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Item Biological and Ecological Aspects of Field Released Fire Ant Decapitating Flies Pseudacteon spp. (Diptera: Phoridae), Parasitoids of Red Imported Fire Ants Solenopsis invicta Buren (Hymenoptera: Formicidae)(2010-01-14) Puckett, Robert T.Multiple Pseudacteon phorid fly species, including P. tricuspis and P. curvatus, have been released in the southern United States beginning in 1997 and 2003 (respectively) to serve as biological control agents against red imported fire ants Solenopsis invicta Buren (hereafter referred to as RIFA). Field research in the United States on phorid/RIFA interactions has addressed establishment and spread of released species. Additionally, studies are needed on phorid biology and ecology with respect to spatial distribution and phenology, phorid/habitat associations and phorid-mediated affects on RIFA foraging patterns. A suite of manipulative laboratory and field experiments/observations were conducted to 1) develop a novel phorid sampling device to provide uniform and repeatable sampling of flies, 2) assess spatial distributions and phenology of Pseudacteon tricuspis and P. curvatus, 3) assess P. tricuspis and P. curvatus habitat associations and 4) assess phorid-mediated affects on RIFA foraging patterns and caste ratios. PTS Traps (developed for this research) are significantly more effective than previous sampling methods in terms of mean number of flies collected, efficiency of use and % trap success. Data collected with these traps allowed for the determination of patterns of species-specific phenology and relative densities through time and speciesspecific numerical/spatial superiority (Chapter IV). P. curvatus was significantly more abundant than P. tricuspis in only one of the habitat types sampled (df (160) = 4.57, P < 0.005). P. tricuspis densities did not differ significantly among habitat type. Llaboratory experiments revealed that phorid-exposed RIFA colonies foraged less intensively diurnally (df = 1,558; P < 0.05) and more intensively nocturnally (df = 778; P < 0.05) relative to control colonies. Field data regarding this compensatory nocturnal foraging shift did not corroborate those of the laboratory work. In the field there was no significant difference in foraging intensity during nocturnal (df (18) = -0.486, P = 0.633) and diurnal (df (18) = 1.375 P = 0.186) sampling periods. Lastly, chi-square analysis of RIFA forager size-classes revealed significant differences between phorid-infested (treatment) and phorid-free (control) sites (X 2 = 6811.85, df = 3, P < 0.05) with a significantly greater proportion of small RIFA foragers at the phorid-infested site.Item A comparison of item selection procedures using different ability estimation methods in computerized adaptive testing based on the generalized partial credit model(2010-05) Ho, Tsung-Han; Dodd, Barbara Glenzing; Powers, Daniel A.; Whittaker, Tiffany A.; Vaughn, Brandon K.Computerized adaptive testing (CAT) provides a highly efficient alternative to the paper-and-pencil test. By selecting items that match examinees’ ability levels, CAT not only can shorten test length and administration time but it can also increase measurement precision and reduce measurement error. In CAT, maximum information (MI) is the most widely used item selection procedure. However, the major challenge with MI is the attenuation paradox, which results because the MI algorithm may lead to the selection of items that are not well targeted at an examinee’s true ability level, resulting in more errors in subsequent ability estimates. The solution is to find an alternative item selection procedure or an appropriate ability estimation method. CAT studies have not investigated the association between these two components of a CAT system based on polytomous IRT models. The present study compared the performance of four item selection procedures (MI, MPWI, MEI, and MEPV) across four ability estimation methods (MLE, WLE, EAP-N, and EAP-PS) under the mixed-format CAT based on the generalized partial credit model (GPCM). The test-unit pool and generated responses were based on test-units calibrated from an operational national test that included both independent dichotomous items and testlets. Several test conditions were manipulated: the unconstrained CAT as well as the constrained CAT in which the CCAT was used as the content-balancing, and the progressive-restricted procedure with maximum exposure rate equal to 0.19 (PR19) served as the exposure control in this study. The performance of various CAT conditions was evaluated in terms of measurement precision, exposure control properties, and the extent of selected-test-unit overlap. Results suggested that all item selection procedures, regardless of ability estimation methods, performed equally well in all evaluation indices across two CAT conditions. The MEPV procedure, however, was favorable in terms of a slightly lower maximum exposure rate, better pool utilization, and reduced test and selected-test-unit overlap than with the other three item selection procedures when both CCAT and PR19 procedures were implemented. It is not necessary to implement the sophisticated and computing-intensive Bayesian item selection procedures across ability estimation methods under the GPCM-based CAT. In terms of the ability estimation methods, MLE, WLE, and two EAP methods, regardless of item selection procedures, did not produce practical differences in all evaluation indices across two CAT conditions. The WLE method, however, generated significantly fewer non-convergent cases than did the MLE method. It was concluded that the WLE method, instead of MLE, should be considered, because the non-convergent case is less of an issue. The EAP estimation method, on the other hand, should be used with caution unless an appropriate prior θ distribution is specified.Item Convective-Resolving Regional Climate Simulations for the Amazon Basin: Comparison with TRMM Rainfall Data(2012-08-21) Kinney, Nichole 1987-With increasing computational power, simulations of regional climate are now becoming possible on convective-resolving grids, thus eliminating the need for a convective parameterization. In the present study, a series of seasonal calculations using the Weather Research and Forecasting (WRF) model are computed at 4-km grid spacing, which reasonably resolves most convective systems. Simulations are computed for both the DJF and MAM seasons as averaged over 2005-2008, with a model domain covering the majority of the Amazon Basin and the adjacent South American coastline. Precipitation statistics are computed and compared to satellite rainfall retrieval data from the 13-year Tropical Rainfall Measuring Mission (TRMM) record. For comparison, a set of companion simulations with 12-km grid spacing are also computed, using the Kain-Fritsch convective parameterization. As compared to the 12-km runs, the 4-km simulations show significant improvement in the overall mean rain rate, the rain rate probability distributions, and the diurnal evolution and timing of precipitation. Both the 4-km and 12-km cases capture the coastal propagating signal and the interior basin-wide diurnal oscillation; however, the 4-km case shows better timing and evolution statistics. Compared to TRMM, the 4-km case rains too infrequently, but is more likely to produce rain events at high rain rates, thus resulting in a similar overall average rain rate. Overall, the present calculations show significant promise for computing regional rainfall patterns on convective-resolving grids.Item Development of a Microfluidic Device for Synthesis of Lipid Bi-Layer In-Situ(2010-01-14) Banneyake, Bm U.Lipid bi-layers are ubiquitous components of biological cells and are found in a variety of cell components. In biological membranes, lipid bi-layer membranes carry membrane proteins, which control transport of material and communication of signals in and out the cell. There are several disadvantages involved with patch clamping method as a way of studying biological membranes and protein interactions. Hence, artificial synthesis of bi-layer has been of great interest in basic biophysical studies, drug discoveries in pharmaceutical studies and study of protein nanopores for precise engineering applications. However, conventional lipid bi-layer synthesis techniques require skilled operators, have low repeatability (reliability), have portability restrictions and result in unstable bi-layers having a short lifetime. In this investigation a novel microfluidic device and a method for artificial synthesis of lipid bi-layer in-situ are explored. In the proposed method, lipid trapped at an aperture on a Teflon sheet, is thinned to form a lipid bi-layer by a continuous flow of buffer solution on both sides of the aperture in the microfluidic device. The microfluidic device is expected to have advantages from its compact design. Further, the new approach is expected to be repetitive and good for automation removing the requirement of a skilled operator. The microfluidic device was fabricated using two glass substrates. Two channels of ? ? shape were etched and through holes were fabricated at all four terminal ends of the microchannels on each glass substrate. A thin Teflon sheet carrying a 100?m diameter hole was sandwiched between the two glass wafers forming two sets of microchannels on both sides of the aperture. An analytical microfluid model of the microchannels was developed to investigate the nature of the flow and to select microchannel parameters. Experiments using the proposed device were performed to verify the feasibility of the novel approach for lipid bi-layer synthesis. Experimental results suggest formation of a lipid bi-layer at an aperture on the Teflon sheet but further investigation might be necessary for verification. Life time of the bi-layer is short mainly due to low quality of the used aperture.Item Space Shuttle Program (SSP) retirement and NASA transition to the Vision for Space Exploration (VSE)(2009-08) Reyes, Carlos Joel; Duvic, Robert Conrad, 1947-; Ambler, TonyOn January 14, 2004, President George W. Bush announced the Vision for Space Exploration (VSE). The goals of the vision include developing a new generation launch capability while completing assembly of the International Space Station (ISS) and retiring the Space Shuttle by 2010. In support of this goal, the Space Shuttle Program (SSP) initiated evaluation of hardware, infrastructure, and workforce skill mix needed to continue Space Shuttle flights until the projected 2010 retirement. The SSP also studied how NASA will deploy personnel from, and use the facilities of, the SSP to ensure that the Space Shuttle operates safely through its final flight, and to ensure personnel and facilities from the SSP are effectively transitioned to NASA’s exploration programs. NASA funding, like other federal agencies, is affected by various factors including domestic and international political environments, current and emerging technologies available to meet agency goals, and sustainability and potential economic return of federal expenditures. In this paper I will present a retrospective analysis of federal budget allocations to NASA as a percentage of the Federal Budget from years 1958 to 2010 (adjusted to 1979 dollars). The classic method for calculating net present value (NPV) is not well suited for projecting potential value of future R&D technologies. A quantitative analysis of R&D technologies transferred to private industry will be presented, as well as a description of a method of evaluating their significance will discussed relative to current budgetary considerations will likely for past, current and upcoming funding cycles. The opportunity at hand for NASA’s transition from SSP to Constellation in support of the VSE initiative is to advocate their culture as R&D innovators and emphasize the future benefit of increased funding.Item Structural control Architecture Optimization for 3-D Systems Using Advanced Multi-Objective Genetic Algorithms(2010-01-14) Cha, Young JinThe architectures of the control devices in active control algorithm are an important fact in civil structural buildings. Traditional research has limitations in finding the optimal architecture of control devices such as using predefined numbers or locations of sensors and dampers within the 2-and 3-dimensional (3-D) model of the structure. Previous research using single-objective optimization only provides limited data for defining the architecture of sensors and control devices. The Linear Quadratic Gaussian (LQG) control algorithm is used as the active control strategy. The American Society of Civil Engineers (ASCE) control benchmark building definition is used to develop the building system model. The proposed gene manipulation genetic algorithm (GMGA) determines the near-optimal Pareto fronts which consist of varying numbers and locations of sensors and control devices for controlling the ASCE benchmark building by considering multi-objectives such as interstory drift and minimizing the number of the control devices. The proposed GMGA reduced the central processing unit (CPU) run time and produced more optimal Pareto fronts for the 2-D and 3-D 20-story building models. Using the GMGA provided several benefits: (1) the possibility to apply any presuggested multi-objective optimization mechanism; (2) the availability to perform a objective optimization problem; (3) the adoptability of the diverse encoding provided by the GA; (4) the possibility of including the engineering judgment in generating the next generation population by using a gene creation mechanisms; and (5) the flexibility of the gene creation mechanism in applying and changing the mechanism dependent on optimization problem. The near-optimal Pareto fronts obtained offer the structural engineer a diverse choice in designing control system and installing the control devices. The locations and numbers of the dampers and sensors in each story are highly dependent on the sensor locations. By providing near-Pareto fronts of possible solutions to the engineer that also consider diverse earthquakes, the engineer can get normalized patterns of architectures of control devices and sensors about random earthquakes.Item Structure-Property Relationships in Carbon Nanotube-Polymer Systems: Influence of Noncovalent Stabilization Techniques(2010-01-20) Liu, LeiA variety of experiments were carried out to study the dispersion and microstructure of carbon nanotubes in aqueous suspensions and polymer composites with the goal to improve the electrical conductivity of the composites containing nanotubes. Epoxy composites containing covalently and noncovalently functionalized nanotubes were compared in terms of electrical and mechanical behavior. Covalent functionalization of nanotubes is based on chemical attachments of polyethylenimine (PEI) whereas noncovalent functionalization takes place through physical mixing of nanotubes and PEI. The electrical conductivity is reduced in composites containing covalently functionalized nanotubes due to damage of the tube?s conjugated surface that reduces intrinsic conductivity. Conversely, the mechanical properties are always better for epoxy composites containing covalently functionalized nanotubes. Clay particles were used as a rigid dispersing aid for nanotubes in aqueous suspensions and epoxy composites. When both nanotubes and clay were introduced into water by sonication, the suspension is stable for weeks, whereas the nanotubes precipitate almost instantly for the suspension without clay. In epoxy composites, nanotubes form separated clusters of aggregation, whereas a continuous threedimensional nanotube network is achieved when clay is introduced. Electrical conductivity of the epoxy composite is shown to significantly improve with a small addition of clay and the percolation threshold is simultaneously decreased (from 0.05 wt% nanotubes, when there is no clay, to 0.01 wt% when 2 wt% clay is introduced). The addition of clay can also improve the mechanical properties of the composites, especially at higher clay concentration. Weak polyelectrolytes (i.e., pH-responsive polymers) were also studied for their interaction with nanotubes and the electrical properties of the dried composite films. When dispersed by sonication, Nanotubes show pH-dependent dispersion and stability in poly(acrylic acid) water solution, as evidenced by changes in suspension viscosity and cryo-TEM images. The nanotube suspensions were then dried under ambient conditions and the composite films exhibit tailorable nanotube dispersion as a function of pH. The percolation threshold and maximum electrical conductivity are reduced when the pH is changed from low to high. Some other pH-responsive polymers were also studied, but their pH-dependent viscosity and conductivity were not as large or reversible as poly(acrylic acid).Item The 'Noble Lie' and Tensions in Moral Sensibility that Form the Platonic Grid; Making Modern Day 'Dogs of War'(2010-07-14) Lasse, Stephen R.This inquiry explores the possibility of applying principles from Plato?s education system in the Republic to modern military leadership development programs. Both are concerned with producing a ?guard-dog? that will serve the interests of the state rather than exploit vulnerable civilians. Plato proposes educating guardians with a natural disposition to believe the ?noble lie,? that it is better to serve others than to pursue selfinterest for personal gain; but, would the proper tension in moral sensibilities prescribed by the Platonic Grid help or hinder a military leader to successfully act on the battlefield? First, I examine Plato?s theory to familiarize military leaders with the education system from the Republic; including his views on unity, reality, the theory of the forms, and recollection of knowledge that underlie Plato?s enquiry into the nature of justice, and lead to the need for inner harmony of the soul through the proper tension of wisdom, courage, and temperance to rule the three elements of the soul. Then I analyze the key leaders from the Battle of Balaclava, the Battle of Gettysburg, and the siege of the Alamo for possible correlations of the application of the Platonic Grid aligned with the ?noble lie? to success on the battlefield. This includes inquiry into the likelihood that belief in the ?noble lie? can motivate soldiers to make the ultimate sacrifice. I conclude by examining how Plato?s theories could be assimilated into a military pedagogy to produce modern day ?dogs of war? that leads to the startling conclusion that adherence to the ?noble lie? could also be in the self-interest of the guardian who seeks to serve the best interest of her nation.Item THE EMPEROR’S TREASURE WITHOUT THE WALLS(2012-04-19) Huang, Yu-Han; Lan, Ni; Vardeman-Winter, Jennifer; Draper, JasonTo fill the gaps in research on strategically integrating public segmentation and relationship management (Kim & Ni, in press), this study explored using simultaneously the Situational Theory of Publics and Relationship Management Theory in the context of museum/tourism public relations. An experimental research design was used in which 336 subjects from Taiwan were asked to offer their perceptions of their own problem recognition, constraint recognition, involvement recognition, referent criterion, relationship outcomes, experience use history, museum visitation purposes, and intention for future visitation before and after the exposure to a museum digitalization campaign.Item The Perceptions of Principals and Assistant Principals on Their Role in Parental Involvement(2012-04-19) Harrist, Lisa; Prater, Doris; MacNeil, Angus; Busch, Steve; Emerson, Michael W.Rios-Harrist, Lisa. "The Perceptions of Principals and Assistant Principals on Their Role in Parental Involvement." Unpublished Doctor of Education Thesis, University of Houston, May 2011. Abstract This study examines the beliefs of school principals and assistant principals regarding the role of parents in the educational process of their children. Henderson and Berla (1994) indicated that parental involvement was linked to higher student achievement. The purpose of the study was to determine the perceptions of principals and assistant principals in regard to their role in parental involvement. The study analyzed archival data of two surveys collected from 310 principal participants and 374 assistant principal participants from the Gulf Coast Region of Southeast Texas. The data was collected through cognitive interviewing and traditional survey techniques. The study analyzed survey responses of three open-ended questions and one Likert-type response. Sixty-four percent of principals and sixty-six percent of assistant principals reported that a high level of parental involvement is appropriate and necessary. These strong beliefs held constant across school levels, school geographic areas, and TEA school accountability ratings. Elementary principals (47.0%) and assistant principals (35.2%) of the “High Level of Parental Involvement” category tended to place more value on the importance of parental involvement. Principals (51.0%) in the suburban school geographic area and assistant principals (53.8%) in the urban school geographic area of the “High Level of Parental Involvement” category placed more value on the importance of parental involvement. Principals (47.0%) and assistant principals (50.0%) at campuses with an Acceptable TEA Accountability Rating of the “High Level of Parental Involvement” category placed more value on the importance of parental involvement. Principals revealed 18 strategies and assistant principals revealed 21 strategies they utilize to encourage parental involvement on campus. The most frequent strategies used by principals and assistant principals included the following: Events (62.3%), (46.8%) Communication (55.0%), (58.6%), PTA or PTO (19.4%), (9.6%), and Volunteering (11.3%), (8.0%), respectively. The results of this study are relevant to current administrators, aspiring administrators, and administrator preparation programs. In addition, this study provides a more comprehensive profile of the perceptions of principals and assistant principals in relation to their role in parental involvement. Access to and understanding of such factors may greatly impact the professional development and training of educational leaders, principals, and assistant principals.Item The phiX174 Lysis Protein E: a Protein Inhibitor of the Conserved Translocase MraY(2010-07-14) Zheng, YiMost bacteriophages release progeny virions at the end of the infection cycle by lysis of the host. Large phages with double-stranded DNA genomes use a multigene strategy based on holins, small membrane proteins, and bacteriolytic enzymes, or endolysins. Holins mediate the control of endolysin activity and thus the timing of lysis. Phages with small genomes only encode a single protein for cell lysis. There are three known unrelated single protein lysis systems: the ?X174 E protein, the MS2 L protein, and the Q? A2 protein. None of these phages encodes a cell wall degrading activity, and previous work has shown that the lytic activity of E stems from its ability to inhibit the host enzyme, MraY, which catalyzes the formation of lipid I, the first lipid intermediate in cell wall synthesis. The purpose of the work described in this dissertation was to characterize the ?X174 E-mediated inhibition of MraY using genetic and biochemical strategies. A fundamental question was why no large phages use the single gene system. This was addressed by constructing a recombinant phage, ?E, in which the holin-endolysin based lysis cassette of ? was replaced with E. ?E was compared with ? in genetic and physiological experiments, with the results indicating that the holin-endolysin system increases fitness in terms of adjusting lysis timing to environmental conditions. Using ?E, physiological experiments were conducted to characterize the interaction between E and MraY in vivo. Transmembrane domains (TMD) 5 and 9 have been identified as the potential E binding site by isolating MraY mutants resistant to E inhibition. The five Eresistant MraY mutants were found to fall into three classes, which reflect the apparent affinity of the mutant proteins for E. Finally, an assay for MraY activity employing the dansylated UDP-MurNAc-pentapeptide and phytol-P, was used to demonstrate the inhibition of MraY by purified E protein. It was determined that E is a non-competitive inhibitor for MraY in respect with both substrates. A model for E-mediated inhibition of MraY was proposed, in which E binds to TMDs 5 and 9 in MraY and thus inactivates the enzyme by inducing a conformational change.