Previous evidence has shown that Parkinson disease (PD) has a heritable component, but only a small proportion of the total genetic contribution to PD has been identified. Genetic heterogeneity complicates the verification of proposed PD genes and the identification of new PD susceptibility genes. Our approach to overcome the problem of heterogeneity is to study a population isolate, the mid-western Amish communities of Indiana and Ohio. We performed genome-wide association and linkage analyses on 798 individuals (31 with PD), who are part of a 4,998 member pedigree. Through these analyses, we identified a region on chromosome 5q31.3 that shows evidence of association (p-value < 1 x 10-4) and linkage (multipoint HLOD = 3.77). We also found further evidence of linkage on chromosomes 6 and 10 (multipoint HLOD 4.02 and 4.35 respectively). These data suggest that locus heterogeneity, even within the Amish, may be more extensive than previously appreciated.

Integrated silicon (Si) photonics represents one of the key technologies for developing compact high speed optical systems for computing and telecommunications. In such systems, electric buses are replaced with integrated Si waveguides which transport light across the chip. In order to implement high density networks, it is inevitable that waveguides will need to be crossed to transport information across orthogonal directions. However, when two or more waveguides cross, light is scattered due to the abrupt change in the modal index resulting in losses of up to 40 percent. This loss occurs to both the environment as well as the overlapped waveguide, causing cross-talk into the other channel resulting in false signals. Current Si based waveguide crosses require either a large footprint or are limited in the number of waveguides that can be crossed simultaneously. In this work, we develop integrated gradient index elements based on the Maxwell Fisheye (MFE) to provide low-loss and massively parallel optical waveguide crossings. To realize a crossing, waveguides which are modal index matched to the MFE are coupled across the lens wherein the output of one waveguide is imaged to the input of its partner on the opposite side. Based on this methodology, we present full-wave modeling of the device demonstrating a 0.1 dB loss (97.7% transmission) per crossing for an overall waveguide cross footprint of 28.26 square microns, among the most efficient designs to date. We also propose how this device can be realized using smoothly tapered Si waveguides to provide the required 2D gradient refractive index profile.

As the limits of silicon based transistors are approached, carbon nano-electronics represents a promising alternative to traditional semiconducting transistors. Silicon-dioxide hinders the electron transport through carbon transistors as well as obscuring information about their transport. Diamond is a promising new dielectric for use with carbon transistors which may remedy these problems. This project is concerned with the development of diamond thin films for use as dielectric substrates in FETs. Diamond films were grown, trying to minimize thickness and conductivity. Diamond was chosen as a material due to its wide band gap, as well as its radiation hardness. This would allow inspection of the effects of radiation on the transistor elements in our FETs. These films were characterized using a number of techniques to assess their viability as dielectric substrates. Once the viability was established, the surface was modified to create an optimal interface for the transistors that would be transferred to the surface. Finally, transfer of carbon based transistors was attempted.

White light-emitting diodes (LEDs) are the lighting of the future due to their potential energy savings and the proven success with monochromatic LEDs. However, white LEDs require an expensive fabrication process involving the incorporation of many different monochromatic semiconductors into a single LED; this is often referred to as color mixing. In 2005, a new class of semiconductors was discovered which is called ultrasmall CdSe quantum dots. This new class of material emits perfect, white light, so the integration of ultrasmall CdSe quantum dots into LEDs would result in the eradication of all the costs associated with color mixing. Since its discovery, the brightness of ultrasmall CdSe nanocrystals has increased over time from a ~2% quantum yield to ~31 with a brightening method which has been termed the formic acid treatment. This thesis pertains to the improvement and LED amalgamation of these brighter ultrasmall CdSe quantum dots. In particular, many experiments were done with the goal of improving the formic acid treatment, and in the process, much was discovered about the mechanics of the brightening method. The last chapter of the thesis concludes about the results and gives possible future directions including characterization methods and another possible brightening method.

This work offers a new paradigm for building intelligent software systems that facilitate on-line learning. The research investigated effects of adopting intelligent agent techniques to an on-line learning environment. KnowBots (or Knowledge Robots) are intelligent agents created specifically for this research. These KnowBots employed intelligent agent techniques to provide assistance to learners and facilitators who participated in a series of on-line workshops. The KnowBot architecture created was based on a study of repetitive tasks of human workshop facilitators. KnowBots automated and reduced the number of these routine tasks. The study specifically captured experimental results of using KnowBots in two sessions of the ALN on-line workshop, Getting Started Creating On-line Courses. Using two experimental groups, the effect of the use of KnowBots on workshop completion was examined as well as the effects of KnowBots on other factors such as facilitation time and learner satisfaction. The findings showed that intelligent agent technology holds promise for application to on-line learning and indicated that the use of KnowBots was positively associated with higher learner completion rates in the workshops. In addition, KnowBots implemented a learning-support tool that reminded learners about deadlines. The support KnowBots were found to be effective autonomous motivators. In sum, the results of this research suggest that the application of agent technology to on-line learning holds great promise.

INTEGRATION OF TRANSPORTATION AND EMERGENCY SERVICES: IDENTIFYING CRITICAL INTERFACES, OBSTACLES, AND OPPORTUNITIES KRISTEN E. SHEPHERD Dissertation under the direction of Professor Mark D. Abkowitz Transportation and emergency services professionals interact in many situations, ranging from routine traffic accidents to large-scale events. Coordination between these groups is essential for effective and efficient response to various types of incidents. The term emergency transportation operations (ETO) represents all actions taken in regards to any incident occurring on the transportation infrastructure or requiring use of the transportation infrastructure, in order to protect health and safety. The purpose of this research was three-fold: (1) determine if a need for improvement in ETO exists, the importance of interagency coordination in realizing such improvement, and the associated benefits and challenges of enhancing coordination; (2) determine the impact of organizational factors on coordination and to identify the institutional, operational, technological, and financial factors that impact ETO coordination; and (3) identify short term initiatives that could improve coordination, as well as explore the potential for change agents based on organizational design theory that would result in long term ETO improvement. The findings from this research support the hypothesis that improvements in ETO are needed, and better coordination between transportation and emergency services is necessary. This research also concluded that institutional, operational, technological, and financial changes are necessary to improve ETO. In the short-term, the most important and feasible initiatives to improve coordination are (1) including more transportation topics in training for emergency response personnel and vice versa, perhaps through new interagency training programs; (2) increasing participation in multi-agency operations planning for all types of hazards; and (3) improving interoperability of communication and other information technologies. Greater coordination between these groups will only occur if organizational changes are made that induce ETO organizations to work together, sharing a common vision and objectives for success. Potential organizational design changes to improve coordination include implementing the functional design with horizontal linkages organizational structure, including such devices as shared information systems, task forces, full-time integrators, and teams. Furthermore, the Keiretsu model for multi-organizational relationships may offer added ETO coordination.

Single-event burnout in power diodes is studied using coupled electro-thermal simulations. A two-dimensional rectangular diode structure is designed and steady-state electrical characteristics are simulated. Single-event effects are simulated using an ion-strike modeled after data reported in the literature and transient characteristics are simulated following the strike. Ion-strike simulations are performed under isothermal conditions to study temperature-dependent device properties. Coupled electro-thermal simulations are performed to study a thermal feedback loop as a possible failure mechanism. Single-event burnout is not observed for the power diode and a thermal feedback loop is not identified. Highly localized temperature rise near pn junction is observed along the strike direction. Impact-ionization induced charge is responsible for local power generation that leads to this temperature rise. Further, two-dimensional axi-symmetric or 3D simulations could provide more incite into single-event burnout of power diodes.

Adequately preparing for and responding to potential terrestrial (land-based) chemical spills are critical to the protection of human health and ecology. In this research, an environmental risk management system is developed to support analysis and facilitate decision-making for terrestrial chemical spill planning and response. This system is designed to serve a variety of stakeholders, including managers and policy-makers, who would benefit from generating screening level environmental risk assessments without requiring a technical background or collection of detailed environmental and chemical data. Areas of potential application include transportation routing, industrial zoning, environmental regulatory compliance and enforcement, spill response, and security planning. The system leverages geographic information systems (GIS) technology to assess and delineate the immediate threat to human and environmental receptors from terrestrial chemical spills. It characterizes a spilled chemicals ability to immediately impact human health, groundwater, surface water, and soil resources, and incorporates these four receptors into an overall measure of terrestrial chemical risk. The methodology driving this characterization is a risk index model, which is supported by a comprehensive database containing information on chemical properties and environmental resources. This model differs from previous environmental risk indices in that it: 1) accounts for attributes of the local environment and contaminant in question, 2) requires almost no data input or scientific knowledge from the user, 3) creates an easy-to-understand visual output that supports the decision process, and 4) has the potential for transferability to sites throughout the United States. In establishing proof of concept, the system is applied to a case study of a representative area in the United States. The potential terrestrial spill of several different chemicals is considered across all areas of Geauga County in the State of Ohio. Utilizing the system, risk assessment results are generated and visually displayed. The implications of these results are discussed in terms of how they impact decisions involving transportation routing, industrial zoning, environmental regulatory compliance and enforcement, spill response, and security planning.

How visual targets are selected for eye movements is a fundamental neural coding problem for all animals that see with a fovea. The strength of the model of the neuron as a coincidence detector suggests neural synchrony is a plausible, if not intrinsic, part of the cortical code. Moreover, synchrony has been proposed as a neural mechanism for the allocation of attention in visual processing. To investigate a synchronous ensemble code for saccadic target selection in the frontal eye field (FEF), the gravity algorithm was applied to simultaneously recorded neurons in a macaque monkey performing color singleton search. In addition to developing an original measure of statistical significance for the gravity method, this thesis demonstrates the existence of synchrony in the search process. The functional influence of synchrony in the distribution of visual attention, however, or in gating broad population responses in FEF, requires further interpretation.

This dissertation examined the use and variations of African American Language by middle school students. It focused on the relationships of African American Language to the social and cultural identities and academic achievements of students in educational settings. A second focus examined the educational complexities surrounding the uses of African American Language use by students in traditional classroom environments. Over a seven-month period, data were collected on interactions involving the use of African American Language in an eighth grade language arts classroom. Key classroom events and student interviews were examined utilizing the cultural analysis of discourse, thematic, and microethnographic analysis. Also examined were the cultural models for the use and meaning of African American Language and for cultural identity held by five African American Language student speakers. The study also examined the central role of prosody in signaling particular social and cultural identities and explored the significance of students adopting such identities across varying spaces in and outside of the classroom as a means to navigate social existences in a predominantly African American school community.