Browsing by Subject "radiation"
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Item An Analysis of a Spreader Bar Crane Mounted Gamma-Ray Radiation Detection System(2013-04-08) Grypp, Matthew DOver 95% of imports entering the United States from outside North America arrive via cargo containers by sea at 329 ports of entry. The current layered approach for the detection only scans 5% of cargo bound for the United States. This is inadequate to protect our country. This research involved the building of a gamma-ray radiation detection system used for cargo scanning. The system was mounted on a spreader bar crane (SBC) at the Port of Tacoma (PoT) and the applicability and capabilities of the system were analyzed. The detection system provided continuous count rate and spectroscopic data among three detectors while operating in an extreme environment. In a separate set of experiments, 60Co and 137Cs sources were positioned inside a cargo container and data were recorded for several count times. The Monte Carlo N-Particle (MCNP) code was used to simulate a radioactive source inside an empty cargo container and the results were compared to experimentally recorded data. The detection system demonstrated the ability to detect 60Co, 137Cs, 192Ir, highly-enriched uranium (HEU), and weapons-grade plutonium (WGPu) with minimum detectable activities (MDA) of 5.9 ? 0.4 microcuries (?Ci), 19.3 ? 1.1 ?Ci, 11.7 ? 0.6 ?Ci, 3.5 ? 0.3 kilograms (kg), and 30.6 ? 1.3 grams (g), respectively. This system proved strong gamma-ray detection capabilities, but was limited in the detection of fissile materials Additional details of this system are presented and advantages of this approach to cargo scanning over current approaches are discussed.Item An external dose reconstruction involving a radiological dispersal device(Texas A&M University, 2007-04-25) Hearnsberger, David WayneRecent events have underscored the need for the United States government to provide streamlined emergency response procedures and subsequent dose estimations for personnel responding to incidents involving radioactive material. Indeed, the National Council on Radiation Protection and Measurements Report No. 138 (NCRP 2001) indicates that exposures received by first responders will be important for a number of reasons, including planning for the appropriate use of key personnel in an extended emergency situation. In response, the Department of Homeland Security has published Protective Action Guides (DHS 2006) to help minimize these exposures and associated risks. This research attempts to provide some additional radiological exposure knowledge so that an Incident Commander, with limited or no information, can make more informed decisions about evacuation, sheltering-in-place, relocation of the public, turn-back levels, defining radiation hazard boundaries, and in-field radiological dose assessments of the radiation workers, responders, and members of the public. A method to provide such insight begins with providing a model that describes the physics of radiation interactions, radiation source and geometry, collection of field measurements, and interpretation of the collected data. A Monte Carlo simulation of the model is performed so that calculated results can be compared to measured values. The results of this investigation indicate that measured organ absorbed doses inside a tissue equivalent phantom compared favorably to the derived organ absorbed doses measured by the Panasonic thermoluminescence dosimeters and with Monte Carlo ??????N?????? Particle modeled results. Additionally, a Victoreen 450P pressurized ion chamber measured the integrated dose and these results compared well with the Panasonic right lateral TLD. This comparison indicates that the Victoreen 450P ionization chamber could potentially serve as an estimator of real-time effective dose and organ absorbed dose, if energy and angular dependence corrections could be taken into account. Finally, the data obtained in this investigation indicate that the MCNP model provided a reasonable method to determine organ absorbed dose and effective dose of a simulated Radiological Dispersal Device in an Inferior-Superior geometry with Na99mTcO4 as the source of radioactive material.Item Comparison between Model Simulations and Measurements of Hyperspectral Far- infrared Radiation from FIRST during the RHUBC-II Campaign(2012-02-14) Baugher, ElizabethSurface downward far-infrared (far-IR) spectra were collected from NASA?s Far-Infrared Spectroscopy of the Troposphere (FIRST) instrument from August to October 2009 at an altitude of 5.4 km near the summit of Cerro Toco, Chile. This region is known for its dry, cold, and dominantly clear atmosphere, which is optimal for studying the effects, that water vapor and cirrus clouds have on the far-IR. Comparisons with Line-By-Line Discrete Ordinants Radiative Transfer model, LBLDIS, show that FIRST observes the very fine spectral structure in the far-IR with differences as small as +/- 0.7% for both clear-sky and cloudy-sky simulations. Clear sky model analysis demonstrated the greatest sensitivity to atmospheric conditions is between 300 and 500 cm-1. The cloudy-sky simulations demonstrated that the far-IR radiation has minimal sensitivity to cloud particle effective radius, yet is very sensitive to cloud optical thickness at wavenumbers between 400 - 600 cm-1. In fact, cirrus optical thickness found to be inferred from the brightness temperature differences at 250 and 559.5 cm-1. Aerosols proved to reduce downwelling radiance by half that a clear-sky would emit, but had little effect on the total far-IR radiative forcing. Furthermore, these far-IR measurements open a new window to understanding the radiative impacts of various atmospheric constituents such as water vapor and clouds, and to understanding and modeling the Earth?s climate and energy budget.Item Contour Collimation Systems to be Used for Murine Irradiation(2013-05-06) Uhlemeyer, James RichardThree collimators were designed and built with mouse irradiation in mind. They were made to have a shapeable aperture that could deliver strange or complex dose shapes to spots on the animals. Current collimators are either custom-built, expensive, or only provide limited dose shapes. These provide self-customizable collimation at a minimum of cost. A mouse holder was also devised to reproducibly hold a mouse under the collimator. Construction of the holder and of each collimator is also covered. Each collimator was analyzed for flaws, holes, and penumbral width across various shapes of interest. A Norelco MG300 X-ray generator at the Texas A&M Nuclear Science Center was used in these tests. The lead collimator had a radial penumbra of 1.2 mm. The clay / lead shot collimator had a radial penumbra of 1.6 mm. The brass collimator had a radial penumbra of 1.75 mm. Vertical and horizontal penumbras are dependent on distance from the center of the beam. All readings are + 0.3 mm according to the resolution of the scanner used in this experiment. Each collimator is useful for different purposes.Item Diet, Disease State, and the Space Environment Modify the Intestinal Microbiota and Mucosal Environment via Microbiota-directed Alterations in Colonocyte Signalling(2013-11-25) Ritchie, Lauren EMicrobial dysbiosis and toll-like receptor (TLR) signaling play a role in colonic injury and inflammation. Ulcerative colitis and radiation are known to alter microbiota, and diets containing polyphenols impact bacterial populations. We hypothesized that diet can mitigate dextran sodium sulfate (DSS) colitis (sorghum bran diets containing polyphenols) and space environment-induced alterations (normal iron content) in colonic microbiota and TLR signaling. To test this we utilized two experimental paradigms; DSS-induced colitis (3% DSS, 48-hr, 3 exposures, 2 wk separation), and three models to emulate the space environment: 1) fractionated low linear energy transfer (LET) ? radiation (RAD) (3 Gy) and high Fe diet (IRON) (650 mg/kg), 2) high LET Si particle exposure (50 cGy) and 1/6 G hind limb unloading (HLU), and 3) 13 d spaceflight. Bran diets upregulated proliferation, and repair protein (TFF3 and TGF?) and short chain fatty acid (SCFA) transporter (Slc16a1 and Slc5a8) expression post-DSS. Diet significantly affected 24-hr fecal butyrate production, with Cellulose and Black bran having numerically higher concentrations. Two predominant phyla were identified, Firmicutes and Bacteroidetes, and this ratio was higher in Cellulose DSS. Post DSS#3 the proportion of Bacteroidales, Clostridiales, and Lactobacillales was reduced compared to post DSS#2 for all diets. Black bran non-DSS rats had the highest richness and diversity. Colonic injury negatively correlated with the proportion of Firmicutes, Actinobacteria, and Lactobacillales, and positively correlated with Unknown and Unclassified groups. Bran diets reduced the severity of epithelial injury, maintained fecal butyrate, and prevented microbial dysbiosis and depletion during DSS-induced colitis. IRON+RAD decreased SCFA concentrations. Low and high LET radiation, HLU, IRON and spaceflight increased Bacteroidetes and decreased Firmicutes. HLU and spaceflight increased Clostridiales and decreased Lactobacillales. RAD and IRON+RAD animals had increased Lactobacillales and significantly lower Clostridiales compared to CON and IRON. TLR9 and IL-6 were downregulated by RAD. TLR4, TFF3 and TGF? differentially changed with IRON and spaceflight. Microgravity independently affected the microbiota, regardless of radiation energy or dose. Each environmental insult differentially altered the microbiota and mucosal gene expression, with distinct diet, microgravity, and radiation effects observed. Bran diets mitigated deleterious effects of colitis, maintained barrier integrity, and prevented microbiota dysbiosis.Item Effects of dietary fat and fiber on the oxidative status of the small intestine and colon of rats(Texas A&M University, 2006-08-16) Sanders, Lisa MerleColon cancer is one of the most commonly diagnosed cancers in the US, yet small intestine cancer is a rare event. While there are many similarities between these two tissues, inherent differences such as redox status, may contribute to the variation in cancer occurrence. We examined the difference in reactive oxygen species (ROS) generation, antioxidant enzyme activity and oxidative DNA damage in the small and large intestine of rats under normal conditions and following exposure to exogenous oxidative stress. Basal ROS and antioxidant enzyme activities were greater in the colon than the small intestine, and the balance of ROS to antioxidant enzymes in the colon was more pro-oxidant than in the small intestine. During oxidative stress, ROS and oxidative DNA damage were greater in the colon than the small intestine. Thus the colon responds to oxidative stress less effectively than the small intestine, possibly contributing to increased cancer incidence at this site. We next wanted to understand how diets containing a combination of fish or corn oil and pectin or cellulose may alter the redox environment of the colon. ROS, oxidative DNA damage, antioxidant enzyme activity and apoptosis were measured in colonocytes of rats fed one of four diets containing either corn oil or fish oil and cellulose or pectin. Measurements were madein rats untreated with carcinogen and rats exposed to a chemical carcinogen and radiation. In rats not treated with a carcinogen, fish oil enhanced ROS, and fish oil/pectin suppressed antioxidant enzymes as compared to corn oil/cellulose. Oxidative DNA damage was inversely related to ROS in the fish oil/pectin diet and apoptosis was enhanced relative to other diets. In carcinogen treated and irradiated rats, a similar protective effect was seen with fish oil/pectin as evidenced by a reduction in oxidative DNA damage and enhancement of apoptosis. This suggests that a diet containing fish oil/pectin may protect against colon carcinogenesis by modulation of the redox environment to promote apoptosis and minimize oxidative DNA damage.Item Effects of High Dietary Iron and Gamma Radiation on Oxidative Stress and Bone(2013-04-19) Yuen, Evelyn PAstronauts in space flight missions are exposed to increased iron (Fe) stores and galactic cosmic radiation, both of which independently induce oxidative stress. Oxidative stress can result in protein, lipid, and DNA oxidation. Recent evidence has linked oxidative stress to bone loss with aging and estrogen deficiency. Whether the increased iron stores and radiation that astronauts face are exacerbating their extreme bone loss while in space is unclear. We hypothesized that elevated iron levels (induced by feeding a high iron diet) and gamma radiation exposure would independently increase markers of oxidative stress and markers of oxidative damage and result in loss of bone mass, with the combined treatment having additive or synergistic effects. Male Sprague-Dawley rats (15-weeks old, n=32) were randomized to receive an adequate (45 mg Fe/kg diet) or high (650 mg Fe/kg diet) Fe diet for 4 weeks and either 3 Gy (8 fractions, 0.375 Gy each) of 137Cs radiation (?RAD) or sham exposure every other day over 16 days starting on day 14. Serum Fe and catalase and liver Fe and glutathione peroxidase (GPX) were assessed by standard techniques. Immunostaining for 8-hydroxy-2-deoxyguanosine (8-OHdG, marker of DNA adducts) quantified the number of cells with oxidative damage in cortical bone. Bone histomorphometry assessed bone cell activity and cancellous bone microarchitecture in the metaphyseal region. Ex vivo pQCT quantified volumetric bone mineral density (vBMD); bone mechanical strength was assessed by 3-pt bending at the midshaft tibia and compression of the femoral neck. High Fe diet increased liver Fe and decreased volume per total volume (BV/TV). ?RAD decreased osteoid surface per bone surface (OS/BS) and osteocyte density. The combined treatment increased serum catalase, liver GPX, and serum iron and decreased cancellous vBMD and trabecular number (Tb.N). High Fe diet and ?RAD independently increased number of osteocytes stained positive for 8-OHdG, with the combined treatment exhibiting twice as many osteocytes positively stained compared to the control. Higher serum Fe levels were associated with higher oxidative damage (r =0.38) and lower proximal tibial cancellous vBMD (r =?0.38). Higher serum catalase levels were associated with higher oxidative damage (r =0.48), lower BV/TV (r =?0.40) and lower cancellous vBMD (r =?0.39). High dietary iron and fractionated 137Cs ?RAD leads to a moderate elevation in iron stores and results in oxidative damage in bone and are associated with decreased cancellous bone density. Moderate elevations in iron stores are not only found in astronauts, but also naturally occur in healthy human populations. This healthy population with elevated iron stores may also have increased levels of oxidative stress in the body. Elevated levels of oxidative stress not only increase one?s risk for accelerated bone loss, but also the risk of developing other chronic diseases such as insulin resistance, hypertension, dyslipidemia, and metabolic syndrome.Item Estimating the exposure to first receivers from a contaminated victim of a radiological dispersal device detonation(2009-05-15) Phillips, Holly AnneThe threat of a Radiological Dispersal Device (RDD) detonation arouses the concern of contaminated victims of all ages. The purpose of this study was to investigate the dose to a uniformly contaminated five-year old male. It also explores the exposure rates surrounding the victim to be used by first receivers to estimate their exposure from the victim. The victim was modeled as an anthropomorphic phantom using the BodyBuilder program. A thin layer of source material was added to the surface of the phantom?s skin to simulate whole-body contamination. The computer code MCNP5 was used to tally the doses to the individual organs of the phantom and create a mesh to generate contour exposure rate lines. Using an activity of 37 GBq m-2, the five-year-old victim received an effective dose 158.23 mSv in one hour. Contour lines were produced that showed the exposure rates around the victims ranging from 0.5 to 10 R/h. The contour exposure-rate contour lines were also generated after the removal of contaminated clothing. Removing the victim?s clothing reduced the exposure rates by eighty percent.Item Experiments for the Measurement of LNG Mass Burning Rates(2012-07-16) Herrera Gomez, Lady CarolinaLiquefied Natural Gas (LNG) is a commonly used flammable fuel that has safety concerns associated with vapor dispersion and radiation emitted from pool fires. The main objective of this effort is to advance the knowledge of pool fires and to expand the data that is commonly used to validate semi-empirical models. This includes evaluation of the methods that are utilized to obtain experimental values of mass burning rates, which are used in models where semi-empirical correlations cannot be applied. A total of three small-size experiments designed to study the radiative characteristics of LNG pool fires were carried out at Texas A & M University's Brayton Fire Training Field (BFTF). This set of experiments was designed to study how the heat feedback from the fire to the pool surface is subsequently distributed through the liquid volume and the validity of different methods for measuring burning rates. In this work, a number of semi-empirical correlations were used to predict the characteristics of the flame and examine the predictive accuracy of these correlations when compared to the values obtained experimentally. In addition, the heat transferred from the energy received at the pool's surface to the surroundings was investigated. Finally, the parameters that influenced the measurement of radiative head feedback to the liquid pool were analyzed to investigate potential causes of calibration drift in the instrumentation. The results of this work provided information regarding the validity of certain techniques for the measurement of mass burning rates and the use of correlations to predict the characteristics of an LNG pool fire on a small-scale. The findings from this work indicate that the energy received at the liquid surface was used entirely for evaporation and no indications of transmission to the surroundings were observed. Lastly, it was found that during the experiments, the sink temperature of the sensor was not constant, and therefore, the readings of the radiative heat were unreliable. This was due to the insufficient cooling effect of the water circulated. It was later shown in the laboratory that through a series of qualitative tests, a change of 20?C in the cooling water resulted in a calibration drift.Item Improving Targeted Radionuclide Therapy Using Nuclear Nanotechnology(2013-05-03) Evans, Jordan AndrewThe objectives of this thesis are to produce radioactive antibody-conjugated gold nanoparticles to improve the efficacy of targeted radionuclide therapy for the treatment of cancer, and to demonstrate that this product can be produced at Texas A&M University. We have proposed a method for determining the distribution of radioactive nuclei per nanoparticle, which is critical for determining radiotherapeutic efficacy. Using the distribution of radioactive nuclei per nanoparticle, we have produced methods for calculating the radiative dose to tissue using nano-improved targeted radionuclide therapy, but more importantly we propose procedures to experimentally determine the efficacy of targeted radionuclide therapy improved by application of radioactive nanomaterials in combination with immunotherapy, nanomaterial cytotoxicity, and other cancer therapies such as chemotherapy. These methods can also be used to determine the efficacy of combinatory treatments as a function of time. Characterization of the antibody-nanoparticle attachment is critical; we have demonstrated successful antibody-nanoparticle conjugation using atomic force microscopy, dynamic light scattering, and agarose gel electrophoresis, providing more conclusive evidence of successful conjugation compared to flow cytometry. We provide a mathematical derivation from basic electron-transport principles which demonstrates the theoretical dosimetric advantages of applying radioactive nanomaterials to targeted radionuclide therapy. The general formulae can be applied to any tumor size, any radionuclide, and any pharmacokinetic nanoparticle distribution throughout the body, ultimately allowing a quick method of approximating the necessary activation time and treatment dosage parameters for a specific patient without burdensome Monte Carlo computational simulations. We further demonstrated that nano-TRT dosage to tumors should be considered as a function of radial position rather than average, as the dose across the tumor may be noticeably non-uniform causing some portions of the tumor to receive (potentially) significantly less dose than average.Item Low dose radiation interations with the transformation growth factor (TGF)-beta pathway(2009-05-15) Maslowski, Amy JesseA major limiting factor for long-term, deep-space missions is the radiation dose to astronauts. Because the dose to the astronauts is a mixed field of low- and high-LET radiation, there is a need to understand the effects of both radiation types on whole tissue; however, there are limited published data on the effects of high-LET (linearenergy- transfer) radiation on tissue. Thus, we designed a perfusion chamber system for rat trachea in order to mimic in vivo respiratory tissue. We successfully maintained the perfused tracheal tissue ex vivo in a healthy and viable condition for up to three days. In addition, this project studied the effects of high-LET Fe particles on the overall transformation growth factor (TGF)-beta response after TGF-beta inactivation and compared the results to the TGF-beta response post x-ray irradiation. It was found that a TGF-beta response could be measured in the perfused tracheal tissue, for x-ray and Fe particle irradiations, despite the high autofluorescent background intrinsic to tissue. However, after comparing the TGF-beta response of x-ray irradiation to High-Z-Highenergy (HZE) irradiation, there was not a significant difference in radiation types. The TGF-beta response in x-ray and HZE irradiated perfusion chambers was also measured over time post irradiation. It was found that for 6 hour and 8 hour post irradiation, the TGF-beta response was higher for lower doses of radiation than for higher doses. This is in contrast to the 0 hour fixation which found the TGF-beta response to increase with increased dose. The inverse relationship found for 6 hour and 8 hour fixation times may indicate a threshold response for TGF-beta response; i.e., for low doses, a threshold of dose must be reached for an immediate TGF-beta response, otherwise the tissue responds more slowly to the irradiation damage. This result was unexpected and will require further investigation to determine if the threshold can be determined for the 250 kVp x-rays and 1 Gev Fe particles.Item Mechanical Properties, Thermal Stability and Radiation Damage of Ferritic Steels Processed by Thermal Mechanical Treatments(2014-08-04) Song, MiaoThe dramatically increasing demand for energy stimulates scientists all over the world to consider the possible ways to meet future energy needs. The application of atomic energy has been demonstrated to be a reliable, economic, and environmental friendly choice by the reactors operating today for half century. Lessons have been learned during the operation of generation I-III reactors. To avoid an unanticipated failure, high performance structural materials still represent a crucial component for extending the operation life of current reactors and the design of generation IV nuclear reactors and future fusion reactors. Due to their superior radiation tolerance, ferrite steels are currently the primary candidate under examination for generation IV or future fusion reactors. Whereas considerable data have been published on modification of the chemical composition of ferrite steels and evaluation of their overall performance, few attempts have been tried to process the existing ferrite steels by plastic deformation and evaluate the performance and properties improvements. The deformation technique introduced here is equal channel angular extrusion (ECAE). During ECAE, severe shear strain (on the order of several hundred percent) is introduced into a material by extrusion through a channel of constant cross section that contains an abrupt angle. The work presented in this dissertation is an attempt to apply ECAE to reactor steels of interest-namely T91 and 12Cr ODS. T91 (modified 9Cr-1Mo steel) is widely used and a commercialized material. 12Cr ODS is an oxide dispersion strengthened ferrite steel developed based on the reduce activation concept and targeted for cladding at elevated temperature. The pros and cons for such an approach were evaluated based on the influence of such a plastic deformation on mechanical performance, thermal stability and radiation damage or tolerance. In general, ECAE processed materials show improved strength and radiation tolerance. However, thermostability and ductility are sacrificed. The latter is not a potential problem because during service at elevated temperatures, the ECAE processed materials can regain ductility within a short period. Attention should be paid to the degeneration of thermostability after ECAE deformation.Item Mutable Detector Array Software for the Detection of Gamma Emissions in Classrooms and the Field(2012-10-19) Hearn, Gentry CharlesDetector arrays are required for many applications in health and defense. Whether searching for contraband or controlling radioactive spread after an event, a "passive" data collection strategy is a key component. This can take the form of portal monitors attached to a fixed location or a movable array, attached to a vehicle or person, which searches for abnormalities in the radiation background. The main goal of this project was to create software that would allow the digiBASE-E to be used to create arrays of gamma detection instruments and gather data over a long span of time. To take full advantage of the digiBASE-E, the software focused on the list mode capabilities of these devices. List mode attaches a timestamp to each detection event. Every particle detected can be traced to a particular point in time, and the full history of the device?s detection over the acquisition period can be reconstructed. The list mode ability of the digiBASE-E is a powerful tool for producing arrays of detectors, as a more familiar spectrum can be generated for any arbitrary section of time, even after-the-fact. The software package, called "CraneWow", was field tested at the Port of Tacoma in August of 2011. Perl scripts included as part of the package were used to partially analyze the data collected, allowing for verification of the proof-of-concept's success. The software was written in C/C++, with supplemental scripts written in Perl to facilitate processing of the data once collected. Additionally, a user manual and programming guide were written to allow easy use and maintenance of the software.Item Radon (Rn-222) and thoron (Rn-220) emanation fractions from three separate formations of oil field pipe scale(Texas A&M University, 2004-11-15) Fruchtnicht, Erich HaroldOver the course of normal oil well operations, pipes used downhole in the oil and petroleum industry tend to accumulate a mineral deposit on their interior, which restricts the flow of oil. This deposit, termed scale, will eventually occlude the interior diameter of the pipe making removal from service and descaling a cost effective option. The pipes are sent to cleaning yards where they remain until descaling can be performed. This storage period can potentially create a health concern not only because of the external radiation exposure but also because of the radon gas emissions, both of which are due to the radioactive minerals contained in the scale. It was believed that the structure of the scale is formed tightly enough to prevent much of the radon from becoming airborne. The goal of this research was to determine the emanation fractions for the rattled scale samples from three formations. A high purity germanium detector was used to measure the activities of the parents and progeny of radon, and electret ion chambers were used to measure the concentration of radon emanated from the scale. The emanation fractions of between 4.9x10-5 and 1.08x10-3 for radon were a factor of approximately 100 smaller than previous research results. For thoron, the fractions were and 5.72x10-8 and 4.92x10-7 for thoron with no previous research to compare. However, information that pertains to the temperature dependence of emanation was included in this research and was not available for previous, similar research. Therefore, differences in the environment (e.g., temperature, humidity, etc.) in which the previous experiments were conducted, as well as differences in the scale formation types used, could account for the discrepancy. In addition, measuring the emanation fractions of the rattled scale was a method of determining whether surface to volume ratio dependence existed. After acquiring the emanation fractions, insufficient evidence of any surface to volume ratio dependence could be found.Item The effects of diet and ionizing radiation on azoxymethane induced colon carcinogenesis(Texas A&M University, 2006-10-30) Mann, John CliffordThe ability of ionizing radiation to enhance colon carcinogenesis and the role of diet in this process has not been documented. We hypothesized that radiation would enhance the formation of aberrant crypt foci, ACF, known precursor lesions to colon cancer, by suppressing apoptosis and upregulating proliferation in colonocytes. Diets contained a combination of fish oil or corn oil and either pectin or cellulose. We exposed 40 male Sprague-Dawley rats to 1 Gy ionizing radiation (1 GeV Fe) 10 d prior to injection with AOM. Colons were resected at the promotion stage of carcinogenesis (7 wk post initial injection) and assayed for ACF and apoptosis. Radiation treatment increased (P=0.0327) the incidence of high multiplicity ACF (foci with four or more aberrant crypts) and decreased (P=0.0340) the apoptotic index compared to non-irradiated rats. Radiation also resulted in an increase (P<0.0001) in the proliferative index compared to the nonirradiated rats. The fish oil containing diets resulted in fewer (P=0.0002) high-multiplicity ACF compared to the corn oil treatment. Dietary pectin significantly increased (P=0.0204) the apoptotic index compared to cellulose treatment. These data suggest that ionizing radiation can work synergistically with AOM and increase the formation of high-multiplicity ACF, upregulate cellular proliferation and decrease apoptosis in colonocytes. The data also suggest that diets containing fish oil and pectin may protect against colon cancer by increasing apoptosis and reducing the formation of high multiplicity ACF.Item Wave Energy Extraction from an Oscillating Water Column in a Truncated Circular Cylinder(2013-07-19) Wang, HaoOscillating Water Column (OWC) device is a relatively practical and convenient way that converts wave energy to a utilizable form, which is usually electricity. The OWC is kept inside a fixed truncated vertical cylinder, which is a hollow structure with one submerged open end in the water and with an air turbine at the top. The research adopts potential theory and Galerkin methods to solve the motion of the OWC. Based on the air-water interaction model, optimal OWC design for energy extraction from regular wave is explored. The hydrodynamic coefficients in scattering and radiation potential are solved using Galerkin approximation. The numerical results for the free surface elevation have been verified by a series of experiments conducted in the University of New Orleans Towing Tank. The effect of geometric parameters on the response amplitude operator (RAO) of OWC is studied and amendment of the equation for evaluating the natural frequency of the OWC is made. Using the model of air-water interaction under certain wave parameters and OWC geometric parameters, a computer program OWC Solution is developed to optimize the energy output from the system. Optimization results by the program OWC Solution lead to an effective method to design the OWC system.