Studies have been made to determine the limits of tolerance to
gamma radiation for 15 cultures of the following bacterial species
both in culture media and in irradiation-sterilized seafoods (crab-meat,
halibut and shrimp) inoculated with Salmonella (seven species),
Shigella (three species), and one species each of Neisseria, Myco-bacterium, Esctrerichia, Proteus...
The quality of radiation-pasteurized halibut stored at 34°F
was evaluated subjectively and objectively over a period of 18 weeks.
Results of flavor evaluation and chemical analyses showed that the
storage life of halibut irradiated at 0.50, 0.75 and 1.00 megarad was
extended more than threefold. Although irradiated samples were
consistently...
The over-tenderization of irradiated-sterilized meat is one
of the more important adverse effects resulting from the use of
irradiation for the preservation of meat. Although research has
been reported on the activity and effect of the inherent proteolytic
enzymes of irradiated meat, very little work has been directed toward
the...
Pasteurization radiation offers a new means of extending the
refrigerated storage life of foods. This procedure avoids many of
the undesirable changes which result when sterilization radiation is
used and still eliminates most of the spoilage organisms.
Shrimp was treated with 5 ppm chlortetracycline and subjected
to pasteurization levels of...
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...
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...
Ultraviolet-B radiation (UVB) is an abiotic stressor in both terrestrial and aquatic systems. The stratospheric ozone layer, depleted due to anthropogenic activities and the cause of elevated UVB at earth's surface over the last four decades, is predicted to recover by 2065. However, UVB levels in aquatic systems may continue...
Spacecrafts experience radiation in the course of their operation
and all electronic equipment on board these spacecrafts has to
be designed to withstand the effects of this radiation.
This thesis describes the effects of total ionization dose (TID)
and single event transients (SET) in phase-locked loops - an
important circuit...
An ecological study of a microorganism similar to that isolated
in 1956 and designated as Micrococcus radiodurans indicated
that the organism could be isolated from several different environments.
By taking advantage of its radio-resistivity, high levels of
gamma radiation were used in the isolation procedures to inactivate
most of the...
Because of the potential elevated-temperature applications
of high-purity vanadium in nuclear reactors an
investigation was conducted to determine the effects of
nuclear irradiation upon the properties of the pure metal.
The results of this investigation indicated that the effects
caused by irradiation, increased strength and hardness and
decreased ductility, could...
Several fuels are being investigated for fast breeder reactor
applications. One promising concept is sphere-pac mixed carbide
fuel. As a part of the development of this fuel concept it is
necessary to determine the behavior of the irradiated fuel for safe
and reliable operation on a sound economic basis. It...
Global atmospheric pollution from chlorofluorocarbons has the
potential of causing significant reductions in the concentrations of
stratospheric ozone. If the production of chlorofluorocarbons were
to continue into the future at the rate prevalent in 1977, the
steady state reduction in total global ozone could be between five
percent to ten...
Radiation studies were performed on compound semiconductor heterostructure devices. The objective was to understand the degradation processes caused by the exposure of these devices to radiation. Preliminary experiments were focussed on studying the degradation phenomenon in single heterojunctions and single quantum wells. It was found that ionizing radiation like gamma...
Exposure to moderately high levels of ionizing radiation (<20 Gy) has in some instances shown a hormetic effect in numerous vegetable-type crops. Past experiments performed in outdoor cultivars have shown a somewhat unpredictable increase in growth rate with a higher overall yield in a specified time when the seeds are...
Gamma irradiation survival curves of Salmonella enteriditis,
Salmonella paratyphi A, Salmonella cholerasuis, Salmonella
pullorum and Streptococcus pyogenes were determined in crabmeat
and in Hartsell's broth. The survival pattern of Staphylococcus
aureus in crabmeat was also determined.
A "tailing off" was found in the survival patterns of
Salmonella paratyphi A, Salmonella...
The focus of this thesis is to determine the biological impact of dose from
brachytherapy sources commonly used in cancer treatment. To achieve this goal, the
Monte Carlo code PENELOPE was used to simulate point sources of four different
isotopes (¹⁰³Pd, ¹²⁵I, ¹³⁷Cs, and ⁹⁰Sr) in an infinite medium of...
Ultraviolet-B radiation (UV-B) has been suggested as a factor contributing to global amphibian population declines. While ambient UV-B levels damage the eggs and embryos of some amphibian species, few studies have addressed how UV-B affects other life history stages or sublethal responses. My dissertation focuses on (1) investigations of sublethal...
The electron, gamma and neutron radiation degradation of III-V semiconductors
and heterojunction bipolar transistors (HBTs) is investigated in this thesis.
Particular attention is paid to InP and InGaAs materials and InP/InGaAs
abrupt single HBTs (SHBTs). Complete process sequences for fabrication of
InP/InGaAs HBTs are developed and subsequently employed to produce...
Many experiments are being conducted to find compounds that offer radioprotection against radiation damage and that are also non-toxic. It is hopeful that in the future, research for this technology will benefit patients undergoing cancer treatment by reducing radiation damage to normal cells and therefore reducing short and long term...
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...
Circuits operating outside the earth’s atmosphere are more vulnerable to cosmic radiation and require special design consideration. The purpose of this work is to explore methods of mitigating the effect of radiation in phase locked loop (PLL) circuits. Several voltage controlled oscillators (VCOs) and two complete PLLs are designed and...
This dissertation is an exploration of the material response to Terahertz (THz) radiation. Specifically we will explore the ultrafast electron dynamics in the nonperturbative regime in semiconductors that have been patterned with nanoantenna arrays using broadband, high intensity, THz radiation. Three main semiconductor materials will be studied in this work....
Microstructure changes in uranium and uranium/metal alloys due to radiation damage are of great interest in nuclear science and engineering. Titanium has attracted attention because of its similarity to Zr. It has been proposed for use in the second generation of fusion reactors due to its resistance to radiation-induced swelling....
Space radiation biology is an emerging field of research with a focus on improving the
health and safety of astronauts in low-Earth orbit (LEO) and deep-space missions. Eye
health is especially important to astronaut functionality. Recent studies have found an
increased risk of cataract formation in astronauts with higher lens...
Artificial substrates colonized by diatoms from Yaquina Estuary, Oregon, were exposed to solar visible radiation and three levels of ultraviolet radiation (UV-B, 290-320 nm). Flow-through microcosms were constructed inside a glasshouse to serve as chambers for the artificial substrates. The artificial substrates were sampled during three spring/summer experiments. Chlorophyll a...
A model is developed that allows the prediction of the stress-strain
distribution in a mixed carbide sphere pac fuel pin during
irradiation. The model is coupled with a previously developed model
for the thermal behavior of the pin. The one-dimensional (radial at
various axial locations) solution is for quasi-steady pin...
Electron and neutron irradiation effects in InGaP/GaAs single heterojunction bipolar transistors are investigated in this thesis. Devices with different emitter sizes and grown by two different growth techniques were examined. Based on the physics of heterojunction bipolar transistors and concepts of radiation damage mechanisms, the irradiation effects were analyzed. The...
Over the past decade the International Commission on Radiological Protection has developed a comprehensive approach to environmental protection that includes the use of Reference Animals and Plants (RAPs) to assess radiological impacts on the environment. For the purposes of calculating radiation dose, the RAPs are approximated as simple shapes that...
The increasing use of medical procedures using ionizing radiation has increased significantly in recent years. In 1987, the National Council on Radiation Protection Report 93 (NCRP) reported that the average exposure ionizing radiation was 53mRem/year (0.53mSv/year). In their most recent study on radiation exposures NCRP Report 160 in 2009, the...
Internal dosimetry is challenging and relies on estimates using MIRD or ICRP biokinetic models. To address this, we looked at gene expression analysis in whole blood from radiotherapy patients. Patients with relapsed or refractory neuroblastoma who received ¹³¹I-mIBG at UCSF were used to correlate internal ionizing radiation (IR) dose with...
'Hot particle' skin dosimetry calculations are commonly performed using homogeneous dose-point kernels (DPK) in conjunction with scaling and backscatter models to account for non-homogeneous geometries. A new scaling model for determining the actual DPK for beta-particles transmitted by a high-Z source material has been developed. The model is based on...
The neutron and electron radiation effects in Ill-V compound semiconductor heterostructure devices are studied in this thesis. Three types of devices investigated are AlGaAs/GaAs high electron mobility transistors (HEMTs), AlGaAs/InGaAs/GaAs heterostructure insulated gate field effect transistors (HIGFETs), and InP/InCaAs/InGaAs single heterojunction bipolar transistors (SHBTs). HEMTs and HIGFETs are primarily investigated...
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...
Scaling the supply voltage into the sub/near-threshold domain is one of the most effective methods for improving the energy efficiency of next-generation electronic microsystems. Unfortunately, the relationship between low-voltage operation and radiation-induced soft error rate is not widely known, as little research has been previously performed and reported for soft-error...
Quantitative procedures were developed to determine the effect of variability in the model parameters required for the estimation of microbial shelflife and thermal processing time. Monte Carlo simulations combined with these predictive models were implemented in Microsoft Excel™. In the first study,
predictive models were used for shelf-life predictions based...
The first study utilized ova transfer in sheep and involved
hormonal treatments for synchronization of estrus and superovulation
in an investigation of crossbred maternal influences on inbred and
linecross lambs.
Synchronization of estrus in ewes was achieved effectively
with either oral progestogen, 6 α-methyl-17α-hydroxy-progesterone
acetate (60 mg./ewe/day), or intramuscular injections...
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...
The ion implantation process is a very precise, controllable, and
reproducible method used to enhance material properties of finished
components such as ball bearings. Essentially, the target material is
bombarded by accelerated ions to form a thin alloyed layer in the
substrate. As the ions deposit their kinetic energy in...
The inert gas ion bombardment of solid surfaces has
found many uses in the field of analytical chemistry. In
one method of spectrochemical analysis, inert gas ion
bombardment in a glow discharge is used to produce an atomic
vapor, representative of the sample bulk, which is analyzed
using atomic absorption...
The radiation effects in III-V heterojunction devices are investigated in this thesis. Two types of heterojunction devices studied are InGaP/GaAs single heterojunction bipolar transistors (SHBTs) and GaN-based heterojunction light emitting diodes (LEDs). InGaP/GaAS HBTs are investigated for high energy (67 and 105 MeV) proton irradiation effects while GaN heterojunction LEDs...
Plant form is a compromise between resource gathering, reproduction and
the tolerance to physical demands of the abiotic and biotic environment. In
an agricultural field in addition to the natural factors causing stress, humans
also introduce physical and mechanical stresses, and chemical pesticides
into the environment. Many of these factors...
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4.2 Effectof ultraviolet-B (UVB) radiationon survival of
Italian ryegrass seedlings of a
Published January 1985. Facts and recommendations in this publication may no longer be valid. Please look for up-to-date information in the OSU Extension Catalog: http://extension.oregonstate.edu/catalog
Global amphibian declines have been attributed to numerous and often synergistic causes, such as invasive species, pathogens, and ultraviolet-B (UV-B) radiation. The effects of these stressors are context dependent and can vary with location, species, and populations. As sensitivity to UV-B has shown inconsistencies across amphibian taxa, it can be...
Cutaneous melanoma remains the deadliest form of skin cancer arising from malignant transformation of pigment-producing melanocytes, with a diagnosis of metastasis indicating a median survival rate of less than a year. Solar ultraviolet (UV) radiation, especially childhood sun exposure, is an important etiological risk factor of melanoma. This DNA damage...
Deer grazing outside your window can be a welcome sight, unless
the deer are eating your favorite flowers. Their spring and summer
browsing can kill or severely damage young garden and landscape plants.
Once deer are attracted to your yard, discouraging them is not easy. But, there are ways you...
The Demonstration of Ecosystem Management Options (DEMO) study is a large-scale, multi-year, interdisciplinary project examining the effects of various levels and patterns of green-tree retention on multiple forest features. Six retention levels and patterns were examined and replicated across six blocks of predominately Douglas-fir forested land in western Oregon and...
Uranium is the most common radionuclide that found in the nature. It is a radionuclide with a very low specific activity. There is limited data on plan uptake of uranium. This research was to determine the plant uptake of uranium, calculate the concentration ratio, and estimate the dose from eating...
Significant inputs of hydrocarbons are continually released into the environment from anthropogenic and natural sources. Some of the most toxic hydrocarbon compounds are polycyclic aromatic hydrocarbons. Polycyclic aromatic hydrocarbons are known for their ability to absorb ultraviolet light and enhance toxicity. Generally, PAHs exert their toxicity via narcosis but UV-absorbing...
Staphylococcus aureus is a human pathogen capable of producing enterotoxins causing staphylococcal food poisoning, one of the most economically important foodborne diseases in the U.S. This pathogen may be introduced to pre-cooked tuna meat used for the production of canned tuna because significant manual handling occurs after cooking of the...
Honeybees and honey combs are good indicators of environmental contamination and can be important for dose calculations. In the event of reactor accidents and nuclear weapon testing, the released radioactive materials are likely to be transported through various environmental pathways as well as by humans and animals, including bees. Due...
The multifaceted role of the environment in regulating the structure and dynamics of biological communities has long fascinated ecologists and motivated much debate and research. Now, in a time of accelerated global changes due to human impacts, the need to understand how the environment shapes communities has gained new urgency....
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Table 2.4. 3-way ANOVA table testing effectof species and treatment on total drilling by
Although it is generally assumed that the intensifying abiotic environment is the primary effect of drought on aquatic organisms, drought-induced top predator extinctions may be an important underlying mechanism. I used manipulative experiments to disentangle the impacts of drying and top predator extinctions on arid-land aquatic invertebrate communities. I then...
The pigeon guillemot (Cepphus columba) population in Prince William Sound has failed to recover from declines that occurred both before and after the Exxon Valdez Oil Spill (EVOS). Post-spill studies of pigeon guillemot breeding biology have identified three potential factors limiting recovery: (1) predation on eggs and nestlings; (2) declines...
Mule deer (Odocoileus hemionus hemionus) and Rocky Mountain elk (Cervus canadensis nelsoni; hereafter elk) populations in northeast Oregon have declined in the past 10 to 20 years. Concurrent with these declines, cougar (Puma concolor) populations have apparently increased, leading to speculation that predation by cougars may be responsible for declining...
Bumble bees provide vital pollination services in both native and agricultural landscapes. However, in recent years, bumble bee populations have experienced global population declines. The primary causes of these declines have been attributed to the environmental impacts of pathogens, pesticide use and habitat fragmentation. While research has examined the impacts...
Livestock grazing has been indirectly related to sage-grouse (centrocercus
urophasianus) declines in the western United States and southern Canada; however,
there is a lack of scientific research that directly relates the two. Our objective was
to investigate the influence of livestock herbivory on sage-grouse nesting habitat by
determining the spatial...
Recent research conducted throughout the Northern California Current (NCC) on the ecology of Pacific salmon (Oncorhynchus spp.) indicates that variable ocean conditions affect the community composition of zooplankton in the nearshore environment which, in turn, can affect the quality of prey for fish, sea birds and mammals. Interannual variability in...
Populations of organisms are influenced by both top-down (predator driven) and bottom-up (environment or resource driven) effects. Seabird research has largely focused on bottom-up factors influencing reproduction, with little emphasis on top-down. Our goal was to better understand top-down impacts on colonial nesting seabirds over a range of spatio-temporal scales....
Reintroduction of wolves to Yellowstone National Park (YNP) in 1995-96 provided a rare opportunity to observe the response of an ecosystem to the return of a top predator, including possible reversal of decades of decline of aspen, cottonwood, and tall willows suppressed by intensive herbivory on elk winter ranges. To...
Concentrations of selenium (Se), manganese (Mn), zinc (Zn), cadmium (Cd), lead (Pb) and arsenic (As) were measured in the water column, sediment and biota, in conjunction with selected physicochemical data, from representative wetland types at a mining site within Salt Lake County, Utah, USA. The selected field sites included Oolitic...
A greater than 10-fold increase in Canada goose (Branta canadensis) populations over the past several years has resulted in concerns over grazing impacts on grass seed production in the mid-Willamette Valley, Oregon. This study was designed to develop methods to quantify and statistically analyze goose-grazing impacts on seed yields of...
This study was an investigation of lotic macroinvertebrate distribution in northeastern Oregon at two different spatial and biological scales. Examination of assemblages at a limited spatial scale revealed relationships with natural and disturbance gradients and led to questions about distribution of a population at broader spatial scales. In a 16...
In this study the impact of episodic events on levels of bioavailable trace metals Zn,
Cu, Cr, Cd, Pb, and As (III) were determined for the lower Willamette River in Oregon.
In addition, a comparison among three alternative methods for estuary sampling was
conducted. Potential adverse human health risk associated...
Observations of the Oregon coast’s physical oceanography over the last few decades have revealed falling dissolved oxygen levels associated with seasonal upwelling, as well as rising water temperatures. In extreme cases, these changes have been associated with die-offs, redistribution, and decreased abundance and diversity of benthic fish and invertebrates. Many...
Bees provide critical pollination services to diverse agricultural crops, native plants and trees. Globally, there are reports of bee declines which have been attributed to diseases, exposure to pesticides and changes in land use that are believed to have led to a reduction in foraging resources and nesting habitats for...
The objectives of the experiment were to: 1) determine the relationship
between overstory canopy cover and ungulate herbivory on understory production
composition and diversity and 2) determine the effects of timber harvest, ungulate
herbivory and season of use on botanical composition and nutritional quality of
beef cattle diets. Three randomly...
Food webs consist of a combination of bottom-up (resource-driven) and top-down (predator-driven) effects. The strength of these effects depends on the context in which they occur. I investigated food web (trophic) relationships between wolf (Canis lupus) predation, elk (Cervus elaphus) herbivory, aspen (Populus tremuloides Michaux) recruitment, and fire. The study...
The Pigeon Guillemot (Cepphus columba) is now the only species of marine bird in Prince William Sound (PWS), Alaska that is listed as "not recovering" on the Exxon Valdez Oil Spill (EVOS) Trustee Council's Injured Resources List and has shown no sign of population recovery. During the 20 years since...
Lichens play many important roles in subarctic terrestrial ecosystems by fixing nitrogen, colonizing rock and gravel, stabilizing otherwise bare soil, adding significantly to vegetation biodiversity and serving as the primary food for caribou in the winter. In these chapters, I analyzed lichen community and ecological trait structure along environmental gradients,...
I investigated the relationship between harlequin duck (Histrionicus histrionicus) behavior and lack of recovery from the Exxon Valdez oil spill in Prince William Sound, Alaska. First, I evaluated the hypothesis that harlequin ducks in winter have little flexibility to increase foraging time in response to disturbance because they are constrained...
Olive ridley sea turtles (Lepidochelys olivacea) present an interesting case study of the conservation of wildlife species that aggregate in high densities and have served as resources for human consumption. Ridleys exhibit synchronized mass-nesting behavior,
during events called "arribadas," where thousands of females lay eggs together in a small area...
Delayed tree mortality is an unpredictable occurrence when prescribed burning is implemented. Fire scorched trees may die as the result of crown scorching, stem charring, root injury, bark beetle attack, or through a combination of these factors. This study examined ponderosa pine mortality and the incidence of two bark beetle...