Digitized Theses and Dissertations (1922–2004)
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This collection contains Texas A&M University theses and dissertations written between 1922 and 2004.
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In 2004, the Texas A&M University’s Office of Graduate and Professional Studies (OGAPS) began requiring electronic submission of theses and dissertations. Prior to this, Texas A&M University theses and dissertations were bound and shelved at the University Libraries. The theses and dissertations in this collection were digitized by the University Libraries.
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Item Ancient Egyptian hull construction(1993) Haldane, Cheryl Ward; Bass, George F.,; Grider, Sylvia; MacGilvray, Daniel F.; Steffy, J. Richard; van Doorninck, Frederick H.,Nautical archaeological resources from ancient Egypt provide the most complete picture of boatbuilding traditions in the ancient world before the Classical period. Models, representations, economic and religious texts, and more than 20 wooden hulls allow us to trace the development of nautical technology in Egypt between 5,000 and 2,500 years ago. Although contact with Nubia, Palestine, and Syria is attested from the beginnings of the Early Dynastic Period, the idiosyncrasies of Egyptian hull construction, when viewed in light of later Mediterranean traditions, imply independent development and persistent use of native techniques to fasten planks and create stable, sturdy hulls. By studying how Egyptian hulls were built, and where they fit into the fabric of society, we can gain some sense of the complex solutions to practical problems faced by Egyptian shipwrights. Whether swift warships, giant cargo carriers, elaborate wooden imitations of papyrus rafts, or heavily laden seagoing vessels, Egyptian watercraft incorporated design and technological features as complex, and durable, as those of the more visible stone monuments of ancient Egypt.Item Ecological correlates of Harris' hawk grouping in southern Texas(2002) Appelt, Christopher Warren; Packard, Jane M.; De Young, Charles A.I surveyed Harris' hawk (Parabuteo unicinctus) grouping relative to rainfall and landscape patterns at eight southern Texas study sites during the fall non-breeding season. Objectives were to: I) determine relationships among landscape use, grouping and abundance across sites, 2) characterize variation in grouping associated with rainfall patterns in the brushland and grassland ecoregions of the study area, and 3) explore which landscape measures best explained within site variation in grouping, considering 3 spatial scales (mesohabitat, territory, home range). Although abundance was higher (17.1 ± 4.1 hawks/100km) than reported for more arid regions, observations of groups (>2 hawks) varied across sites (0.113 ± 0.037 groups/observation). Groups were not observed at 3 of 4 sites in the wetter, eastern grassland, where abundance was slightly lower than brushland. One grassland site with abundant hawks and groups was a drier, habitat fragment in a landscape devoid o f woody vegetation. Abundance correlated with grouping but not with the landscape variables measured. However, hawks were typically found in areas with less fragmented woody vegetation. Vegetation strata differed between random points and hawk locations at 5 sites, four of which had groups, but differences could not be generalized across sites. Sightings of 3 hawks were more likely to be at brushland than grassland locations (z = 2.34, p < 0.05). Larger groups (4-5 hawks) and groups with young-of-the-year were sighted infrequently with no differences between ecoregions. Two indices of grouping were significantly negatively correlated with rainfall recorded near each site in the same year, but not with indices o f rainfall during the previous year. Only subtle differences in landscape vegetation were found between areas around grouped and non-grouped Harris' hawk locations. I compared vegetation patterns at three ecologically appropriate scales. The greatest differences were observed at the finest scale (simulating mesohabitat), leading to hypotheses related to prey availability for this group-hunting predator and distribution of scarce resources (e.g., water). Results were interpreted relative to the Ecological Constraints Model predicting groups in harsh environments. To refine testable predictions from this model, I recommend using spatially explicit landscape measures to document distribution of resources relative to groups.Item Antiestrogenic and antimitogenic effects of 2,3,7,8-Tetrachlorodibenzo-para-dioxin (TCDD) : in vitro mechanistic studies(1993) Rowlands, Justin Craig; Safe, Stephen H.; Burghardt, Robert C.; Phillips, Timothy D.; Ramos, Kenneth S.2,3,7,8 -Tetrachlorodibenzo-p-dioxin (TCDD) is a broad spectrum antiestrogen which works through the aryl hydrocarbon (Ah) receptor. The estrogen receptor (ER) positive hum an ovarian carcinoma cell lines PE01, PE04 and PE06 expressed the Ah receptor with properties similar to the AhR from other human cells. However, TCDD-induced P450IA1 mRNA levels, ethoxyresorufin O-deethylase (EROD) activity and an AhR-DRE complex only in the PEO4 cells. 17β-Estradiol (E2) stimulated PEO4 and PEO6 cell proliferation and the E2-induced cell growth was suppressed by TCDD in both of these cell lines. These data show that TCDD exhibits antiestrogenic activity in ER-positive ovarian carcinoma cell lines which is not dependent on P450IA1 induction. The antiestrogenic and antimitogenic activity of TCDD was investigated in the E2 responsive MCF-7 hum an breast cancer cells. TCDD suppressed E2-, IGF-1-, Insulin-, E2 plus IGF-1- and E2 plus Insulin-induced cell proliferation. The steady-state mRNA levels for the ER and IGF-1 receptor were not effected by TCDD or any other treatments. However, TCDD inhibited E2-induced pS2 mRNA steady-state levels and the constitutive expresion of HER -2/neu receptor mRNA steady-state levels were suppressed after TCDD-treatment. TCDD-inhibited or suppressed E2-induced expression of immediate early oncogenes c-myc and c-fos and TPA and E2-induced AP-l-TRE binding. Alternatively, treatment of MCF-7 cells with TPA-inhibited TCDD-induced AhR-DRE binding and expression of Fos oncoprotein suppressed TCDD dependent AhR transactivation of a CAT reporter gene in both MCF-7 and Hepa 1c1c7 cells. Moreover, in Hepa 1c1c 7 cells, Fos and Jun inhibited the formation of a TCDD-dependent AhR-DRE complex and AhR was precipitated with Fos antibodies. These results were consistent with the formation of a nuclear Ah receptor-Fos complex and support a novel mechanism to explain some fo the antimitogenic and antiestrogenic effects of TCDD.Item Kinetic modeling of the Fischer-Tropsch synthesis(1990) Zimmerman, William H.; Bukur, Dragomir B.; Gadalla, Ahmed M.; Rosynek, Michael P.; Watson, Albert R.The objective of this work was to develop a kinetic model to describe the conversions and selectivity typical of iron based Fischer-Tropsch catalysts, and to apply the model in simulations of typical laboratory reactors. The model accounts for the formation of paraffins and olefins up to an arbitrary carbon number, and disappearance rates can be calculated from known stoichiometry. Equilibrium adsorption was assumed for CO, CO2, H2, and H2O, and accounts for product and reactant inhibition on rates. There was no significant difference in model results using a steady-state adsorption model and an equilibrium model, but the equilibrium model has the advantage of requiring fewer kinetic parameters. The final model requires 8 constants for Fischer-Tropsch, plus additional constants for water-gas shift kinetics (one in this study). Three types of reactors were considered: gas phase stirred tank and fixed bed (plug flow) reactors, and a stirred tank slurry reactor. The gas phase stirred tank is a simple, well defined reactor used in the model development, while the fixed bed reactor was chosen to represent the common laboratory fixed bed. The slurry reactor is another common laboratory reactor, but the reaction occurs on catalyst in the liquid phase formed by condensing the high molecular weight products of the reaction. Vapor-liquid equilibrium with simultaneous chemical reaction was used to account for the condensation. Non-Schulz-Flory distributions were obtained in the slurry reactor simulations due to olefin readsorption followed by chain growth. Higher concentrations of the high molecular weight olefins in the liquid phase cause the non-Schulz-Flory behavior. The adsorption also gives the trend of decreasing olefin content with carbon number expected from experiment. Both of the gas phase reactors (fixed bed and stirred tank) exhibited nearly classical Schulz-Flory distributions under most conditions. In the fixed bed, conversion increases along the length of the reactor, which leads to changes in selectivity with position. The integral effect of the selectivity profiles causes some carbon number dependence on α and olefin content, but the deviations from classical distributions are significant only at low carbon numbers...Item Fissure characteristics related to moisture adsorption stresses in rice(1994) Lan, Yubin; Kunze, Otto R.; Sweat, Vincent E.; Suter, Dwayne A.; Rooney, Lloyd W.Rice kernels may develop fissures due to internal stresses when subjected to moisture adsorbing environments. Rice kernels were initially conditioned to three equilibrium relative humidities (ERH) of 46, 62, and 80%, and then were exposed to high relative humidity (RH) environments of 65, 86, and 100% for different periods. All experiments were conducted at 21$spcirc$C. Results showed that grains equilibrated to 46 and 62% ERH would fissure when exposed to either 86 or 100% RH. For rice grains at 46% ERH, the cumulative percentage of fissured kernels (CPFK) increased as the exposure humidity increased with all of the kernels fissuring at 100% exposure humidity. The CPFK decreased sharply as the initial moisture level increased with no kernels developing fissures when rice grains at 80% ERH were exposed to 86 and 100% RH. The cumulative number of fissures (CNF) in rice grains increased with exposure RH and exposure time. The retardation times were analyzed by using the experimental values and finite element techniques. The moisture adsorption rates (MAR) for different forms of rice and RH were determined. The experimental results were compared with the finite element analysis. The moisture gradients in a rice kernel during moisture adsorption were calculated. The causes and characteristics of rice fissures from moisture stresses were investigated. The finite element method was used to obtain numerical solutions to the moisture diffusion equation and stress-strain relationship equation. Therefore, two finite element models were derived from the mathematical analysis. The first model solved the moisture diffusion within the rice kernel while the second simulated the internal expansion and contraction of the kernel and evaluated the magnitude of the local strains and stresses. The three major stress components, namely axial, radial, and tangential stresses were studied in relation to failure tensile strength and local strain energy density of distortion by the finite element program. Axial stresses are the primary reason for fissures to develop in a rice kernel; tangential stresses may cause a rice grain to fissure parallel to the longitudinal axis; radial stresses do not cause a rice grain to fissure. The largest tensile stresses occur at the center of a kernel where the fissure usually starts.Item Granulosa cell lines as models of ovarian carcinogenesis(1990) Stein, Lisa Sue; Burghardt, Robert C.; Stoica, George; Tiffany-Castiglioni, Evelyn; Wilson, Van G.Cell lines derived from rat ovarian granulosa cells were established as an epithelial model system for studies of in vitro transformation. A series of experiments focused on analysis of an unusual nuclear distribution of the oncogene products T-antigen and p53 in an SV40- transformed cell line, DC3. Antibodies to T-antigen and p53 were used in conjunction with morphological and biochemical approaches to explain the nature of these antigens in DC3 cells as compared to COS-1, an established SV40-transformed cell line. Approaches included indirect immunofluorescence, double immunolabelling, cell cycle analysis, confocal microscopy, immunogold electron microscopy, nuclear fractionation, Western blot analysis, and DNA transfection of SV40 genes into both primary granulosa and DC3 cells. The results suggested that the unusual distribution of T-antigen and p53 in DC3 cells appears to be characteristic of interphase and is probably not due to gross structural alterations in either protein. A second series of experiments focused on developing a series of cell lines representative of progressive steps in the multistep process of malignant transformation. Primary granulosa cells and a spontaneously immortalized cell line, SIGC, represented the normal state and an intermediate step in transformation, respectively. Several morphological and functional properties of SIGC were evaluated with respect to those of normal granulosa cells. Cell lines further in the transformation pathway were generated by transfecting SIGC with pSV3neo and from tumor explants of transfected cells from a nude mouse. A dye transfer technique showed that progressive stages of transformation were correlated with a progressive loss of gap junction mediated cell-cell communication. The results of this study suggest that the in vitro transformation model system consisting of several cell lines derived from ovarian granulosa cells may be useful for studies of the fundamental nature of transformation in cell types other than those of fibroblast origin. These studies include using DC3 cells for investigation of novel functions of T-antigen, and SIGC cells for transfection or infection with other oncogenes in order to investigate the impact of their expression on cell-cell communication and other growth properties in an epithelial model system.Item Attitudes of small-scale fishermen in Pangandaran, Indonesia toward selected governmental programs, the occupation of fishing, and risk(1990) Mursidi, Tyas Rudito Sigit; Christiansen, James E.; Herring, Donald R.; Larke, Alvin; Peterson, E. Wesley F.This study analyzed selected problems of small-scale fishermen in Indonesia, related to governmental assistance, fishing as an occupation, and their willingness to take risk associated with fishing practices. The population of 979 small-scale fishermen in Sub-district Pangandaran, Ciamis, West Java, Indonesia were studied from May 1989 to August 1989. A sample of 126 fishermen consisting of small (< 10 gross tons) boat owners and workers on boats was chosen using stratified random sampling. Data were collected through personal interviews. Attitude scales were constructed using factor analysis. Cronbach's [alpha] values were calculated and ranged from 0.64 to 0.94.Item Developmental regulation of heat shock proteins : 70.1 in murine embryos and 70.1 and 70.4 in bovine embryos(1993) Fuller, David Thompson; Kraemer, Duane C.; Collisson, Ellen; Kochevar, Deborah T.; Peterson, David; Tiffany-Castiglioni, Evelyn; Womack, JamesHeat stress causes embryonic mortality in the bovine and in the mouse. A group of proteins known as heat shock proteins (HSPs) are synthesized in response to heat stress and are thought to enhance cellular thermotolerance. Because gene expression begins at variable developmental stages in post-fertilization embryos, early stage embryos may not synthesize heat shock proteins. The hypothesis states that heat shock proteins are not present in the early embryo, thus embryos are susceptible to hyperthermic conditions. In order to detect heat shock gene transcription in a limited number of embryos at early embryonic stages, we developed a 1-tube polymerase chain reaction (PCR) based protocol that minimized RNA loss and enhanced sensitivity of transcription detection. In this protocol, embryonic gDNA was cleaved between primer sites with DNAase; endogenous RNAases were inhibited with a RNAase inhibitor; and RNA integrity was maintained with E. coli rRNA. Samples were reverse transcribed to form cDNA which was then amplified with PCR. The 1-tube protocol was used to synthesize cDNA from mRNA transcripts which were transcribed from a heat inducible heat shock protein gene from murine embryos. Transcripts from HSP 70.1 were detected during the first four days of gestation in murine embryos. The 1-tube protocol was also used to identify the presence of mRNA transcripts from two bovine genes, HSP 70.1 and 70.4. In these studies, two developmental stages were evaluated in the bovine: prior to the 8 to 16-cell stage (3-5 cells) and at 12-16 cells. Heat shock protein 70.1 transcripts appeared during the 12 to 16-cell stage in both control and heat shocked embryos. Transcription was detected from HSP 70.4 before the 8 to 16-cell stage in both control and heat shocked embryos. However, by the 12 to 16-cell stage, only the control embryos synthesized HSP 70.4 mRNA transcripts. We concluded that the 1-tube protocol was sensitive and allowed detection of both murine and bovine heat shock transcripts during early, thermolabile developmental stages. Detection of HSP 70 transcripts at the earliest stages of development suggests that HSP 70 gene expression may be necessary but was not sufficient to protect embryos from thermal stress.Item Relationship of epipelic algae populations and shrimp culture at Corpus Christi, Texas(1990) Marin, Mirna; Lawrence, Addison A.; Murphy, Brian R.; Ficht, Thomas A.; Fryxell, Greta A.; Strawn, Robert K.The unchecked growth of diatoms and cyanobacteria is a major concern in shrimp mariculture. Diatom blooms are often stimulateded, to increase productivity in ponds; at the same time, mariculturists may try to control cyanobacteria blooms because of toxic effects. Use of Solricin 235 and Simazine to control cyanobacterial growth in shrimp (Penaeus vannamei) culture ponds was evaluated. Solricin treatment significantly reduced cyanobacterial density (as measured by C-phycoerythrin concentration). Simazine treatment did not reduce cyanobacterial densities. Neither treatment significantly affected physicochemical parameters (temperature, dissolved oxygen, and pH), nutrient (nitrogen, phosphorus, and silicate) dynamics, chlorophyll concentrations or shrimp survival and growth. Natural ingestion of diatoms by P. vannamei postlarvae in relation to supplementary feed was evaluated. Diatom genera, cell condition (full and empty), and number were determined in shrimp guts and fecal pellets. For the first time it was demostrated that P. vannamei postlarvae grazed actively on epipelic diatoms, especially before feed was applied to the system. Postlarvae showed selectivity in diatom grazing and utilization, with Nitzschia and Navicula being the principal taxa utilized. The impact of shrimp postlarval culture on the temporal dynamics of planktonic and epipelic diatom assemblages in raceways was evaluated through grazing exclosure studies. Diatom communities were dominated by the epipsammic species Synedraulna, and four epipelic species Navicuia stundlii. Amphora coffeaeformis. Nitzschia socialis, and Nitzschia #1. The four epipelic species were selectively grazed by shrimp postlarvae. Epipelic diatoms may contribute significantly to postlarval shrimp production. Further research is needed on the interactions of shrimp postlarvae and A. coffeaeform is A this epipelic diatom is a domoic acid- producing form that may cause shrimp mortality.Item An agricultural sector analysis of the United States sugar import policy(1990) Tanyeri-Abur, Aysen; McCarl, Bruce A.; Baye, Michael; Cheng-Chang, Ching; Knutson, Ronald; Peterson, E. Wesley F.The United States has maintained a sugar import quota since 1982. This policy, while supporting U.S. producer prices and incomes at a high level, has caused consumers to pay more for sugar and has reduced the incomes of foreign sugar producers. It has also stimulated domestic sugar production along with development of sugar substitutes such as High Fructose Corn Syrup (HFCS) which contributed to the fall in sugar demand. The quota policy has been criticized by previous economic studies and in the GATT trade negotiations. This study extends previous analyses to look at effects of sugar policy changes from a total sector perspective. The study of potential sugar policy reform was done using a mathematical programming sector model. Substitution between HFCS and sugar in sweetener using industries was explicitly modeled. A baseline scenario was constructed and validated using 1986 data which was then compared to alternative policy runs where: (i) the sugar quota was removed, and (ii) a target price was implemented. Comparisons were made with and without farm program provisions for the other sectoral commodities. The results show differing implications in the sugar industry as compared to the agricultural sector. Quota removal raised the welfare of domestic sugar consumers and foreign sugar producers but resulted in a lower welfare level for domestic sugar producers. Welfare for the rest of the society increases with the removal of the quota only if distortions arising from farm programs are eliminated. In the farm program runs, both the removal of the quota and the imposition of target prices resulted in a lower net social welfare compared to the case with the quota. Acreage substitutions towards other crops result in a social welfare loss because of increased government payments. This result provides an empirical example of the theory of the second best as the costs of other distortions outweigh the sugar gains. However, when farm programs for the other crops are eliminated, quota removal results in an increase in net social benefit.Item Theoretical and numerical studies of organized convective lines(1994) Liu, Changhai; Moncrieff, Mitchell W.; Zipser, Edward J.; Chang, Ping; Djuric, Dusan; North, Gerald R.; Stewart, Robert H.An extensive study of organized convection is carried out through an analytical approach and numerical modeling, with specific emphasis on the dynamics of two-dimensional convective lines. A hierarchical generalization of dynamic models is made by adding more realism and by introducing a distinct overturning-type jump updraft. The basic form of the momentum flux profile displays a striking similarity in the models. Shear in the jump inflow and baroclinic vorticity generation only alter the detailed shape of the momentum flux, but they have significant influences on selecting convective regimes. Based on the 22 and 23 June soundings during COPT81 experiment, a series of simulations are conducted with a two-dimensional version of the non-hydrostatic cloud model. Two distinct mechanisms associated with the generation of convective cells are identified: the cold outflow forcing from decaying cells and the initiation by gravity waves. The role of ice microphysics depends on environmental conditions. For the case of strong convective instability, ice impact is important to the system-scale structure but not essential to the convective-scale dynamics. On the other hand, in the situation of weak convective instability, ice effect is crucial to reproduce the observed storm. There is a profound universality in the vertical flux of line-normal momentum in the simulations. The archetypal model is capable of replicating the shape of the line-normal momentum flux reasonably but underestimates the amplitude. The application of the buoyant-type model considerably improves the momentum-flux prediction. The eddy transport is almost independent of the shear in both the initial and domain-averaged wind profiles. In contrast, in the line-parallel direction the eddy transport behaves largely in a down-gradient sense. The Schneider-Lindzentype formulation fails to represent the line-normal momentum flux but predicts the along-line momentum flux well. An idealized model is constructed to examine the density current in non-conservative fluids and sheared environments. It is shown that the incorporation of a stable stratification enhances the depth and propagation of density currents; the opposite behavior is found in buoyant fluids. In a sheared environment the density current deepens and moves faster if the shear changes from negative to positive.Item Selective alkylation of toluene with methanol over pentasil-type catalysts(1993) Ghaeli, Hooshang; Anthony, Rayford G.; Akgerman, Aydin; Clearfield, Abraham; Gadalla, Ahmed M.Para xylene is a valuable aromatic compound, because of the demand for oxidation to form tetraphthalic acid, a feed stock for polyester resin and fibers. A relatively high cost is associated with obtaining it in 99+% purity. Purification of para xylene requires separation from three close boiling C8 aromatics i.e. m-xylene, o-xylene, and ethylbenzene and subsequent isomerization of the remaining ortho and meta xylene isomers to an equilibrium mixture. The removal of ethylbenzene is another source of complication. To study the effect of acid sites in pentasil-type catalyst on the toluene alkylation, and para xylene selectivity, four catalysts with different cations in the frame work were synthesized. These catalyst were synthesized to have a SiO2/M2O3=70, where M is Al, B, Fe, or La. X-ray diffraction patterns of these catalysts indicated that all of these catalysts have a pentalsil-type structure. The results of temperature programmed desorptions (TPD) of ammonia indicate that A1ZSM-5 and FeZSM-5 have three different acid sites, weak, medium and strong. The TPD of ammonia of BZSM5 and LaZSM-5 showed a fourth type acid site. The effect of temperature, residence time, and feed composition on alkylation of toluene with methanol over these catalysts were studied. The A1ZSM-5 produced a xylene composition comparable to the equilibrium composition. Alkylation of toluene with methanol over BZSM-5, FeZSM-5, and LaZSM-5 produce xylene composition different than the equilibrium one. The LaZSM-5 catalyst produced the highest para xylene selectivity. The para xylene composition in the xylene isomers was as high as 92%. The p-xylene isomerization over A1ZSM-5, and LaZSM catalysts, indicate that the minimization of the isomerization reaction is the cause of the high para selectivity. All of the catalysts used in this investigation showed relatively rapid deactivation. The cause of the catalyst deactivation is the coke formation inside of the catalyst pores.Item Submersed weed management with triploid grass carp in waterlily production ponds(1990) Santha, Calista Rohini; Strawn, R. Kirk; Gatlin, Delbert M.; Grant, William E.; Martyn, Raymond D.; Neill, William H.Weed control by triploid grass carp (Ctenopharyngodon idella Val.) in waterlily (Nymphaea cultivars) production ponds was investigated and simulated. The 4 x 2 factorial experiment involved eight duplicated treatments consisting of four levels of weed control and two waterlily cultivars. Treatments included a no-weeding control, 2 manual weeding, 1 and 2 grass carp per 52.5-m^2 experimental pen. Initial and monthly densities of aquatic weed biomass, species composition, number of hydrilla (Hydrilla verticillata Royle) turions in soil core samples, and upper surface leaf areas and total number of flowers produced per waterlily plant were measured in each pen until complete weed control occurred in both grass-carp treatments. Generally, biomass of aquatic weeds differed significantly among weed-control treatments. Weed biomass in the manual-weeding treatment was lower than in all others soon after initiation of the experiment; in both grass-carp treatments, weed reduction was evident only after winter. Diversity of weed types was very low during the experiment, and succession occurred with changing seasons. Hydrilla was dominant at the beginning of the experiment and watermilfoil (Myriophyllum spicatum L.) near termination. Hydrilla turions in soil increased in fall, and decreased in spring and summer. The competitive effect of weeds on the growth of waterlilies was clearly seen in the latter part of the experiment, with significantly greater leaf areas in the manual-weeding, 1-carp pen^-1 and 2-carp pen^-1 treatments over the control. Following weed elimination, some grass carp ate waterlilies; whereas, others did not. A systems model was developed to simulate the effect of grazing by grass carp on the dynamics of weed biomass in a shallow water body in south Texas. Fish growth was a function of assimilation and metabolism. The model was parameterized using available information from the literature and results of the field experiment. It predicted that a stocking density of 110[plus or minus]7 grass carp ha^-1 (vegetated) would be required to reduce vegetation to 40% of its maximum biomass in the second summer. Two selected management schemes were simulated to estimate the grass carp density necessary to achieve continuous vegetation control at the 40% level.Item An investigation of the effects of variance components on the performance of job shop dispatching policies(1990) Wood, James Ralph; Phillips, Don T.; Smith, Donald R.; Garcia-Diaz, Alberto; Newton, H. JosephThe objectives of this research are twofold. First, to investigate the impact of unequal processing time variances on overall shop performance. Second, to implement strategies for improving job shop performance by designing priority dispatching policies that include measures of system statistical variability. The approach is through a statistical- experiment in which processing time variances, at specified machines, are systematically increased while holding processing means constant. The job shops modeled herein deviate from mainstream research which traditionally assumes that processing times are known prior to the implementation of the priority rules. Instead, this study examines a stochastic environment in which operation processing times are random variables from mutually independent probability distributions. It is assumed that the only information available for jobs waiting for service, are their operation processing time distribution. Hence, the priority dispatching policies examined herein are based solely on means and variances instead of exact information. A capstone of this research is the development of four new priority dispatching policies that include components of system variability. In simulated cases these four rules are compared against five commonly studied dispatching rules. The results indicate that that the four variance inclusive rules perform as well or better than the five traditional dispatching rules, in every criterion measured.Item Empowerment processes in shelters for battered women(1991) Love, Gayle Dienberg; Zey, Mary; Grider, Sylvia; McIntosh, Alex; Sell, JaneThree major dimensions of the empowerment process are identified (actors, goals, guidelines for practice) through a review of the literature on the practice of empowerment. Subsequently, empowerment is formally defined as a process in which a more powerful actor, A, makes resources available to a less powerful actor, B, that would otherwise be unavailable, actor B uses those resources, and change results. A theoretical model based on this definition is developed which specifies that resources are made available through the implementation of any or all of five empowerment strategies by agents of empowerment. The validity of these ideas is explored in a study of shelters for battered women. Multiple methods are used to assess manifestation of empowermment strategies and change experienced by residents. The data indicate that all five empowerment strategies are implemented, and that shelter residents experience both structural and developmental change. Issues relating to changes in the theoretical model as a result of the study are discussed, and suggestions for future research are given, along with propositions and hypotheses to guide that research.Item Computer simulation studies of radiation damage to biomolecules : gamma-ray irradiation of polyuridylic acid(1994) Lau, How Mooi; Bolch, Wesley E.; Petty, Frederick C.; Poston Sr., John W.; Giedroc, David P.; McLain Jr., Milton E.The objective o f this dissertation is to investigate the physical and chemical mechanisms involved when ionizing radiation interacts with biological m olecules in aqueous solution. Polyuridylic acid has been selected as the model for this study due to its relatively well characterized radiation chemistry and its similarity to DNA, the critical radiation target of the cell. Free radicals attack the uracil and ribose sugar by forming adducts with the base or by abstracting a hydrogen atom from the sugar moiety. The adducts are called intermediate radicals which will either release a hydrogen molecule or a water molecule to become the original base or they will abstract a hydrogen from the sugar moiety o f an adjacent nucleotide. The abstraction o f a hydrogen from the sugar moiety is assumed to be followed by a strand break and a base release. Only the free radicals *OH, H* and which are produced by radiolysis o f water play important role in causing damage to biomolecules. Previously performed irradiation experiments with DNA model systems, such as poly(U), are simulated in complete detail by a Monte Carlo computer code, namely OREC and RADLYS. OREC is the code for the transport of electrons through water. RADLYS simulates the prechemistry and early chemical stage of electron track development. These codes were modified to simulate the radiolysis of poly(U) in aqueous solution. In this dissertation, detailed discussions are given o f the modifications to the OREC and RADLYS codes for the simulation and the development of poly(U) as a molecular model for radiation damage to biomolecules. The 60Co Gy(E) values for strand break and base release are determined to be 1.77 and 2.00, respectively. If the radius of the cylinder is halved and length increased four times, the corresponding 60Co Gy(E) values are 2.35 and 2.75, respectively. The latter set of data displays a close agreement with those obtained experimentally by von Sonntag (1987). Detailed discussions on the comparisons of the calculational and experimental data are presented in this report. Simulations under other irradiation conditions are also reported.Item Regulation and evolution of the patatin multigene family : suggestions of combinatorial interactions directing tissue-specific gene expression(1992) May, Gregory DeWitt; Park, William D.; Cobb, D. Gregory; Davis, Scott K.; Funkhouser, Edward A.While much has been written about the evolution of new tissues or organs, little is known about the origin of the regulatory elements that direct gene expression in new structures. Questions also arise about how new regulatory elements are integrated into the complex physiology of new tissues. To examine these questions, the patatin multigene family was used as a model system. Patatin is a family of lipid acyl hydrolases that accounts for 30-40% of the total protein in potato tubers. The Class-I genes, which produce the majority of the patatin protein in tubers, can also be induced to express at high levels in stems and leaves by 0.2 -0.3 M sucrose. However, under normal conditions, they are almost totally tuber-specific. To examine how "tuber-specific" genes could have evolved from regulatory elements in non-tuberizing species, the expression of the endogenous patatin genes in tomato and tobacco were compared to that of potato Class-I patatin promoters using transgenic plants. Patatin promoters were also isolated and characterized from tobacco and evolutionarily divergent species of wild potato. These promoters contain sequences characteristic of both the Class-I and Class-II patatin genes. However, their patterns of expression are unlike those of any previously reported patatin genes. They were neither sucrose inducible nor tuber-specific and were wound-inducible, unlike potato Class-I patatin genes which are turned off by wounding. Because the major soybean vegetative storage protein (VSP) serves similar roles in soybeans to that served by patatin in potatoes, vsp promoter expression in transgenic potato plants was also examined. Although vsp is normally expressed in soybean leaves, it was tuber-specific when introduced into potato plants. Like Class-I patatin, vsp could be induced to express in leaves by sucrose, but unlike patatin, vsp could also be induced by methyl jasmonate, systemin and oligourinides...Item An examination of workplace justice, attitudes, and behavior : the case of layoffs(1991) Ratcliff, Shannon Lacelle; Youngblood, Stuart A.; Samuelson, Charles; Schoenfeldt, Lyle; Woodman, Richard W.This study examined the influence of procedural, interpersonal, and distributive justice on perceptions of fairness and workplace attitudes and behaviors for layoff victims and survivors. Self-report survey instruments were used to collect longitudinal data from victims and cross-sectional data from survivors. The study was conducted in an organization that was undergoing a staff reduction. Correlational analyses revealed that procedural justice was positively related to fairness perceptions for layoff victims and survivors and that distributive justice was also positively related to fairness perceptions for layoff victims. Perceptions of interpersonal justice and organizational commitment were positively related to job satisfaction for layoff victims and survivors. Justice perceptions were also found to be related to organizational commitment. Procedural justice was positively related to commitment for layoff victims and survivors. Interpersonal justice was also positively related to commitment for victims. In a counterintuitive finding, distributive justice and organizational commitment were negatively correlated for layoff victims. Procedural justice and organizational commitment were positively related to victims' willingness to recruit for former employer, while only organizational commitment was significantly related to survivors' willingness to recruit for the employer. Justice perceptions were not related to survivors' turnover intentions. An individual difference variable, self-efficacy, was found to significantly influence victims' willingness to recruit for the former employer and job satisfaction. Strengths and weaknesses, managerial and practical implications of the study, and suggestions for future research are discussed.Item Plowshares into swords : the decision to mobilize the National Guard in 1940(1990) Sligh, Robert Bruce; Hill, Larry D.; Beaumont, Roger; Carlson, David; Hall, Claude; Krammer, ArnoldIn September 1939, as Europe went to war, the United States had an Army rated seventeenth in the world. The National Guard was a force, although partially equipped and trained, that could augment it. The Army quickly won presidential approval to increase both the Guard's size and its training, but not to the levels the Army wished. President Franklin D. Roosevelt was hesitant to take too large a step for the largely isolationist populist. The Army, too, moved cautiously in its efforts to train and reorganize the National Guard. The National Guard Association represented the Guard's officer corps and possessed one of the most effective lobbies at that time. It had long sought an increased national defense and funds without incurring substantial Federal control. From 1939 through 1941, the Association, at the behest of Milton A. Reckord, its able lobbyist, set aside its concerns over Federal control, if only briefly, and cooperated with the Army, but only if the Federal government paid for more troops and equipment. While the Association attempted to balance its state and national concerns, Congress grappled with the political costs of mobilizing citizen soldiers. Isolationists in particular faced the dilemma of strengthening national defense and restricting the growth of presidential power. Public Law 96 passed in August 1940 provided for the mobilization of the National Guard for one year, but restricted its use to US possessions and the Western Hemisphere. In 1941 Roosevelt requested Congress to retain Guardsmen, Reservists, and draftees. While retention of the Guard was not in serious doubt, it was tied to keeping draftees beyond one year. Passage of retention legislation by one vote denoted the nation's division over the nation's possible evolvement in the war. The Acts of 1940 and 1941 tested the National Guard as an instrument of national defense and expanded the Federal government's powers over the Guard. Federalized units served as training grounds for draftees and effective combat units. Mobilization brought another result. Congress had expanded its power to use the Guard as a Federal reserve force, effectively removing it from the state' hands, a point finally clarified in 1990 by the Supreme Court.Item Total factor productivity in Mexican manufacturing : an analysis of the sources of growth, 1975-85(1993) Anderson, Sammy Kent; Kolari, James; Pugh, David; Etter, Wayne; Sweeney, Donald; Zardkoohi, AsgharThis study provides an analysis of the effects of Mexico's industrial development policies on the structure and productivity of its manufacturing base between 1975 and 1985. Because virtually every aspect of the economy was controlled by the government during those years, its trade and development policies have been credited with creating both the greatest industrial expansion and the worst economic crisis in its history. The methodology employed to assess the structural changes in manufacturing is based on the transcendental logarithmic production function which explicitly measures the marginal productivities and elasticities of output with respect to labor, capital and material inputs. In addition, this methodology provides an empirical measure of total factor productivity (TFP), or increase in output not accounted for by increases in factor inputs. The results indicate that TFP contributed negatively to the production process, declining 1.02 percent while growth in output was in excess of 31 percent. The marginal productivity and contribution of capital declined 6.15 percent and 12.12 percent, respectively, more the result of a decline in capital return than from reduced investment. The contribution of labor declined 2.57 percent owing to a 29.75 percent reduction in real wages, as employment grew 55.96 percent. Increases in the prices of material inputs caused its share in the value of output to increase 5.56 percent while the marginal productivity grew a modest 0.12 percent. Trade orientation had no detectable effect on TFP due to relatively insignificant changes in trade performance. Exports grew in real terms but remained a small part of total output (5.3 percent in 1985). Import substitution grew 22.0 percent but imports accounted for only 7.8 percent of domestic use in 1985. Government trade and development programs were primarily responsible for the over-all decline in productivity but not for the variations in TFP among the sectors. Efforts to promote productivity though control of technology transfer, investment, ownership, and financial incentives proved ineffective against extensive protectionist measures and currency controls. These actions provided an anti-export bias and a disincentive to investment in technology.