Global increases in ultraviolet-B radiation (UVBR:290-
320 nm) resulting from decreases in stratospheric ozone
concentration have the potential to alter marine primary
production and affect global climate and marine trophic
dynamics. Effects of UVBR on phytoplankton carbon fixation
were determined from open ocean exposure studies conducted
off the coast of...
Anthropogenic releases of trace gases into the
atmosphere are causing a decrease in stratospheric ozone
concentrations and a subsequent increase in solar
ultraviolet-B (UV-B)(280-320 nm) radiation reaching the
earth's surface. The objective of this study was to
determine the acute effects of enhanced UV-B radiation on
the primary production of...
Previous observations of light levels and phytoplankton abundances along the Oregon coast demonstrated that phytoplankton attenuated light sufficiently to potentially limit the growth of intertidal macrophytes and therefore structure local intertidal communities. Inspired by this observation, in spring 2004, I initiated a study to quantify the direct and indirect benthic...
There has been increased concern about radiation dose to the female breasts, with approximately 200,000 new breast cancers being diagnosed each year in the United States. The unprecedented increase in the use of radiologic exams on younger women has also raised some additional concerns about how procedures are performed. The...
This gamma irradiation study was conducted to establish an LD50 of the hop (Humulus lupulus L.) cultivar Cascade . The overall, long term goal is to generate replacement hop cultivars by inducing minor but significant DNA alterations with gamma radiation to improve agronomic quality without changing the brewing profile. The...
The International Commission on Radiological Protection (ICRP) has modeled twelve reference animal and plant (RAP) species using simple geometric shapes in Monte–Carlo (MCNP) based simulations. The focus has now shifted to creating voxel phantoms of each RAP to advance the understanding of radiation interactions in nonhuman biota. The work contained...
My thesis explored the effects of and potential mediating mechanisms for an important environmental stressor, ultraviolet-B (UVB) radiation. UVB radiation has negative effects on organisms in both terrestrial and aquatic systems. I used meta-analysis to quantify the effects of UVB radiation on a diversity of aquatic organisms (Chapter 2). UVB...
Iodoacetic acid and diphenylamine were used in this study to
elucidate the mechanisms of resistance of Micrococcus radiodurans
to radiation. This organism, a gram positive, non-spore forming,
salmon-pink, tetracoccus has a LD₅₀ of 213,000 R when grown in
the absence of radio-modifying agents.
M. radiodurans, when grown in media containing...
Quantity variations in pigments and lipid classes were determined
following γ-irradiation of Micrococcus radiodurans, Sarcina
lutea, and Pseudomonas aeruginosa.
Pigmentation was determined by extraction with organic solvents
and measured as optical density at 475 mμ for M. radiodurans
and S. lutea, and 410 mμ for Ps. E aetuginosa. Pigments of...