Upregulation of intracellular and secreted acid phosphatases (APases) is a universal response of orthophosphate-starved (-Pi) plants. APases hydrolize Pi from a broad spectrum of phosphomonoesters at an acidic pH. Plant APases belong to a relatively large multigene family whose specific functions in Pi metabolism are poorly understood. This study focuses on the identification and characterization of cell wall (CW) localized purple acid APases (PAPs) upregulated by -Pi Arabidopsis thaliana. Three glycosylated PAP isozymes secreted into the CW of -Pi Arabidopsis suspension cells were purified and identified by peptide mass fingerprinting using mass spectrometry (MALDI-TOF MS) and N-terminal microsequencing as AtPAP12 (At2g27190; subunit size 60-kDa), AtPAP25 (At4g36350; subunit size 55-kDa) and AtPAP26 (At5g34850; subunit size 55-kDa). Both AtPAP12 and AtPAP26 were previously shown to be upregulated and secreted by –Pi Arabidopsis to scavenge Pi from extracellular organic-P. However, the novel AtPAP25 has never been suggested to be involved in the plant Pi-starvation response. Biochemical characterization of AtPAP25 revealed a monomeric 55 kDa protein. Similar to other PAPs it was purple-in-solution and insensitive to tartrate. Glycoprofiling via LC MS/MS revealed highly complex NXS/T glycosylation motifs at Asn172, Asn367 and Asn424. I hypothesize that these motifs play a role in AtPAP25 targeting and function. Kinetic characterization revealed a broad pH optimum centered at 5.6 and inhibition of activity by several common APase inhibitors. AtPAP25 exhibited broad substrate selectivity, low Vmax, and a Km (phosphoenolpyruvate) value of 0.52 mM. Immunoblot and semi-quantitative RT-PCR transcript analysis indicated that AtPAP25 is exclusively synthesized under –Pi conditions. Deduced amino acid sequences were compared using multiple sequence alignment and phylogenetic analysis. Growth of atpap25 T-DNA insertion mutant knockout seedlings was completely arrested when transferred to a soluble Pi deficient organic-P containing soil mix, pointing to a potential regulatory function of AtPAP25 during nutritional Pi stress. Overall, this research is helping to shed light on the functional importance of specific PAP isozymes in facilitating plant acclimation to nutritional Pi deficiency. This is important because there is an urgent need to engineer Pi-efficient transgenic crops to minimize the huge input of expensive, non-renewable, and polluting Pi fertilizers in agriculture. / Thesis (Master, Biology) -- Queen's University, 2012-09-10 08:28:21.631

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The performance of plastered straw bale walls with respect to wind-driven rainfall was investigated in this thesis. The absorption coefficient, which describes the rate of water infiltration, was measured for 14 plaster types, twelve different earth plasters and cement and lime plasters. The absorption coefficient was measured during uptake of water from a free reservoir. The effective porosity of these plasters, which describes the moisture storage capacity and the degree of protection that a plaster offers to straw bales, was also determined by submersion in water. An analytical model employing the absorption coefficient, the effective porosity, and climatic data was used to predict and compare plaster performance and to demonstrate the usefulness of this type of data. Simulated wind-driven rainfall experiments were also conducted on two plaster types. The results indicate that the static test used to measure the absorption coefficient can reasonably be used to predict actual wind-driven rainfall infiltration.

This thesis is an experimental study of turbulent flows over smooth and rough walls in a channel that consists of an upstream parallel section to produce a fully developed channel flow and a diverging section to produce an adverse pressure gradient (APG) flow. The roughness elements used were two-dimensional square ribs of nominal height k = 3 mm. The ribs were secured to the lower wall of the channel and spaced to produce the following three pitches: 2k, 4k and 8k, corresponding to d-type, intermediate and k-type rough walls, respectively. For each rough wall type, the ribs were inclined at 90°, 45° and 30° to the approach flow. The velocity measurements were performed using a particle image velocimetry technique. The results showed that rib roughness enhanced the drag characteristics, and the degree of enhancement increased with increasing pitch. The level of turbulence production and Reynolds stresses were significantly increased by roughness beyond the roughness sublayer. It was observed that the population, sizes and the level of organization of hairpin vortices varied with roughness and more intense quadrant events were found over the smooth wall than the rough walls. APG reinforced wall roughness in augmenting the equivalent sand grain roughness height, turbulence production and Reynolds stresses. APG also reduced the sizes of the hairpin packets but strengthened the quadrant events in comparison to the results obtained in the parallel section. The secondary flow induced by inclined ribs significantly altered the distributions of the flow characteristics across the span of the channel. Generally, the mean flow was less uniform close to the trailing edge of the ribs compared to the flows at the mid-span and close to the leading edge of the ribs. The Reynolds stresses and hairpin packets were distinctly larger close to the trailing edge of the ribs. Rib inclination also decreased the drag characteristics and significantly modified the distributions of the Reynolds stresses and quadrant events. In the parallel section, the physical sizes of the hairpin packets were larger over 45° ribs whereas in the diverging section, the sizes were larger over perpendicular ribs.

This thesis explores the critical question of the ethics of creation as it emerges to the forefront of contemporary thought in the late twentieth century. The question is examined through three independent yet interrelated motifs: the legend of the Golem, the symbol of the Western Wall in Jerusalem, and the literature of Franz Kafka. An understanding of these three motifs, in all their implications, can provide valuable commentary and insightful reflections so that a discourse on a possible moral and ethical ground for affirmative creation can be engaged. It is imperative, in light of the destructive potentiality of our creative making, to address this discourse if architecture is to regain cultural relevance.

The current design procedure for cantilever structures on spread footings in the Texas Department of Transportation (TxDOT) is based on horizontal pressure that is calculated by using Rankine's and Coulomb's theory. These are classical Geotechnical Engineering methods. Horizontal earth pressure due to moisture and volume change in high plasticity soil is not determined by these classical methods. However, horizontal pressure on most of the cantilever retaining structures in Texas is determined by following the classical methods. In recent years, a number of consultants have considered the horizontal pressure due to swelling on cantilever retaining structures in Texas. However, the proposed horizontal pressure by consultants is 10-20 times higher than the classical horizontal pressure. This method of cantilever retaining structure design without knowing the real pressure and stress pattern increases the thickness of the wall, and raises the cost of construction. This study focuses on providing adequate patterns of lateral earth pressure distribution on cantilever retaining structures in expansive soil. These retaining wall structures are subject to swelling pressures which cause horizontal pressures that are larger than the classical especially near the ground surface. Beside the prediction of lateral earth pressure distribution, the relations between water content, volume change and suction change are determined. Based on the laboratory testing program conducted, Soil Water Characteristic Curves (SWCC) are determined for a site located at the intersection of I-35 and Walters Street in San Antonio, Texas. Additionally, relations between volume change with confining pressure curve, water content change with the change of confining pressure curve, water content change with change of matric suction and volume change with change of matric suction curves are generated based on laboratory tests. There are a number of available mass volume measurement methods that use mostly mercury or paraffin to obtain volume measurements. Although these methods are reported in the literature, they are not used in practice due to application limitations like safety, time, and cost. In order to overcome these limitations, a new method was developed to measure the volume of soil mass by using sand displacement. This new method is an inexpensive, safe, and simple way to measure mass volume by Ottawa sand.

Precast prestressed hollow core units are commonly used in the construction of the flooring system in precast buildings. These units without transverse reinforcement bars are designed to resist seismic loading as replacement for fixed-base precast wall panels in the construction of warehouse buildings. Thus, this research seeks to investigate the seismic performance of the units constructed as a subassemblage (single wall) subjected to biaxial loading and as a superassemblage (multi-panel) subjected to quasi-static lateral loading. A design procedure for warehouse building using precast hollow core walls under Damage Avoidance Design (DAD) is proposed. In addition, a risk assessment under Performance-Based Earthquake Engineering (PBEE) is evaluated using the latest computational tool known as Incremental Dynamic Analysis (IDA). A comparative risk assessment between precast hollow core walls and fixed-base monolithic precast wall panels is also performed. Experimental results demonstrate that rocking precast hollow core walls with steelarmouring do not suffer any non-structural damage up to 2.0% drift and minor structural damage at 4.0% drift. Results revealed that the wall with unbonded fuse-bars and 50% initial prestressing of unbonded tendons performed the best compared with other types of energy dissipators. Furthermore, 12mm diameter of fuse-bar is recommended as there is no uplifting of the foundation beam during ground shaking. Hence, this type of energy dissipator is used for the construction of seismic wall panels in warehouse buildings. One of the significant findings is that the capacity reduction factor (Ø ) which relates to global uncertainty of seismic performance is approximately equal to 0.6. This value can be used to estimate the 90th percentile of the structures without performing IDA. Therefore, the structural engineers are only required to compute Rapid-IDA curve along with the proposed design procedure.

Recent earthquakes have highlighted the vulnerability of existing structure to seismic loading. Current seismic retrofit strategies generally focus on increasing the strength/stiffness in order to upgrade the seismic performance of a structure or element. A typical drawback of this approach is that the demand on the structural and sub-structural elements can be increased. This is of particular importance when considering the foundation capacity, which may already be insufficient to allow the full capacity of the existing wall to develop (due to early codes being gravity load orientated). In this thesis a counter intuitive but rational seismic retrofit strategy, termed "selective weakening" is introduced and investigated. This is the first stage of an ongoing research project underway at the University of Canterbury which is focusing on developing selective weakening techniques for the seismic retrofit of reinforced concrete structures. In this initial stage the focus is on developing selective weakening for the seismic retrofit of structural walls. This is performed using a series of experimental, analytical and numerical investigations. A procedure for the assessment of existing structural walls is also compiled, based on the suggestions of currently available code provisions. A selective weakening intervention is performed within an overall performance-based retrofit approach with the aim of improving the inelastic behaviour by first reducing the strength/stiffness of specific members within the structural system. This will be performed with the intention of modifying a shear type behaviour towards a flexural type behaviour. As a result the demand on the structural member will be reduced. Once weakening has been implemented the designer can use the wide range of techniques and materials available (e.g. use of FRP, jacketing or shotcrete) to ensure that adequate characteristics are achieved. Whilst performing this it has to be assured that the structure meets specific performance criteria and the principles of capacity design. A target of the retrofit technique is the ability to introduce the characteristics of recently developed high performance seismic resisting systems, consisting of a self centring and dissipative behaviour (commonly referred to as a hybrid system). In this thesis, results of experimental investigations performed on benchmark and selectively weakened walls are discussed. The investigations consisted of quasi-static cyclic uni-directional tests on two benchmark and two retrofitted cantilever walls. The first benchmark wall is detailed as typical of pre-1970's construction practice. An equivalent wall is retrofitted using a selective weakening approach involving a horizontal cut at foundation level to allow for a rocking response. The second benchmark wall represents a more severe scenario where the inelastic behaviour is dominated by shear. A retrofit solution involving vertically segmenting the wall to improve the ductility and retain gravity carrying capacity by inducing a flexural response is implemented. Numerical investigations on a multi-storey wall system are performed using non linear time history analysis on SDOF and MDOF lumped plasticity models, representing an as built and retrofitted prototype structure. Calibration of the hysteretic response to experimental results is carried out (accounting for pinching and strength degradation). The sensitivity of maximum and residual drifts to p-delta and strength degradation is monitored, along with the sensitivity of the peak base shear to higher mode affects. The results of the experimental and analytical investigations confirmed the feasibility and viability of the proposed retrofit technique, towards improving the seismic performance of structural walls.