Reduced organic sulfur: Analysis and interaction with mercury in the aquatic environment

Reduced organic sulfur (ROS) compounds are environmentally ubiquitous and play an important role in sulfur cycling as well as in biogeochemical cycles of toxic metals, in particular mercury. Development of effective methods for analysis of ROS in environmental samples and investigations on the interactions of ROS with mercury are critical for understanding the role of ROS in mercury cycling, yet both of which are poorly studied. Covalent affinity chromatography-based methods were attempted for analysis of ROS in environmental water samples. A method was developed for analysis of environmental thiols, by preconcentration using affinity covalent chromatographic column or solid phase extraction, followed by releasing of thiols from the thiopropyl sepharose gel using TCEP and analysis using HPLC-UV or HPLC-FL. Under the optimized conditions, the detection limits of the method using HPLC-FL detection were 0.45 and 0.36 nM for Cys and GSH, respectively. Our results suggest that covalent affinity methods are efficient for thiol enrichment and interference elimination, demonstrating their promising applications in developing a sensitive, reliable, and useful technique for thiol analysis in environmental water samples. The dissolution of mercury sulfide (HgS) in the presence of ROS and dissolved organic matter (DOM) was investigated, by quantifying the effects of ROS on HgS dissolution and determining the speciation of the mercury released from ROS-induced HgS dissolution. It was observed that the presence of small ROS (e.g., Cys and GSH) and large molecule DOM, in particular at high concentrations, could significantly enhance the dissolution of HgS. The dissolved Hg during HgS dissolution determined using the conventional 0.22 μm cutoff method could include colloidal Hg (e.g., HgS colloids) and truly dissolved Hg (e.g., Hg-ROS complexes). A centrifugal filtration method (with 3 kDa MWCO) was employed to characterize the speciation and reactivity of the Hg released during ROS-enhanced HgS dissolution. The presence of small ROS could produce a considerable fraction (about 40% of total mercury in the solution) of truly dissolved mercury (< 3 kDa), probably due to the formation of Hg-Cys or Hg-GSH complexes. The truly dissolved Hg formed during GSH- or Cys-enhanced HgS dissolution was directly reducible (100% for GSH and 40% for Cys) by stannous chloride, demonstrating its potential role in Hg transformation and bioaccumulation.

BIKE – Bicycle Knowledge Explorer (Palm Beach)

This route planner, funded by the Palm Beach Metropolitan Planning Organization (MPO), is a joint effort by Florida International University GIS Center and University of Florida Geomatics Program at Fort Lauderdale Research and Education Center. It is designed as a planning tool for bicyclists. Assistance was received from the Palm Beach County Bicycle, Greenways, Pedestrian Advisory Committee.

BIKE – Bicycle Knowledge Explorer [Miami-Dade]

This route planner, funded by the Miami-Dade Metropolitan Planning Organization(MPO), is a joint effort by Florida International University GIS Center and University of Florida Geomatics Program at Fort Lauderdale Research and Education Center. It is designed as a planning tool for bicyclists. Assistance was received from the Miami-Dade County Bicycle/Pedestrian Advisory Committee and various cyclists and transportation professionals.

BIKE – Bicycle Knowledge Explorer [Broward County]

This route planner, funded by the Broward Metropolitan Planning Organization (MPO), is a joint effort by Florida International University GIS Center and University of Florida Geomatics Program at Fort Lauderdale Research and Education Center. It is designed as a planning tool for bicyclists. Assistance was received from the Broward County Bicycle/Pedestrian Advisory Committee and various cyclists and transportation professionals.

An analysis of Haitian parents' perceptions of their children with disabilities

Parental involvement is an integral part of the educational system in the U.S. Yet, parents from non-mainstream racial/ethnic backgrounds have not fully grasped the nature of parental involvement expectations in the educational process and how these expectations may impact student achievement. The purpose of this study was to identify Haitian parents’ perceptions of their children with disabilities and the education these children were receiving. Several authors have conducted studies on parents of children with disabilities to better gain an understanding of the level of their involvement with their children’s education, their perceptions of the children, and their views on the school system (Harry, 1992a, 1992b). In this study, Haitian parents of children with disabilities were interviewed using an interview protocol. Through these interviews, this study explored 10 Haitian parents’ perceptions of their child with a disability, the education the child was receiving, their interaction with the school system, and how the disability had affected their relationship with their child and their involvement with the school. Findings of the present study revealed that these Haitian parents seldom disagreed with school personnel and did not seem to fully grasp the different methods available to address their concerns as parents of children with disabilities nor the role they were expected to play in the process. The majority did not have basic literacy skills in Creole or English. The parents in this study were overwhelmed by school written communication. Additionally, this study discovered that parents’ perceptions were guided by two core concepts: coping mechanisms and locus of control. Parents with an internal locus of control, who tended to be more educated, focused inward to find solutions to problems encountered. Those with an external locus of control relied on outside influences to resolve their problems. Parental involvement was strongly influenced by their values, beliefs, customs, and conceptual knowledge about disability; all closely aligned with culture and acculturation. Overall, these parents’ perceptions greatly influenced their thoughts and behaviors when they realized that their children with disabilities might fall short of their immigrant dreams of success they held for these children.

Dynamic image precompensation for improving visual performance of computer users with ocular aberrations

With the progress of computer technology, computers are expected to be more intelligent in the interaction with humans, presenting information according to the user's psychological and physiological characteristics. However, computer users with visual problems may encounter difficulties on the perception of icons, menus, and other graphical information displayed on the screen, limiting the efficiency of their interaction with computers. In this dissertation, a personalized and dynamic image precompensation method was developed to improve the visual performance of the computer users with ocular aberrations. The precompensation was applied on the graphical targets before presenting them on the screen, aiming to counteract the visual blurring caused by the ocular aberration of the user's eye. A complete and systematic modeling approach to describe the retinal image formation of the computer user was presented, taking advantage of modeling tools, such as Zernike polynomials, wavefront aberration, Point Spread Function and Modulation Transfer Function. The ocular aberration of the computer user was originally measured by a wavefront aberrometer, as a reference for the precompensation model. The dynamic precompensation was generated based on the resized aberration, with the real-time pupil diameter monitored. The potential visual benefit of the dynamic precompensation method was explored through software simulation, with the aberration data from a real human subject. An "artificial eye'' experiment was conducted by simulating the human eye with a high-definition camera, providing objective evaluation to the image quality after precompensation. In addition, an empirical evaluation with 20 human participants was also designed and implemented, involving image recognition tests performed under a more realistic viewing environment of computer use. The statistical analysis results of the empirical experiment confirmed the effectiveness of the dynamic precompensation method, by showing significant improvement on the recognition accuracy. The merit and necessity of the dynamic precompensation were also substantiated by comparing it with the static precompensation. The visual benefit of the dynamic precompensation was further confirmed by the subjective assessments collected from the evaluation participants.

A practical system for hands-off computer interaction based on electromyogram (EMG)/eye gaze tracking (EGT)

Effective interaction with personal computers is a basic requirement for many of the functions that are performed in our daily lives. With the rapid emergence of the Internet and the World Wide Web, computers have become one of the premier means of communication in our society. Unfortunately, these advances have not become equally accessible to physically handicapped individuals. In reality, a significant number of individuals with severe motor disabilities, due to a variety of causes such as Spinal Cord Injury (SCI), Amyothrophic Lateral Sclerosis (ALS), etc., may not be able to utilize the computer mouse as a vital input device for computer interaction. The purpose of this research was to further develop and improve an existing alternative input device for computer cursor control to be used by individuals with severe motor disabilities. This thesis describes the development and the underlying principle for a practical hands-off human-computer interface based on Electromyogram (EMG) signals and Eye Gaze Tracking (EGT) technology compatible with the Microsoft Windows operating system (OS). Results of the software developed in this thesis show a significant improvement in the performance and usability of the EMG/EGT cursor control HCI.

An Analysis of Haitian Parents' Perceptions of Their Children With Disabilities

Parental involvement is an integral part of the educational system in the U.S. Yet, parents from non-mainstream racial/ethnic backgrounds have not fully grasped the nature of parental involvement expectations in the educational process and how these expectations may impact student achievement. The purpose of this study was to identify Haitian parents’ perceptions of their children with disabilities and the education these children were receiving. Several authors have conducted studies on parents of children with disabilities to better gain an understanding of the level of their involvement with their children’s education, their perceptions of the children, and their views on the school system (Harry, 1992a, 1992b). In this study, Haitian parents of children with disabilities were interviewed using an interview protocol. Through these interviews, this study explored 10 Haitian parents’ perceptions of their child with a disability, the education the child was receiving, their interaction with the school system, and how the disability had affected their relationship with their child and their involvement with the school. Findings of the present study revealed that these Haitian parents seldom disagreed with school personnel and did not seem to fully grasp the different methods available to address their concerns as parents of children with disabilities nor the role they were expected to play in the process. The majority did not have basic literacy skills in Creole or English. The parents in this study were overwhelmed by school written communication. Additionally, this study discovered that parents’ perceptions were guided by two core concepts: coping mechanisms and locus of control. Parents with an internal locus of control, who tended to be more educated, focused inward to find solutions to problems encountered. Those with an external locus of control relied on outside influences to resolve their problems. Parental involvement was strongly influenced by their values, beliefs, customs, and conceptual knowledge about disability; all closely aligned with culture and acculturation. Overall, these parents’ perceptions greatly influenced their thoughts and behaviors when they realized that their children with disabilities might fall short of their immigrant dreams of success they held for these children.

Dynamic Image Precompensation for Improving Visual Performance of Computer Users with Ocular Aberrations

With the progress of computer technology, computers are expected to be more intelligent in the interaction with humans, presenting information according to the user's psychological and physiological characteristics. However, computer users with visual problems may encounter difficulties on the perception of icons, menus, and other graphical information displayed on the screen, limiting the efficiency of their interaction with computers. In this dissertation, a personalized and dynamic image precompensation method was developed to improve the visual performance of the computer users with ocular aberrations. The precompensation was applied on the graphical targets before presenting them on the screen, aiming to counteract the visual blurring caused by the ocular aberration of the user's eye. A complete and systematic modeling approach to describe the retinal image formation of the computer user was presented, taking advantage of modeling tools, such as Zernike polynomials, wavefront aberration, Point Spread Function and Modulation Transfer Function. The ocular aberration of the computer user was originally measured by a wavefront aberrometer, as a reference for the precompensation model. The dynamic precompensation was generated based on the resized aberration, with the real-time pupil diameter monitored. The potential visual benefit of the dynamic precompensation method was explored through software simulation, with the aberration data from a real human subject. An "artificial eye'' experiment was conducted by simulating the human eye with a high-definition camera, providing objective evaluation to the image quality after precompensation. In addition, an empirical evaluation with 20 human participants was also designed and implemented, involving image recognition tests performed under a more realistic viewing environment of computer use. The statistical analysis results of the empirical experiment confirmed the effectiveness of the dynamic precompensation method, by showing significant improvement on the recognition accuracy. The merit and necessity of the dynamic precompensation were also substantiated by comparing it with the static precompensation. The visual benefit of the dynamic precompensation was further confirmed by the subjective assessments collected from the evaluation participants.