Coibamide A is a highly methylated cyclic depsipeptide isolated from Panamanian marine filamentous cyanobacteria as part of an International Cooperative Biodiversity Groups (ICBG) program based in Panama. This structurally unique agent exhibits potent cancer cell toxicity with an unprecedented selectivity profile in the National Cancer Institute (NCI) 60 cell line...
The isoprenoid pathway is one of the major biosynthetic pathways of secondary metabolites. Isoprenoids with a C₂₀ skeleton are known as diterpenoids and are derived from the common precursor, geranylgeranyl diphosphate (GGPP). This dissertation describes approaches to discover the diterpene synthase enzymes which provide the backbone structures for pleuromutilin and...
In recent years, the methyl erythritol phosphate (MEP) pathway to isoprenoids has been the subject of intensive research. The interest is because isoprenoids have important roles in many cellular processes essential for the survival of several pathogenic organisms, making the inhibition of this pathway an attractive target for the drug...
We exhibit long-lived resonances in scattering from two-dimensional soft cage potentials comprised of three and four Gaussian peaks. Specific low-energy resonances with very narrow width are shown to correspond to classical multiple-reflection events. These states have much larger probability densities inside the cage than outside and mimic bound states in...
We consider development of sand ripples in shallow water flows which do not reach an equilibrium height but have a time-varying ripple height that slowly reaches a maximum value and then is quickly destroyed by the fluid. A simple scenario to explain the time periodic behavior of the sand ripples...
The discovery of the methylerythritol phosphate pathway (the MEP pathway) as an alternate pathway for isoprenoid biosynthesis in some organisms including most bacteria, malarial parasites and plants, but not in animals, has stimulated extensive studies in this area. Research has revealed the potential of finding novel antibacterials, antimalarial drugs, and...
This dissertation describes studies of isoprenoid biosynthesis in the
phytoflagellate Euglena gracilis. Elucidation of a novel isoprerioid pathway, the 2-Cmethyl-D-erythritol-4-phosphate (MEP) pathway, in addition to the generally known
mevalonate (MVA) pathway, led to extensive exploration of the distribution of both pathways in a variety of organisms. To date, photosynthetic eukaryotes...
This dissertation details the investigation of an alternate pathway to
isoprenoids that occurs in plants and microorganisms, the non-mevalonate
pathway. This exploration of the pathway focuses on the second step, the
conversion of 1-deoxy-D-xylulose-5-phosphate (DXP) to 2-C-methylerythritol-4-phosphate (MEP) by the enzyme DXP isomeroreductase (DXR). These studies led to an appreciation...
As a result of its atomic structure, carbon fiber produced from mesophase pitch
has a high electrical conductivity and high tensile strength. Others have used carbon fiber
as a resistive heating unit to accelerate matrix solidification in carbon fiber-polymer
matrix composites.
In this study, a unidirectional carbon fiber reinforced polymer...
We used recent phenomenological form factors to calculate the effect of on-shell
two-pion exchange in nucleon-nucleon scattering below the two-pion production
threshold. As expected, the contributions of partial wave amplitudes are all negligible.
We also noticed that the relativistic spin-operator decomposition of the
scattering amplitude is not unique at certain...
A new method for evaluating the Lyapunov exponent for a Hamiltonian system
involves a spatial evaluation, rather than a numerical time integration. The
introduction of a novel vector field to the phase space allows the Lyapunov exponent
to be expressed in a form that does not involve time. The Lyapunov...
We develop a technique to express the nucleon pole strength and bare mass in terms of renormalized quantities. Starting from a general unrenormalized self energy we determine the bare mass and the pole strength. For determining the pion content of the nucleon we discuss the leading renormalization loop. We relate...
We introduce a relativistic model for pion-nucleon scattering which includes an elementary
delta dressed by its decay. Crossing-symmetric single-particle exchange
is augmented by parametrized multiple-scattering interactions, with covariant sideways
form factors in both 3- and 4-field vertices. Causality is enforced by dispersion
relations. Unitary fits to observed on-shell amplitudes are...
A Willamette Valley farm cooperative was interested
in evaluating locations for their canning facilities based on
the criterion of minimizing aggregate distance to their contract
farms. This location problem presented an excellent opportunity
for a geographic application project as it was characterized by
one, a spatial distribution of farms and...
The major purpose of this study was to identify those social behaviors
of children which a particular group of parents perceived as important in
the process of socialization. This purpose was in direct support of
Western Regional Research Project W-144. The study also investigated
changes in parental evaluations of children's...
The major purpose of this study was to assess changes
in behavioral understanding and attitudes students may have
experienced in association with their participation in a
high school child development course. In addition, assessments
were made of changes in subject's perceptions cf:
1) marriage role expectation, 2) self-concept, and 3)...
The purpose of this study was to investigate the selfconcept by
examining the relationships among self-perception, behavioral understanding,
and teacher performance. The subjects were 53 female
college students enrolled in one of three practicum classes offered by
the Family Life Department of Oregon State University. Subjects in
Group A (n=33)...