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Articles 2791 - 2820 of 3798

Full-Text Articles in Physical Sciences and Mathematics

Chemomechanical Polymers As Sensors And Actuators For Biological And Medicinal Applications, Hans-Jörg Schneider, Kazuaki Kato, Robert M. Strongin Aug 2007

Chemomechanical Polymers As Sensors And Actuators For Biological And Medicinal Applications, Hans-Jörg Schneider, Kazuaki Kato, Robert M. Strongin

Chemistry Faculty Publications and Presentations

Changes in the chemical environment can trigger large motions in chemomechanical polymers. The unique feature of such intelligent materials, mostly in the form of hydrogels, is therefore, that they serve as sensors and actuators at the same time, and do not require any measuring devices, transducers or power supplies. Until recently the most often used of these materials responded to changes in pH. Chemists are now increasingly using supramolecular recognition sites in materials, which are covalently bound to the polymer backbone. This allows one to use a nearly unlimited variety of guest (or effector) compounds in the environment for a …


Interview With Dianne Stefani-Ruff, Portland Farmers Market, 2007 (Audio), Dianne Stefani-Ruff Jul 2007

Interview With Dianne Stefani-Ruff, Portland Farmers Market, 2007 (Audio), Dianne Stefani-Ruff

All Sustainability History Project Oral Histories

Interview of Dianne Stefani-Ruff by Jennifer Bennett on July 31st, 2007.

The interview index is available for download.


Interview With Roger Allen Konka, Springwater Farm, 2007 (Audio), Roger Allen Konka Jul 2007

Interview With Roger Allen Konka, Springwater Farm, 2007 (Audio), Roger Allen Konka

All Sustainability History Project Oral Histories

Interview of Roger Allen Konka by Michael Schott on July 29th, 2007.

The interview index is available for download.


Interview With Lyle N. Stanley, Gee Creek Farm, 2007 (Audio), Lyle N. Stanley Jul 2007

Interview With Lyle N. Stanley, Gee Creek Farm, 2007 (Audio), Lyle N. Stanley

All Sustainability History Project Oral Histories

Interview of Lyle N. Stanley by Aaron Veal at Portland State University on July 28th, 2007.

The interview index is available for download.


Interview With Kathy & Matt Unger, Unger Farms, 2007 (Audio), Kathy Unger, Matt Unger Jul 2007

Interview With Kathy & Matt Unger, Unger Farms, 2007 (Audio), Kathy Unger, Matt Unger

All Sustainability History Project Oral Histories

Interview of Kathy and Matt Unger by Alix Lefler at Cornelius, Oregon on July 25th, 2007.

The interview index is available for download.


Biosedimentology Of Thermal Features In The Uzon Caldera, Kamchatka, Russia : Implications For Biosignature Formation, Jessica Christine Goin Jul 2007

Biosedimentology Of Thermal Features In The Uzon Caldera, Kamchatka, Russia : Implications For Biosignature Formation, Jessica Christine Goin

Dissertations and Theses

Modern hot springs serve as a habitat for microorganisms similar in metabolism, morphology, and cellular structure to the microbes that existed relatively early in Earth history. To maximize our ability to interpret evidence for these microorganisms and their communities in the rock record, we need to understand how their biosignatures form and become preserved.

This biosedimentological study of four thermal features in the Uzon Caldera (K4 Well, Ochki Pool, Thermophile Spring, and Zavarzin Pool) focused on identifying how chemical, physical and biological inputs contribute to the characteristics of sinter biofabrics. The biofabrics of K4 Well outflow channel were studied in …


Graduate Teaching Assistants' Statistical Knowledge For Teaching, Jennifer Ann Noll Jul 2007

Graduate Teaching Assistants' Statistical Knowledge For Teaching, Jennifer Ann Noll

Dissertations and Theses

This dissertation explores graduate teaching assistants’ (TAs’) statistical knowledge for teaching. Data collection methods that enabled the exploration of TA s’ statistical knowledge for teaching include: (a) a task-based web survey administered to 68 TAs from 18 universities across the United States; and, (b) a series of three taskbased interviews with a subset of five TAs from the larger survey population. Through and Strauss, 1967), I investigated the ways in which TAs reason about sampling tasks, and how they think about teaching and student learning in relation to sampling ideas. Building on past research in statistics education on K-12 and …


Hydrilla Verticillata - An Aquatic Invader!, Vanessa Howard Jul 2007

Hydrilla Verticillata - An Aquatic Invader!, Vanessa Howard

Center for Lakes and Reservoirs Publications and Presentations

Brochure on hydrilla


Green Crab Management: Reduction Of A Marine Invasive Population, Catherine E. De Rivera, Edwin D. Grosholz, Greg Ruiz, Amy A. Larson, Rebecca L. Kordas, Mark Sytsma Jul 2007

Green Crab Management: Reduction Of A Marine Invasive Population, Catherine E. De Rivera, Edwin D. Grosholz, Greg Ruiz, Amy A. Larson, Rebecca L. Kordas, Mark Sytsma

Environmental Science and Management Faculty Publications and Presentations

The overall goal of this study is to develop and demonstrate the capacity for local eradication of adult Carcinus maenas, European green crabs. This represents a conceptual shift in development of management options to address established invasions in marine systems, extending and exploring the application of terrestrial successes in this area. Specifically, this project tests the effects of removing green crabs from Bodega Harbor on the green crab population and on native shore crabs eaten by green crabs.


Pend Oreille River, Box Canyon Model: Model Scenario Simulations, Chris Berger, Robert Leslie Annear, Scott A. Wells Jul 2007

Pend Oreille River, Box Canyon Model: Model Scenario Simulations, Chris Berger, Robert Leslie Annear, Scott A. Wells

Civil and Environmental Engineering Faculty Publications and Presentations

The Washington Department of Ecology is interested in developing a temperature Total Maximum Daily Load (TMDL) allocation for the Pend Oreille River between the Albeni Falls Dam (U.S. Army Corps of Engineer’s reservoir) and Box Canyon Dam as shown in Figure 1. The Pend Oreille drainage basin is shown in Figure 2. An existing model of the Box Canyon reach was updated from CE-QUALW2 Version 3.0 to Version 3.5. This current research involves improving the calibration of the original model (1997 and 1998) and expanding the model using 2004 as an additional data set for calibration.

The use of field …


Potentiometric And Relaxometric Properties Of A Gadolinium-Based Mri Contrast Agent For Sensing Tissue Ph, Ferenc K. Kálmán, Mark Woods, Peter Caravan, Paul Jurek, Marga Spiller, Gyula Tircso, Róbert Király, Ernő Brücher, A. Dean Sherry Jun 2007

Potentiometric And Relaxometric Properties Of A Gadolinium-Based Mri Contrast Agent For Sensing Tissue Ph, Ferenc K. Kálmán, Mark Woods, Peter Caravan, Paul Jurek, Marga Spiller, Gyula Tircso, Róbert Király, Ernő Brücher, A. Dean Sherry

Chemistry Faculty Publications and Presentations

The pH-sensitive contrast agent, GdDOTA-4AmP (Gd1) has been successfully used to map tissue pH by MRI. Further studies now demonstrate that two distinct chemical forms of the complex can be prepared depending upon the pH at which Gd3+ is mixed with ligand 1. The desired pH-sensitive form of this complex, referred to here as a Type II complex, is obtained as the exclusive product only when the complexation reaction is performed above pH 8. At lower pH values, a second complex is formed that, by analogy with an intermediate formed during the preparation of GdDOTA, we tentatively assign …


Modeling Effects Of Channel Complexity And Hyporheic Flow On Stream Temperatures, Chris Berger, Scott A. Wells Jun 2007

Modeling Effects Of Channel Complexity And Hyporheic Flow On Stream Temperatures, Chris Berger, Scott A. Wells

Civil and Environmental Engineering Faculty Publications and Presentations

Stream temperatures are affected by multiple forcing functions, including surface heat exchange (including solar radiation, evaporation, conduction, and net long wave radiation) and hyporheic flows. Each of these forcing functions is directly influenced by the level of channel complexity in the stream channel and riparian shading. The interrelationship between channel complexity, hyporheic flow and stream temperature is highly complex, and efforts to manage for habitat diversity by managing channel complexity could result in unintended consequences on stream temperature. When planning modifications to stream channel complexity, consideration should be given to the effects such moderations could have on stream temperatures.

Urbanization …


Albumin-Binding Paracest Agents, M. Meser Ali, Mark Woods, Eul Hyun Suh, Zoltan Kovacs, Gyula Tircsó, Piyu Zhao, Vikram D. Kodibagkar, A. Dean Sherry May 2007

Albumin-Binding Paracest Agents, M. Meser Ali, Mark Woods, Eul Hyun Suh, Zoltan Kovacs, Gyula Tircsó, Piyu Zhao, Vikram D. Kodibagkar, A. Dean Sherry

Chemistry Faculty Publications and Presentations

Lanthanide complexes (Eu3+, Gd3+ and Yb3+) of two different 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid tetraamide derivatives containing two (2) and four (3) O-benzyl-L-serine amide substituents were synthesized and their chemical exchange saturation transfer (CEST) and relaxometric properties were examined in the presence and absence of human serum albumin (HSA). Both Eu2 and Eu3 display a significant CEST effect from a single slowly exchanging Eu3+-bound water molecule, making these PARACEST complexes potentially useful as vascular MRI agents. Yb2 also showed a detectable CEST effect from both the Yb3+-bound water protons and the …


A Qualitative Analysis Of Hybrid Control Systems, Anca Georgeta Williams May 2007

A Qualitative Analysis Of Hybrid Control Systems, Anca Georgeta Williams

Dissertations and Theses

Hybrid Control Systems are increasingly investigated as models for control systems where the interaction between continuous and discrete processes is tightly integrated. As yet, there is no general agreement as to what constitutes a canonical hybrid system. Rather various subclasses of systems combining continuous evolution and discrete event characteristics are analyzed for each application. In this dissertation we first unify the presentation of hybrid systems with a rich model which encompasses most examples of interest. We classify the available results and show how they fit together within the different subcategories. In the main part of the dissertation we prove that …


The Effects Of Coypu Myocaster Coypus (Nutria) Trapping On The Water Quality Of South Johnson Creek, Beaverton, Oregon, Deborah Jean Frankel May 2007

The Effects Of Coypu Myocaster Coypus (Nutria) Trapping On The Water Quality Of South Johnson Creek, Beaverton, Oregon, Deborah Jean Frankel

Dissertations and Theses

Nutria are semi-aquatic rodents, non-native to Oregon. They are an invasive species that damage stream banks with burrowing and cause destruction of native vegetation; activity that may cause deterioration of stream water quality. I hypothesized that my study's duration and pattern of nutria trapping along South Johnson Creek would be sufficient to lead to a significant change in turbidity, dissolved oxygen (DO), total dissolved solids (TDS), total solids (TS), and total suspended solids (TSS).


Microbial Biosignatures In High-Iron Thermal Springs, Mary Nichole Parenteau May 2007

Microbial Biosignatures In High-Iron Thermal Springs, Mary Nichole Parenteau

Dissertations and Theses

Debate exists regarding whether abiotic or biotic mechanisms were responsible for the oxidation of Fe2+ and the subsequent accumulation of ferric (Fe3+) iron assemblages in Precambrian Banded Iron Formations (BIFs). Direct paleontological evidence for a microbial role in the deposition of BIFs has been sought in the occurrence of microfossils and lipid biomarkers in these structures.

This study has characterized the formation of such biosignatures in modern iron deposits. The metabolic impact of microbes on Fe2+ oxidation in this system has previously been described (Pierson et al., 1999; Pierson and Parenteau, 2000). Cyanobacterial and filamentous anoxygenic …


Non-Thiol Reagents Regulate Ryanodine Receptor Function By Redox Interactions That Modify Reactive Thiols, Benjamin S. Marinov, Rotimi O. Olojo, Ruohong Xia, Jonathan J. Abramson May 2007

Non-Thiol Reagents Regulate Ryanodine Receptor Function By Redox Interactions That Modify Reactive Thiols, Benjamin S. Marinov, Rotimi O. Olojo, Ruohong Xia, Jonathan J. Abramson

Physics Faculty Publications and Presentations

The Ca(2+) release channel (CRC) from sarcoplasmic reticulum (SR) is rich in thiol groups, and their oxidation/- reduction by thiol reagents activates/inhibits the CRC. Most channel regulators are not thiol reagents, and the mechanism of their action is illusive. Here the authors show that many channel activators act as electron acceptors, while many channel inhibitors act as electron donors in free radical reactions. The channel activator, caffeine, and the CRC inhibitor, tetracaine, are shown to interact competitively, which suggests that there exists a common site(s) on the CRC, that integrates the donor/acceptor effects of ligands. Moreover, channel activators shift the …


Thin Film Solar Cells Using Zno Nanowires, Organic Semiconductors And Quantum Dots, Kaitlyn Vansant May 2007

Thin Film Solar Cells Using Zno Nanowires, Organic Semiconductors And Quantum Dots, Kaitlyn Vansant

Dissertations and Theses

A thin film organic/ inorganic hybrid solar cell was fabricated by incorporating ZnO nanowires, n- and p-type organic semiconductors and inorganic quantum dots. The basic cell design involved the electrodeposition of ZnO nanowires grown on a substrate coated with a transparent conductive oxide. The ZnO nanowires were coated with a thin layer of an organic n-type material, followed by a deposition of inorganic quantum dots. A p-type polymer layer was subsequently deposited and the sample was then contacted with gold to form a quantum dot layer sandwiched between a p-n junction of organic conductive materials.

Various materials and processing methods …


Selected Chemistry Of Biologically-Active Thiols : N-Acetylpenicillamine And 2-Mercaptobenzothiazole In Nitrosothiol Formation And Role In Allergic Contact Dermatitis Respectively, Itai Chipinda Apr 2007

Selected Chemistry Of Biologically-Active Thiols : N-Acetylpenicillamine And 2-Mercaptobenzothiazole In Nitrosothiol Formation And Role In Allergic Contact Dermatitis Respectively, Itai Chipinda

Dissertations and Theses

Two biologically-active thiols, N-acetylpenicillamine (NAP) and 2-mercaptobenzothiazole (MBT), were studied in this thesis. NAP is known to combine with nitric oxide (NO) to produce S-nitroso-N-acetylpenicillamine (SNAP) and MBT is a known allergen.

The formation, reaction dynamics, and detailed kinetics and mechanism of the reaction between nitrous acid (HNO2), prepared in situ, and NAP to produce SNAP were studied. The reaction is first order in nitrite, NAP and acid in pH conditions at or slightly higher than the pKa of HNO2. Both HPLC and quadrupole time-of-flight mass spectrometry techniques confirmed the formation of SNAP and the absence of any other products. …


Riparian Shade Assessment And Restoration Priorities Analysis In The Damascus Urban Growth Boundary Expansion Area, Robin K. Leferink Apr 2007

Riparian Shade Assessment And Restoration Priorities Analysis In The Damascus Urban Growth Boundary Expansion Area, Robin K. Leferink

Environmental Science and Management Professional Master's Project Reports

An important component of progressive urban planning is the protection and restoration of riparian environments, particularly in the Pacific Northwest where increasing stream temperatures threaten the survival of endangered salmonids and other cold-water biota. Restoration projects are often led by watershed councils or other grassroots organizations with limited resources, and it is essential that these groups have an efficient and effective approach to determine priority areas where their efforts can be directed to achieve the greatest ecological benefit. The purpose of this project was to quantify existing riparian shade levels and identify priority reaches for shade restoration on Clackamas River …


Systems Ideas And Sustainability, Martin Zwick Apr 2007

Systems Ideas And Sustainability, Martin Zwick

Systems Science Faculty Publications and Presentations

Slides from a presentation that provides an outline of ideas to understand how systems science and systems theory is related to, and can work for, sustainability. It illustrates how sustainability requires input from many disciplines, including graph theory, game theory, and thermodynamics, and is dependent on theories from ecology, sociology, and history.


Invasive Cordgrasses - Spartina Species - Estuarine Invaders!, Vanessa Howard Mar 2007

Invasive Cordgrasses - Spartina Species - Estuarine Invaders!, Vanessa Howard

Center for Lakes and Reservoirs Publications and Presentations

Brochure on invasive Spartina


Seasonal Changes In Allocation, Growth, And Photosynthetic Responses Of The Submersed Macrophyte Egeria Densa Planch. (Hydrocharitaceae) From Oregon And California, Toni Garrett Pennington Feb 2007

Seasonal Changes In Allocation, Growth, And Photosynthetic Responses Of The Submersed Macrophyte Egeria Densa Planch. (Hydrocharitaceae) From Oregon And California, Toni Garrett Pennington

Dissertations and Theses

Many rooted macrophytes form a dense canopy on the water surface that is detrimental to aquatic organisms, water quality, navigation, and recreation. Control of invasive macrophytes may be improved when management activities are linked to the plant's biology. The purpose of this research was to evaluate seasonal changes in the morphology, growth rates, allocation patterns and photosynthetic responses of a clonal submersed macrophyte. Egeria densa Planch. (Hydrocharitaceae) is highly invasive in the USA where it forms dense surface canopies in freshwater ecosystems. Using E. densa the following hypotheses were evaluated: (1) flowering stems have reduced capacity for vegetative growth as …


A Bridge To Coordination Isomer Selection In Lanthanide(Iii) Dota-Tetraamide Complexes, Jeff Vipond, Mark Woods, Piyu Zhao, Gyula Tircsó, Jimin Ren, Simon G. Bott, Doug Ogrin, Garry Kiefer, Zoltan Kovacs, A. Dean Sherry Feb 2007

A Bridge To Coordination Isomer Selection In Lanthanide(Iii) Dota-Tetraamide Complexes, Jeff Vipond, Mark Woods, Piyu Zhao, Gyula Tircsó, Jimin Ren, Simon G. Bott, Doug Ogrin, Garry Kiefer, Zoltan Kovacs, A. Dean Sherry

Chemistry Faculty Publications and Presentations

Interest in macrocyclic lanthanide complexes such as DOTA is driven largely through interest in their use as contrast agents for MRI. The lanthanide tetraamide derivatives of DOTA have shown considerable promise as PARACEST agents, taking advantage of the slow water exchange kinetics of this class of complex. We postulated that water exchange in these tetraamide complexes could be slowed even further by introducing a group to sterically encumber the space above the water coordination site, thereby hindering the departure and approach of water molecules to the complex. The ligand 8O2-bridged-DOTAM was synthesized in a 34% yield from cyclen. …


Biogeochemical Stoichiometry Of Antarctic Dry Valley Ecosystems, John E. Barrett, Ross A. Virginia, W. Berry Lyons, Diane M. Mcknight, John Charles Priscu, Peter T. Doran, Andrew G. Fountain, Diana H. Wall, D. L. Moorhead Feb 2007

Biogeochemical Stoichiometry Of Antarctic Dry Valley Ecosystems, John E. Barrett, Ross A. Virginia, W. Berry Lyons, Diane M. Mcknight, John Charles Priscu, Peter T. Doran, Andrew G. Fountain, Diana H. Wall, D. L. Moorhead

Geography Faculty Publications and Presentations

Among aquatic and terrestrial landscapes of the McMurdo Dry Valleys, Antarctica, ecosystem stoichiometry ranges from values near the Redfield ratios for C:N:P to nutrient concentrations in proportions far above or below ratios necessary to support balanced microbial growth. This polar desert provides an opportunity to evaluate stoichiometric approaches to understand nutrient cycling in an ecosystem where biological diversity and activity are low, and controls over the movement and mass balances of nutrients operate over 10–10⁶ years. The simple organisms (microbial and metazoan) comprising dry valley foodwebs adhere to strict biochemical requirements in the composition of their biomass, and when activated …


Lake Whatcom Model Calibration With Variable Stoichiometry In Sediments - Revised, Chris Berger, Scott A. Wells Feb 2007

Lake Whatcom Model Calibration With Variable Stoichiometry In Sediments - Revised, Chris Berger, Scott A. Wells

Civil and Environmental Engineering Faculty Publications and Presentations

This memorandum discusses model calibration and enhancements made to the Lake Whatcom water quality model. Model development and initial calibration were documented in the report “Lake Whatcom Water Quality Model” (Berger and Wells, 2005). The Lake Whatcom water quality model has been converted from CE-QUAL-W2 version 3.2 to version 3.5 (Cole and Wells, 2006).


Computation Of Dark Frames In Digital Imagers, Ralf Widenhorn, Armin Rest, Morley M. Blouke, Richard L. Berry, Erik Bodegom Feb 2007

Computation Of Dark Frames In Digital Imagers, Ralf Widenhorn, Armin Rest, Morley M. Blouke, Richard L. Berry, Erik Bodegom

Physics Faculty Publications and Presentations

Dark current is caused by electrons that are thermally exited into the conduction band. These electrons are collected by the well of the CCD and add a false signal to the chip. We will present an algorithm that automatically corrects for dark current. It uses a calibration protocol to characterize the image sensor for different temperatures. For a given exposure time, the dark current of every pixel is characteristic of a specific temperature. The dark current of every pixel can therefore be used as an indicator of the temperature. Hot pixels have the highest signal-to-noise ratio and are the best …


The Structure And Function Of Small Nucleolar Ribonucleoproteins, Steve Reichow, Tomoko Hamma, Adrian R. Ferré-D’Amaré, Gabriele Varani Feb 2007

The Structure And Function Of Small Nucleolar Ribonucleoproteins, Steve Reichow, Tomoko Hamma, Adrian R. Ferré-D’Amaré, Gabriele Varani

Chemistry Faculty Publications and Presentations

Eukaryotes and archaea use two sets of specialized ribonucleoproteins (RNPs) to carry out sequencespecific methylation and pseudouridylation of RNA, the two most abundant types of modifications of cellular RNAs. In eukaryotes, these protein–RNA complexes localize to the nucleolus and are called small nucleolar RNPs (snoRNPs), while in archaea they are known as small RNPs (sRNP). The C/D class of sno(s)RNPs carries out ribose- 20-O-methylation, while the H/ACA class is responsible for pseudouridylation of their RNA targets. Here, we review the recent advances in the structure, assembly and function of the conserved C/D and H/ACA sno(s)RNPs. Structures of each of the …


Middle Columbia River Aquatic Nuisance Species Survey, Robyn Draheim, Mark D. Sytsma, Rich Miller, Jeffery Cordell Jan 2007

Middle Columbia River Aquatic Nuisance Species Survey, Robyn Draheim, Mark D. Sytsma, Rich Miller, Jeffery Cordell

Center for Lakes and Reservoirs Publications and Presentations

Aquatic nonindigenous species (ANS) in the middle Columbia and lower Snake rivers were surveyed during the summer of 2006. The project area included eight reservoirs and the free-flowing, Hanford Reach on the Columbia River. We also conducted a literature review to create a complete list of ANS for the study area.


Oregon Spartina Response Plan, Mary Pfauth, Mark Sytsma, Dennis Isaacson Jan 2007

Oregon Spartina Response Plan, Mary Pfauth, Mark Sytsma, Dennis Isaacson

Center for Lakes and Reservoirs Publications and Presentations

Four introduced, invasive species of Spartina (cordgrass) have been present in estuarine areas of the U.S. west coast for over a century. These Spartina species are ecological engineers- they cause severe alternations in the hydrology and food webs of invaded estuaries that are detrimental to native wildlife and commercial and recreational uses. Oregon has been relatively free of these weeds, with only two known infestations. One infestation was eradicated by Oregon Department of Agriculture and the other is currently under eradication by The Nature Conservancy.