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The Meyer-Neldel Rule For Diodes In Forward Bias, Ralf Widenhorn, Michael Fitzgibbons, Erik Bodegom

Physics Faculty Publications and Presentations

We analyzed the temperature dependence of the forward current of a silicon diode. Instead of representing the data in the ordinarily used current versus voltage graph, the currents are plotted for different voltages as a function of the inverse temperature. The constant voltage curves can be fitted linearly and the extrapolations of the fits seem to merge to one common focal point. Hence, we demonstrate that a real diode follows the Meyer-Neldel rule (MNR). It is shown that the MNR is due to a shift of the current from ideal-diode to high-injection-diode behavior. We will argue that the merging of …

Vertical Nanowire Light-Emitting Diode, Rolf Könenkamp, Robert Campbell Word, C. Schlegel

Physics Faculty Publications and Presentations

We report room-temperature, white-color electroluminescence in vertically oriented ZnO nanowires. Excitonic luminescence around 380 nm is observed as a shoulder on a broader defect-related band covering all of the visible range and centered at 620 nm. The ZnO nanowires are grown in a low-temperature process on SnO₂-coated glass substrates, employing a technique that is suitable for large-area applications. The nanowires are robustly encapsulated in a thin polystyrene film deposited from high-molecular-weight solutions. Electron injection occurs through the transparent SnO₂ layer, while hole injection is mediated by a p-doped polymer and an evaporated Au contact. Stable device operation …

Toward The Design Of Mr Agents For Imaging Β-Cell Function, Mark Woods, Shanrong Zhang, A. Dean Sherry

Chemistry Faculty Publications and Presentations

The chemistry of Gd3+-based MRI agents has advanced considerably during the past decade toward agents with higher relaxivity and agents that respond to physiology and / or metabolism. This review describes various approaches that have been taken toward the development of responsive contrast agents and discusses the importance of fast water exchange for advancement of targeted Gd3+-based agents with higher sensitivity. The recent discovery of Eu3+ complexes having extraordinarily slow water exchange has opened a new avenue in contrast agent design based upon the chemical exchange saturation transfer (CEST) mechanism. These new paramagnetic complexes called PARACEST agents offer new possibilities …

Lower Columbia River Aquatic Nonindigenous Species Survey 2001-2004, Mark Sytsma, Jeffery Cordell, John Chapman, Robyn Draheim

Center for Lakes and Reservoirs Publications and Presentations

Rates of aquatic nonindigenous species (ANS) introductions and their social, economic, and ecological impacts are increasing. Introductions of nonnative marine organisms have increased exponentially over the last two centuries and expenditures on outreach, control, and research exceed millions of dollars per species for several invaders of particular concern to the United States. These trends suggest that major changes are occurring in the freshwater, estuarine, and marine ecosystems of North America, but their magnitude is probably underestimated.

Report On The Oregon Ballast Water Management Program In 2004, Kiirsten Flynn, Mark Sytsma

Center for Lakes and Reservoirs Publications and Presentations

This report was prepared for the Oregon legislature pursuant to HB 3620, which was passed during the 2003 session of the Oregon legislature to address management of ballast water discharged from ships. The bill removed sediment from the definition of ballast water, allowed discharge of treated ballast water, created a task force on ballast water management, and required this report. Includes List of Acronyms, charts, graphs and maps.

Vertical Nanowire Transistors With Low Leakage Current, Jie Chen, M. C. Lux-Steiner, Rolf Kӧnenkamp, S. Klaumünzer

Physics Faculty Publications and Presentations

A vertical field-effect transistor based on semiconductor nanowires is reported. The fabrication of the device uses a self-supporting flexible nanostructured polymer foil as a template and an electrochemical growth technique for the preparation of the semiconductor. The fabrication process is substantially simpler, and the mechanical robustness is strongly increased as compared to the original device. The channel region of the transistor has a diameter of ∼100 nm and a length of ∼50 nm. Operation in the hole depletion mode allows a change of the transfer conductance by ∼50% when the gate voltages is changed in the range ∓1 V. The …

Synthesis, Relaxometric And Photophysical Properties Of A New Ph-Responsive Mri Contrast Agent: The Effect Of Other Ligating Groups On Dissociation Of A P-Nitrophenolic Pendant Arm, Mark Woods, Garry Kiefer, Simon G. Bott, Aminta Castillo-Muzquiz, Carrie Eshelbrenner, Lydie Michaudet, Kenneth Mcmillan, Siva D.K. Mudigunda, Doug Ogrin, Gyula Tircso, Shanrong Zhang, Piyu Zhao, A. Dean Sherry

Chemistry Faculty Publications and Presentations

Two gadolinium(III) chelates, GdNP-DO3A (1-methlyene-(p-NitroPhenol)-1,4,7,10-tetraazacycloDOdecane-4,7,10-triAcetate) and GdNP-DO3AM (1-methlyene(p-NitroPhenol)-1,4,7,10-tetraazacycloDOdecane-4,7,10-triacetAMide), containing a single nitrophenolic pendant arm plus either three acetate or three amide pendant arms were synthesized and characterized. The properties of the gadolinium, terbium, and dysprosium complexes of these ligands were examined as a function of pH. The extent and mechanism of the changes in water relaxivity with pH of each gadolinium complex was found to differ substantially for the two complexes. The water relaxivity of Gd(NP-DO3A) increases from 4.1 …

Enhancements To Crisp Possibilistic Reconstructability Analysis, Anas Al-Rabadi, Martin Zwick

Systems Science Faculty Publications and Presentations

Modified Reconstructibility Analysis (MRA), a novel decomposition within the framework of set-theoretic (crisp possibilistic) Reconstructibility Analysis, is presented. It is shown that in some cases while 3-variable NPN-classified Boolean functions are not decomposable using Conventional Reconstructibility Analysis (CRA), they are decomposable using Modified Reconstructibility Analysis (MRA). Also, it is shown that whenever a decomposition of 3-variable NPN-classified Boolean functions exists in both MRA and CRA, MRA yields simpler or equal complexity decompositions. A comparison of the corresponding complexities for Ashenhurst-Curtis decompositions, and Modified Reconstructibility Analysis (MRA) is also presented. While both AC and MRA decompose some but …

Willamette River Basin Temperature Tmdl Model: Model Calibration, Chris Berger, Michael Lee Mckillip, Robert Leslie Annear, Sher Jamal Khan, Scott A. Wells

Civil and Environmental Engineering Faculty Publications and Presentations

The State of Oregon Department of Environmental Quality (DEQ) is developing a TMDL for temperature in the Willamette River basin shown in Figure 1. The study area included the Willamette River and all major tributaries (except the Tualatin River where a TMDL process was already concluded). A large section of the Columbia River was also modeled to provide adequate boundary representation of tidal flows in the lower Willamette River. The Willamette River below the Oregon City Falls in the Portland metropolitan area has a typical diurnal tidal range of 1 m. The development of a dynamic model of temperature and …

Teabag: A Debugger For Curry, Stephen Lee Johnson

Dissertations and Theses

This thesis describes TeaBag, which is a debugger for functional logic computations. TeaBag is an accessory of a virtual machine currently under development. A distinctive feature of this machine is its operational completeness of computations, which places novel demands on a debugger. This thesis describes the features of TeaBag, in particular the handling of non-determinism, the ability to control nondeterministic steps, to remove context information, to toggle eager evaluation, and to set breakpoints on both functions and terms. This thesis also describes TeaBag's architecture and its interaction with the associated virtual machine. Finally, some debugging sessions of defective programs are …

Green River Ce-Qual-W2 Project: A Hydrodynamic And Water Quality Study Of The Green River King County, Washington, Tim Kraft, Robert Leslie Annear, Chris Berger, Scott A. Wells

Civil and Environmental Engineering Faculty Publications and Presentations

This report describes the data processing and model calibration performed for a hydrodynamic and water quality model of the Green River, located in King County, Washington. Figure 1 shows the location of the river, and the limits of the section of river that was modeled.

The Green River flows from its headwaters in the Cascade Mountain foothills through the King County, Washington communities of Auburn, Kent, and Tukwila before discharging into the Duwamish River. Two sections of the river were modeled in this project. The Middle Green River begins in the Cascade Mountain foothills east of Tacoma, and continues downstream …

Effects Of Experimental Greenhouse Warming On Phytoplankton And Zooplankton Communities In Fishless Alpine Ponds, Angela L. Strecker, Tyler P. Cobb, Rolf D. Vinebrooke

Environmental Science and Management Faculty Publications and Presentations

The impacts of global warming on aquatic ecosystems are expected to be most pronounced at higher trophic levels in cold-water environments. Therefore, we hypothesized that wanning of fishless alpine ponds would suppress large-bodied consumers (e.g., cladocerans, copepods) and stimulate fast-growing microorganisms (e.g., phytoflagellates, rotifers), thereby altering the community composition and total abundance of zooplankton and phytoplankton. This hypothesis was tested using three blocks of four experimental mesocosms (1000-liter capacity) that were located next to alpine ponds in Banff National Park, Canada. Each block received unfiltered pond water and sediment from a pond following ice out in June 2000. A warming …

Approximate Thermodynamic State Relations In Partially Ionized Gas Mixtures, John D. Ramshaw

Physics Faculty Publications and Presentations

Thermodynamic state relations for mixtures of partially ionized nonideal gases are often approximated by artificially partitioning the mixture into compartments or subvolumes occupied by the pure partially ionized constituent gases, and requiring these subvolumes to be in temperature and pressure equilibrium. This intuitively reasonable procedure is easily shown to reproduce the correct thermal and caloric state equations for a mixture of neutral nonionized ideal gases. The purpose of this paper is to point out that (a) this procedure leads to incorrect state equations for a mixture of partially ionized ideal gases, whereas (b) the alternative procedure of requiring that the …

Impactos Da Exploração Madeireira E Do Fogo Em Florestas De Transição Da Amazônia Legal, André Luiz Silva Monteiro, Carlos Moreira De Souza Jr., Paulo Gonçalves Barreto, Frank Leone De Sousa Pantoja, Jeffrey J. Gerwing

Environmental Science and Management Faculty Publications and Presentations

A exploração de madeira e os incendios têm causado severos danos a florestas na Amazonia. Faltavam estudos sobre os impactos da exploração e do fogo em florestas de transição entre a floresta ombrófila densa e florestas de cerrado. Neste estudo, foram quantificados os impactos de várias intensidades de exploração madeireira e fogo na estrutura e composição de florestas de transição -- em termos de densidade de árvores e de cipós, cobertura do dossel e perturbação do solo e da biomassa acima do solo -- na regiao de Claudia, Mato Grosso. O estudo foi conduzido em 12 propriedades, através de inventários …

Sediment Nutrient Accumulation And Nutrient Availability In Two Tidal Freshwater Marshes Along The Mattaponi River, Virginia, Usa, Jennifer L. Morse, J. Patrick Megonigal, Mark R. Walbridge

Environmental Science and Management Faculty Publications and Presentations

Sediment deposition is the main mechanism of nutrient delivery to tidal freshwater marshes (TFMs). We quantified sediment nutrient accumulation in TFMs upstream and downstream of a proposed water withdrawal project on the Mattaponi River, Virginia. Our goal was to assess nutrient availability by comparing relative rates of carbon (C), nitrogen (N), and phosphorus (P) accumulated in sediments with the C, N, and P stoichiometries of surface soils and above ground plant tissues. Surface soil nutrient contents (0.60–0.92% N and 0.09–0.13% P) were low but within reported ranges for TFMs in the eastern US. In both marshes, soil nutrient pools and …

Toward A Sound Integration Of Isabelle With A Combined Decision Procedure, Tom Harke

Computer Science Faculty Publications and Presentations

I present work on a project to integrate Isabelle, an extremely versatile interactive proof assistant, with a combined decision procedure, the Cooperating Validity Checker (CVC). Isabelle is sound and flexible, however it is often tedious to use. CVC is fully automatic, but only handles decision problems expressible over a relatively weak set of theories including linear arithmetic, uninterpreted functions, data types, and firstorder quantifier-free logic. My goal is to increase the amount of automation in Isabelle, by making it use CVC as an oracle for such problems, but without compromising Isabelle’s soundness.

In this paper I report on the progress …

An Integrated Aquatic Vegetation Management Plan For Blue Lake, Fairview, Oregon, Mary Pfauth, Mark Sytsma

Center for Lakes and Reservoirs Publications and Presentations

Blue Lake, located in Fairview, is on the 1998 Oregon Department of Environmental Quality (ODEQ) 303(d) list of water quality impaired water bodies for violating the upper pH standard (8.5) and supporting abundant aquatic weeds and alge. The lake is eutrophic and has high algal productivity, especially in mid to late summer. Curlyleaf pondweed, a non-native, invasive aquatic plant species, restricts access to and use of Blue Lake by humans. Human uses of the lake which have been impaired including boating, water skiing, fishing, and swimming. Development of the current Integrated Aquatic Vegetation Management Plan was driven by the need …

Waldo Lake Research In 2003, Mark D. Sytsma, John Rueter, Richard Petersen, Roy Koch, Scott A. Wells, Rich Miller, Laura Johnson, Robert Leslie Annear

Civil and Environmental Engineering Faculty Publications and Presentations

This report summarizes the first year of an effort to develop a more complete understanding of the physical, chemical, and biological characteristics that drive the ecological processes of Waldo Lake. Modern limnology recognizes the importance of watershed processes as well as in- lake processes in lake ecosystem functioning. Therefore, the approach included consideration of watershed hydrology and forcing functions that determine hydrodynamics of the system as well physical and chemical factors that may be important in regulating primary production in the lake. Data collected since 1998 was summarized and bathymetry of the basin was mapped using state-of-the-art digital depth sounding …

Willamette River Basin Temperature Tmdl Model: Model Scenarios, Robert Leslie Annear, Michael Lee Mckillip, Sher Jamal Khan, Chris Berger, Scott A. Wells

Civil and Environmental Engineering Faculty Publications and Presentations

The State of Oregon Department of Environmental Quality (DEQ) is developing a TMDL for temperature in the Willamette River basin shown in Figure 1. The study area included the Willamette River and all major tributaries (except the Tualatin River where a TMDL process was already concluded). A large section of the Columbia River was also modeled to provide adequate boundary representation of tidal flows in the lower Willamette River. The Willamette River below the Oregon City Falls in the Portland metropolitan area has a typical diurnal tidal range of 1 m. The development of a dynamic model of temperature and …

The Biodiversity And Biogeochemistry Of Cryoconite Holes From Mcmurdo Dry Valley Glaciers, Antarctica, Dorota L. Porazinska, Andrew G. Fountain, Thomas H. Nylen, Martyn Tranter, Ross A. Virginia, Diana H. Wall

Geography Faculty Publications and Presentations

Once thought of as inert, ice has been increasingly recognized as a habitat suitable for life. The landscape of the MCMurdo Dry Valleys (MCM) of Antarctica is dominated by glaciers, and glacier melt is the primary water source for life in soils, streams, and lakes. The glaciers, despite their cold and lifeless appearance, offer functioning habitats for life. The major objective of this study was to examine biogeochemical characteristics of miniecosystems present in cryoconite holes and to determine links to other components (soils, streams, and lakes) of the dry valley landscape. We examined cryoconite holes from 5 glaciers spanning the …

Projecting Range Expansion Of Invasive European Green Crabs (Carcinus Maenas) To Alaska: Temperature And Salinity Tolerance Of Larvae, Anson Hines, Greg Ruiz, Natasha Gray Hitchcock, Catherine E. De Rivera

Environmental Science and Management Faculty Publications and Presentations

The European Green Crab (Carcinus maenas) is a global invader, successfully colonizing many world regions and having significant ecological and economic impacts. The Green Crab colonized western North America in the late 1980s, spreading primarily northward from the initial establishment in San Francisco Bay to several other bays in northern California, Oregon, and Washington. Initial analysis, based largely upon temperature tolerance of postlarval crabs, suggests Green Crabs will continue to spread and become established throughout much of Alaska. However, establishment of self-sustaining populations in Alaska may be restricted by environmental conditions for reproduction and larval development, instead of the broad …

Climatology Of Katabatic Winds In The Mcmurdo Dry Valleys, Southern Victoria Land, Antarctica, Thomas H. Nylen, Andrew G. Fountain, Peter T. Doran

Geography Faculty Publications and Presentations

Katabatic winds dramatically affect the climate of the McMurdo dry valleys, Antarctica. Winter wind events can increase local air temperatures by 30°C. The frequency of katabatic winds largely controls winter (June to August) temperatures, increasing 1°C per 1% increase in katabatic frequency, and it overwhelms the effect of topographic elevation (lapse rate). Summer katabatic winds are important, but their influence on summer temperature is less. The spatial distribution of katabatic winds varies significantly. Winter events increase by 14% for every 10 km up valley toward the ice sheet, and summer events increase by 3%. The spatial distribution of katabatic frequency …

Coastal Lakes Aquatic Plant Survey Report, Mary Pfauth, Mark Sytsma

Center for Lakes and Reservoirs Publications and Presentations

Invasive, non-indigenous plants can degrade water quality and fish habitat when they invade lakes, ponds, and streams. Changes in plant community architecture in lakes due to invasion by canopy-forming invasive aquatic plants can result in loss of native plant biodiversity and reduction of the structural complexity of the underwater habitat. Differences in photosynthetic biochemistry between non-indigenous and native plants can result in large diurnal pH and dissolved oxygen concentrations.

Environmental Gradients, Community Boundaries, And Disturbance The Darlingtonia Fens Of Southwestern Oregon, Deborah A. Tolman

Dissertations and Theses

The Darlingtonia fens, found on serpentine soils in southern Oregon, are distinct communities that frequently undergo dramatic changes in size and shape in response to a wide array of environmental factors. Since few systems demonstrate a balance among high water tables, shallow soils, the presence of heavy metals, and limited nutrients, conservative efforts have been made to preserve them. This dissertation investigates the role of fire on nutrient cycling and succession in three separate fens, each a different time since fire. I specifically analyze the spatial distributions of soil properties, the physical and ecological characteristics of ecotones between Jeffrey pine …

Infrastructure For Performance Tuning Mpi Applications, Kathryn Marie Mohror

Dissertations and Theses

Clusters of workstations are becoming increasingly popular as a low-budget alternative for supercomputing power. In these systems,message-passing is often used to allow the separate nodes to act as a single computing machine. Programmers of such systems face a daunting challenge in understanding the performance bottlenecks of their applications. This is largely due to the vast amount of performance data that is collected, and the time and expertise necessary to use traditional parallel performance tools to analyze that data.

The goal of this project is to increase the level of performance tool support for message-passing application programmers on clusters of workstations. …

A Software Architecture For Reconstructability Analysis, Kenneth Willett, Martin Zwick

Systems Science Faculty Publications and Presentations

Software packages for reconstructability analysis (RA), as well as for related log linear modeling, generally provide a fixed set of functions. Such packages are suitable for end‐users applying RA in various domains, but do not provide a platform for research into the RA methods themselves. A new software system, Occam3, is being developed which is intended to address three goals which often conflict with one another to provide: a general and flexible infrastructure for experimentation with RA methods and algorithms; an easily‐configured system allowing methods to be combined in novel ways, without requiring deep software expertise; and a system which …

A Comparison Of Modified Reconstructability Analysis And Ashenhurst‐Curtis Decomposition Of Boolean Functions, Anas Al-Rabadi, Marek Perkowski, Martin Zwick

Systems Science Faculty Publications and Presentations

Modified reconstructability analysis (MRA), a novel decomposition technique within the framework of set‐theoretic (crisp possibilistic) reconstructability analysis, is applied to three‐variable NPN‐classified Boolean functions. MRA is superior to conventional reconstructability analysis, i.e. it decomposes more NPN functions. MRA is compared to Ashenhurst‐Curtis (AC) decomposition using two different complexity measures: log‐functionality, a measure suitable for machine learning, and the count of the total number of two‐input gates, a measure suitable for circuit design. MRA is superior to AC using the first of these measures, and is comparable to, but different from AC, using the second.

Modified Reconstructability Analysis For Many-Valued Functions And Relations, Anas Al-Rabadi, Martin Zwick

Systems Science Faculty Publications and Presentations

A novel many-valued decomposition within the framework of lossless Reconstructability Analysis is presented. In previous work, Modified Recontructability Analysis (MRA) was applied to Boolean functions, where it was shown that most Boolean functions not decomposable using conventional Reconstructability Analysis (CRA) are decomposable using MRA. Also, it was previously shown that whenever decomposition exists in both MRA and CRA, MRA yields simpler or equal complexity decompositions. In this paper, MRA is extended to many-valued logic functions, and logic structures that correspond to such decomposition are developed. It is shown that many-valued MRA can decompose many-valued functions when CRA fails to do …

Directed Extended Dependency Analysis For Data Mining, Thaddeus T. Shannon, Martin Zwick

Systems Science Faculty Publications and Presentations

Extended dependency analysis (EDA) is a heuristic search technique for finding significant relationships between nominal variables in large data sets. The directed version of EDA searches for maximally predictive sets of independent variables with respect to a target dependent variable. The original implementation of EDA was an extension of reconstructability analysis. Our new implementation adds a variety of statistical significance tests at each decision point that allow the user to tailor the algorithm to a particular objective. It also utilizes data structures appropriate for the sparse data sets customary in contemporary data mining problems. Two examples that illustrate different approaches …

Reconstructability Analysis Detection Of Optimal Gene Order In Genetic Algorithms, Martin Zwick, Stephen Shervais

Systems Science Faculty Publications and Presentations

The building block hypothesis implies that genetic algorithm efficiency will be improved if sets of genes that improve fitness through epistatic interaction are near to one another on the chromosome. We demonstrate this effect with a simple problem, and show that information-theoretic reconstructability analysis can be used to decide on optimal gene ordering.