Intraocular pressure (IOP) passive sensor modeling, design, fabrication and measurement

This work describes a miniaturized implantable passive pressure sensor and a remote sensing technique for pressure measurement. The sensor device consists of a capacitor array and a coil inductor, which form a high-Q LC type resonator. The capacitor array, which is also membrane structures, is fabricated by surface micromachining technique. The deflection of the membrane depends on the pressure applied to it. The higher the pressure, the larger the deflection, and the larger the capacitor is. This change of the capacitance will also change the resonant frequency of the LC resonator, and it can be detected by various types of coil detectors. One detecting prototype using a secondary resonator is proposed in this work, the sensing distance can be improved to about 1.5cm, which is larger than most of the publication work in this area. This large sensing distance will allow the detector to be integrated into a spectacles frame. It has more accurate results than prior works. The sensor itself can be smaller than 1.5mmx1.5mmx1mm, and after biocompatible material coating, the sensor can be implanted into the human body. This sensor was particularly designed for intraocular pressure (IOP) measurement. It can provide multiple and continuous IOP readouts under everyday conditions, which is desired to monitor any fluctuations of IOP, and it is very useful for glaucoma diagnosis. The sensor can also be implanted into any other part of human body to remotely measure any pressure of a tissue or inside a chamber, e.g. the pulmonary artery

Fate and Transport of Microorganisms in Coastal Subsurface-Experiment and Modeling

The objective of this dissertation was to investigate the fate and transport of microorganisms in coastal subsurface. Two topics were studied: (1) evaluation of the performance of the Marshland Upwelling System (MUS) in removing fecal bacteria and the background recovery after it is shut down; (2) Investigation of the effects of salinity and soluble organic matter (SOM) on sorption of MS-2 and development of a model to describe the sorption and transport process. The MUS showed effective performance in removing fecal bacteria during its 32 month operation period at Bayou Segnette Site. The removal efficiency was increased with its operation as the results of deposition of solid particles from primary wastewater and the growth of biofilms in subsurface. After the MUS shutdown, the subsurface environment recovered completely from the fecal bacteria loading in less than 4 months due to fast fecal bacteria natural die-off. Laboratory experiments were conducted to examine the effects of salinity and SOM on MS-2 sorption in one-dimensional sand and sandy soil columns. A two-site reversible-irreversible sorption model was found to describe MS-2 sorption successfully. In sand column tests, salinity increased MS-2 attachment by compressing double layers on reversible sorption sites and changing reversible sorption sites into irreversible sorption sites by reversing charges on the surface of some sand particles. SOM inhibited MS-2 sorption by expanding the double layer thickness on reversible sites and competing with MS-2 for the same binding place on irreversible sites. In sandy soil column tests, the bonded and dissolved soil organic matters suppressed the salinity and SOM effects and significantly reduced MS-2 adsorption. The bonded soil organic matter reduced sorption sites by occupying a great portion of sorption sites, and the dissolved soil organic matter expanded the double layer thickness on reversible sorption sites and competed with MS-2 for the same binding place. A fate and transport model, coupled with two-site reversible-irreversible sorption process, was developed to describe MS-2 sorption and transport in sand and sandy soil columns. The fate and transport model fitted the experimental data well with corresponding model parameters, which were identified using the BFGS method and sensitivity-equation method

Protein structure recognition: from eigenvector analysis to structural threading method

In this work, we try to understand the protein folding problem using pair-wise hydrophobic interaction as the dominant interaction for the protein folding process. We found a strong correlation between amino acid sequence and the corresponding native structure of the protein. Some applications of this correlation were discussed in this dissertation include the domain partition and a new structural threading method as well as the performance of this method in the CASP5 competition.;In the first part, we give a brief introduction to the protein folding problem. Some essential knowledge and progress from other research groups was discussed. This part include discussions of interactions among amino acids residues, lattice HP model, and the designablity principle.;In the second part, we try to establish the correlation between amino acid sequence and the corresponding native structure of the protein. This correlation was observed in our eigenvector study of protein contact matrix. We believe the correlation is universal, thus it can be used in automatic partition of protein structures into folding domains.;In the third part, we discuss a threading method based on the correlation between amino acid sequence and ominant eigenvector of the structure contact-matrix. A mathematically straightforward iteration scheme provides a self-consistent optimum global sequence-structure alignment. The computational efficiency of this method makes it possible to search whole protein structure databases for structural homology without relying on sequence similarity. The sensitivity and specificity of this method is discussed, along with a case of blind test prediction.;In the appendix, we list the overall performance of this threading method in CASP5 blind test in comparison with other existing approaches

Finite-time generalized synchronization of nonidentical delayed chaotic systems

This paper deals with the finite-time generalized synchronization (GS) problem of drive-response systems. The main purpose of this paper is to design suitable controllers to force the drive-response system realize GS in a finite time. Based on the finite-time stability theory and nonlinear control theory, sufficient conditions are derived that guarantee finite-time GS. This paper extends some basic results from generalized synchronization to delayed systems. Because finite-time GS means the optimality in convergence time and has better robustness, the results in this paper are important. Numerical examples are given to show the effectiveness of the proposed control techniques