We investigate the optimal harvesting strategies for McKendrick type population models. Models of this type endow the population with a continuous age structure. They consist of a partial differential equation with a boundary condition which involves an integral of the solution. We study two problems, the first concerns the yield...
We are at risk of losing the sagebrush steppe in the floristic Great Basin to the invasion of Bromus tectorum L., cheatgrass. The floristic Great Basin includes the Central Basin and Range, the Northern Basin and Range, and the Snake River Plain. The Great Basin receives most of its precipitation...
The research involved development of two ecological
simulation models to explain the complex dimensionality of
chinook salmon (Oncorhynchus tshawytscha) life history
structure (represented by the age composition of the
spawning stock) and management difficulties entailed in the
complexity.
Since different sizes of chinook salmon are thought to
adapt differently to...
Development of a performance analysis for propeller type wind
turbines is presented. The analysis uses a strip theory approach
that includes tip-loss and blade interference. A comparison is
presented between analysis and test data. The comparison indicates
that the analysis predicts wind turbine performance to an accuracy
that is within...
The hypotheses of this study stated the following:
Interaction with the computer game will significantly
increase the class means in: (1) mathematical
achievement, (2) attitudes toward mathematics, and (3)
graphing ability in high school advanced algebra.
ALGEBRA ARCADE is a computerized simulation game
played on a coordinate grid. One can...
The purpose of this study was to compare the Chapter I supplemental mathematics program CAI with other Chapter I supplemental mathematics programs, Prescription Learning and the traditional "pull-out" program, in terms of achievement and retention of mathematics basic skills. There were 577 Chapter I students from 12 middle schools and...
Accurate taxonomy is essential to preservation and management of native
grasses. Four problems in fescue taxonomy were investigated: the identity of the
native fescue that dominates western Oregon and Washington prairies, the relationship
of native Festuca roemeri to closely related grasses, the status of F. howellii and F.
washingtonica, and...
A variety of stakeholders require information about marine systems. In the open ocean, pilots of marine vessels require knowledge about environmental conditions for safe passage and route planning. On the coastline, communities rely on information about nearshore dynamics to increase safety from coastal hazards such as nearshore pollutants, coastal erosion,...
This investigation was designed to investigate the use of an answer-until-correct procedure on multiple-choice quizzes in an independent study mathematics course. This procedure was compared to the standard multiple-choice procedure with respect to student achievement, student anxiety, and test reliability. Using the answer-until-correct procedure students were made immediately aware of...
This study focuses on the development of a methodology
to evaluate safeguardability of various processes in the
nuclear fuel cycle.
National and international implementation of safeguards
systems has been investigated. It was concluded that
proliferation is purely a political question that,
hopefully, can be prevented by international norms and
diplomacy;...
Most vertebrates exhibit seasonality in many life history traits. Such seasonal rhythms are temporally organized via the transduction of environmental cues (e.g., photoperiod, temperature) into appropriate endocrine signals. However, among ectothermic vertebrates that undergo continuous winter dormancy, temperature is the only environmental cue available for synchronizing seasonal rhythms. Most intriguing...
This investigation was designed to study articulation between
Oregon secondary mathematics programs and college mathematics at
Oregon State University. Three main facets of the problem were
studied:
1. The relationship of several factors to the CEEB Level I
Mathematics Achievement Test score.
2. The feasibility of a discriminant function as...
The fungus Nothophaeocryptopus gaeumannii is the causative agent of Swiss needle cast (SNC), a foliar disease of Douglas-fir. Disease is characterized by premature loss of foliage and reduced growth resulting from the inhibition of photosynthesis due to the occlusion of stomata by the ascocarps of N. gaeumannii. Although the disease...
In order to address the energy needs of developing countries and remote communities, Oregon State University has proposed the Multi-Application Small Light Water Reactor (MASLWR) design. In order to achieve five years of operation without refueling, use of 8% enriched fuel is necessary.
This dissertation is focused on core design...
Many studies suggest that weedy plant species are most successful when
soil nitrogen in abundant. Consequently, I used soil nitrogen manipulations to
determine if altering nitrogen would affect the establishment of both weedy and
native plant species in a western Oregon wetland prairie. In two studies, we
added carbon amendments...
Two mathematical computer games, POE and EQUATIONS, were used to
test the effects of games as learning aids in a university entry-level
intermediate algebra course. Specifically, this study investigated
whether use of these games would significantly increase student achievement
in the course and improve student attitude toward mathematics.
EQUATIONS is...
The analysis of rigid hub, three-bladed horizontal-axis,
axisymmetric wind turbines in yaw is made using a linearized,
four-degree-of-freedom model. The linearized equations of motion of
rotor and nacelle are developed using quasi-steady blade element
theory and Lagrange's equations.
The yaw behavior of the system is studied from coefficients of
the...
Development of variable speed horizontal axis wind turbines has resulted in a need for an analysis code with a rotor speed degree-of-freedom. This study develops a five degree-of-freedom time domain computer code that evaluates blade and rotor, mean and cyclic loads with nonlinear aerodynamics together with atmospheric turbulence as a...
This investigation was designed to determine the effectiveness
of video-tape feedback as a technique to modify some selected behaviors
of untrained prospective elementary teachers. Four verbal
and four nonverbal behaviors were considered; they were: teacher
questioning, teacher telling, teacher distractive verbal, teacher
allowing for pupil verbal, teacher constructive nonverbal, teacher...
The purpose of this study has been to investigate the effects of
an activity approach to teaching geometry in certain high schools of
Afghanistan. A brief review of the historical background of mathematics
education especially in Afghanistan has been presented in this
study. Students in the activity approach were involved...
Most existing analyses of the blade loads on horizontal
axis wind turbines are conducted using linear steady-state
aerodynamics, but evaluation of loads resulting from wind
turbulence or gusts may not be adequate using these
techniques. This study develops single-parameter
approximations for both the shed wake and trailing wake
components of...
Rotary dryers are the most commonly used wood drying system in the particleboard industry. These dryers also play an increasingly important role in drying wood residues for fuel. Many potential benefits may be realized through an improved understanding of the rotary drying process. A rotary dryer simulation model was developed,...
An experimental study was made of the average and turbulent
wind characteristics of the flow over a model of a coastal headland.
The scale of the model was 300:1, corresponding to a prototype size
of 500 m.
The data for validation of the model study was obtained from
instruments mounted...
The purpose of this study was to determine the amount of
heterosis in three complex traits in barley and to investigate the
concept of component interaction as a means of producing heterosis.
The complex traits were grain yield, total leaf area, and malting
quality.
Seven varieties of spring barley were...
The objective of this work was to develop a method for determining stochastic loads on horizontal axis wind turbine blades. Stochastic loads caused by wind turbulence are a major consideration in designing for long life, cost effective wind turbines. The rotor blades are of particular concern because the blades are...
Currently there is a lack of documentation on the
types of teaching methods being used to teach elementary
mathematics in Saudi Arabia, To help meet this need, this
research project studied the verbal behavior of Saudi
Arabian elementary mathematics teachers. A two-fold
problem was addressed.
1. To obtain a description...
This investigation was designed to determine whether a remediation
program concurrent to enrollment in the Calculus could be used
to reveal and remedy student deficiencies involving pre-calculus topics,
promoting a greater degree of success in the Calculus. The instructional
model for the program that was investigated consisted of pretesting
the...
The theory of characteristics is discussed and its scope has
been broadened by its application to the most general form of an unsteady,
two-dimensional, compres sible, rotational, axial- symmetric
fluid flow. Numerical procedure for solving such a problem is outlined.
Several boundary conditions which are common in fluid flow
problems...
This investigation was designed to determine the general achievement,
ability to solve applied problems, and attitude toward the role of
mathematics in science of college calculus students grouped in an
experimental class according to academic major during their first
three terms. The subgroups were biology-business, mathematics,
and science-engineering majors. The...
The size of elk herds in Eastern Oregon has become a controversial
issue. Trade-offs exist between the numbers of elk and domestic
livestock on a given area of land, and also between elk and commercial
timber harvesting policies. Disputes arise from differing views as
to proper use of the natural...
Wood and wood-based composites are being used in either
new or more demanding applications. A means is needed to
successfully analyze new materials and to predict their long-term
performance. Two techniques, dynamic mechanical
analysis (DMA) and time-temperature superposition (TTS) offer
a means to accomplish this objective. The outcome of this...
The purpose of this study was to analyze the effect of the use
of vocationally - oriented applications on the achievement and attitude
of community college beginning algebra students. The applications
were chosen to be representative of problems encountered in
a variety of occupations. They were in contrast to the...
Studies were conducted on artificially infected susceptible and
resistant barley varieties in an attempt to determine the effect of
barley yellow dwarf virus on the growth and development of these
plants. A resistant and a susceptible variety were infected at four
stages of growth and harvested at two stages. Roots,...
Knowledge of post-dispersal seed fates and other regeneration characteristics is
crucial for predicting abundances and distributions of populations and, ultimately,
community species composition and diversity. Seed fate studies, however, are rare
primarily due to the difficulty of determining seed fates and causes of mortality.
This thesis investigated post-dispersal seed fates...
The purpose of this research was to study the effect of teachers' written comments on students' homework papers. Fourth, Sixth and ninth grade mathematics classes in Saudi Arabia were selected for the study. The hypotheses for the study stated the following: Teachers' comments significantly increase students' achievement in mathematics. The...
The effect of heterozygosity on the phenotypic stabilities of six
morphological plant characteristics was studied in hybrid crosses of
two self-pollinated barley species Hordeum vulgare L., emend Lam.
and Hordeum distichum L., emend Lam. Experimental material
consisting of parents and their F₁ diallel progeny were grown at two
field locations...
For my research goals I addressed the theoretical importance of
competition in habitat selection of 2 quails and examined the use of
resources in peripheral and core areas. Methodological objectives
were to determine cover and food selection of Texas bobwhite (Colinus
virginianus texanus) and chestnut-bellied scaled quail (Callipepla
squamata castanogastris)...
The binding of eleven polycyclic, aromatic hydrocarbons to the acid
form of poly A has been investigated. The hydrocarbons were chosen to
test a size criterion. Model building showed that some hydrocarbons
could intercalate in the helix and be well protected from contact with
the aqueous solvent. Experimentally it was...
Men are frequently left out of the picture in the study of family planning and sexual risk behavior. This approach means few programs and policies address men's family planning and sexual health issues. There is also a lack of understanding of the role fatherhood plays in men's development and in...
Parallel loops are one of the main sources of parallelism in scientific applications, and many parallel loops do not have a uniform iteration execution time. To achieve good performance for such applications on a parallel computer, iterations of a parallel loop have to be assigned to processors in such a...
Kincaid's lupine (Lupinus oreganus Heller) is a federally listed threatened species native to remnant grassland of western Oregon and southwestern Washington, and is the primary larval host plant of a once thought extinct butterfly, Plebejus icarioides fenderi Macy. Past studies concerning Kincaid's lupine reproduction
suggested that populations may suffer reductions...
Stagnation point heat transfer in a gas undergoing relaxation of its
internal energy is examined by solution of the equations of motion
using the two temperature approach of Wang Chang and Uhlenbeck.
The results are presented in parametric form and show that relaxation effects produce an adiabatic wall temperature above...
The purpose of this study was to describe the leadership development process
of former student leaders at Snow College. More specifically, the study focused on
understanding how, when, and where leadership development took place in their
"lived experience" within the student government at Snow College (Van Manen,
1998). Examining the...
How can an agent generalize its knowledge to new circumstances? To learn
effectively an agent acting in a sequential decision problem must make intelligent action selection choices based on its available knowledge. This dissertation focuses on Bayesian methods of representing learned knowledge and develops novel algorithms that exploit the represented...
Relatively simple methods are developed for obtaining discreet
orientation characterization of preferred orientation from x-ray
diffraction-determined pole figure data. It is demonstrated how this
information, along with the single crystal elastic constants, can be
used to calculate Young's modulus as a function of sheet direction.
Computer programs are developed for...
The purpose of this study was to investigate the effect of untrained and
trained peer tutors on the motor performance of students with developmental
disabilities in integrated physical education classes. This study utilized a single
subject delayed multiple baseline design across subjects.
Six elementary age students with developmental disabilities and...
The spectrophotometric method for the determination of the
acid nonextractable flavin in the proteolytic digest of the trichloroacetic
acid precipitate from the heart muscle preparation has been
examined for the interference of the degraded hemeproteins. The
proteolytic digest was chromatographically separated into the heme
and flavin fractions. Spectrophotometric determinations made...
The design, construction and operation of a fluorometric reaction
rate instrument is described. The instrument is designed for simple
operation with maximum versatility. Advantages and modes of
operation of the system are discussed in detail. The instrument is
used for the kinetics-based determination of trace levels of Ag and Al....
A new method is introduced for incorporating bathymetric uncertainty into predictions of nearshore and river flows (i.e., unstratified flows primarily forced by pressure and radiation stress gradients). The method involves the use of the ensemble Kalman filter (EnKF) as a parameter estimation scheme, where the parameter to be estimated is...
The field of toxicology is challenged with a vast number of environmental chemicals and mixtures to which humans and ecosystems are exposed with limited toxicity data available. Chemical hazard assessment traditionally utilizes mammalian models and can be both cost- and time-limiting and may pose ethical concerns. To rapidly tackle this...
A fossil-calibrated phylogenetic framework based on exemplars from each of the four taxonomic sections within Pinus was created using multiple nuclear and chloroplast loci. Calibration at the well-defined subgeneric split within Pinus with either fossil leaves and cones (ca. 45 million years ago) or fossil wood (ca. 85 million years...
Data from nuclear ribosomal internal transcribed spacer regions (nrITS) and chloroplast DNA (cpDNA) have failed to resolve phylogenetic relationships in Pinus. To provide greater interspecific resolution, five low-copy nuclear genes were developed from mapped conifer anchor loci. Four genes were sequenced from species representing all Pinus subsections. Individual loci do...
Italian ryegrass populations have been identified with evolved resistance to glyphosate in orchards with a history of glyphosate use. Two of these populations were selected to investigate the inheritance of glyphosate resistance. The mechanisms involved in the herbicide resistance were an altered target site for the population SF and reduced...
Wave dispersion and fracture are phenomena that involve. mechanisms triggered at the scale of a material's internal structure. Experiments were performed with a candidate material to judge the hypothesis that wave dispersion measurements can be used to nondestructively predict fracture strength. Wood-based particleboard was chosen as the candidate material because...
Seventy-two species of Blennocampinae in 21 genera and six tribes
are known from the Nearctic region. The adults and known larvae of
all species and genera are keyed, described and illistrated. A
definition of the subfamily, a review of previous work, a table of
host-plant associations, and a discussion of...
While exercise can be prescribed for improving cardiovascular and muscle health, no prescription exists for increasing bone mass. Because bone deformation rate has been identified as an important variable related to osteogenesis, estimates of skeletal loading during human activities likely characterize the associated osteogenic stimulus. However, estimates of body segment...
This study examined time spent in various activities by
farm women. Emphasis was placed on household work time and
how time is apportioned among various household work
activities. Time use of farm women was compared to rural
nonfarm women and urban women. Data were from An
Interstate Comparison of Urban/Rural...
This study examined children's memory for traditional and nontraditional
parental behaviors displayed in story content. Subjects
were 40 male and 40 female preschool children between the ages of 47
and 60 months. Children were read a story portraying a mother and a
father as the main characters. Each character performed...
PCR-based codon-specific random mutagenesis and site-specific mutagenesis were performed to construct a library of 18 amino acid changes at Arg276 in the conserved leucine-loop of the core catalytic domain of human uracil-DNA glycosylase (UNG). Each Arg276 mutant was then overproduced in E. coli cells and purified to apparent homogeneity by...
This study compared wives defined as underemployed by educational
mismatch with not underemployed wives on four major predictor variables--
relative market work advantage; degree of competition in the
female labor market; time demands from family members; and assistance
with childcare and other housework. The data were from NE 113, An...
A strain of the phytopathogenic bacterium Pseudomonas syringae
pv. phaseolicola, a pathogen of common bean Phaseolus vulgaris,
harbors a 150 kilobase pair (kb) plasmid pMC7105. In one strain,
LR719, pMC7105 is stably integrated in the bacterial chromosome.
Imprecise excision of the pMC7105 replicon has been shown to result
in the...
A computer program called SAPWOOD which possesses the
capability of performing linear or nonlinear, static or
dynamic response including seismic excitation for wood-framed
buildings with semirigid connection systems is
presented in this study. Program SAPWOOD is a modification
of the program NONSAP by adding new elements such as a
linkage...
This study examined the effects of stage of preoperational thought, sex and mode of exploration on preschoolers ability to represent a small-scale model configuration of objects. Forty-eight subjects between the ages of 2 years, 5 months and 5 years, 4 months were classed in spatial conceptualization as either Stage I...
This study examined graduate international students'
knowledge, attitudes, experiences, practices, and
satisfaction relating to credit cards. Based on the
literature, international students attending U.S. colleges
and universities were considered an important population to
study because of: (1) internationalization of credit cards
and (2) the lack of credit card research on...
The present experiment examined children's memory for stereotypic
and non-stereotypic sex role content in their reading material.
Twenty-four male and twenty-four female fifth grade subjects read
two short stories, each depicting a male and female character who
exhibited an equal number of masculine and feminine traits and
behaviors. Results of...
Throughout the world, weather-related and other natural phenomena claim thousands of lives and devour billions of dollars annually in recovery efforts. Destruction of life and property in the wake of disasters is devastating, and can have a dramatic impact on families and businesses around the globe. Yet, published works specifically...
Monocrotaline (MCT) is a member of a class of naturally occurring
phytotoxins known as pyrrolizidine alkaloids (PAs). Exposure to PAs can result
in liver and cardiopulmonary lesions as well as lymphoid organ atrophy. In the
present study C57BI/6 (B6) mice received MCT (0-150 mg/kg/day, po) for 14
days. Overt toxicity...
Approximately 600,000 individuals will be eventually released from the prison system and millions will be released from jails across the United States each year (Mukamal et al., 2015). Some of these individuals will make their way to a local community college to make a better life for themselves. There is...
The term "interaction" in evolutionary biology and ecology
describes the relationships among variables in two classes of causal
models. In the first, "interaction" refers to the influence of a
single putatively causal variable on a variable of interest. In the
second class of models, the term applies when a third...
Exposure to TCDD suppresses the generation of immune responses through unknown mechanisms. Interestingly, TCDD enhances inflammatory responses to various stimuli. The goal of the studies presented in this thesis was to examine the role of hyperinflammation in TCDD-induced immunotoxicity. Previously we observed an increase in Mac-1⁺ cells in the spleen...
The nonlinear response of a ten-story steel structure with semirigid
girder connections is studied under conditions of dynamic loading.
The dynamic loading used in this study is the North-South component
of the May 18, 1940 El Centro, California earthquake. To deal
with the complexity of the problem the structure is...
The immune system has been identified as a very sensitive target for the toxic effects of 2,3,7,S-tetrachlorodibenzo-p-dioxin (TCDD). Exposure to TCDD has been shown to disrupt the generation of both cell-mediated and humoral T cell-dependent immunity in laboratory animals; however, the mechanism remains unknown. In this dissertation, the hypothesis is...
Thirty households were randomly selected to examine intra-household gender differentials in work roles and distribution of resources, between adult men and women, and boys and girls. Work related activities were assessed by time used in agricultural work, household work, and income generating work. Distribution of resources was assessed by expenses...