A variety of soil properties have been proposed and tested as potential
indicators of soil quality. This study was conducted in an effort to produce a
standardized soil quality index for systems in Oregon. Soils in both forested and
agricultural systems were sampled in a wide variety of locations, climates,...
Soil response and function were investigated following the adoption of an integrated reduced-tillage and cover-cropped vegetable system in the Willamette Valley of Western Oregon. The experiment was conducted over three cropping seasons (2002-2004) at the Oregon State University Vegetable Research Farm (Corvallis, OR). The design was a randomized complete-block with...
This paper defends a reading of Hennan Melville's Moby-Dick that elevates Ishmael's status from mere narrator of Ahab's tragedy to that of protagonist of his own story, a novel of epistemological seafaring. As a metaphysical quester, Ishmael provides the novel's only reliable and complex vision of the condition of man...
The purpose of this article is to explore student reasoning with regard to problems in logic, particularly those related to the Principle of Mathematical Induction (PMI). The five case studies presented build off of work done by other researchers, most notably Dubinsky and Harel, who both looked at how students'...
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Thomas P. Dick
The purpose of this article is to explore student reasoning with regard to
Increasing regulation and costs of soil fumigation to manage diseases such as
Verticillium wilt caused by soil-borne pathogens have prompted a search for
management alternatives. Single-year microplot experiments were conducted in 2002
and 2003 in central Oregon to evaluate the effects of Austrian winter pea, broccoli,
and Sudan grass green...
The Oregon Long-Term Soil Quality Project was initiated to identify soil
properties that respond rapidly to alternative management practices. Such practices
included winter cover cropping, which was implemented at two experimental research
stations and several grower fields throughout the Willamette Valley. The goal of this
thesis was to identify the...
Two native shrub species (Piliostigma reticulatum and Guiera senegalensis) are prominent vegetation components in farmers’ fields in Senegal. However, their role in nutrient cycling and ecosystem function has largely been overlooked. A study including both laboratory and field experiments was conducted to evaluate potential biophysical interactions of the two shrub...
Nitrogen availability in agricultural soils from fertilizer, plant residue inputs, and soil organic matter has important implications beyond crop yield. Legume winter cover crops and one fourth the recommended N rate on sweet corn resulted in yields equivalent to those at the recommended rate in the Willamette Valley of western...
Common root rot is a major disease of commercially grown snap bean (Phaseolus vulgaris L.) on the irrigated sandy soils of central Wisconsin. The objective of this study was to determine the relationships between soil properties and suppressiveness to common root rot of snap bean (causal agent Aphanomyces euteiches) in...
Piliostigma reticulatum and Guiera senegalensis are two native shrubs that
coexist with row crops in parkland systems of the Sahel of Africa. Although
permanently green all year around in soil depleted in nutrients and dry for a nine-month
period, these shrubs have been largely overlooked. Conventional management of these
shrubs...
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Richard P. Dick
Piliostigma reticulatum and Guiera senegalensis are two native shrubs that
A 2-year field study was conducted on the effects of two sulfur
fertilizers (calcium sulfate or elemental S, 0 or 50 kg S ha⁻¹ yr⁻¹)
on the distribution of sulfur fractions (inorganic sulfate, C-bonded,
ester sulfate, and residual S), arylsulfatase enzyme activity, and
microbial biomass carbon (C) and sulfur (S)...
Responses of biological indicators of soil quality to winter cover cropping were measured on soil samples collected from 6 commercial growers' fields and two experiment research stations in the Willamette Valley of Oregon. The research stations were the North Willamette Research and Extension Center (Aurora, OR), and the Oregon State...
Teachers may be attracted to the use of a game in a learning activity under the presumption that students will find the game experience to be more “fun” than typical classroom activities. The use of a game in a learning activity should help students attain important learning outcomes and engage...
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Thomas P. Dick
Teachers may be attracted to the use of a game in a learning activity
Forest harvest can have significant impacts on forest ecosystems that may influence the capacity of soils to sequester carbon (C). The microbial community controls decomposition, which is a critical process in partitioning litter- and root-C between CO₂ and storage in semi-permanent soil-C pools. The objectives of this study were to...
A method based on fatty acid (FA) analysis is used to profile microbial community structure (MCS). Various extraction protocols are available, which alter the types of FAs extracted from soils. The more time consuming but widely used protocol extracts only FAs from phospholipids (PLFA). This technique is desirable because PLFAs...
The purpose of this study was to address the implementation fidelity of one part of a professional development model developed by the Northwest Regional Educational Laboratory (NWREL). Specifically, this research investigates middle school teachers’ use of a formative feedback guide developed by NWREL staff, examining the reliability with which teachers...
As microelectronic parts trend smaller so do their solder joints. The surface finish on a copper pad is expected to become a significant part of the total solder joint volume and therefore affect mechanical properties of the smaller solder joints. Two sample geometries and four different surface finishes for tin-silver-copper...
The lentil strain of pea seedborne mosaic virus, PSbMV-L, was
distinguished from the standard isolates of PSbMV by a natural inoculum
reservoir in lentil seed and by separate resistance genes in Pisum
and Lens. PSbMV-L was intermediate in symptom severity between the
standard and New Zealand isolates of PSbMV.
Seed...
Contamination of recreational and shellfish waters with fecal pollution is a major water quality issue with associated economic impacts and human health risks. Reliable fecal source identification and rapid, quantitative analyses are essential components of risk assessment. Enteric bacteria that are endemic to specific hosts have a potential role as...
Two summertime days were investigated, 27 and 28 June 1973,
to observe the changes in the environment that led to the severe hailstorm
on 28 June in the National Hail Research Experiment (NHRE)
network, Colorado. Within the network thermodynamic analyses
revealed the 28th to have:
(1) Above-average low-level moisture.
(2)...
The response of sweet corn (Zea mays L. var. rugosa cultivar
Jubilee) to 12 populations and four nitrogen rates was studied in a
field experiment. Populations ranged from 43, 904 to 329,800
plants/ha with nitrogen levels ranging from 0 to 224 Kg/ha. A systematic
spacing design was used. Plant height,...
Zinc Sulfide (ZnS) thin film, with a wide band gap, has been used for many applications, such as buffer layer for CIGS solar cells, light emitting diodes and thin film electroluminescent devices.
In this work, ZnS thin films were prepared using two different deposition processes. In the first method, ZnS...
The rapid decline of marine ecosystems worldwide and the failure of traditional single species management pushed for the development of ecosystem-based conservation measures such as marine protected areas (MPA) to slow the loss of marine biodiversity. One approach to MPA creation advocates targeting marine megafauna (e.g., marine mammals, seabirds, sharks,...
This study investigated how the use of supercalculators
(HP 28S and HP 48SX) affects students' conceptual understanding of
differential and integral calculus. Students (n = 324) from 12
institutions throughout the United States studied an experimental
curriculum emphasizing multiple representations (symbolic,
numerical, graphical). (The curriculum was developed through the
Oregon...
The purpose of this study was to investigate teaching models that may aid in
improving student's understanding of how to interpret graphs of kinematic variables.
The teaching models that were considered incorporated the use of cooperative groups
and calculator-based laboratory instruments, alone and in concert. The subjects used in
this...
This study investigated associations among teachers' pedagogical content beliefs,
approaches to teaching, and their students' achievement in a high school Advanced
Placement (AP) Calculus setting. The three major research questions concerned: (a)
how well Al' calculus teachers' pedagogical beliefs about mathematics, curriculum, and
instruction aligned with a constuctivist point of...
A concept image is that collection of all images, pictures, symbols, definitions
and properties associated with any given mathematical concept. One of the
most important components in the mental representation of concepts in the concept
image of advanced mathematical thinkers is visualization. This component, in
turn, is indispensable in the...
This research seeks to answer the question, "What does it mean for a student to
understand the concept of derivative?" A structured way to describe an individual student's
understanding of derivative is developed and applied to analyzing the evolution of that
understanding for each of nine high school seniors during...
Legislation to reduce the annual limit of field burning in Oregon has led to increased study of
alternative non-thermal grass-seed management methods. Of these methods, non-thermal residue
management, in combination with crop rotations and different tillage practices, offer potential to
equal or exceed crop production of conventional thermal production systems....
A teacher's mathematical knowledge for teaching has been shown to have a positive correlation with their students' success (Monk, 1994). So, when half of the students that start out in a STEM major switch out to a non-STEM major before graduation to in large part to instructors pedagogical methods and...
Sampling with seine and trawl from May 1974 to November 1976 indicated that the species composition and distribution of fishes in Tillamook Bay through time is primarily related to the movements of marine species in and out of the estuary. Northern anchovy (Engraulis mordax), surf smelt (Hypomesus pretiosus), and shiner...
In this dissertation, we use Fourier-analytic methods to study questions of equidistribution on the compact abelian group Zp of p-adic integers. In particu- lar, we prove a LeVeque-type Fourier analytic upper bound on the discrepancy of sequences. We establish p-adic analogues of the classical Dirichlet and Fejér kernels on R/Z,...
Aquatic animals are exposed to a variety of natural and
anthropogenic xenobiotics. Biotransformation of xenobiotics was
examined in three aquatic animals: a primitive mollusc (chiton);
a shellfish which is an important human food source (oyster);
and, a lower vertebrate model for toxicological studies (rainbow
trout). Since digestive glands of Cryntochiton...
The ocean fishery is an example of a common property
resource industry. Behavior of commercial fishermen is
determined by a complex set of economic, environmental and
social factors. All of these factors contribute to the
individual fisherman's success.
Fishermen learn to cope with the variability inherent
to their occupation. Two...
If P is an integer polynomial denote the degree of P by ∂(P) and let H(P) be the maximum of the absolute value of the coefficients of P. Define Λ(P)=2[superscript ∂(P)]H(P) and for a fixed prime p let C[subscript p] denote the completion of the algebraic closure of the p-adic...
A sucrose density-gradient ultracentrifugation technique for
obtaining microsomes has been developed. This technique has
advantages over the classic differential centrifugation technique, in
that it is faster, is better suited to work with small quantities of
tissue, and offers the opportunity to work with a defined microsomal
sub-cellular fraction, rather than...
The induction of drug-metabolizing enzymes is a
complex biochemical process manifested not only by
increases in various cytochrome P-450 isozymes and
related activities, but also by alterations in
endoplasmic reticulum membranes. Little work has been
done to examine how cytochrome P-450 inducing agents
influence other cellular processes, such as
phospholipid...
An accurate assessment of leaching losses in the vadose zone requires measurement of both solute and water flux to compute flux concentrations (C[subscript F]). Leachate collected at a depth of 1.2 m in 32 passive capillary samplers (PCAPS), which sample soil-pore water continuously at tensions of 0–50 cm H₂O was...
The purpose of this study was to investigate solution strategies that Thai second graders used to solve addition and subtraction word problems. Fifty-eight children participated in this study, 40 children took a written test, and 18 children participated in an interview. In addition, two classrooms were selected for observation, and...
Counting problems are rich in opportunities for students to make meaningful mathematical connections and develop non-algorithmic thinking; their accessible nature and applications to computer science make counting problems a valuable part of mathematics curricula. However, students struggle in various ways with counting, and while previous studies have indicated that listing...
This thesis consists of four chapters. Literature is
reviewed in Chapter 1. Chapter 2 describes an addition
series experiment to determine the influence of species
density and proportion on vegetative and reproductive yield
of spring wheat and Lolium multiflorum. Chapter 3 consists
of a growth analysis experiment to determine whether...
The purpose of this study was to determine if differences exist among NCAA
divisions I, II and III as well as between Athletic Directors and Primary Women Administrators
with regard to the perceived competencies and preparatory coursework required
of athletic administrators.
A mail survey utilizing a six point forced choice...
Since harvest levels of many of the world's fisheries are not likely to increase in
the foreseeable future, resource managers and seafood processors need to develop
improved strategies to maximize the utilization and benefits of current catches. In
addition to increasing utilization and benefits, seafood processors are subject to the...
The Willamette Valley of Oregon has high rates of winter precipitation that cause leaching losses of residual fertilizer nitrogen (N) as nitrate (NO₃). Cover crops may have potential to mitigate N loss. Shallow groundwater was sampled for 11 years from plots planted in summer vegetables with and without winter cover...
Experiments were conducted to compare differences in P uptake
characteristics between two winter wheat cultivars Stephens and
Yamhill (Triticum aestivum L) as related to root morphologies.
Root length, root surface area and mean root radius were compared.
Plant roots and shoots were separately analyzed for P content.
The cultivars were...
Although legumes have been widely studied for their nitrogen-fixing ability, it is uncertain to what extent legume cover crops achieve their nitrogen-fixing potential under the climatic conditions encountered in western Oregon. Furthermore, it is unknown what factors control the proportions of legume cover crop N that are either sequestered into...
Generalization is a fundamental mathematical practice across all disciplines and content areas (Amit & Klass, 2005; Lannin, 2005; Pierce, 1902; Vygotsky, 1986; Ellis, Lockwood, Tillema & Moore, 2017). While a considerable amount of research has been conducted on students' generalizing activity in algebraic contexts (Amit & Klass 2005; Becker &...
The purpose of this study was to determine if
computer assisted instructional (CAI) tutorials in high
school biology differ in effectiveness in terms of
student academic achievement when compared with the more
traditional lecture/discussion type of instruction.
Additionally, student attitudes toward CAI were measured
using a student attitude questionnaire.
The...
There are many reasons toward why students withhold such negative mindsets toward the subject of mathematics. This thesis builds upon previously conducted research concerning affect and confidence in mathematical problem solving, confidence that students exhibit about themselves, and combinatorial thinking and activity.
This work compares the condensation heat transfer and pressure drop for zeotropic refrigerant R-454C and its individual components, R-32 and R-1234yf, in horizontal microfin tubes. One microfin tube has a 4 mm outer diameter, 0.18 mm wall thickness, and a surface area ratio of 1.56. The second tube has a...
Non-alcoholic Steatohepatitis (NASH) is an emerging form of liver disease associated with obesity, type II diabetes and dyslipidemia. As the prevalence of these metabolic conditions increases, so too has the occurrence of NASH in all sectors of the population. The pathology of this disease is similar to its alcoholic form,...