We present the results of a new and high sensitivity study of the neutral hydrogen (HI) gas in three early type edge-on spiral galaxies, NGC 4157, NGC 3600 and NGC 2683. All three galaxies reveal HI disks that extend nearly or more than twice the length of the optical disk, which ubiquitously reveal asymmetries and warps. We model each galaxy using a three-dimensional kinematic model to derive the empirical parameters of the density distribution functions and rotation curves. A Gaussian function is unanimously found to best represent the density distribution in the plane of the galaxies. We also find that there is in fact a thick HI disk extending into the halo of two of three of these galaxies with scale heights on kpc. scales. This gas suggests the existence of two separate widespread components: a thin, high intensity disk component, normally rotating, and a vast, low intensity halo component, rotating at slower velocities with respect to the disk. This vertical velocity gradient is perhaps our most significant finding in addition to the discovery of the two new HI halos. We also find an unevenly distributed small-scale component of the gas in the form of shell-like and filamentary structures that extend from the disk into the halo. In all three systems we find unique kinematic and structural peculiarities including an HI disk extending four times the optical disk, a declining rotation curve, a companion, expanding bubbles, disk warps, etc. Several physical parameters are derived such as neutral hydrogen and dynamic masses, systemic velocities, HI radii, HI halo masses, etc. All of our findings are investigated and discussed in depth for each of the three galaxies. / Thesis (Master, Physics, Engineering Physics and Astronomy) -- Queen's University, 2009-09-03 19:47:31.786

Ascent of magma results in drastic drops of pressure and temperature during eruption. Exsolution or dissolution of water changes the physical and chemical properties of the magma and can promote or inhibit the formation of bubbles, crystals and cracks. The microstructural relations between bubbles, crystals and cracks are important records of processes immediately before and during volcanic eruptions and during deposition of volcanic products. This is an integrated study of analyses, conceptual and numerical models of textural relations, and water distribution patterns of natural and experimentally altered samples. Synchrotron Fourier transform infrared spectroscopy and focal plane array detectors open new possibilities for the analysis of the spatial distribution of volatiles in volcanic rocks. New ways of sample preparation, measurements and data analyses helped to create water distribution maps with spatial resolutions that are close to the diffraction limit (~3 μm). In order to constrain eruptive processes and mechanisms of lava emplacement, I describe textural features in volcanic glasses including bubbles, flow bands of crystals or bubbles, spherulites and different generations of cracks. In experiments, bubbles were grown under isobaric conditions, at one or two cooling steps, their textures were described and volume changes tracked. Water distribution patterns in the glass around the textures were described and categorized, and where possible, diffusion modeling was used to infer temperature- and timescales of formation. Rocks that are quenched within short periods of time after bubble growth preserve negative gradients of water toward the bubble margins. These gradients are generally not observed if the sample is kept at high temperatures for extended periods. If, however, a second step of cooling is added, water may be re-dissolved into the surrounding melt, which may lead to the complete resorption of bubbles. A conceptual of water redistribution during bubble resorption or collapse is used to interpret water heterogeneities across linear flow banding. These heterogeneities can be caused by shearing of bubbly magma, leading to collapse, degassing and resorption of water into the melt, creating a bubble free melt. Anhydrous spherulitic crystals grow both above and below the glass transition temperature (Tg) redistributiong water into the surrounding melt. Below Tg, cracks form and are successively hydrated by magmatic water from crystal growth or by meteoric water at temperatures far below Tg. The hydrated perlitic cracks in the samples of this study formed at elevated temperatures and are distinct from cracks formed at ambient temperatures without hydrated margins. This study shows that the heterogeneous distribution of water in volcanic rocks preserves the complex and non-linear degassing and cooling history of eruptive products. The timescales and temperatures discovered here provide new ways to interpret textural observations, water distribution patterns and signals of shallow volcanic unrest.

The later stages of separated shear layer transition within separation bubbles developing over a NACA0018 airfoil operating at a chord Reynolds number of 105 and at angles of attack of 0, 5, 8, and 10 degrees were investigated experimentally in a wind tunnel. Several experimental tools, including a rake of six boundary-layer hot-wire anemometers, were used to perform measurements over the model. Novel high-speed flow visualization performed with a smoke-wire placed within the separated shear layer showed that roll-up vortices are shed within separation bubbles forming on the suction side of the airfoil. The structures were found to convect downstream and eventually break down during laminar-to-turbulent transition. Top view visualizations revealed that, at angles of attack of 0, 5, and 8 degrees, roll-up vortices form coherently across the span and undergo significant spanwise deformations prior to breaking down. At angles of attack of 5 and 8 degrees, rows of streamwise-oriented structures were observed to form during vortex breakdown. Statistics regarding the formation and development of shear layer roll-up vortices were extracted from high-speed flow visualization sequences and compared to the results of boundary layer measurements. It was found that, on the average, roll-up vortices form following the initial exponential growth of unstable disturbances within the separated shear layer and initiate the later stages of transition. The onset of these nonlinear stages was found to occur when the amplitude of velocity disturbances reached approximately 10% of the free-stream velocity. The rate of vortex shedding was found to fall within the frequency band of the unstable disturbances and lie near the central frequency of this band. The formation of vortices has been linked to the generation of harmonics of these unstable disturbances in velocity signals acquired ahead of mean transition. Once shed, vortices were found to drift at speeds between 33% and 44% of the edge velocity. Vortex merging at an angle of attack of 5?? was investigated. It was found that the majority of roll-up vortices proceed to merge with either one or two other vortices. Vortex merging between two and three vortices was found to occur periodically in a process similar to vortex merging in plane mixing layers undergoing subharmonic forcing of the most amplified disturbance. The flapping motion of the separated shear layer was investigated by performing a cross-correlation analysis on the high-speed flow visualization sequences to extract vertical displacement signals of the smoke within the shear layer. The frequency of flapping was found to correspond to the unstable disturbance band. At an angle of attack of 5??, it was found that the separated shear layer has a low-frequency component of flapping that matches a strong peak in velocity and surface pressure spectra that lies outside the unstable disturbance frequency band. The spanwise development of disturbances was assessed in the aft portion of the separation bubbles by performing a cross-correlation analysis on signals acquired simultaneously across the span with the rake of hot-wires. The spanwise correlations between signals was found to be well-correlated ahead of shear layer roll-up, after which disturbances became rapidly uncorrelated ahead of mean reattachment. These results were found to be linked to the coherent roll-up and subsequent breakdown of roll-up vortices.

Data from a growing number of research studies indicate that children with hearing loss are delayed in Theory of Mind (ToM) development when compared to their typically developing, hearing peers. While other researchers have studied the developmental trajectories of ToM in school-age students who are deaf and hard of hearing (DHH), a limited number have addressed the need for interventions for this population. The present study extends the current research on ToM interventions to the PreKindergarten and Kindergarten levels. This study used a single-case multiple-baseline multiple-probe across skills design with replications across classrooms to examine the effects of a ToM intervention on participants’ false belief understanding as well as outcomes on a near generalization measure (i.e., Sally-Anne Task, Baron-Cohen, Firth, Leslie, 1985) and a far generalization measure (i.e., five-task ToM developmental scale, Wellman & Liu, 2004). A thought bubble intervention (i.e., a visual representation of what people are thinking) developed by Wellman and Peterson (2013) was modified in key areas: (a) participants were substantially younger than the population in the original study and thus required a pre-teaching phase addressing vocabulary and materials, (b) manipulable materials were created from the description provided in the Wellman and Peterson (2013) study along with parallel materials used in assessment probes, (c) a certified teacher of DHH children provided direct instruction to participants in a small group setting, (d) study length was increased to 25 weeks, and (e) methodological design change (i.e., group design to single-case design). These modifications addressed the need for evidence-based ToM interventions that are both proactive and easily implemented by teachers in a classroom setting. Results from the single-case design portion of the study indicate a functional relation between the thought bubble intervention and the participants’ acquisition of the targeted skills in each stage, although progress was not uniform. Results from the pre-post assessments indicate that the children did make progress up the scale, however, children who used spoken language tended to proceed faster through the stages than those who used sign language. These results inform the field in regard to the efficacy and feasibility of a ToM intervention for young DHH children.

The current work has developed a CFD model to characterise a pseudo-annular photocatalytic bubble column reactor. The model development was divided into three stages. Firstly, hydrodynamic assessment of the multiphase fluid flow in the vessel, which incorporated residence time distribution analysis both numerically and experimentally for validation purposes. Secondly, the radiation distribution of the UV source was completed. The final stage incorporated the kinetics for the degradation the model pollutant, sodium oxalate. The hydrodynamics were modelled using an Eulerian-Eulerian approach to the multiphase system with the standard k- turbulence model. This research established that there was significant deviation in the fluid behaviour in the pseudo-annular reactor when compared with traditional cylindrical columns due to the nature of the internal structure. The residence time distribution study showed almost completely mixed flow in the liquid phase, whereas the gas phase more closely represented plug flow behaviour. Whilst there was significant dependence on the superficial gas flow rate the mixing behaviour demonstrated negligible dependence on the liquid superficial velocity or the liquid flow direction, either co- or counter- current with respect to the gas phase. The light distribution was modelled using a conservative variant of the Discrete Ordinate method. The model examined the contribution to the incident radiation within the reactor of both the gas bubbles and titanium dioxide particles. This work has established the importance of the gas phase in evaluating the light distribution and showed that it should be included when examining the light distribution in a gas-liquid-solid three-phase system. An optimal catalyst loading for the vessel was established to be 1g/L. Integration of the kinetics of sodium oxalate degradation was the final step is developing the complete CFD model. Species transport equations were employed to describe the distribution of pollutant concentration within the vessel. Using a response surface methodology it was shown that the reaction rate exhibited a greater dependency on the lamp power that the lamp length, however, the converse was true with the quantum efficiency. This work highlights the complexity of completely modelling a photocatalytic system and has demonstrated the applicability of CFD for this purpose.

The dissolution of quantum sized CdS and MnO2 particles in water was conducted using 20 kHz ultrasound. CdS particles were found to dissolve chemically via an oxidation process while MnO2 particles dissolved via a reductive process. It was found that the dissolution of the colloids could be controlled via the addition of surface active chemicals to solution and by varying the saturation gas type. In the presence of Na2S or propan-2-ol and argon gas, the dissolution of CdS was inhibited, whereas the addition of alcohols (methanol, ethanol, propan-2-ol, butan-1-ol and pentan-1-ol) to the MnO2 system led to an increase in the amount of dissolution for a given time of sonication. This increase in dissolution was found to be dependent on the ability of the surface active radical scavenger to accumulate around the bubble interface during the cavitation process. Eventually, at higher alcohol concentration there was a plateau or a limiting value reached for the efficiency of colloid dissolution which was common for each alcohol. (For complete abstract open document)

Thesis (Ph. D.)--Ohio State University, 2007. / Title from first page of PDF file. Includes bibliographical references (p. 152-167).

Thèse (D.Eng.)--Université du Québec à Chicoutimi, 2000. / Document électronique également accessible en format PDF. CaQCU

Thesis (M.S.)--Oregon State University, 2008. / Printout. Includes bibliographical references (leaves 79-81). Also available on the World Wide Web.

Thesis (Ph. D.)--Ohio State University, 2007. / Title from first page of PDF file. Includes bibliographical references (p. 145-161).