radiation, nutrients, and moisture) has been established in the literature. Belowground ecosystem stocks and functions, such as soil organic carbon (SOC), dissolved organic carbon (DOC), and belowground productivity have also been related to the...
The objective of this research was to assess the variability of POP deposition by snow on a 10 km spatial scale by measuring the POP concentrations in fresh-fallen snow from remote alpine sites. Samples of pre-metamorphic snow were concurrently collected from three remote alpine sites, of matched altitude and exposure,...
The specific objectives of this dissertation are to determine subsurface flow
behaviors across different antecedent wetness conditions from a top-down perspective
and to mechanistically assess the hydrological controls on DOC and N transport at the
hillslope and catchment scale. The study area is a small catchment where hillslopes
issue directly...
Changes in the type and amount of plant inputs can occur gradually, as with succession, or rapidly, as with harvesting or wildfire. With global change it is anticipated that both gradual and immediate scenarios will occur at increasing frequency. Changes in vegetation inputs alter the quality and quantity of soil...
In January-February 1971 five replicate 0.07 m² Van Veen grabs
were obtained from each of 12 stations in Arthur Harbor and nine Van
Veen grabs were obtained from two stations in nearby Bismark Strait.
The 69 grab samples yielded 78,395 individuals which were separated
into 282 taxa, including 108 species...
A. W. N. Pugin was a driving force in the Gothic Revival movement in England during the first half of the nineteenth century. He was an architect and a writer who expounded on the virtues of reviving Gothic architecture, not only for its reflection of the sacred mystery of ancient...
Biodiversity losses in terrestrial, freshwater, and marine systems are accelerating at a global scale and the most threatened vertebrate taxa are those associated with freshwater habitats. The causes of biodiversity losses are often complex and include synergistic effects of natural and human-induced stressors, such as habitat loss and fragmentation, urbanization,...
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Andrew R. Blaustein Deanna H. Olson
Biodiversity losses in terrestrial, freshwater
This dissertation presents a different approach to understanding how amphibians are responding to disease through ontogeny. Although numerous efforts have been conducted to understand host responses to the fungus Batrachochytrium dendrobatidis (Bd), studies have been restricted to distinct developmental stages. This dissertation provides information on host response to Bd across...
High Temperature Gas Reactors (HTGRs) are positioned to disrupt local and global markets via their unique ability to produce carbon-free process heat, high efficiency power generation, and passively safe operational features. However, significant impediments still exist to delay deployment of this particular technology, including a lack of experimental data, verified...
Myoglobin (Mb) was extracted from Pacific sardine and added to Pacific whiting surimi to measure its effects on protein gelation. The purity of Mb extract was determined by SDS-PAGE. Mb extracted using ethanol showed higher purity than Mb extract using ammonium sulfate. The addition of 0.2% Mb significantly reduced breaking...
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Jae W. Park
Myoglobin (Mb) was extracted from Pacific sardine and added to Pacific
whiting
Increased sales of surimi seafood, with the majority as crabstick in the United States indicates that surimi based products are becoming more popular. With growing popularity, there is increased competition for market share. Under these circumstances, some companies may be willing to sacrifice product quality in order to facilitate manufacture...
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Jae W. Park
protein. The protein content and quality of raw surimi are varied by fish
A PC based on-line advanced plant simulator (OLAPS)
for high quality simulations of Portland General
Electric's Trojan Nuclear Facility is presented. OLAPS
is designed to simulate the thermal-hydraulics of the
primary system including core, steam generators, pumps,
piping and pressurizer. The simulations are based on a
five equation model that...
Recent geophysical and geological investigations of the Tibetan plateau have given rise to conflicting models of plateau growth and deformation, where the presence and extent of partial melt in the crust could be a determining factor. Here we investigate the attenuation structure of the crust and upper mantle, as attenuation...
Urban landscape water use is increasingly a focus of water conservation efforts. This is especially true in the arid and semi-arid regions of the western United States where increased demand, environmental concerns, and extended periods of drought have created chronic water shortages. However, until recently, little attention has been paid...
A growing body of work reveals that animal-mediated pollination is negatively affected by anthropogenic disturbance. Landscape-scale disturbance results in two often inter-related processes: (1) habitat loss, and (2) disruptions of habitat configuration (i.e. fragmentation). Understanding the relative effects of such processes is critical in designing effective management strategies to limit...
X-ray computed tomography is a noninvasive imaging modality capable of reconstructing exact density values of 3D objects. Computed tomography machines are deployed across the world to provide doctors with an image that reveals more detail than a standard x-ray image. We investigate algorithms based on exact computed tomography reconstruction formulas...
The expansion of native, woody plants is a global phenomenon with characteristics and effects that are often indistinguishable from exotic invasions. These expansions have largely been driven by altered fire regimes and favorable climatic conditions. In the Great Basin of western North America, expansion of conifers such as western juniper...
This dissertation presents results from three studies that address major scientific questions in glacial geology and paleoclimatology for the late Pleistocene and Holocene using relatively new geochemical and statistical techniques. Each of the studies attempts to answer a longstanding question in the respective field using geochemical or statistical methods that...
North America, with over 400 species of Astragalus (Fabaceae), is one of three major centers of diversity, all of which comprise the majority of the nearly 1750 species of Astragalus worldwide. One of the most diverse species, Astragalus lentiginosus of Section Diphysi, is a polymorphic complex of over 40 varieties,...