The ozone present in the atmosphere filters incident solar
ultraviolet (UV) radiation such that only the longer wavelengths of
the total UV spectrum emitted by the sun reach the earth's surface.
Atmospheric increases in nitrogen oxides and chlorofluoromethanes
represent a threat to the existence of this protective screen. As
the...
Roughskin newts, Taricha granulosa (Skilton), were exposed to
UV-B (280-320nm), UV-A (321-380 nm), and visible radiation from
fluorescent sunlamps (Westinghouse FS40) that were filtered with
cellulose acetate film. UV-B controls were exposed to irradiation
from sunlamps that were filtered with Mylar-D, a polyester film
that effectively absorbed UV-B radiation while...
The brine shrimp, Artemia, was used as an experimental
organism to study the effects of ⁶⁰Co gamma irradiation on the reproductive
performance of an animal population. The total reproductive
ability of the brine shrimp was fractionated into various components
and the effects of irradiation on each of these components
was...
The effects of changes in dosimetry conditions on the radiation
sensitivity of a constant biological population were determined.
The organism used for this study was the strain B of
Escherichia coli. The percentage survivals of these cells in an
aqueous solution were determined at the same total exposure with
different...
The effect of 2-aminoethyl-2-thiopseudourea[superscript .]Br[superscript .]HBr (AET),
2-mercaptoethylamine[superscript .]HC1 (MEA) and trisodium calcium chelate of
diethylenetriaminepentaacetic acid (CaNa₃DTPA) on the radiosensitivity
of rat fetus was investigated. A total of 1256 fetuses were
critically examined.
Exposure of rats to 200 r whole-body X-irradiation at 9.5 days
of gestation resulted in a...
Beginning with the discovery of x-rays by Wilhelm
Konrad Roentgen in 1895, man has had the capacity to
greatly increase radiation levels of his environment,
especially with the advent of nuclear weapons in recent
years. Radioisotopes are finding progressively wider
use in medicine, research, power production, etc., with
increased hazards...
The effects of ultraviolet (UV) irradiation on photosynthesis and
various partial reactions involving the individual photoreactions of
photosynthesis were examined. These reactions included photo-reduction in adapted green algae, Hill reaction, cyclic photophosphorylation,
the 520 nm absorbance change and variable-yield fluorescence.
The reactions were measured in spinach chloroplasts and
isolated chloroplasts...
Reduction of stratospheric ozone caused by human
perturbation with halocarbon compounds and the consequent
increase in mid-wavelength ultraviolet radiation (UV-B
radiation. 290-320 nm) reaching the earth's surface could
have deleterious ecological effects on marine primary
producers. Unialgal and mixed cultures of Thalassiosira
pseudonana and Thalassiosira weisflogii were exposed to
three...
There were two studies involved in the thesis research. In the
first study, variation in the amount of adenohypophysis gonadotropins
among 22 individual beef bulls were investigated. These bulls
represented four inbred lines, and six linecrosses. The bulls were
raised in the Oregon State University purebred herd.
The bulls were...