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Purpose: The purpose of this study is to investigate the prevalence of intraosseous vascular canals in the lateral wall of the maxillary sinus by utilizing high quality Cone Beam Computerized tomography (CBCT) scans. Material and Methods: 111 CBCTs that were obtained in a private practice were randomly selected from 500 CBCTs. The CBCTs were obtained from 2007 to 2011 with an iCAT CBCT unit. Then were reconstructed and imported into Simplant pro 15 software. Among the 111 selected CBCT images 13 scans that were not covering the sinus cavity entirely or had poor quality (e.g. scattering) were excluded from the study. All the CT scans were examined for presence or absence of intraosseous anastomosis by a single investigator. All the para-axial sections were carefully observed on both left and right side. The focus was on the area that most commonly the lateral window is prepared. In other words, the main area that was evaluated was from Distal of canine to distal of second molar on each side. Result: From initial 111 selected CBCTs, 13 were excluded due to either quality or the range of coverage. 52 (53%) were female and the rest 46 (47%) were male. 54 (55.1%) anastomosis noted among the 98 CBCTs that were evaluated. In other words, in 196 sinuses that were evaluated 27.5% of them had intraosseous anastomosis. Conclusion: the presence of intraosseous vascular canals in the lateral wall of the maxillary sinus is not a prevalent finding. Learning of the presence of intraosseous anastomosis in the lateral wall of the maxillary sinus would help with minimizing bleeding complications associated with the lateral wall approach sinus augmentation technique. Therefore, evaluation of the CBCT for anatomical variations is recommended prior to sinus augmentation surgeries. / Oral Biology

An increasing appreciation for the role of small RNA regulators prompted us to investigate the scope of RNA regulation in the bacterium, Streptomyces coelicolor. Our search revealed an antisense RNA that corresponds to the upstream region of four genes encoding cell wall cleavage enzymes (cell wall hydrolases), and a previously uncharacterized population of transfer RNA (tRNA) cleavage products. Further characterization of the 'tRNAs led to the discovery that S. coelicolor tRNAs are cleaved into 'tRNA halves' in a developmentally regulated fashion. All tRNAs seem to be susceptible to tRNA cleavage, although a bias was detected for tRNAs specifying highly used codons. To date, our work is the sole description of 'tRNA half production in a bacterium, and recent studies suggest that it is a widespread phenomenon among eukaryotic organisms. In a separate line of investigation, we noticed that a previous study had predicted that the genes associated with the antisense RNA are under the control of a riboswitch- a regulatory RNA element that directly controls gene expression in response to specific conditions. Our multifaceted characterization of this system began with the construction and phenotypic analyses of deletion mutant strains for several of the cell wall hydrolase-encoding genes. We demonstrate that S. coelicolor cell wall hydrolases are involved in germination, vegetative growth, and sporulation. Finally, we studied the potential for riboswitch regulation of one of the cell wall hydrolase-encoding genes, rpfA. RpfA is a resuscitation: Qromoting factor protein that is important for the revival of dormant bacteria, including the human pathogen and S. coelicolor relative - Mycobacterium tuberculosis. Our investigation uncovered evidence suggesting that the riboswitch region is involved in the regulation of rpfA, and we identified specific conditions under which it is repressed. This work represents a novel paradigm in the regulation of cell wall hydrolase expression. / Thesis / Doctor of Philosophy (PhD)

<p>An experimental investigation was conducted to analyze the effectiveness of repairing and retrofitting the intersections of flanged concrete block shear walls using surface-bonded fiber-reinforced polymer (FRP) laminates for seismic load applications. A total of 18 specially designed flange-web intersecting wall assemblages were tested using 5 different schemes. Tests included wall intersections reinforced with unidirectional FRP with the fibers oriented perpendicular to loading direction (90°), parallel to loading direction (0°) and bi-directional (90°/0°), (90°/0°)2 and (45°/135°) to applied load direction. The behaviour of each wall specimen is discussed with respect to its failure mode, strength and deformation characteristics. Results showed that the laminates significantly increased the shear strength of concrete block shear walls junction. In addition, the fiber orientation influenced the failure mode, strength and stiffness. Moreover, depending on the fiber orientation, a significant enhancement to the post-peak load energy absorption capacity of the web-flange intersection can occur. The improved post-peak behaviour addressed the benefits of retrofitting concrete block wall intersections for seismic load applications. The FRP-retrofitted specimens were capable of reaching between 90% to 390% increase in strength compared to the umetrofitted specimen constructed with traditional steel joint reinforcement.</p> / Thesis / Master of Engineering (MEngr)

Recirculating turbulent flow within a cavity with an inlet wall jet was examined. In steady water flow velocity profiles were constructed with measurements taken with a Laser Doppler Anemometer system mounted on a traversing mechanism. Two test cases were examined Re jet = 1167 and Re jet = 3231 as well as developing wall jet profiles. The results are presented with mean velocity plots and turbulent kinetic energy contours. Comparisons are then made with results obtained using a finite difference computational scheme based on the k - e turbulence model. Good agreement was obtained between the computer code predictions and the experimental data. / Thesis / Master of Engineering (ME)

Mycobacteria are atypical bacteria possessing unusual cell envelopes comprised of an outer membrane, covalently linked to an arabinogalacatan-peptidoglycan structure via waxy mycolic acids, in addition to the conventional inner membrane. This thick and highly impermeable cell envelope is a major deterrent to antibiotic treatment of clinically relevant mycobacterial pathogens, including Mycobacterium tuberculosis (Mtb), which infects a third of the world’s population and kills millions each year. Thus, the regulation of mycobacterial cell envelope biosynthesis is of great interest for the development of more effective therapeutics for treating Mtb infections. Using the model organism Mycobacterium smegmatis (M. smegmatis), we identified a novel protein, Spe2, with an unknown role in the biosynthesis of the cell envelope glycolipids lipomannan (LM) and lipoarabinomannan (LAM). Based on the observation that Δspe2 mutants produce truncated LM/LAM, I speculated Spe2 might enhance the elongation of these products. Here, I use biochemical assays to show Spe2 is localized to the periplasm where it can directly interact with the LM/LAM biosynthetic pathway. I further utilize a genetic approach to demonstrate that Spe2 acts at the stage in which the mannosyltransferase MptA mediates periplasmic LM elongation. Moreover, native polyacrylamide gel electrophoresis (PAGE) and co-immunoprecipitation techniques failed to reveal Spe2 protein binding partners. Together, these data suggest Spe2 is a periplasmic protein involved in regulating LM/LAM biosynthesis, perhaps through direct interactions with LM intermediates.

Wind tunnel experiments will continue to be a primary source of validation data for many types of mathematical and computational models in the aerospace industry. The increased emphasis on accuracy of data acquired from these facilities requires understanding of the uncertainty of not only the measurement data but also any correction applied to the data. One of the largest and most critical corrections made to these data is due to wall interference. In an effort to understand the accuracy and suitability of these corrections, a statistical validation process for wall interference correction methods has been developed. This process is based on the use of independent cases which, after correction, are expected to produce the same result. Comparison of these independent cases with respect to the uncertainty in the correction process establishes a domain of applicability based on the capability of the method to provide reasonable corrections with respect to customer accuracy requirements. The statistical validation method was applied to the version of the Transonic Wall Interference Correction System (TWICS) recently implemented in the National Transonic Facility at NASA Langley Research Center. The TWICS code generates corrections for solid and slotted wall interference in the model pitch plane based on boundary pressure measurements. Before validation could be performed on this method, it was necessary to calibrate the ventilated wall boundary condition parameters. Discrimination comparisons are used to determine the most representative of three linear boundary condition models which have historically been used to represent longitudinally slotted test section walls. Of the three linear boundary condition models implemented for ventilated walls, the general slotted wall model was the most representative of the data. The TWICS code using the calibrated general slotted wall model was found to be valid to within the process uncertainty for test section Mach numbers less than or equal to 0.60. The scatter among the mean corrected results of the bodies of revolution validation cases was within one count of drag on a typical transport aircraft configuration for Mach numbers at or below 0.80 and two counts of drag for Mach numbers at or below 0.90. / Ph. D.

The aerodynamic flow and fluctuating surface pressure of a plane, turbulent, two-dimensional wall jet flow into still air over smooth and rough surfaces has been investigated in a recently constructed wall jet wind tunnel testing facility. The facility has been shown to produce a wall jet flow with Reynolds numbers based on the momentum thickness, Re<SUB>&delta</SUB> = &deltaU<SUB>m</SUB>/&nu, of between 395 and 1100 and nozzle exit Reynolds numbers, Re<SUB>j</SUB> = U<SUB>m</SUB>b/&nu, of between 16000 and 45000. The wall jet flow properties (&delta, &delta<SUP>*</SUP>, &theta, y<SUB>1/2</SUB>, U<SUB>m</SUB>, u<SUP>*</SUP>, etc.) were measured and characterized over a wide range of initial flow conditions and measurement locations relative to the wall jet source. These flow properties were measured for flow over a smooth flow surface and for flow over roughness patches of finite extent. The patches used in the current study varied in length from 305 mm to 914 mm (between 24 and 72 times the nozzle height, b) and were placed so that the leading edge of the patch was fixed at 1257 mm (x/b = 99) downstream of the wall jet source. These roughness patches were of a random sand grain roughness type and the roughness grain size was varied throughout this experiment. The tests covered roughness Reynolds numbers (k<SUP>+</SUP>) ranging from less than 2 to over 158 (covering the entire range of rough wall flow regimes from hydrodynamically smooth to fully rough). For the wall jet flows over 305 mm long patches of roughness, the displacement and momentum thicknesses were found to vary noticeably with the roughness grain size, but the maximum velocity, mixing layer length scale, y<SUB>/2</SUB>, and the boundary layer thickness were not seen to vary in a consistent, determinable way. Velocity spectra taken at a range of initial flow conditions and at several distinct heights above the flow surface showed a limited scaling dependency on the skin friction velocity near the flow surface. The spectral density of the surface pressure of the wall jet flow, which is not believed to have been previously investigated for smooth or rough surfaces, showed distinct differences with that seen in a conventional boundary layer flow, especially at low frequencies. This difference is believed to be due to the presence of a mixing layer in the wall jet flow. Both the spectral shape and level were heavily affected by the variation in roughness grain size. This effect was most notable in overlap region of the spectrum. Attempts to scale the wall jet surface pressure spectra using outer and inner variables were successful for the smooth wall flows. The scaling of the rough wall jet flow surface pressure proved to be much more difficult, and conventional scaling techniques used for ordinary turbulent boundary layer surface pressure spectra were not able to account for the changes in roughness present during the current study. An empirical scaling scheme was proposed, but was only marginally effective at scaling the rough wall surface pressure. / Ph. D.

This research produced a new class of skin friction gages that measures wall shear even in shock environments. One test specimen separately measured wall shear and variable-pressure induced moment. Through the investigation of available computational modeling methods, techniques for accurately predicting gage physical responses were developed. The culmination of these model combinations was a design optimization procedure. This procedure was applied to three disparate test conditions: 1) short-duration, high-enthalpy testing, 2) blow-down testing, and 3) flight testing. The resulting optimized gage designs were virtually tested against each set of nominal load conditions. The finalized designs each successfully met their respective test condition constraints while maximizing strain output due to wall shear. These gages limit sources of apparent strain: inertia, temperature gradient, and uniform pressure. A unique use of bellows provided a protective shroud for surface strain gages. Oil fill provided thermal and dynamic damping while eliminating uniform pressure as a source of output voltage. Two Wheatstone bridge configurations were developed to minimize temperature effects first from temperature gradient and then from spatially varying heat flux induced gradient. An inertia limiting technique was developed that parametrically investigated mass and center of gravity impact on strain output. Multiple disciplinary computational simulations of thermal, dynamic, shear, moment, inertia, and instrumentation interaction were developed. Examinations of instrumentation error, settling time, filtering, multiple input dynamic response, and strain gage placement to avoid thermal gradient were conducted. Detailed mechanical drawings for several gages were produced for fabrication and future testing. / Ph. D.

In many situations in the world, the amount of resources available for use is limited. This statement is especially true in the cells of living organisms. During the translation process in protein synthesis, ribosomes move along the mRNA strand constructing proteins based on the sequence of codons that form a gene. The totally asymmetric simple exclusion process (TASEP) models well the translation process. However, these genes are constantly competing for ribosomes and other resources in the cell. To see how finite resources and competition affects such a system, we must construct a simple model to account for the limited resources. We consider coupling multiple TASEPs to a finite reservoir of particles where the entry rate of particles into the TASEPs depends on the number of particles left in the reservoir. Starting with a single TASEP connected to the reservoir, we study the system using both Monte Carlo simulations and theoretical approaches. We explore how the average overall density, density profile, and current change as a function of the number of particles initially in the reservoir for various parameters. New features arise not seen in the ordinary TASEP model, even for a single TASEP connected to the pool of particles. These features include a localized shock in the density profile. To explain what is seen in the simulations, we use an appropriately generalized version of a domain wall theory. The dynamics of the TASEPs with finite resources are also studied through the power spectra associated with the total particle occupancy of each TASEP and the reservoir. Again, we find new phenomena not seen in the power spectrum of the ordinary TASEP. For a single constrained TASEP, we find a suppression at low frequencies when compared to the power spectrum of the ordinary TASEP. The severity of this suppression is found to depend on how the entry rate changes with respect to the number of particles in the pool. For two TASEPs of different lengths, we find an enhancement of the power spectrum of the smaller TASEP when compared to the ordinary TASEP's power spectrum. We explain these findings using a linearized Langevin equation. Finally, we model competition between ten genes found in Escherichia coli using a modified version of the TASEP. This modified version includes extended objects and inhomogeneous internal hopping rates. We use the insight gained from the previous studies of finite resources and competition as well as other studies to gain some insight into how competition affects protein production. / Ph. D.