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  • Thesis

  • Authors: Hu, Changhong (2006)

  • Ultrasound imaging is a well-established and widely used clinical technique that shows the cross-sectional image of human tissues. Conventional ultrasound systems are targeted at imaging the heart or abdominal organs and the spatial resolution at this frequency range is on the order of a few millimeter. An ultrasound system will be capable of providing a better spatial resolution if higher frequencies are used. High frequency ultrasonic imaging (> 20 MHz) using single element transducers has been shown to be clinically useful in ophthalmology, dermatology, small animal and intravascular imaging. In recent years, more studies have been carried out on the development of high frequency array transducers. Due to the fact that beamforming electronics is not yet commercially available fo...

  • Thesis

  • Authors: Xie, Qing (2006)

  • Most of today s software users interact with the software through a graphical user interface (GUI), which constitutes as much as 45-60% of the total code. The correct¬ness of the GUI is necessary to ensure the correctness of the overall software. Although GUIs have become ubiquitous, testing GUIs for functional correctness has remained a ne¬glected research area. Existing GUI testing techniques are extremely resource intensive primarily because GUIs have very large input spaces and evolve frequently. This dis¬sertation overcomes the limitations of existing techniques by developing a process with supporting models, techniques, and tools for continuous integration testing of evolving GUI-based applications. The key idea of this process is to create three concentric testing loops, each...

  • Thesis

  • Authors: Perez, Natalia (2006)

  • In this study, shear strength and volume change behavior of unsaturated soils is evaluated using axis-translation test methods and advanced testing equipment designed to provide accurate volume change determination during specimen shearing. Tests were performed on a wide range of soil types with net normal stress from 20 to 250 kPa and matric suction from 20 to 700 kPa. This data set adds significantly to the existing database of unsaturated soil properties. The triaxial test data was analyzed using the extended Mohr-Coulomb equation proposed by Fredlund et al (1978). A hyperbolic curve was fit to the (kb versus suction relationship, and a correlation between the hyperbolic curve parameters and soil index properties was developed. Volume change behavior for the soils was related to...

  • Thesis

  • Authors: Shoaf, Kari (2006)

  • Antiadhesion therapy has been found to be a very promising means to prevent and treat infections in the respiratory, urinary, and gastrointestinal tract. Despite the considerable research interest in antiadhesives, relatively little is known about the ability of commercial dietary oligosaccharides, such as prebiotics, to inhibit pathogen adherence. The goal of this research was to determine if commercially available prebiotic oligosaccharides could function as antiadhesive agents against enteropathogenic E. coli (EPEC). To investigate the ability of prebiotics to inhibit EPEC adherence, inhibition assays were performed by comparing adherence rates of EPEC on HEp-2 and Caco-2 cells in the presence of galactooligosaccharides (GOS), inulin, fructooligosaccharides, lactulose, or raffin...

  • Thesis

  • Authors: Singh, Swaroop Swaran (2006)

  • This present study deals with designing a real-time remote handheld ECG monitoring system and evaluating its potential usefulness in early detection of heart conduction problems. The raw ECG recordings were sent by the handheld monitor (client) to a remote server, which performed an on-line ECG analysis and sent the results back to the client. Real-time feedback provided to the client included display of ECG, results of ECG analysis and alarms (if required). The objective of this work was to determine its effectiveness in real-time identification of particular pattern preceding ventricular fibrillation. The remote server identified the occurrence of QRS complex and premature ventricular contractions and monitored ECG for ventricular tachycardia and variations in heart rate variab...

  • Thesis

  • Authors: Jia, Weiwei (2006)

  • Electro-osmotic grouting is a new foundation improvement technique proposed to treat low permeability, liquefiable silty soils underneath existing structures for the purpose of liquefaction-mitigation. This technique uses a d.c. current to introduce water soluble grout materials and reactants into the silty soils. Setting time of injected grouts can be controlled by adjusting the concentration and sequence of introduction of various components. Both experimental and numerical studies were performed in this research. Experiments were conducted to prove the feasibility of electro-osmotic injection under 1-D and 3-D conditions, to quantify the increase of liquefaction resistance in silty soils due to electro-osmotic grouting, and to design grout mixes feasible for electro-osmotic grou...

  • Thesis

  • Authors: Harden, John Michael (2006)

  • Many soil and aquifer systems in the United States have been subjected to chemical contamination from past industrial and military activities. While many remediation technologies are currently being applied, in situ chemical oxidation (ISCO) is one option that is often favored because of its potential for fast remediation times and high user control. This technology involves the direct injection of chemical oxidizers (e.g. hydrogen peroxide, ozone, or permanganate) into targeted contaminant zones within the subsurface, and it has been proven to be amenable to both BTEX compounds and other volatile organic compounds such as chlorinated solvents. This study had several key objectives. Firstly, multiple soil samples, each containing an elevated level of a targeted chemical constitue...

  • Thesis

  • Authors: Ong, Kate K. (2006)

  • Organophosphorus acid anhydrolase (OPAA) was successfully encapsulated in situ into silica and organically-modified silica materials using the acid-catalyzed hydrolysis and co-condensation of tetramethylorthosilicate and organosiloxanes via the non-surfactant templated sol-gel process. To begin, studies with guanidinium hydrochloride and urea indicated the enzyme was susceptible to denaturation (i.e., unfolding) and renaturation. The urea study followed the simple two-stage folding model with an estimated Gibbs free energy value of 1.5 kcal/mol. A systematic approach was developed to prepare the mesoporous materials to encapsulate enzymes. The enzyme was found to be damaged by methanol that was generated as a by-product of sol-gel reactions. This setback was alleviated by a simple l...

  • Thesis

  • Authors: Gong, Haipeng (2006)

  • Since the introduction of Pauling's groundbreaking =dell, numerous experiments have shown that hydrogen-bonded secondary structure is an important factor in protein folding. Under folding conditions, the linear polypeptide chain can form marginally stable elements of secondary structure on a rapid time scale. Such elements, which are in dynamic equilibrium with their respective coil states, interact with one another, further organizing and stabilizing the protein. We hypothesize that this latter step is rate limiting in the folding of a protein domain. To validate this idea, I tested whether the logarithm of the folding rate constant is linearly correlated with a protein's secondary structure content. The observed, large correlation coefficient is consistent with our hypothesis and ...

  • Thesis

  • Authors: Liu, Ruiqiang (2006)

  • Copper sulfate has been the most commonly used algaecide for about a century in the U.S. to control the off-flavor problem caused by blue-green algae in channel catfish (Ictalurus punctatus) ponds. In 2001, the ~80,000 hectares of channel catfish ponds in the U.S. received a total dose of 4,000,000 kg of CuSO4•5H2O or 1,000,000 kg of Cu2+. However, no detailed studies have been available pertaining to the potential adverse impacts of the copper applied in catfish ponds on human and environmental health. A pilot-scale study and various field measurements at commercial ponds were conducted to investigate the environmental fate of copper applied as an algaecide in catfish ponds. In the pilot study, a total of 774 g Cu(II) were applied to an experimental catfish pond over a period of 1...