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Jung, Jae Won, 1969- (Texas A&M University, May 2003)[more][less]
Abstract: A beta-emitting glass seed was proposed for the brachytherapy treatment of prostate cancer. Criteria for seed design were derived and several beta-emitting nuclides were examined for suitability. 142Pr was selected as the isotope of choice. Seeds 0.08 cm in diameter and 0.9 cm long were manufactured for testing. The seeds were activated in the Texas A&M University research reactor. The activity produced was as expected when considering the meta-stable state and epi-thermal neutron flux. The MCNP5 Monte Carlo code was used to calculate the quantitative dosimetric parameters suggested in the American Association of Physicists in Medicine (AAPM) TG-43/60. The Monte Carlo calculation results were compared with those from a dose point kernel code. The dose profiles agree well with each other. The gamma dose of 142Pr was evaluated. The gamma dose is 0.3 Gy at 1.0 cm with initial activity of 5.95 mCi and is insignificant to other organs. Measurements were performed to assess the 2-dimensional axial dose distributions using Gafchromic radiochromic film. The radiochromic film was calibrated using an X-ray machine calibrated against a National Institute of Standards and Technology (NIST) traceable ion chamber. A calibration curve was derived using a least squares fit of a second order polynomial. The measured dose distribution agrees well with results from the Monte Carlo simulation. The dose was 130.8 Gy at 6 mm from the seed center with initial activity of 5.95 mCi. AAPM TG-43/60 parameters were determined. The reference dose rate for 2 mm and 6 mm were 0.67 and 0.02 cGy/s/mCi, respectively. The geometry function, radial dose function and anisotropy function were generated. URI: http://handle.tamu.edu/1969.1/5738 Files in this item: 1
etd-tamu-2007A-NUEN-Jung.pdf (2.847Mb) -
Hoskins, Sara Grace (Texas A&M University, December 2003)[more][less]
Abstract: Within the collections of the Museu de Angra do Heroismo (Terceira Island, Azores, Portugal) are nine cast bronze guns from the 16th century. Most were raised from the seafloor between the 1960s and 1990s, but this study comprises the first in-depth research into their design and manufacture. The importance of this kind of study lies in the fact that ordnance is commonly found on shipwrecks of this time. A greater knowledge of guns will help provide information about the ships from which they came. Careful documentation and study of the Museu de Angra cannon will add greatly to their value as museum exhibits, by allowing museum patrons to better understand where the guns came from, how they were cast, and why they were important. This documentation adds to our knowledge of Western European gunfounding technology during the sixteenth century, as four different countries commissioned the guns: Portugal, Spain, France, and England. With detailed documentation and publication, the Museu de Angra bronze guns can be added to the bibliography of ordnance of this period, which will aid future researchers who encounter similar pieces. The Museu de Angra bronze guns, as symbols of the military and naval power of the countries that commissioned them, were sent aboard ships, into the field, and mounted on fortress walls. Bronze guns of this time period are particularly important, as bronze was an expensive commodity, and the demand for ordnance was increasing rapidly. Countries developed more effective ways to make use of iron for the founding of guns, and the use of bronze became more symbolic of wealth. The information that each gun contains includes both the cutting-edge military technology of the time and the artistic statement of the founder. Some of the finest metalwork of the period was displayed in cast bronze guns, and due to the founding techniques, no two are the same, making each an important piece of history. URI: http://handle.tamu.edu/1969.1/556 Files in this item: 1
etd-tamu-2003C-ANTH-Hoskins-1.pdf (10.11Mb) -
Stefanou, Nikolaos, 1978- (Texas A&M University, May 2006)[more][less]
Abstract: Hard disk drive applications require a high Spurious Free Dynamic Range (SFDR), 6-bit Analog-to-Digital Converter (ADC) at conversion rates of 1GHz and beyond. This work proposes a robust, fault-tolerant scheme to achieve high SFDR in an av- eraging flash A/D converter using comparator chopping. Chopping of comparators in a flash A/D converter was never previously implemented due to lack of feasibility in implementing multiple, uncorrelated, high speed random number generators. This work proposes a novel array of uncorrelated truly binary random number generators working at 1GHz to chop all comparators. Chopping randomizes the residual offset left after averaging, further pushing the dynamic range of the converter. This enables higher accuracy and lower bit-error rate for high speed disk-drive read channels. Power consumption and area are reduced because of the relaxed design requirements for the same linearity. The technique has been verified in Matlab simulations for a 6-bit 1Gsamples/s flash ADC under case of process gradients with non-zero mean offsets as high as 60mV and potentially serious spot offset errors as high as 1V for a 2V peak to peak input signal. The proposed technique exhibits an improvement of over 15dB compared to pure averaging flash converters for all cases. The circuit-level simulation results, for a 1V peak to peak input signal, demon- strate superior performance. The reported ADC was fabricated in TSMC 0.18 ??mCMOS process. It occupies 8.79mm2 and consumes about 400mW from 1.8V power supply at 1GHz. The targeted SFDR performance for the fabricated chip is at least 45dB for a 256MHz input sine wave, sampled at 1GHz, about 10dB improvement on the 6-bit flash ADCs in the literature. URI: http://handle.tamu.edu/1969.1/2469 Files in this item: 1
etd-tamu-2005A-ENGR-Stefanou.pdf (1.120Mb) -
Ayala, Julio Enqrique, II, 1979- (Texas A&M University, December 2005)[more][less]
Abstract: Recently, there is a growing interest in applying electronic circuit design for biomedical applications, especially in the area of nuclear magnetic resonance (NMR). NMR has been used for many years as a spectroscopy technique for analytical chem- istry. Previous studies have demonstrated the design and fabrication of planar spiral inductors (microcoils) that serve as detectors for nuclear magnetic resonance mi- crospectroscopy. The goal of this research was to analyze, design, and test a prototype integrated sensor, which consisted of a similar microcoil detector with analog components to form a multiple-channel front-end for a magnetic resonance imaging (MRI) system to perform microspectroscopy. The research has succeeded in producing good function- ality for a multiple-channel sensor. The sensor met expectations compared to similar one-channel systems through experiments in channel separation and good signal-to- noise ratios. URI: http://handle.tamu.edu/1969.1/4729 Files in this item: 1
etd-tamu-2005C-ELEN-Ayala.pdf (1.933Mb) -
Kaltenberg, Amanda May, 1980- (Texas A&M University, December 2004)[more][less]
Abstract: A hull-mounted 38-kHz phased-array acoustic Doppler current profiler (ADCP) was used to acoustically survey the continental margin of the northern Gulf of Mexico (GOM) during 6 cruises in 2002-2003. This is the first backscatter survey with a 38-kHz ADCP in the Gulf of Mexico. ADCPs have been used as a proxy to measure the volume backscatter return from plankton in the water column, however previous studies were restricted to the upper 200 to 300 meters due to the relatively high frequency of operation (150-300 kHz) of the transducers. In addition to measuring deep water current velocities, the 38-kHz phased-array ADCP can measure Relative Acoustic Backscatter Intensity (RABI) as deep as 1000 meters. The daytime depth of the main deep scattering layer at 400 to 500 meters was resolved, and locally high backscatter intensity can be seen down to 800 meters. The objectives were to determine how to analyze RABI from the instrument to resolve scattering layers, and then to seek secondary deep scattering layers of potential prey species below the main deep scattering layer, from 600 to 800 meters in the feeding range for Gulf of Mexico sperm whales. Based on RABI from the 38-kHz ADCP, secondary DSLs in sperm whale diving range were more commonly recorded over the continental shelf than in the deep basin region of the Gulf of Mexico. The daytime depths of migrating plankton showed variation depending on physical circulation features (cyclone, anticyclone, proximity to Mississippi river, and Loop Current) present. Vertical migrations compared between concurrently running 38 and 153-kHz ADCPs showed an overlap of acoustic scatterers recorded by the two instruments, however the 153-kHz instrument has much finer vertical resolution. Vertical migration rates were calculated and simultaneous net tow samples from one of the cruises was used to compare abundance estimates by the two methods. URI: http://handle.tamu.edu/1969.1/1387 Files in this item: 1
etd-tamu-2004C-2-OCNG-Kaltenbe.pdf (1.442Mb) -
Zhuang, Wei, 1974- (Texas A&M University, May 2003)[more][less]
Abstract: A three dimensional (3-D) capacitance extraction algorithm based on a kernel independent hierarchical method and geometric moments is described. Several techniques are incorporated, which leads to a better overall performance for arbitrary interconnect systems. First, the new algorithm hierarchically partitions the bounding box of all interconnect panels to build the partition tree. Then it uses simple shapes to match the low order moments of the geometry of each box in the partition tree. Finally, with the help of a fast matrix-vector product, GMRES is used to solve the linear system. Experimental results show that our algorithm reduces the linear system's size greatly and at the same time maintains a satisfying accuracy. Compared with FastCap, the running time of the new algorithm can be reduced more than a magnitude and the memory usage can be reduced more than thirty times. URI: http://handle.tamu.edu/1969.1/5794 Files in this item: 1
etd-tamu-2006A-CEEN-Zhuang.pdf (1.740Mb) -
Malagon Nieto, Camilo, 1978- (Texas A&M University, May 2003)[more][less]
Abstract: The complex interrelations among the different physical processes involved in acid fracturing make it difficult to design, and later, to predict the outcome of stimulation jobs. Actual tendencies require the use of computational models to deal with the dynamic interaction of variables. This thesis presents a new study of acidized surface textures by means of a laser profilometer to improve our understanding of the remaining etched surface topography and its hydraulic response. Visualization plots generated by the profilometer identified hydrodynamic channels that could not be identified by the naked eye in acidized surfaces. The plots clarified the existence of rock heterogeneities and revealed how the processes of dissolution function in chalk rock. Experimental data showed clearly that the effect of dissolution depends on the type of rock and the fluid system; dolomite, for example, dissolves more rapidly but more roughly than limestone. Fluid leakoff rate and temperature also affect the dissolution. Further research is necessary to clarify the effects of conductivity. URI: http://handle.tamu.edu/1969.1/5771 Files in this item: 1
etd-tamu-2007A-PETE-Malagon.pdf (35.27Mb) -
Anderson, Christopher Dean, 1979- (Texas A&M University, December 2003)[more][less]
Abstract: The purpose of this project is to develop a software framework, a 3D engine, which will generate images to be projected onto facets of a spatially immersive display (SID). The goal is to develop a software library to support the creation of images of specified 3D environments which are specific to the display geometries of a polyhedral class of SIDs. Part of this goal is developing auxiliary software to allow this library to be thoroughly tested. When properly working, the images being displayed on adjoining faces of the SID appear spatially and temporally consistent with one another, creating the illusion that the user is within a surrounding three-dimensional space. URI: http://handle.tamu.edu/1969.1/1307 Files in this item: 1
etd-tamu-2003C-VIZA-Anderson-1.pdf (2.118Mb) -
Lau, Ryan, 1981- (Texas A&M University, May 2003)[more][less]
Abstract: Relatively little is known about marine controlled-source electromagnetic surveys (MCSEM) used to detect hydrocarbon reservoirs. Typical MCSEM require the use of inversion to generate a model of the subsurface. We utilize a 3D finite-element forward model to simulate a MCSEM survey. With the results we were able to determine the strengths and weaknesses of each transmitter and receiver configuration that would best detect a shallow hydrocarbon target. Careful selection of the correct configuration is important as we have found that incorrect transmitter orientation, offset and receiver measurement component can yield misleading results. Using the ideal configuration we were able to directly image the hydrocarbon target without the use of inversion modeling. The direct image is able to show the hydrocarbon target's shape and edges without any ambiguity. The direct image of the target can potentially be used to refine 3D inversion modeling, or be used in conjunction with seismic profiles to refine seismic picks. URI: http://handle.tamu.edu/1969.1/5790 Files in this item: 1
etd-tamu-2006A-GEOP-Lau.pdf (384.0Kb) -
Naz, Asma, 1971- (Texas A&M University, December 2004)[more][less]
Abstract: The objective of my research is to revive and practice the art of traditional pictorial maps in 3D cartographic visualization. I have chosen to create both graphical and statistical pictorial maps which can be used for the purpose of tourism and data representation respectively. Some traditional hand-drawn and sculptural pictorial maps of famous artists have been picked out to start as a base for my work. The goal was to recreate or imitate the style, character and features of these traditional hand-drawn and sculptural maps with 3D computer graphics and to analyze how effectively 3D tools can be used to communicate map information. I also wanted to explore ways to make these maps interactive on the Web and have them accessible to a large number of viewers. The results show a number of interactive 3D pictorial maps of different countries and continents. These maps are initially built with Maya, a 3D modeling software, and converted into web pages using the Viewpoint Technology. For statistical maps, Mel scripts have been used in Maya to take input from the user and change the shape of models accordingly to represent data. These maps are interactive and navigable and are designed to be easily accessible on the Web. URI: http://handle.tamu.edu/1969.1/1571 Files in this item: 1
etd-tamu-2004C-VIZA-Naz.pdf (3.134Mb) -
Thomas, Ryan Douglas (Texas A&M University, August 2003)[more][less]
Abstract: In the northern Gulf of Mexico, seafloor hydrocarbon fluid and gas seepage is an ubiquitous process on the continental margin. Although seafloor seepage and seep-related features (mud volcanoes, carbonate formation) have been studied for many years, little is known about their mechanisms of formation and the relationship of sub-surface structure to current seep activity. In this study, we examined three seafloor seeps in the Garden Banks and Mississippi Canyon areas using exploration and reprocessed 3D multi-channel seismic (MCS) data augmented with side-scan sonar (Garden Banks site) to characterize hydrocarbon seep activity and develop an understanding of the processes that led to their formation. Side-scan sonar data provided high resolution coverage of the seafloor while the exploration seismic data were used to image near and deep sub-surface features. Additionally, the 3D amplitude extraction maps were useful in delineating amplitude anomalies often associated with seep related activity. The reprocessed 3D seismic data were used to map in greater detail near seafloor features and amplitude anomalies. Using remote sensing geophysical data, we were effectively able to map sub-surface features such as salt topography, seep-related faults and geophysical indicators of hydrocarbons and correlate them with seafloor amplitude anomalies and fault traces in order to characterize seep activity level. The southern mud volcano in the Garden Banks site is characterized as an established high flux seep vent owing to signs of active seepage and sediment flows as well as the build-up of hard grounds. The northern mud volcano in the area, with greater hard ground build-up and fewer signs of active seepage represents an established low flux seep vent. In the Mississippi Canyon area, the data suggest that the seep mound can be characterized as a mature high flux vent due to the extensive build-up of hard ground, evidence of gas hydrates and signs of active seepage and sediment flows. The mechanisms of formation are similar between the two study sites. Upwelling salt appears to have fractured the sub-surface leading to the formation of fault induced depressions. Mapping of geophysical indicators of hydrocarbons implies that hydrocarbon migration is occurring along bedding planes to the fault systems underlying the depressions. Here they appear to migrate vertically to the seafloor creating the topographic features and seafloor amplitude anomalies that characterize the seeps URI: http://handle.tamu.edu/1969.1/1176 Files in this item: 1
etd-tamu-2003B-2003070408-Thom-1.pdf (4.113Mb) -
Arzuman, Sadun (Texas A&M University, December 2002)[more][less]
Abstract: In this study, the structure, depositional system, and the seismic stratigraphy of the VLE 196 area, Block V in Lamar Field were interpreted using 3-D seismic data and well logs to characterize structural and depositional settings of the Guasare-Misoa interval. To demonstrate structural settings of the study area 3-D seismic data were interpreted. Three main seismic reflectors, which are the Late Eocene unconformity, Guasare, and La Luna formations, were picked. The most dominant structure in the area is the VLE 400 Fault which was interpreted as a left-lateral strike-slip reverse fault due to its behaviors as a reverse fault in cross sections and as a strike-slip fault in strike sections. The VLE 400 Fault subdivides the VLE 196 area into two main structural blocks, a downthrown block in the western part and the upthrown block in the eastern part of the field where the hydrocarbons were trapped. Several en echelon normal and reverse faults were located along the both sides of the area. The main importance of these faults are that they fractured the La Luna source rock and created migration pathways through the reservoir layers of the Misoa Formation. To interpret depositional system of the Guasare-Misoa interval, tops of the C4 and C5 intervals and associated C4 layers were picked based on well logs and lithofacies maps were prepared. The results of this part of the study show that the sandstones of the Misoa Formation are delta front and fluvial/distributary channel facies of delta system. The net sand thickness map of the C4 interval also exhibits southeast northwest contour patterns reflecting depositional axes in the area. Shaly units of the C4 interval interpreted as potential seals and are of variable thickness and extend. Seismic stratigraphic interpretation of the area shows that the four main seismic facies are dominant which mainly represent the recent sediments, "C" sands of the Misoa Formation, underlying Colon and Mito Juan shales, and basement respectively. Some distributary eroded channel fill structures were also observed within the Misoa Formation, but they were not continuous through the area because of the intensive faulting. URI: http://handle.tamu.edu/1969.1/557 Files in this item: 1
etd-08192002-204126-1.pdf (9.269Mb) -
Yum, HoNam, 1976- (Texas A&M University, August 2004)[more][less]
Abstract: In this thesis, a 6-beam combiner using multiplexed holograms in dye-doped polymer is investigated. It is realized by recording six superimposed holographic gratings, which show uniform diffraction efficiency. The coupled wave theory for N superimposed gratings is more generalized and is used to analyze the amplitudes of diffracted waves in three different boundary conditions. Multiple-ring diffracted beam analysis is proposed to determine the dynamic range of a holographic material. The M/# is evaluated by recording a single hologram and counting the number of ring patterns in the diffracted beam. This analysis is extended to assess the equalized grating strength of N superimposed holograms. Six holograms with the equalized grating strength which can be assigned within the dynamic range of our material and show maximum diffraction efficiency are recorded. The phase locking of five beams to one reference beam is performed using PZT controller. The designs of lock-in amplifier, ramp generator and servo using commercial chips are demonstrated. The readout set-up used to split one single beam into six coherent copies is presented. The function of each part of the PZT controller in the readout set-up is discussed in detail. The intensity profile of an N-beam combiner is investigated by varying the phase angle between adjacent input waves. The entire solution which describes the amplitude of a combined beam is derived from generalized coupled wave theory. A simplified experimental set-up without a complicated PZT controller is demonstrated using a planoconvex lens. In order to provide six coherent light sources in future work, the injection locking of a single laser diode to the master laser diode is performed. An expected read-out setup is proposed to carry out both the achievement of six coherent sources and a 6 beam combination. URI: http://handle.tamu.edu/1969.1/2759 Files in this item: 1
etd-tamu-2004B-ELEN-Yum.pdf (1.690Mb) -
Bias, Joshua P., 1978- (Texas A&M University, December 2005)[more][less]
Abstract: The immediate effects of teasing on children and adolescents are well documented, but in recent years, the long-term effects of teasing on adults have gained research attention. Recollections of teasing during youth have been shown to be related to increased psychosocial distress during adulthood. The present study focused on replicating the findings of previous work, as well as expanding the existing knowledge base concerning teasing and adulthood. Eightyfour adult participants completed a questionnaire packet designed to measure teasing history and perception, and levels of depression, anxiety, self-esteem, and life satisfaction. Results indicated that recalled teasing experiences from youth are related to psychosocial distress in adulthood. Teasing experiences were related to increased rates of depression and anxiety, lower self-esteem, and reduced life satisfaction. Notable differences were also found between the frequency and focus content of teasing between youth and adulthood. Implications for practice and recommendations for future research are presented. URI: http://handle.tamu.edu/1969.1/4981 Files in this item: 1
etd-tamu-2005C-CPSY-Bias.pdf (236.1Kb) -
Frantzen, Michelle E. Gunn, 1977- (Texas A&M University, December 2005)[more][less]
Abstract: Application of surface wave plasma technology for effective abatement of environmentally harmful gases such as perfluorocompounds and chlorofluorocarbons is investigated. Perfluorocompounds (PFCs) are gases that contribute to forced global warming and have been favored for wafer etch and chamber clean applications in the semiconductor industry. Chlorofluorocarbons (CFCs) are ozone depleting gases that were used as refrigerants for commercial and domestic condensers and air conditioners, but current reserves still pose threats to environmental sustainability. Increased average global temperatures and further destruction of the ozone layer have prompted proposal of international initiatives such as the Montreal Protocols and the Kyoto Agreement to curtail emissions of such fugitive gases into the environment. These have increased the need for effective abatement technologies to control such emissions and include surface wave plasma abatement, the subject of this dissertation. Surface wave plasmas are considered high frequency non-equilibrium traveling wave discharges in contrast to the more frequently used standing wave discharges. The use of surface wave plasmas have the advantages of a variety of discharge vessel shapes, reproducibility of application, numerous operating conditions and large plasma volumes which ultimately produce low, molecular weight byproducts that are associated with high effective electron temperatures but low heavy particle temperatures. For these reasons, surface wave plasma abatement technology was developed for the destruction and removal of PFCs and CFCs. Results include final destruction and removal efficiencies (DREs) for octafluorocyclobutane greater than 99.8%, dichlorodifluoromethane greater than 99.995% and trichlorofluoromethane greater than 99.999% using moderate applied microwave powers of less than 2000 watts with the production of low molecular weight byproducts, such as CO2, CO, HF and HCl, that prevent environmentally harmful process emissions from entering the atmosphere. Characterizations of the initial and final products were accomplished by the use of Fourier transform infrared spectroscopy and quadrupole mass spectrometry to provide independent quantitative analyses of plasma processes. In addition to these analytical methods, Global_Kin a kinetic model, of plasma reactions were conducted and compared to all the experimental data determined in order to facilitate understanding of the chemistry involved in the surface wave plasma abatement applications studied. Basic plasma reaction mechanisms were determined for the abatement of octafluorocyclobutane and dichlorodifluoromethane. URI: http://handle.tamu.edu/1969.1/4734 Files in this item: 1
etd-tamu-2005C-CHEM-Frantzen.pdf (780.5Kb) -
Wongchai, Sasicha (Texas A&M University, December 2003)[more][less]
Abstract: The purpose of this study was to investigate the ability of the Kolbe A Index to predict learners' attitudes and achievements within a web-based training context. The Index is used to measure the conative capacities of individuals. The Index translates raw scores into four Action Modes: Fact Finder, Follow Thru, Quick Start, and Implementor. A web-based simulation of training on customer service excellence was created containing four modules designed to match the respective learning style of each of the four Action Modes suggested by the Kolbe Corporation. Research questions were as follows. To what extent do the four Kolbe A Index Action Modes predict 1) how well learners will like content formatted to match the learning styles of the four Modes, 2) how well learners will remember content formatted to match the learning styles of the four Modes, and 3) how well the learners will remember the content regardless of the format? Three experts in applications of the Kolbe A Index then validated the simulation. Five other experts, each with a Ph.D. in the social sciences, validated the evaluation of learners' attitudes and achievements. Then a pilot study to collect data for a reliability analysis was conducted. Sixty graduates from an international program in economics in Thailand participated in this study. Data were collected entirely through the Internet and in English. Multiple linear regression analyses with backward stepping method were performed to answer the research questions. Based on the limitations and data analyses of this study, the Kolbe A Index Action Modes did not predict how well learners liked content formatted to match the learning styles of the four Modes, how well learners remembered content formatted to match the learning styles of the four Modes, nor how well the learners remembered the content regardless of the format. More research is needed to explore how the Kolbe A Index Action Modes can be used to predict learners' attitudes and achievements. URI: http://handle.tamu.edu/1969.1/558 Files in this item: 1
etd-tamu-2003C-EHRD-Wongchai-1.pdf (648.6Kb) -
Wang, Michael Wei-Lueng, 1982- (Texas A&M University, May 2003)[more][less]
Abstract: The electron transport characteristics of Oligoaniline molecular junctions terminated with thiol-ends are analyzed with the density functional theory and the Green's function approach. The molecular junction consists of an Oligoaniline molecule attached to metal electrodes at each end. By applying an electric field, the molecule conducts a current that depends on either the molecular conformation or the ionization state. Ab initio optimization methods are performed on various Oligoaniline systems to analyze how different conformational changes are associated with different conductivities. The density functional theory and Green's function are used to calculate the density of states, transmission probability functions, and current-voltage calculations for each Oligoaniline system to complement the results from the molecular analysis. An inelastic tunneling spectrum analysis is also performed through frequency calculations to examine the different characteristics of each conducting state. Molecular orbits of each conformation was used to investigate further the relation between structure and electrical properties of the molecular junction. The combined results from the different calculations provided insight into the possible mechanisms for electron transfer throughout the junction. URI: http://handle.tamu.edu/1969.1/5914 Files in this item: 1
etd-tamu-2006A-CHEN-Wang.pdf (5.943Mb) -
Serpedin, Nesrin (Texas A&M University, December 2003)[more][less]
Abstract: The leaner mouse carries an autosomal recessive mutation in the α1A subunit of neuronal P/Q-type voltage gated calcium ion channels. Due to this mutation, the leaner mouse exhibits severe ataxia, absence seizures and paroxysmal dyskinesia. Mutations in this same gene in humans cause: episodic ataxia type 2, familial hemiplegic migraine, spinocerebellar ataxia type 6 and probably the newly recognized form of human inherited epilepsy. Decreased amplitude of calcium current in cerebellar Purkinje cells and decreased calcium buffering capacity suggest that failure of calcium homeostasis may lead to the neurodegeneration observed in these mutant mice. Both sexes are affected. Despite their neurological dysfunction, homozygous leaner mice are able to breed and produce viable offspring. The survival rate for these pups is highly correlated with early fostering to normal lactating dams. This thesis studies the reproductive dysfunction observed in female homozygous leaner mice and is divided into four parts: onset of puberty, estrous cycle, pregnancy and litter assessment, and hormone levels. We have discovered that the onset of puberty is precocious in leaner females compared to age-matched wild type females, and leaner mice spend more time in estrous than age-matched wild type females. Also, we have observed that leaner mice became pregnant less readily than wild type mice, but once pregnant, female leaner mice produced more pups per litter compared with wild type mice. The number of corpora lutea observed in leaner mice is greater than in wild type mice. In leaner mice, the number of corpora lutea in the ovary corresponding to the uterine horn with the highest number of offspring is larger than the number of corpora lutea found in the ovary corresponding to the other uterine horn. Radioimmunoassays of estradiol hormone levels at postnatal day 28 shows higher levels in leaner compared to age-matched wild type mice. However, at postnatal day 28, the luteinizing hormone levels are similar in both categories of mice. This study of reproductive dysfunction in leaner mice was performed to gain further understanding about the role of intracellular calcium ion signaling in neuronal regulation of reproductive processes in females. URI: http://handle.tamu.edu/1969.1/559 Files in this item: 1
etd-tamu-2003C-TOXI-serpedin-1.pdf (805.2Kb) -
Evetts, Elizabeth A.; Peterson, Jacqueline A. (September 30, 2009)[more][less]
Abstract: The above- and below-ground litter from fallen foliage and root exudates and their decomposition has an impact on forest soil. The objective of this research project was to determine the effect of above- and below-ground litter manipulation on the retention and release of dissolved organic carbon (DOC), dissolved organic nitrogen (DON), nitrate and ammonium in the soil profile at 0-5 and 5-15 cm depths. The soils were obtained from a Long Term Ecological Research site in the Sikfokut Forest in Hungary. The site is a mature oak forest and the soil has no organic layer; the leaf litter sits directly on the A horizon. There are six treatments applied to the soil: doubling of annual leaf litter (DL), doubling of annual wood litter (DW), removal of annual leaf litter (NL), removal of roots (NR), removal of leaf and roots (NI) and control (C). Each plot is 7 x 7 m, and each soil sample taken was 15 x 15 cm square. A stock solution of leaf litter was added in different concentrations to soils from each treatment in a 50 mL centrifuge tube. Because I was investigating retention or release of carbon and nitrogen, I inverted the tube gently over a period of 2 hours prior to centrifugation and removal of supernatant. The supernatant solution was analyzed for DOC, DON, ammonium and nitrate to determine retention and release values for each dependant upon the different treatments. The results of the study were interesting. Dissolved organic nitrogen was neither retained nor released in the 0-5 cm layer for any treatment yet nitrate, typically considered a mobile anion showed retention and release in this layer. In the 5-15 cm layer we had no retention or release of nitrate but dissolved organic nitrogen was retained and released between the solid and solution phases. URI: http://handle.tamu.edu/1969.1/88040 Files in this item: 1
Evetts_Approved_Thesis.pdf (131.3Kb) -
Shah, Diti, 1982- (Texas A&M University, August 2006)[more][less]
Abstract: Historical events captured in an abstract manner have the ability to produce a profound effect on the emotions. The purpose of this research is to create a time-based computer media work, using dialogue from playwright Anne Nelson's The Guys, based on the September 11, 2001 attacks on the World Trade Center in New York City, with emphasis on visual imagery, particularly the use of line and color, to enhance the dramatic and emotional content of the piece. The stylistic direction of the thesis work is greatly influenced by selected works of abstract expressionists Robert Motherwell and Franz Kline, whose artwork was shaped by the social backdrop of World War II. URI: http://handle.tamu.edu/1969.1/4448 Files in this item: 3
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