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Western Washington University

2013

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Articles 31 - 60 of 63

Full-Text Articles in Physical Sciences and Mathematics

Compact Bilinear Operators And Commutators, Árpád Bényi, Rodolfo H. (Rodolfo Humberto) Torres Jan 2013

Compact Bilinear Operators And Commutators, Árpád Bényi, Rodolfo H. (Rodolfo Humberto) Torres

Mathematics Faculty Publications

A notion of compactness in the bilinear setting is explored. Moreover, commutators of bilinear Caldeŕon-Zygmund operators and multiplication by functions in a certain subspace of the space of functions of bounded mean oscillations are shown to be compact.

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Iterative Scheme For Solving Optimal Transportation Problems Arising In Reflector Design, Tilmann Glimm, Nick Henscheid Jan 2013

Iterative Scheme For Solving Optimal Transportation Problems Arising In Reflector Design, Tilmann Glimm, Nick Henscheid

Mathematics Faculty Publications

We consider the geometric optics problem of finding a system of two reflectors that transform a spherical wavefront into a beam of parallel rays with prescribed intensity distribution. Using techniques from optimal transportation theory, it has been shown previously that this problem is equivalent to an infinite-dimensional linear programming (LP) problem. Here we investigate techniques for constructing the two reflectors numerically by considering the finite dimensional LP problems which arise as approximations to the infinite dimensional problem. A straightforward discretization has the disadvantage that the number of constraints increases rapidly with the mesh size, so only very coarse meshes are …

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Anisotropic Classes Of Inhomogeneous Pseudodifferential Symbols, Árpád Bényi, Marcin Bownik Jan 2013

Anisotropic Classes Of Inhomogeneous Pseudodifferential Symbols, Árpád Bényi, Marcin Bownik

Mathematics Faculty Publications

We introduce a class of pseudodifferential operators in the anisotropic setting induced by an expansive dilation A which generalizes the classical isotropic class Smγ,δ of inhomogeneous symbols. We extend a well-known L 2-boundedness result to the anisotropic class S0δ,δ(A), 0 ≤ δ < 1. As a consequence, we deduce that operators with symbols in the anisotropic class S01,0(A) are bounded on L p spaces, 1 < p < ∞.

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The Riesz Basis Property Of An Indefinite Sturm-Liouville Problem With Non-Separated Boundary Conditions, Branko Ćurgus, Andreas Fleige, Aleksey Kostenko Jan 2013

The Riesz Basis Property Of An Indefinite Sturm-Liouville Problem With Non-Separated Boundary Conditions, Branko Ćurgus, Andreas Fleige, Aleksey Kostenko

Mathematics Faculty Publications

We consider a regular indefinite Sturm–Liouville eigenvalue problem −f′′ + q f = λ r f on [a, b] subject to general self-adjoint boundary conditions and with a weight function r which changes its sign at finitely many, so-called turning points. We give sufficient and in some cases necessary and sufficient conditions for the Riesz basis property of this eigenvalue problem. In the case of separated boundary conditions we extend the class of weight functions r for which the Riesz basis property can be completely characterized in terms of the local behavior of r in …

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Solving Separable Nonlinear Equations Using Lu Factorization, Yun-Qiu Shen, Tjalling Ypma Jan 2013

Solving Separable Nonlinear Equations Using Lu Factorization, Yun-Qiu Shen, Tjalling Ypma

Mathematics Faculty Publications

Separable nonlinear equations have the form F(y,z) ≡ A (y)z + b(y) = 0, where the matrix A(y)∈ R m × N and the vector b(y) ∈ Rmare continuously differentiable functions of y ∈ Rn and z ∈ RN. We assume that m ≥ N + n, and F'(y,z) has full rank. We present a numerical method to compute the solution (y∗, z∗) for fully determined systems (m = N+ n) and compatible overdetermined systems (m …

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Secrecy Coverage, Amites Sarkar, Martin Haenggi Jan 2013

Secrecy Coverage, Amites Sarkar, Martin Haenggi

Mathematics Faculty Publications

Motivated by information-theoretic secrecy, geometric models for secrecy in wireless networks have begun to receive increased attention. The general question is how the presence of eavesdroppers affects the properties and performance of the network. Previously, the focus has been mostly on connectivity. Here we study the impact of eavesdroppers on the coverage of a network of base stations. The problem we address is the following. Let base stations and eavesdroppers be distributed as stationary Poisson point processes in a disk of area n. If the coverage of each base station is limited by the distance to the nearest eavesdropper, …

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The Planet, 2013, Winter, James Rogerts, Huxley College Of The Environment, Western Washington University Jan 2013

The Planet, 2013, Winter, James Rogerts, Huxley College Of The Environment, Western Washington University

The Planet

No abstract provided.

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Post-Caledonian Brittle Fault Zones On The Hyperextended Sw Barents Sea Margin: New Insights Into Onshore And Offshore Margin Architecture, Kjetil Indrevær, Steffen G. Bergh, Jean-Baptiste Koehl, John-Are Hansen, Elizabeth R. Schermer, Arild Ingebrigtsen Jan 2013

Post-Caledonian Brittle Fault Zones On The Hyperextended Sw Barents Sea Margin: New Insights Into Onshore And Offshore Margin Architecture, Kjetil Indrevær, Steffen G. Bergh, Jean-Baptiste Koehl, John-Are Hansen, Elizabeth R. Schermer, Arild Ingebrigtsen

Geology Faculty Publications

Onshore-offshore correlation of brittle faults and tectonic lineaments has been undertaken along the SW Barents Sea margin off northern Norway. The study has focused on onshore mapping of fault zones, the mapping of offshore fault complexes and associated basins from seismic interpretation, and the linkage of fault complexes onshore and offshore by integrating a high-resolution DEM, covering both onshore and offshore portions of the study area, and processed magnetic anomaly data. This study shows that both onshore and offshore brittle faults manifest themselves mainly as alternating NNE–SSW- and ENE–WSW-trending, steeply to moderately dipping, normal fault zones constituting at least two …

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Unlocking The Secrets Of Al-Tobermorite In Roman Seawater Concrete, Marie D. Jackson, Sejung R. Chae, Sean R. Mulcahy, Cagla Meral, Rae Taylor, Penghui Li, Abdul-Hamid Emwas, Juhyuk Moon, Seyoon Yoon, Gabriele Vola, Hans-Rudolf Wenk, Paulo J.M. Monteiro Jan 2013

Unlocking The Secrets Of Al-Tobermorite In Roman Seawater Concrete, Marie D. Jackson, Sejung R. Chae, Sean R. Mulcahy, Cagla Meral, Rae Taylor, Penghui Li, Abdul-Hamid Emwas, Juhyuk Moon, Seyoon Yoon, Gabriele Vola, Hans-Rudolf Wenk, Paulo J.M. Monteiro

Geology Faculty Publications

Ancient Roman syntheses of Al-tobermorite in a 2000-year-old concrete block submerged in the Bay of Pozzuoli (Baianus Sinus), near Naples, have unique aluminum-rich and silica-poor compositions relative to hydrothermal geological occurrences. In relict lime clasts, the crystals have calcium contents that are similar to ideal tobermorite, 33 to 35 wt%, but the low-silica contents, 39 to 40 wt%, reflect Al3+ substitution for Si4+ in Q2 (1Al), Q3 (1Al), and Q3 (2 Al) tetrahedral chain and branching sites. The Al-tobermorite has a double silicate chain structure with long chain lengths in the b [020] crystallographic direction, and …

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Structural And Functional Characterization Of Villin Domain 6 And Supervillin N-Terminal Fragments, Stanislav Fedetchkine Jan 2013

Structural And Functional Characterization Of Villin Domain 6 And Supervillin N-Terminal Fragments, Stanislav Fedetchkine

WWU Graduate School Collection

The protein villin is a member of the gelsolin superfamily, and regulates cytoskeleton formation in the brush border at the apical end of epithelial cells. The six villin domains (V1-V6) form which contain a Ca²+ -dependent actin-binding site associated with the V1-V3 fragment. The six villin domains are homologous to gelsolin and have ~50% sequence identity. In the absence of calcium, gelsolin adopts a compact, inactive conformation stabilized by a 12-residue C-terminal helix. This helix locks domains G2 and G6 as a "latch" in low calcium and releases at higher calcium levels. Tyrosine phosphorylation, phosphatidylinositol 4,5-bisphosphate (PIP2) and calcium concentration …

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Phytoplankton Ecology In Four High-Elevation Lakes Of The North Cascades, Wa, Siana Wong Jan 2013

Phytoplankton Ecology In Four High-Elevation Lakes Of The North Cascades, Wa, Siana Wong

WWU Graduate School Collection

The objective of my project was to describe phytoplankton ecology in high-elevation lakes of the North Cascades, WA. I conducted my field study using a small-scale ecosystem approach encompassing four lakes in the same watershed near Mt. Baker. I used exploratory data analyses to identify spatial and seasonal patterns in phytoplankton and water chemistry. Chlorophyll-a levels were less than 2.5 μg/L, and total nitrogen and phosphorus levels were below 198 and 15.9 μg/L, respectively, indicating the low-production and nutrient-poor nature of these lakes. Chlorophyll-a was weakly correlated with total nitrogen (Kendall's tau = 0.25, p < 0.05) but was not correlated with most other water chemistry variables (p > 0.05). In the phytoplankton dataset, …

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Relationship Between Lake Whatcom Algae Density, Water Quality And Filtration Rate At The Bellingham Water Treatment Plant, Wa, Bowei He Jan 2013

Relationship Between Lake Whatcom Algae Density, Water Quality And Filtration Rate At The Bellingham Water Treatment Plant, Wa, Bowei He

WWU Graduate School Collection

During the summer of 2009, the Bellingham drinking water treatment plant experienced severe reductions in filtration rates, resulting in mandatory water restrictions. Since then, summer water filtration rates continued to approach critical levels. In 2011, I conducted a study to investigate the phytoplankton and ambient water quality patterns in Lake Whatcom source water to see if any parameters could be used to predict low water filtration rates. In addition, I evaluated water quality and phytoplankton cell densities at different depths at the intake located in Lake Whatcom to see if drawing source water from different depths could help reduce water …

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Development Of Surface-Enhanced Raman Based Sensors, Elizabeth C. (Elizabeth Cecilia) Wellner Jan 2013

Development Of Surface-Enhanced Raman Based Sensors, Elizabeth C. (Elizabeth Cecilia) Wellner

WWU Graduate School Collection

While the medical field incorporates various imaging methods for diagnosis and treatment, there is a need for continual development of real-time in vivo imaging techniques in this field. A surface-enhanced Raman scattering (SERS) based fiber optic sensor is reported. An optical fiber was coated in gold nanoparticles, capable of Raman scattering. SERS active molecules were adsorbed onto the gold nanoparticle film, and SERS spectra obtained. Using 4-mercaptopyridine as a SERS reporter molecule, the chemical environment surrounding the probe was determined by the analysis of the pH sensitive SERS spectra. The methods of preparation and characterization of the SERS-based fiber sensors …

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Cougar Genetic Variation And Gene Flow In A Heterogeneous Landscape, Matthew J. (Matthew James) Warren Jan 2013

Cougar Genetic Variation And Gene Flow In A Heterogeneous Landscape, Matthew J. (Matthew James) Warren

WWU Graduate School Collection

Management of game species requires an understanding not just of population abundance, but also the structure of and connections between populations. Like other large-bodied carnivores, the cougar (Puma concolor) exhibits density -dependent dispersal and is capable of long-distance movement; in the absence of barriers to movement, these traits should lead to high connectivity between individuals and a lack of genetic differentiation across areas of continuous habitat. Previous research has suggested that cougar movement may be influenced by landscape variables such as forest cover, elevation, human population density, and highways. I assessed the population structure of cougars (Puma concolor) in Washington …

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Assessment Of Riparian Conditions In The Nooksack River Basin With The Combination Of Lidar, Multi-Spectral Imagery And Gis, Erica M. Capuana Jan 2013

Assessment Of Riparian Conditions In The Nooksack River Basin With The Combination Of Lidar, Multi-Spectral Imagery And Gis, Erica M. Capuana

WWU Graduate School Collection

Riparian areas are a complex component of stream ecosystems and provide critical habitat for Pacific salmon (Oncorhynchus spp.). Comprehensive techniques are needed for assessing riparian areas that can be used on small and large regional scales. I examined the application of airborne LiDAR and high resolution multi-spectral imagery from the World View-2 (WV-2) satellite to analyze riparian landcover and riparian forest structure in the Nooksack River Watershed. I employed an object-oriented approach to segment the imagery into meaningful objects consisting of groups of pixels. I examined the advantages of the four additional spectral bands from the 8-Band World View-2 Image …

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Effects Of Ocean Acidification On Dispersal Behavior In The Larval Stage Of The Dungeness Crab And The Pacific Green Shore Crab, Anna-Mai F. (Anna-Mai Florentine) Christmas Jan 2013

Effects Of Ocean Acidification On Dispersal Behavior In The Larval Stage Of The Dungeness Crab And The Pacific Green Shore Crab, Anna-Mai F. (Anna-Mai Florentine) Christmas

WWU Graduate School Collection

The influence of acidification of the world's oceans on marine populations and communities is a subject of growing concern. In the case of crustaceans, issues such as calcium dynamics of the molting process and direct effects on survival and development rates of larvae have received, at most, limited attention. My thesis research looked at phenomena that are important in the success of larval crustacean stages, but have received no attention; namely, the effects of ocean acidification on the swimming speeds, feeding rate, and gross growth efficiency of stage one larvae of the Dungeness crab, Metacarcinus (Cancer) magister, and the Pacific …

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Regional Risk Assessment Of The Puyallup River Watershed And The Evaluation Of Low Impact Development In Meeting Management Goals, Eleanor Hines Jan 2013

Regional Risk Assessment Of The Puyallup River Watershed And The Evaluation Of Low Impact Development In Meeting Management Goals, Eleanor Hines

WWU Graduate School Collection

The Relative Risk Model (RRM) is a tool used to calculate and assess the likelihood of effects to endpoints when multiple stressors occur in complex ecological systems. In this study a Bayesian network was used to calculate relative risk and uncertainty (BN-RRM) in the Puyallup River Watershed. First, I calculated the risk of prespawn mortality of coho salmon. Second, I evaluated the effect of low impact development (LID) as a means to reduce risk. Prespawner mortality in coho salmon within the Puyallup watershed was the endpoint selected for this study. A conceptual model showing causal pathways between stressors and endpoints …

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Synthesis And Reactivity Of Pyridinediimine Iron Complexes: For The Breakdown Of Carbon Dioxide, Zachary Thammavongsy Jan 2013

Synthesis And Reactivity Of Pyridinediimine Iron Complexes: For The Breakdown Of Carbon Dioxide, Zachary Thammavongsy

WWU Graduate School Collection

The increase of greenhouse gases in our atmosphere, particularly carbon dioxide (CO2), has been recognized by the scientific, industrial, and political communities. The increase in CO2 concentration has been connected to negative effects on our environment (global warming). Despite the negative associations of CO2, chemists can synthesize useful organic products and fuel from it. Ideally, the two electron reduction of CO2 to CO can provide one of the two products of synthesis gas (CO and H2), which is used in the Fischer-Tropsch process to produce diesel fuel. This thesis aims to convert CO2 to CO, using a cheap and abundant …

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Thermal And Hydrological Conditions Of The Goethe Rock Glacier, Central Sierra Nevada, California, Jezra Beaulieu Jan 2013

Thermal And Hydrological Conditions Of The Goethe Rock Glacier, Central Sierra Nevada, California, Jezra Beaulieu

WWU Graduate School Collection

The potential of rock glaciers in the Sierra Nevada to provide critical hydrological reservoirs and ecological habitats in a changing climate remains largely untested. In an effort to constrain the microclimatic contributions of buried ice, continuous temperatures were recorded in the near-surface debris of a variety of ice-cored and associated landforms in the Goethe cirque from August 2011 and July 2012 (Goethe rock glacier=GRG, valley-wall rock glaciers=VRG, Recess Peak debris=RPD, talus=TAL, ranging from most ice to least ice). In addition, continuous meteorological conditions on the rock glacier and stage of the main meltwater outwash stream were recorded to assess temporal …

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Structural And Functional Characterization Of A Permuted Hemoglobin, Michael P. (Michael Patrick) Murphy Jan 2013

Structural And Functional Characterization Of A Permuted Hemoglobin, Michael P. (Michael Patrick) Murphy

WWU Graduate School Collection

The tetrameric composition of human hemoglobin complicates protein engineering efforts that are required to improve its potential as an oxygen-carrying therapeutic. In our research to design a single-chain version of the hemoglobin molecule (scHb), we have co-expressed a circularly permuted human β-globin (cp-β) with human α-globin. At micromolar concentrations, the purified recombinant globins appear to associate to form an α-cpβ heterodimer in solution rather than the expected α2-cpβ2 heterotetramer. Compared to recombinant human hemoglobin, the α-cpβ heterodimer exhibits a stronger ligand binding affinity. Knowledge of the intermolecular interactions favoring formation of the α-cpβ heterodimer will be instrumental in understanding the …

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Determining Garnet Crystallization Kinetics From Growth Zoning And Mn-Calibrated Sm-Nd Ages, Rose Bloom Jan 2013

Determining Garnet Crystallization Kinetics From Growth Zoning And Mn-Calibrated Sm-Nd Ages, Rose Bloom

WWU Graduate School Collection

By working under the assumption that garnet strongly fractionates Mn, the change in measured XMn from the core to rim of a garnet can be used to represent the progression of time since nucleation. Core, mantle, and rim zones from nine snowball garnets collected at the Pinney Hollow Formation, Townshend Dam, VT were analyzed using electron probe microanalysis (EPMA) as well as Sm/Nd isotopic methods. Two-point garnet-matrix Sm/Nd ages are complex, with some showing apparent reverse age zoning and unrealistically young ages. Therefore, some garnet ages were culled, including those with poor 147Sm/144Nd ratios (< 0.75), low Nd concentrations (> 0.2 ppm), and rim ages …

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Silk Fibroin-Based Conducting Polymer Composite Electrodes And Their Use As Electromechanical Actuators, Isabella S. Romero Jan 2013

Silk Fibroin-Based Conducting Polymer Composite Electrodes And Their Use As Electromechanical Actuators, Isabella S. Romero

WWU Graduate School Collection

In order to produce conductive, biocompatible and mechanically robust materials for use in bioelectrical applications, we have developed a new strategy to selectively incorporate poly(pyrrole) (Ppy) into constructs made from silk fibroin. Here, we demonstrate that covalent attachment of negatively charged, hydrophilic sulfonic acid groups to the silk protein can selectively promote pyrrole absorption and polymerization within the modified films to form a conductive, interpenetrating network of Ppy and silk that is incapable of delamination. To further increase the conductivity and long-term stability of the Ppy network, a variety of small molecule sulfonic acid dopants were utilized and the properties …

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Mountain Goat Genetic Diversity And Population Connectivity In Washington And Southern British Columbia, Leslie C. (Leslie Claire) Parks Jan 2013

Mountain Goat Genetic Diversity And Population Connectivity In Washington And Southern British Columbia, Leslie C. (Leslie Claire) Parks

WWU Graduate School Collection

Anthropogenic alterations to natural landscapes and the associated habitat fragmentation, habitat degradation, and climatic shifts threaten biodiversity from the local to the global scale. These perturbations disrupt historical patterns of gene flow causing reduced population connectivity, loss of genetic diversity, and increased risk of extinction. A landscape that is permeable to animal movement counteracts local population fluctuations, increases genetic diversity, increases adaptive potential, and provides corridors for range shifts in response to climate change. Maintaining population connectivity is critical for the conservation of small populations isolated by fragmented landscapes. This strategy requires an accurate understanding of the landscape's effect on …

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Factors Affecting The Distribution And Abundance Of The Salish Sucker (Catostomus Sp.): An Endemic And Endangered Transboundary Fish Population, Nathaniel S. (Nathaniel Stuart) Lundgren Jan 2013

Factors Affecting The Distribution And Abundance Of The Salish Sucker (Catostomus Sp.): An Endemic And Endangered Transboundary Fish Population, Nathaniel S. (Nathaniel Stuart) Lundgren

WWU Graduate School Collection

The Salish sucker (Catostomus sp.) is a recently described endemic fish species with a patchy distribution and a narrow geographic range in western Washington and southwestern British Columbia. In this study I examined populations within the Nooksack River watershed, attempting to elucidate the environmental factors contributing to observed patterns of distribution and abundance. I hypothesized that hypoxic and hyperthermic conditions during the summer months would restrict Salish sucker distribution. I tested this hypothesis by measuring dissolved oxygen concentrations, temperature, and Salish sucker abundance and movement at eight sites in the Bertrand Creek and Fishtrap Creek sub-basins. The results of this …

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Synthesis Of Alignable Fluorophores For Use In Luminescent Solar Concentrators, Willie E. Benjamin Jan 2013

Synthesis Of Alignable Fluorophores For Use In Luminescent Solar Concentrators, Willie E. Benjamin

WWU Graduate School Collection

Luminescent Solar Concentrators (LSCs) collect and concentrate sunlight for use in solar power generation. First proposed over 30 years ago, LSCs are simple devices consisting of a planar waveguide coated or impregnated with a fluorophore. Sunlight absorbed by the fluorophore, reemitted into the waveguide, and concentrated at the edges of the collector. The most substantial problem with previous iterations of LSC technology is that they suffer from escape cone losses (photons lost through the top and bottom of the waveguide) that limited their size and efficiency. In this study, the reduction in escape cone losses was studied through alignment of …

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Summer Phytoplankton Diversity In Small Lakes Of Northwest Washington, Rachael D. (Rachael Dawn) Gravon Jan 2013

Summer Phytoplankton Diversity In Small Lakes Of Northwest Washington, Rachael D. (Rachael Dawn) Gravon

WWU Graduate School Collection

I sampled forty lakes in the Puget Sound region of northwest Washington to investigate the relationship between water quality, site characteristics, and algal composition. Water samples were collected during the summer of 2008 to measure nutrients, alkalinity, chlorophyll-a, dissolved oxygen, specific conductance, and temperature. Watershed characteristics were recorded to assess shoreline composition and dominant land use. Phytoplankton samples were collected, preserved, and concentrated in settling chambers to determine taxonomic composition and algal biovolume. Unpreserved phytoplankton samples were also collected and used to generate a species list for each lake. The data were examined using correlation analysis and hierarchical clustering to …

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M-Addition, Tim Mesikepp Jan 2013

M-Addition, Tim Mesikepp

WWU Graduate School Collection

This study builds upon the work of Gardner, Hug and Weil [1, Section 6] by further exploring the properties of M-addition. It is shown that several well-known theorems on Minkowski addition have M-addition parallels, including results involving intersections, the valuation property and the convex hull. The last of these enables us to detail su cient conditions for when the M-sum of convex polytopes is a convex polytope. Nested operations of M-addition are also examined and an M-addition generalization of the Shapley-Folkman Lemma and a related bound are offered.

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Characterization Of Coarse Sediment Transport On A Mixed Sand And Gravel Beach: Cherry Point Aquatic Reserve, Blaine, Washington, Meghan E. (Meghan Elizabeth) Weaver Jan 2013

Characterization Of Coarse Sediment Transport On A Mixed Sand And Gravel Beach: Cherry Point Aquatic Reserve, Blaine, Washington, Meghan E. (Meghan Elizabeth) Weaver

WWU Graduate School Collection

This study examines coarse-sediment transport behavior on a mixed sand and gravel (MSG) beach at Cherry Point Aquatic Reserve in Blaine, Washington. Radio Frequency Identifier (RFId) Passive Integrated Transponder (PIT) tags were used to trace large pebbles and cobbles (51 - 129 mm in diameter) between mid-January and early-March, 2012. Transport data were combined with wind, current and water level data recorded by nearby weather stations, as well as wave data collected by an offshore pressure sensor, into a comprehensive data set. Tide, wind and wave parameters were then input into XBeach, a relatively new nearshore numerical model [Roelvink et …

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Metamorphic Evolution Of The Northwest Chelan Block, North Cascades, Washington, Aaron A (Aaron Arthur) Fitts Jan 2013

Metamorphic Evolution Of The Northwest Chelan Block, North Cascades, Washington, Aaron A (Aaron Arthur) Fitts

WWU Graduate School Collection

The Cascades crystalline core (CC) is the fault bound southern extension of the Coast Plutonic Complex, a Cretaceous orogenic welt that forms the northernmost section of the North American Cordillera. Of primary interest in this study is the tectonic history of the Cascade River region in the northwest of CC. The Sibley Creek area of the Cascade River region is a zone of high-grade metamorphic rocks bound by Cretaceous plutons to the north, east, and west and the Tertiary Entiat fault to the south. Analysis of deformed and undeformed granitic plutons in the area could help constrain the absolute ages …

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Diastereoselective Intramolecular Carbonyl Hydrosilation For Complex Polyketide Synthesis, Casey R. Medina Jan 2013

Diastereoselective Intramolecular Carbonyl Hydrosilation For Complex Polyketide Synthesis, Casey R. Medina

WWU Graduate School Collection

It has been found that β-hydroxyketone compounds can be reduced to the corresponding 1,3-diol through an intramolecular carbonyl hydrosilation. Furthermore, because this hydrosilation proceeds through a cyclic 6-membered ring transition state, this reduction can be performed diastereoselectively by placing a stereocenter on the 6-membered ring transition state. Prior to further investigations into this diastereoselective intramolecular carbonyl hydrosilation, a streamlined synthesis of β-hydroxyketone compounds has been developed. This new synthesis features an enone diboration/oxidation sequence found to be successful on a broad scope of enones in high yields. Further studies have shown that placing a stereocenter outside of the transition state …

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