Thesis (Ph. D.)--Washington State University. / Includes bibliographical references.

Thesis (M. Phil.)--University of Hong Kong, 1989.

This thesis investigates the geometric and topological constraints placed on the quotient space of a Fuchsian or Kleinian group by requiring that the group admits a fundamental domain which is simultaneously a Ford domain and a Dirichlet domain. In the case of Fuchsian groups, a direct correspondence with reflection groups is proved, and this result is used to first find explicitly the 23 non-cocompact arithmetic maximal hyperbolic reflection groups in the group of isometries of the hyperbolic plane, and subsequently to test whether these groups are all congruence. In the case of Kleinian groups, similar results are shown, and some examples of reflection groups are considered. / text

Land has always been the focus of public debates among scholars, policy makers and local populations due to its scarcity in face of population explosion and rapid urban growth. This is particularly so in the case of China. In order to support an unprecedented rate of urbanization, the institutional mechanism of land expropriation has been widely adopted by the government of the People's Republic of China over the last three decades. However, the effect of this institutional mechanism in rural China has become increasingly controversial. On one side, it is one of the most powerful tools to assemble land for urban development. Moreover, by means of land expropriation and land conveyance, local governments are capable of collecting substantial revenues to fund urban development. On the other side, the exclusive power of local governments over land expropriation, which is derived from the land management system, makes it possible for local governments to manipulate the price at which land is taken from farmers. In practice, local governments expropriate suburban or rural land at a low price and then lease it at a much higher price in land market. Therefore, inequitable compensation for land expropriation has led to numerous conflicts and social tensions between local governments and land-loss farmers. The issue of land expropriation and compensation has been identified as one of most primary sources of social discontents and complaints. Even though a growing number of studies have been conducted on the urbanization and regional development in China, a thorough cause–effect elaboration of the issue of land expropriation and compensation in rural China has rarely been carried out within the political regime. This thesis analyzes the institutional framework of land expropriation and compensation in rural China from the perspectives of property rights and land management system. In addition, it discloses the opportunities for Chinese legal system to solve this issue by borrowing legal norms, wisdoms and experience from other jurisdiction, such as the United States and Germany. Furthermore, it aims to improve and reconstruct the legal framework of compensation by elaborating the concept of long-term reciprocity. Three primary questions would be elaborated in this thesis. Is the compensation for land expropriation in rural China equitable? If the compensation is not equitable, how has such an inequity been caused? And most importantly, how to improve the compensability of land expropriation? / published_or_final_version / Real Estate and Construction / Doctoral / Doctor of Philosophy

This dissertation explores magnetic-field- and electric-current-driven domain-wall motion in thin-film-based magnetic microstructures. Conventional thin-film growth and microstructure fabrication techniques including electron-beam lithography and focused ion beam milling are used to fabricate nanometer-scale one-dimensional and two-dimensional magnetic structures that support magnetic domains (regions of different magnetization orientation separated by domain walls). A high-spatial resolution, hightemporal resolution technique for measuring the field- or current- driven dynamics of the domain walls, based on the magneto-optic Kerr effect, is developed and used to study the wall dynamics. Field-driven domain-wall motion at slow magnetic field sweep rates is dominated by Barkhausen jumps, the discontinuous random movement of domain-wall displacements. The experiments described represent one of the first successful attempts to extend the study of Barkhausen effects into the two-dimensional region. The experiments successfully probe velocity distributions, jump amplitude distributions, and attempt to address issues that pertain to the universal exponents that describe the scaling behavior of Barkhausen jump distribution function including effects of dimensionality and sweep-rate effects on the exponents. A novel dual-beam magneto-optical experiment is performed on thin-film microstructure that probes negative Barkhausen jumps (jumps that oppose the direction favored by Zeeman energy driving the magnetic reversal). A new mechanism for negative Barkhausen jumps is proposed that accounts for the observed effects. Domain-wall motion driven by (spin-polarized) electric current is studied in nanoscale thin-film based wires. The experiments address issues pertaining to the basic mechanisms responsible for current-driven domain-wall motion, which are believed to be the adiabatic spin-torque mechanism and non-adiabatic mechanisms. The experiments described are the first true time-resolved measurements of current-driven displacements, and the results reveal new information about the stochastic properties of current-driven domain wall displacements. The results also provide information on domain-wall velocities and spin-flip efficiencies that address issues related to spin-torque mechanisms.

Three goals of this research were: 1) to develop a field-scale research facility that could be used for conducting a variety of soil water experiments in both deep (greater than 2 meters) and near-surface soils where the soil water balance could be accurately determined; 2) to develop a transient experimental technique for calibrating time domain reflectometry (TDR) probes; and 3) to study the use of vertically-installed TDR probes for measuring near-surface soil water movement in a field setting, and to compare these measurements with those made by the weighing lysimeter. The weighing lysimeter facility consists of two lysimeter tanks, 4.0 m deep and 2.5 m in diameter, which rest atop a scale with a resolution of ±200 g, equivalent to ±0.04 mm of water on the surface. Data collection is completely automated with a data logger and personal computer. Both lysimeters are instrumented with TDR probes, tensiometers, and pore water solution samplers; thermocouples are installed in one lysimeter for measuring temperature. The TDR probes were calibrated using a transient method known as upward infiltration. The method is rapid, allows the soil to remain unchanged during the experiment, and provides many data points. The upward infiltration method was tested using two different length probes in soils of three textures. Results show that the upward infiltration method is stable, repeatable, and provides accurate dielectric constants and calibration curves. Four, vertically-installed TDR probes of different lengths (200, 400, 600, and 800 mm) were placed in the lysimeter at ground surface to measure water added and water lost during a one-month period in the presence of daily irrigated turfgrass. The purpose of this study was to compare changes in soil water storage as measured by the TDR system, against measurements made using the weighing lysimeter. The TDR probes detected diurnal changes in water content due to irrigation and evapotranspiration, even when these amounts changed slightly from day to day. The TDR probes underestimated the measurements of both water added and water loss, as confirmed using measurements from the weighing lysimeter. The presence of a 47-mm thick biomass above the TDR waveguides retained water that otherwise would have percolated the soil surface into the measurement domain of the probes. Addition and loss of water in the biomass were recorded by the lysimeter, but not by the TDR probes, thus explaining the underestimation. Modeling of near-surface water movement with the HYDRUS model showed very similar water movement behavior as measured by the TDR probes. This confirms our hypothesis that TDR would a useful tool for measuring diurnal changes in water content for irrigation scheduling.

Contaminants can enter groundwater through the unsaturated zone as dissolved solutes. To predict the location and extent of these contaminants, transport parameters such as pore water velocity y and dispersion coefficient D are required. These parameters are often obtained through transport experiments. The goal of this study is to determine y and D using time domain reflectometry (TDR) technique. Using TDR for transport experiments under unsaturated conditions, we investigated the effects of volumetric water content θᵥ, distance of flow path, and draining-wetting history on D. TDR was used to measure θᵥ, and salt concentration in twenty-one unsaturated column experiments. The 105 cm-long column was homogeneously packed with silica sand (particle size: 53 to 425 pm). Ten TDR probes at ten depths were used to obtain in situ breakthrough curves and a chloride electrode was used to measure effluent breakthrough curves at the bottom of the column. A 35 mM NaC1 (sodium chloride) was used as the tracer with 20 mM NaC1 as background solution. We developed a three-parameter expression relating θᵥ, to measured dielectric constant Kₐ: θᵥ =aKₐᵅ + b. This calibration expression fits as closely or better than the "universal polynomial" and is also consistent with the well-known mixing model. For an isotropic soil with homogeneous water distribution, this expression is further simplified to two parameters by taking α = 0.5. The effects of temperature, porosity, soil solid and bound water can be taken into account by varying a and b of the two-parameter expression. TDR measurements have been shown to be sensitive to bound water and not particular sensitive to the other factors. To calculate y and D from breakthrough curves of step-input experiments, a new moment analysis method has been developed. The transport parameters obtained from this new method show a little difference from the parameters determined from the convection-dispersion equation using the CXTFIT model (a published computer program for estimating solute transport parameters from observed breakthrough curves). Our results demonstrated that D is dependent on measurement methods and concentrations of experimental solutions.

No description available.

The mitochondrial tyrosyl tRNA synthetases (mtTyrRS) from certain fungii are found to be bifunctional enzymes that aid in group I intron splicing in addition to charging tRNA[superscript Tyr]. This splicing activity is conferred by several insertions that are unique to these mtTyrRS. Initial biochemical evidence suggested the similar tertiary structures of the tRNA and the intron enable binding of the protein to both. However, a recently solved co-crystal structure showed that the tRNA and intron were bound on opposite faces of the protein. The intron was bound almost exclusively by a novel surface formed by several insertions in the protein. This work presents the structure of the C-terminal domain of the A. nidulans mtTyrRS (PDB ID -- 2ktl). NMR results show that the C-terminal domain contains an S4 fold with a mixed [beta]-sheet and two anti-parallel [alpha]-helices that pack against these strands. The strands [beta]1 and [beta]5 are parallel, and [beta]2 to [beta]5 are arranged anti-parallel to each other. The C-terminal domain from A. nidulans mtTyrRS has three insertions in its sequence that make it almost twice the size of bacterial TyrRS. NMR results show that insertion 3 at the N-terminus of the domain is flexible. Insertion 4 is contained in the loop connecting [beta]2-[beta]3 and does not have a well defined structure. Insertion 5 and the C-terminal extension form two helices, [alpha]5 and [alpha]6 that fold away from the core of the protein. An extended helix ([alpha]4) between strands [beta]3 and [beta]4 was identified by NMR. Based on structural alignments with bacterial TyrRS, this helix was classified as a novel insertion 4b in the C-terminal domain. Conserved positively charged residues used to bind the tRNA are found in the turn between the anti-parallel [alpha]-helices and the turn connecting strands [beta]4-[beta]5. Based on a comparison with other TyrRS structures, the three insertions are positioned away from the tRNA binding site. The insertions form a novel RNA binding surface that could interact with the intron. Since these insertions are found in loop and termini regions, they could be a structural adaptation acquired by these splicing mtTyrRS. NMR spectra of the full length TyrRS from B. stearothermophilus and mtTyrRS from A. nidulans indicate that the motion of the C-terminal domain is coupled to that of the full length protein. This provides new information regarding the organization of the full length TyrRS. / text

Currently there is no consensus on how to account for the lateral earth pressures when designing drilled shaft retaining walls in expansive clay soils. Typically an equivalent fluid pressure is assumed which can range from 40 psf/ft to over 100 psf/ft. The range of assumptions currently in use can cause more than a factor of two difference in the maximum bending moment in the shaft. This range could cause the walls to be over-designed or under-designed. A full-scale test drilled shaft retaining wall was constructed on a site underlain by approximately 50 feet of the expansive Taylor Clay. Analysis of the wall is intended to provide information to be considered in design about the effects of the moisture cycles which cause shrinking and swelling. In order to monitor the moisture changes within the clay, 20 Time Domain Reflectometry (TDR) probes were installed behind the wall. This thesis discusses the monitoring plan, calibration, installation, and initial results from these probes. The objectives of this thesis is to provide information regarding the site conditions and reasons for using TDR probes for this project and to describe the monitoring plan, calibration, installation, and the field performance of the TDR probes and the moisture values that have been seen on the site to date. Previous studies show that difficulties can be expected when using TDR probes in highly plastic clays. Results from this study are typical of these results seen previously. The initial results show that 4 of the 20 probes are recording reasonable waveforms. However, the waveforms cannot be analyzed using conventional methods. This result was because the waveform reflection that indicates the end of the probe cannot be defined due to attenuation of the signal, which is typical of highly conductive soils. Also, the large amount of scatter in the electrical conductivity values does not allow for the moisture content to be correlated to the electrical conductivity. In order to use the TDR probes to measure moisture content at the project site, an alternative method needs to be employed to analyze available waveforms. If another method can be successfully employed for the functional probes, the subsequent step would involve recovering the probes that are not functioning properly in order to get a moisture profile along the full cantilevered height of the wall. Direct moisture measurements should also be taken periodically to provide a moisture profile. / text