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Hydrogeological modeling of Northern Ireland drumlins in three dimensions2014 April 1900 (has links)
The need to renew and expand civil infrastructure, combined with an increased acknowledgement of a changing climate, has highlighted the need to incorporate the influence of climatic factors into the design of infrastructure. In geotechnical engineering, this includes understanding how climate influences the performance of slopes associated with engineered cuttings in pre- existing natural landforms. This understanding extends to both hydrological and hydrogeological conditions, both of which are often analyzed using numerical modeling of surface water and groundwater.
Climate change predictions for Northern Ireland indicate that the amount and intensity of rainfall and extreme weather events will increase. This has raised concerns regarding the stability of existing engineered cut-slopes and the design of future highway and railway infrastructure. Recent studies have indicated that there is a link between pore pressure cycles and softening of slope structures, especially in clay rich materials typical of glacial till drumlins in Northern Ireland. These pore pressure fluctuations are caused by seasonal changes in the rate of recharge which then propagate through the deeper hydrogeologic system. As a consequence, the design of these cuttings requires that the hydrogeological response of these landforms to seasonal climate variations be incorporated into geotechnical designs.
Two dimensional hydrogeological simulations are typically used in engineering practice. The main objective of this study was to evaluate the sensitivity of these simulations to dimensionality (two- and three-dimensions). The primary focus was on steady state groundwater flow within two drumlins with large slope cuts. Two- and three-dimensional groundwater models were developed using available information for a highway and a railway study site. The performance of each of these models was then compared to field monitoring from each site. A series of sensitivity studies were undertaken to evaluate the influence of key material properties and boundary conditions.
Estimated recharge rates were found to range from 21 to 31 mm year-1 for both the railway (Craigmore) and highway (Loughbrickland) study sites. The hydraulic head distribution at the Craigmore site was similar for both dimensional simulations with a “best-fit” recharge rate of 50 to 60 mm year-1. At the Loughbrickland site, similar hydraulic head distributions with the “best-fit” recharge rate of 80 mm year-1 were reached in both dimensions.
Overall, the research completed here emphasized the importance of gathering appropriate data prior to conducting development of hydrogeological models. As more data is made available, the overall complexity of the system can be better understood. As the complexity of the problem increases, the requirements for understanding the hydrogeological system in all three-dimensions becomes more important.
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Understanding of charge effects in pickering emulsions and design of double pickering emulsion templated composite microcapsulesWang, Hongzhi 12 January 2015 (has links)
Particle stabilized emulsions, also known as Pickering emulsions, have been widely used in many industry applications. While the breadth of potential applications for Pickering emulsions keeps growing, our fundamental understanding of Pickering emulsions is still poor. My thesis work addresses both fundamentals and applications of particle stabilized emulsions. In the fundamental part of this thesis work, we investigated the effects of particle charge on particle adsorption and the particle contact angle, and to investigate their ensuing consequences for the stability of Pickering emulsions. We provided the first experimental hint that the widely overlooked image charge repulsion can hinder the adsorption of particle to the oil-water interface and prevent the formation of Pickering emulsions. Consistently with the experimental suggestion, our theoretical model also confirmed that the image charge repulsion has the right order of magnitude, relative to the other forces acting on the particle, to impede particle adsorption and Pickering emulsification. For the conditions in which particle adsorption to the liquid interface does occur, the particle contact angle will play an important role in influencing the stability and type of Pickering emulsions. Our experimental work showed that the equilibrium contact angle of particles at interfaces and the type of emulsions preferentially stabilized by these particles can be strongly affected by the particles' charging state, which we attribute to a free energy contribution from the electric field set up by the charged particle and its asymmetric counterion cloud. A very simplistic calculation considering only the dipole field as the leading contribution and treating the water phase as a perfect conductor, found that the energy stored in the field is indeed strong enough and shows sufficient variation with the particle position to shift the equilibrium position significantly from where it would be based on interfacial tension alone. In a separate, more application oriented part of this thesis work, we have fabricated microcapsules from double Pickering emulsions and demonstrated that the combined use of hard silica particles and pH-responsive dissoluble polymer particles at the emulsion interface imparts a combination of pH-responsiveness (stimulated pore opening) and structural integrity to resulting capsules. We have further demonstrated the first double Pickering emulsion templated capsules in which interfacial polymerization was carried out at both emulsion interfaces, yielding a capsule with two composite shells, composed of polyurethane and silica particles, and characterized the transport of a model cargo through the capsules walls as well as the capsules' mechanical properties.
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Multisensory aspects of the spatial cuing of driver attentionHo, Cristy January 2006 (has links)
The primary goal of the empirical research outlined in this thesis was to examine a number of the factors contributing to the design of more ergonomic multisensory warning signals, that is, signals that elicit efficient and effective responses from interface operators under demanding conditions. To achieve this goal, a series of experiments was conducted in order to examine the nature and consequences of the crossmodal links inherent in spatial attention between various different sensory modalities, such as audition, vision, and touch, in an applied setting. In particular, a laboratory-based simulated driving task was used to investigate the effectiveness of various different auditory and vibrotactile cues in orienting a driver's attention to potential emergency driving events seen through the front windscreen or rearview mirror. The results of the first set of auditory spatial cuing experiments highlighted a significant performance advantage when the target driving events occurred in the cued, rather than the uncued, direction, with the biggest benefits being seen following spatially-predictive auditory or verbal cues. The second set of vibrotactile spatial cuing experiments demonstrated the potential utility of vibrotactile warning signals for presenting spatial information to car drivers, and the results were successfully replicated in a study using a high-fidelity driving simulator. The third set of experiments, incorporating an orthogonal task design, were conducted in order to examine the mechanisms responsible for the advantageous spatial cuing effects reported in the earlier experiments. Taken together, the results demonstrated that while directional congruency between a warning signal and target driving event may be sufficient to facilitate performance due to the priming of the appropriate response, attentional facilitation (i.e., perceptual enhancement) typically requires the co-location of the cue and target within the same functional region of space. In sum, this thesis demonstrates the potential value of approaching the design of effective multisensory warning signals for human operators by studying the information processing mechanisms in the human brain. The findings outlined here add to the literature concerning the brain's differential representation of stimuli presented in peripersonal as opposed to extrapersonal space. Further experimental chapters detail experiments that examined verbal directional cuing, olfactory cuing, and crossmodal interactions in virtual haptic environments.
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Seismic retrofit of a reinforced concrete bridge bentCoulombe, Chantal. January 2007 (has links)
This research project is the second part of a research program carried out by Itagawa (2005) who studied the seismic response of a half-scale model of an existing Montreal bridge built in the 1960's. This project studies the seismic behaviour of the retrofit carried out on the frame structure studied in the first part of the research program. The retrofit was made following the requirements of the current Canadian Highway Bridge Design Code (CHBDC). The philosophy of the CHBDC is to provide flexural yielding in the ductile elements so that brittle failure modes such as shear are prevented. This capacity-design approach resulted in a ductile response and significant energy dissipation of the retrofitted structure. / The retrofit was designed in accordance with the CHBDC provisions. The cap beam and the beam-column joint regions were strengthened with a reinforced concrete sleeve containing additional transverse and longitudinal bars so that plastic hinging would form in the columns. This retrofit represents minimum intervention to improve the response of the frame. The retrofit frame was then subjected to both gravity loads and reversed cyclic loading to simulate seismic loading on the structure. The predictions of the response of the retrofitted frame provided reasonable estimates of first yielding in the column and the general yielding of the frame. Although the columns would not meet the requirements for ductile columns, they had sufficient shear strength and did exhibit a displacement ductility of about 2.3.
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Regional assessment of the effects of land use on water quality: A case study in the Oldman River Basin, AlbertaHowery, Jocelyn 11 1900 (has links)
Protecting and managing Canadian water resources in the face of growing cumulative effects and non-point source pollution from development (industrial, agricultural, and urban), depends on defensible, scientifically founded, watershed assessments. The objectives of this research were to broadly characterize the spatial and temporal patterns in water quality (total phosphorus and total nitrogen concentration, export and yield) across a land use disturbance gradient (forest, agriculture, urban) to elucidate pressures on water quality from specific landscape regions within the three headwater sub-basins of the Oldman River basin. While the water quality in the Oldman basin, remains fairly pristine, important spatial differences in nutrient production were evident between the upstream (predominantly forested) and the downstream (mixed agricultural/forested) reaches within the sub-basins. Using the pressure state response model as a framework to link landscapes to observed water quality, it was also found that phosphorus contamination may be an issue in the headwaters. / Water and Land Resources
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A Meta-Analysis of School-Based Problem-Solving Consultation Outcomes: A Review from 1986 to 2009Davis, Cole 2012 August 1900 (has links)
School-based problem-solving consultation is an indirect problem-solving process where the consultant works directly with the teacher in order to solve a current work problem of the teacher. The focus of school-based problem-solving consultation was to remediate a current difficult; however, during school-based problem-solving consultation, the teacher developed coping skills that improved his/her ability to handle future problems. Although the subject of several previous syntheses of the literature attesting to its promise, the current state of school-based problem consultation effectiveness was not known.
This study sought to update the school-based problem-solving consultation effectiveness literature as measured by conducting a meta-analysis spanning the years 1986 to 2009. A secondary goal was to identify variables that functioned as moderators. Following procedures advocated by Lipsey and Wilson in 2001, 19 studies were identified producing 205 effect sizes. However, these effect sizes were not calculated independently. Instead, the effect sizes from each study were averaged in order to form a mean effect size per study. The mean effects were then averaged to form the omnibus mean effect size.
The omnibus mean effect size from the 19 studies was g = 0.42, with a range of -0.01 to 1.52 demonstrating a medium-sized effect. This effect size was more modest in magnitude when compared to the previous school-based problem-solving consultation meta-analyses; however, the results indicated that school-based problem-solving consultation positively impacted client-level outcomes. With the exception of grade level, moderator analyses produced little information in terms of statistical differences between and among categories for “teacher type of class, consultant type, school type, referral source, referral reason, consultation model, comparison group, intervention type, design quality, outcome measured, and data type. For grade level, students in the “Other/Not Specified” category benefited most from school-based problem-solving consultation when compared to the “Elementary (K-6)” category. In addition to examining the omnibus mean effect size and potential moderators, limitations and implications for practice and future research were discussed.
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Formulation approaches to minimise injection site reactions of poorly soluble drugsWu, Zimei, n/a January 2006 (has links)
Purpose: The aim of this study was to investigate the usefulness of formulation approaches to minimise injection site reactions for poorly soluble drugs. The specific objectives were to modify the injection site reactions by identification of irritant components in the formulation and control of their release kinetics; and to gain understanding of formulation approaches to create a favourable microenvironment in the tissues allowing better tissue tolerance and drug absorption.
Methods: Physicochemical properties of the model drug, ricobendazole (RBZ) were characterised using conventional methods. Three formulation approaches to minimise irritancy of the low pH RBZ solution were assessed. An in vitro method using 96-well microplates and a microtiter plate reader was used for detection of drug precipitation on dilution for formulation characterisation. Cellular damage by the formulations was investigated in L929 fibroblasts using 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxy phenyl)-2-(4-sulfophenyl)-2H-tetrazolium (MTS) and lactate dehydrogenase (LDH) assays. Tissue tolerance and pharmacokinetics were simultaneously investigated after subcutaneous injection in sheep. A low pH RBZ solution was used as a reference formulation.
Results: Preformulation studies showed that RBZ was practically insoluble in water and oils, and was slightly soluble in commonly used co-solvents. Solubility was slightly improved by complexation with hydroxypropyl-β-cyclodextrin (HP-β-CD, K₁:₁ = 311 M⁻�) or a combination of low pH (> 2) with surfactants or co-solvents. A U-shaped pH-solubility profile in aqueous solutions indicated that RBZ is an ampholyte. pKa values measured by absorbance spectroscopy and pH solubility methods were 3.45 and 3.76 (basic) and 9.82 and 9.53 (acidic) respectively. The partition coefficient was 14.3 - 15.2 at pH 6 - 9 and less at higher or lower pH. In aqueous solutions, RBZ showed a V-shaped pH-degradation rate profile and was most stable at pH 4.8. Degradation pathways were identified as hydrolysis and oxidation.
Three RBZ injectables (5%) were obtained by modification of the low pH RBZ solution; addition of 20% HP-β-CD, incorporation into a w/o emulsion, and a microemulsion (ME). On dilution with SPB, the onset time of drug precipitation was prolonged and the rate was reduced in the presence of HP-β-CD. The w/o emulsion had a low viscosity (< 60 mPa.s) and exhibited Newtonian flow. Drug release versus the square root of time was linear and the release rate could be adjusted by phase ratio and droplet size. Drug release was found to be by diffusion. A coarse emulsion layer appeared at the interface between the ME and buffer. Drug release from the ME was faster than from the emulsion and was linear with the square root of time. On titration into SPB, the three formulations showed controlling effects on the release of H₃O⁺ compared to the reference formulation. RBZ (0.1 mg/ml) was more toxic to L929 cells than the co-solvent propylene glycol (50 mg/ml). The formulations showed greater cytotoxicity than their vehicles in the order: ME > RBZ solution = emulsion > HP-β-CD. HP-β-CD and emulsion excipients showed little or no cytotoxicity. The MEs exhibited more toxicity in the LDH assay than in the MTS assay.
A reversed phase HPLC assay for simultaneous determination of RBZ and its metabolite in sheep plasma using an isocratic system with UV detection was developed and used in the pharmacokinetic studies. Plasma samples were prepared by solid phase extraction. A suitable internal standard was selected by quantitative structure-retention relationships analysis. The composition of a ternary mobile phase was optimised with the assistance of multiple linear regression. The assays were linear over the concentration range 10 - 1000 ng/ml for both analytes (r > 0.999) with satisfactory inter-day and intra-day precision and accuracy (CV < 10%). The recoveries for all analytes were > 96%.
A pilot study in sheep suggests that injection of the vehicles (the CD, emulsion and ME) caused virtually no pain on injection or site reactions. Both the reference formulation and its vehicle induced pain on injection and resulted in swollen tissues. Histology after two weeks showed granulation for the formulation, but not the vehicle. In contrast, animals showed virtually no injection site reactions with the ME and emulsion. The HP-β-CD formulation gave transient pain on injection but a two-fold increase in bioavailability compared with the reference. The emulsion produced sustained drug release and increased drug absorption. In the main study, the HP-β-CD vehicle showed good tissue compatibility. Irritation by the HP-β-CD formulation was attributed to the low pH. Cmax, tmax and AUC0-[infinity] for the reference formulation were 1.3 � 0.3 [mu]g/ml, 9.6 � 2.9 h and 36.7 � 9.2 [mu]g�h/ml respectively, while the corresponding data for the HP-β-CD formulation were 2.9 � 0.8 [mu]g/ml, 5.0 � 0.6 h and 54.5 � 15.3 [mu]g�h/ml respectively. The half-life following the injection of the HP-β-CD formulation (5.5 � 2.8 h) was shorter than that of the reference formulation (8.5 � 3.4 h).
Conclusions: Injection site reactions may be minimised by identification of irritant components in a formulation and by controlling their release. Controlling the burst release of the poorly water soluble drug RBZ in a low pH solution could improve tissue tolerance and minimise post-injection precipitation, and hence increase drug bioavailability. In addition, HP-β-CD was a useful local injectable carrier which significantly enhanced the absorption of RBZ after subcutaneous injection in sheep.
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The roles of siderophores in bacterial adhesion to metals and iron transportYang, Jing, n/a January 2009 (has links)
Siderophores are a series of important iron chelators secreted by many bacteria that normally have high affinity of iron ions and contain hydroxamate, catecholate and carboxylate and other ligand groups. These organic ligands play significant roles in bacterial metabolism: solubilising iron (III) from environments, enabling iron uptake and acting as a cell-signalling molecule to control gene expression. Recent observations of initial stages of Pseudomonas aeriginosa biofilm formation on metal oxides surfaces indicate that siderophores may also facilitate bacterial adhesion to metals. However, details of how siderophores interact with metal surfaces and the relationship of their chemical nature with bacterial adhesion were not fully understood. To test the generality of bacteria attachment to metals via siderophores, the adsorption behaviour of siderophores and their functional ligands groups on particle films of metal oxides were investigated with in-situ ATR-IR spectroscopy.
In this study, nanoparticle films of titanium oxide, boehmite, iron oxide and chromium oxyhydroxide were prepared as substrates to simulate titanium, alumnium, stainless steel surface and more detailed work were carried out on titanium dioxide. Monohydroxamic acids (acetohydroxamic acid, N-methylformohydroxamic acid, N-methyl-acetohydroxamic acid and 1-hydroxy, 2-piperidone) and catechol and catechol-like (L-dopa and esculetin) ligands were selected as modelling compounds for the most frequently occured functional groups in natural siderophores. IR spectra of these ligands in aqueous solution and adsorbed on TiO₂ were obtained with a flowing cell system fit to a horizontal accessory by in situ ATR-IR spectroscopy and interpreted based on vibrational mode analysis with density function theory. Results show that all these ligands can form surface complexes with metal surfaces and possible adsorption modes of these molecules were discussed. The pH dependence of absorbance of IR absorption of these adsorbed ligands showed that most of the ligands exhibited maximium adsorption to TiO₂ at about pH 8, only N-methylformohydroxamic acid, 1-hydroxy, 2-piperidone groups having maximum absorption at pH~3 and pH~6.
Infrared spectroscopic studies of adsorbed siderophores (desferroximme B, enterobactin and pyoverdine) were also carried out in variation of concentration and pH. Possible adsorption modes of these iron scavenger ligands on TiO₂ and other metal oxides were discussed. Results showed that all these ligands adsorbed on metal oxide surfaces and form surface complex via hydroxamate or catecholate lignd groups which confirm the generality of siderphore-metal bond formation.
Siderophore based-bacterial adhesion to metals of was conducted with Pesudomonas aeruginosa and E. coli strains on titanium oxide and iron oxide films. These observations support that siderophore play a significant role in bacterial adhesion to metals. Further work needs to be carried out on the wider involvement of siderophores in bacterial adhesion initiation to metals and siderophore-mediated iron transport.
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Performance of brick-veneer steel-framed domestic structures under earthquake loadingGad, Emad F. Unknown Date (has links) (PDF)
This project investigates the performance of brick-veneer cold-formed steel-framed domestic structures when subjected to earthquake-induced loads. It focuses on the effects of the so-called non-structural components, namely, plasterboard lining and brick veneer cladding. An extensive testing program was conducted on a full scale one-room-house measuring 2.3m x 2.4m x 2.4m high. This house was tested at various stages of construction to assess the contribution of the various components. Different types of loading, including non-destructive swept sine wave, destructive pseudo-static cyclic racking and simulated earthquakes were employed to obtain the various characteristics of the structure. The testing program on the test house was complemented by further tests on critical components such as brick ties and plasterboard connections. Detailed analytical models were developed and verified against the experimental results. These models were then used to conduct a sensitivity analysis to study other configurations, identify critical parameters and develop design guidelines. The experimental and analytical results have shown that the plasterboard wall lining can provide lateral bracing to domestic wall frames since they effectively act as shear walls. The performance of wall lining is greatly enhanced when set corner joints, ceiling cornices and skirting boards are considered. The capacity is increased by more than three times when these extra components are taken into account. Plasterboard also exhibits high damping and energy absorption capacity which are beneficial under earthquake loading. Furthermore, the strength and stiffness contributions of plasterboard lining and strap cross braces are additive.
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Penser l'écran sonore : les théories du film parlantMcCann, Mark January 2006 (has links)
The thesis, entitled Penser l'écran sonore : les théories du film parlant ( Thinking the sound screen : theories of the talking film ) aims to provide at once a survey and critique of such theories as have explicitly addressed themselves to film conceived of in its essence as a carrier of acoustically produced meaning. This position would seem to be the merest commonplace, however, review of the literature will show that the study of the cinematic sound object as such was hardly carried out in any systematic manner before the 1980s and the groundbreaking work of Rick Altman, Michel Chion, and Claudia Gorbman. Perhaps the most simple manner of illustrating previous theoretical approaches to this topos would be to indicate the " polar " extremes which mark the limits of the discursive space within which their coverage is inscribed - pessimism and mourning for the silents ( Balász ), dizzying mysticism ( Eisenstein ), Marxian ideological analysis ( Adorno and Eisler ), and various practical suggestions for filmmakers of the type proposed by Reisz and Spottiswoode. The thesis is divided into three along the familiar lines of sound qua sound - concerning that which is valid for all types of sound in the cinema - the voice in cinema, and cinema music. The main approaches to these objects can be similarly broadly characterised as semiological, second - wave semiological, ( i.e. semiology plus psychoanalysis ), cognitivist, and technopragmatic. The intention is to interrogate the merits and the defaults of these approaches by applying them to a range of problematics arising in the three areas listed above. It would of course be ideal if all approaches were to deal with identical questions, however, the internal dynamics of the various methodologies evidently privilege the framing of one question over another : in my opinion this presents its own interest, as the questions which can ( and, perhaps more importantly, cannot ) be posed within a given discursive structure are most revealing of the theoretical framework itself. The importance of cinema sound considered as representation rather than as simple transcription is insisted upon throughout. The limits of multichannelling are established as not greatly extending those already established by stereo. The practice of direct sound - of sound recorded on location or on set in real time - is found to have a distinctly theological dimension. The notion of subjective time as it is experienced by the spectator in the cinema is examined at length. A prominent feminist model of the functioning of sound in the cinema is found to be most unsteady. Finally, an aesthetic of the sound film which utilises the potential of the medium to the highest degree is proposed. A consideration of the lacunae in the field - which remain possibilities for further study - and an extensive bibliography complete the survey. / Thesis (Ph.D.)--School of Humanities, 2006.
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