Increasing demand on freeway facilities is a major challenge facing urban areas in the United States and throughout the world. Active Traffic Management (ATM) strategies can be used to increase the performance of these facilities through improved operations without the significant expenditure associated with adding capacity. One ATM strategy that has been widely deployed in the current state of practice is ramp metering, which controls the traffic demand placed on a freeway. Merge control strategies are less prevalent and largely undeveloped. This study examines the recurrently congested northbound section of Interstate Highway 35 that approaches downtown Austin, Texas. Using the VISSIM microsimulation platform, a model of this segment was developed and calibrated to reflect current peak-hour congestion. Within this model, ramp metering and merge control technologies were implemented. The impacts on traffic throughput, speed and travel time for each of these proposed systems are evaluated. / text

Urban freeway demand that frequently exceeds capacity has caused many agencies to consider many options to reduce congestion. A series of solutions that falls under the Active Traffic Management (ATM) banner have shown promising potential. Perhaps the most popular ATM strategy is ramp metering. Ramp metering involves limiting the access of vehicles to freeways at an entrance ramp. By doing this, freeway throughput, speeds, and travel time reliability can be increased, while the number of traffic incidents can be decreased. This study examines the application of an innovative ramp metering strategy, Intersection Ramp Metering (IRM), at a section of Loop 1 in Austin, TX. IRM implements the ramp metering function at the intersection immediately upstream of the entrance ramp, rather than on the ramp itself. A microsimulation analysis of this application is performed in VISSIM, and the results confirm that freeway throughput (+10%), and system average travel time (-14%), can be improved, as well as several other performance measures. / text

This dissertation explores cathodic electrodeposition mechanisms that describe the synthesis of redox-active electrode materials. Several interesting elements are known to deposit at negative potentials (e.g., Mo, Re, Se), and by extending this work, we can tailor the growth of new binary systems (e.g., MoxRe₁₋xOy, MoxSe₁₋xOy) that have enhanced optical and electronic properties. To grasp the subtleties of deposition and understand how the growth of a particular phase is influenced by other species in solution, several analytical methodologies are used to thoroughly characterize film deposition, including chronocoulometry, voltammetry, nanogravimetry, UV-Visible spectroelectrochemistry, X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and inductively coupled plasma mass spectrometry (ICPMS). Chapter 1 is a general introduction that discusses the growth of redox-active metal oxides and alloys with an emphasis on tuning the composition to enhance material performance. Chapter 2 proposes a mechanistic pathway for the deposition of rhenium films from an acidic perrhenate (ReVIIO₄⁻) solution containing both metallic and oxide components. Unlike many other metal anions, it was observed that ReVIIO₄⁻ adsorbs to the electrode surface prior to reduction. As such, ReVIIO₄⁻ is ideally situated to be a redox-active mediator for other electrochemical reactions, and in Chapter 3, this dissertation explores how ReVIIO₄⁻ increases the deposition efficiency of Mo oxide deposition. Depth profiling XPS supported by electrochemical studies demonstrated that Mo and Re deposit separately to form an inhomogeneous material, MoxRe₁₋xOy (0.6 < x ≤ 1.0). Over a limited potential range from –0.3 V to –0.7 V (vs Ag/AgCl) the rhenium mole fraction increases linearly with the applied voltage. Chapter 4 explores the deposition of MoxSe₁₋xOy, and in this case, the incorporation of Mo species in solution shifts the deposition of Se⁰ to more positive potentials. Depending on the applied potential used, voltammetry experiments suggest that a small amount of Mo (<5%) reduces to the zero-valent phase to yield the photosensitive alloy, MoxSey. Chapter 5 discusses future work and presents preliminary data describing the deposition of Se⁰ on ITO using adsorbed ReVIIO₄⁻ as a redox mediator. / text

When proteins are unable to fold properly in the endoplasmic reticulum (ER), the resultant formation of misfolded proteins causes stress of the ER. Cells with ER stress often have a higher abundance of reactive oxygen species (ROS). Previous studies suggest that ROS could aggravate ER stress by further disrupting the ER protein folding process. More recent studies suggest that the unfolded protein response signaling pathways activated by ER stress could lead to the production of ROS. Such studies lead to the hypothesis that ER stress could be promoted by ROS, and vice versa. The aim of the present study is to test the above hypothesis by studying how ROS could be generated in ER-stressed cells. This is followed by investigating if ROS could increase or decrease the level of ER stress in cells. Finally, the extent of ER stress induced cell death in the presence and absence of ROS is assessed. The treatment of HeLa cells with tunicamycin (Tm), a common ER-stress inducing agent, resulted in the elevation of intracellular ROS that could be detected with the ROS-reactive probe dichlorodihydrofluorescein (DCF), but not dihydroethidium which is relatively specific towards superoxide anion. The Tm-induced elevation of ROS could be prevented by co-incubation of cells with thiol reductants such as dithiothreitol and N-acetylcysteine but not with the free radical scavenger ascorbate. The tunicamycin-induced elevation of ROS level could also be prevented by the over-expression of catalase in HeLa. These data is consistent with the idea that hydrogen peroxide is a major form of ROS produced in Tm-treated cells. In addition to elevation of ROS level, HeLa cells treated with tunicamycin also resulted in the phosphorylation of PERK and eIF2α, and the splicing of XBP-1. In the presence of cycloheximide to inhibit protein synthesis so as to deplete protein substrates for folding in the ER, tunicamycin-induced ER stress was greatly minimized as was evident by the absence of both the phosphorylation of PERK and splicing of XBP-1. However, the phosphorylation of eIF2α and elevation of DCF-detectable ROS remained unaffected. The cycloheximde-resistant phosphorylation of eIF2α could be prevented when cells were co-treated with thiol reductants, or upon the over-expression of catalase. These data suggest that the production of ROS in Tm-treated cells does not require the presence of ER stress as a prerequisite. Furthermore, the ROS so produced could induce phosphorylation of eIF2α without the need to cause ER stress in the first place. The quenching of ROS through the use of thiol reductants, or the over-expression of catalase, had no effect on inhibition of protein synthesis in cells treated with tunicamycin. However, the extent of cell death was significantly increased. The data obtained in this study is not consistent with the idea that ROS is a downstream product of ER stress, capable of inducing more ER-stress by a feedback mechanism. Therefore, a mutually enhancing effect between ER stress and ROS may not exist. The ROS found in stressed cells may serve to extend cellular survival under the condition of continuous stress. / published_or_final_version / Biochemistry / Doctoral / Doctor of Philosophy

Nonylphenol ethoxylates (NPEO) and octylphenol ethoxylates (OPEO), both are alkylphenol ethoxylates (APEO), a type of non-ionic surfactants commonly used in synthetic detergents for household and industrial cleaning purposes. These compounds and their degraded intermediates are xenoestrogens ubiquitously found in runoffs, sewage discharge and sludge. Not only that they persist in our surface waters and sediment, they are also found in the bodies of wildlife and human worldwide. Because of their high volume consumed and their nature as semi-persistent pollutants as well as endocrine disruptors, many developed countries have renounced their use on voluntary basis or through regulatory measure. Hong Kong is situated at the estuary of Pearl River Delta, which is one of the pollution hotspots. It is susceptible to its own water pollutants from municipal sewage (~1,054 million m3/year) and also the discharge (~3.0x109m3/ year) along the river from the industrialized and urbanized Mainland China cities. The local environment and human health are exposed to risks of these chemicals ascribed to rising consumption of detergents and their insufficient removal by sewage treatment, in addition to food intake in particular seafood. However, public awareness about APEO and endocrine disrupting chemicals is low due to no mandatory disclosure and control of these chemicals as well as the uncertainties about their chronic toxicity, based on the survey results of online questionnaires. Several recommendations have been made with reference to overseas regulatory measures and good practices to control and reduce the use of these chemicals. / published_or_final_version / Environmental Management / Master / Master of Science in Environmental Management

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Waveguides are desirable components for energy transmission throughout the electromagnetic spectrum. This thesis experimentally examines a thick slot waveguide for THz guiding and field enhancement. The waveguide is machined from planar copper sheets using the novel technique of femtosecond laser micromachining. In-plane photoconductive THz coupling to a thick slot waveguide is demonstrated using Discontinuous Galerkin Time Domain (DGTD) simulation. The results reveal positive implications for broadband low-loss/dispersion transmission lines up to 1.5 THz. / Graduate / 0544 / 0607 / 0756 / levismith3@hotmail.com

In this thesis I investigate the hosts and cluster environments of a sample of 41 radio galaxies between z = 0.4 and z = 0.6. I use spectroscopic data for a 24 object subsample to investigate their star formation histories via the strength of the 4000A break. I find that the higher radio luminosity or high excitation objects in the sample have evidence for young stellar populations, but the lower radio luminosity or low excitation objects do not. My investigations into the Fundamental Plane (FP) of 18 of the radio galaxies, using the same spectroscopic data as well as data from the literature, show that the Fanaroff- Riley type I objects (FRIs) lie on the FP of local radio galaxies once corrected for passive evolution but the Fanaroff-Riley type II objects (FRIIs) do not. I suggest that an evolution in the size of the host galaxies, aided by a combination of passive evolution and a mass-dependent evolution in the mass-to-light ratios, may explain the observed offsets. Finally, I use wide field multi-band imaging to investigate the cluster environments of the full z ~ 0.5 sample. I find that the environmental overdensity is positively correlated with the radio luminosity and observe a greater number of close companions around the FRIIs than the FRIs (albeit with only nine FRIs in the sample). The cluster environments of the radio galaxies with the greatest host luminosities show tentative evidence for an alignment between the major axis of a galaxy and that of its cluster, whilst there are hints that the objects with the highest radio luminosities have clusters whose major axis is aligned with the position angle of the radio jet. My results suggest a picture in which FRII type radio sources reside in particularly rich cluster environments at z ~ 0.5 but FRI type radio sources in less rich environments. The environment plays a key role in determining both the radio properties of the galaxy and the evolution of its host. The effect of the environment on the emission line properties and star formation histories of the galaxies leads to the overlap seen in the morphological and spectral properties of radio galaxies.

At its most essential drawing consists of the making of marks on a surface, however such an interpretation does not necessarily reflect the diverse practice of artists whose work seeks to challenge the conventions of drawing and establish new boundaries. This abstract documents a practice involving a new consideration for drawing which focuses on the active process of drawing as a physical and perceptual encounter. It proposes that eye movements and their associated cognitive processing can be considered as a drawing generating process. It does not seek to undermine the conventional three-way process of drawing involving eye, hand and brain but presents ideas which push against the established boundaries for drawing practice and has investigated new ways of making and new ways of considering the practice of drawing as a phenomenological contemplation. The proposition for drawing presented in this document, has been developed through a practice-led enquiry over the last eight years and involves using scientific methodologies found within the area of Active Vision. By examining artworks produced within the early part of the period of time defined within this thesis, emergent ideas relating to the act of making in-situ drawings and the recollection of such experiences brought about a series of questions regarding the process of generating a drawing. As the practice developed, using data obtained from different eye-tracking experiments, the author has explored the possibilities for drawing through using scientific methods of tracking the act of looking to investigate the relationship between the observer and the observer entity. Using the relationship between the drawn mark and visual responses to it as the basis for a practice-led period of research, this thesis presents the notion that by using technologies designed for other disciplines artists can explore the potential for drawing beyond the conventions cited above. Through the use of eye-tracking data the artist and author seeks to firmly establish the use of this scientific methodology within an artistic framework. It is a framework that responds to new ways of thinking about spatiality and the relations between sight and thought, taking into account the value of experience within the production of art; how the physical act itself becomes the manifestation of a process of drawing, understanding and knowledge of the world around us.

In this dissertation, novel variational optical-flow and active-contour methods are investigated to address challenging problems in computer vision and shape-based imaging. Starting from traditional applications of these methods in computer vision, such as object segmentation, tracking, and detection, this research subsequently applies similar active contour techniques to the realm of shape-based imaging, which is an image reconstruction technique estimating object shapes directly from physical wave measurements. In particular, the first and second part of this thesis deal with the following two physically inspired computer vision applications. Optical Flow for Vision-Based Flame Detection: Fire motion is estimated using optimal mass transport optical flow, whose motion model is inspired by the physical law of mass conservation, a governing equation for fire dynamics. The estimated motion fields are used to first detect candidate regions characterized by high motion activity, which are then tracked over time using active contours. To classify candidate regions, a neural net is trained on a set of novel motion features, which are extracted from optical flow fields of candidate regions. Coupled Photo-Geometric Object Features: Active contour models for segmentation in thermal videos are presented, which generalize the well-known Mumford-Shah functional. The diffusive nature of heat processes in thermal imagery motivates the use of Mumford-Shah-type smooth approximations for the image radiance. Mumford-Shah's isotropic smoothness constraint is generalized to anisotropic diffusion in this dissertation, where the image gradient is decomposed into components parallel and perpendicular to level set curves describing the object's boundary contour. In a limiting case, this anisotropic Mumford-Shah segmentation energy yields a one-dimensional ``photo-geometric'' representation of an object which is invariant to translation, rotation and scale. These properties allow the photo-geometric object representation to be efficiently used as a radiance feature; a recognition-segmentation active contour energy, whose shape and radiance follow a training model obtained by principal component analysis of a training set's shape and radiance features, is finally applied to tracking problems in thermal imagery. The third part of this thesis investigates a physics-driven active contour approach for shape-based imaging. Adjoint Active Contours for Shape-Based Imaging: The goal of this research is to estimate both location and shape of buried objects from surface measurements of waves scattered from the object. These objects' shapes are described by active contours: A misfit energy quantifying the discrepancy between measured and simulated wave amplitudes is minimized with respect to object shape using the adjoint state method. The minimizing active contour evolution requires numerical forward scattering solutions, which are obtained by way of the method of fundamental solutions, a meshfree collocation method. In combination with active contours being implemented as level sets, one obtains a completely meshfree algorithm; a considerable advantage over previous work in this field. With future applications in medical and geophysical imaging in mind, the method is formulated for acoustic and elastodynamic wave processes in the frequency domain.