CommuniSense: Crowdsourcing Road Hazards in Nairobi

Nairobi is one of the fastest growing metropolitan cities and a major business and technology powerhouse in Africa. However, Nairobi currently lacks monitoring technologies to obtain reliable data on traffic and road infrastructure conditions. In this paper, we investigate the use of mobile crowdsourcing as means to gather and document Nairobi's road quality information. We first present the key findings of a city-wide road quality survey about the perception of existing road quality conditions in Nairobi. Based on the survey's findings, we then developed a mobile crowdsourcing application, called CommuniSense, to collect road quality data. The application serves as a tool for users to locate, describe, and photograph road hazards. We tested our application through a two-week field study amongst 30 participants to document various forms of road hazards from different areas in Nairobi. To verify the authenticity of user-contributed reports from our field study, we proposed to use online crowdsourcing using Amazon's Mechanical Turk (MTurk) to verify whether submitted reports indeed depict road hazards. We found 92% of user-submitted reports to match the MTurkers judgements. While our prototype was designed and tested on a specific city, our methodology is applicable to other developing cities.Comment: In Proceedings of 17th International Conference on Human-Computer Interaction with Mobile Devices and Services (MobileHCI 2015

High-index-contrast electromechanical optical switches

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, June 2011."June 2011." Cataloged from PDF version of thesis.Includes bibliographical references (p. 278-288).System developers are looking to replace protocol-dependent, bandwidth-limited optical networks with intelligent optically-transparent integrated photonic networks. Several electromechanical optical switches are explored with the intent of being utilized as optical switching elements in transparent, integrated photonic networks. The electromechanical optical switches are based on high-index-contrast waveguide optics that is integrated with electrostatic parallel plate actuators on submicron scales. High-index-contrast waveguides are attractive due to their reduced bending radius and low in-plane scattering and optical loss. These qualities of high-index-contrast waveguides make them uniquely suited for low-cost, large-scale integration. The parallel plate actuators are used to control the waveguide light switching by mechanically establishing and terminating light pathways on time scales well below 100s of microseconds. Investigations of light pathway coupling schemes and parallel plate actuator configurations led to the development of several device structures that are categorized in three distinct device generations. Design premiums were placed upon device footprint minimization, polarization independence, high extinction ratios, and operational robustness.by Reginald Eugene Bryant.Ph.D

Development and validation of the child post-traumatic cognitions inventory (CPTCI)

Background: Negative trauma-related cognitions have been found to be a significant factor in the maintenance of post-traumatic stress disorder (PTSD) in adults. Initial studies of such appraisals in trauma-exposed children and adolescents suggest that this is an important line of research in youth, yet empirically validated measures for use with younger populations are lacking. A measure of negative trauma-related cognitions for use with children and adolescents, the Child Post-Traumatic Cognitions Inventory (CPTCI), is presented. The measure was devised as an age-appropriate version of the adult Post-Traumatic Cognitions Inventory (Foa et al., 1999). Methods: The CPTCI was developed and validated within a large (n = 570) sample, comprising community and trauma-exposed samples of children and adolescents aged 6-18 years. Results: Principal components analysis suggested a two-component structure. These components were labelled 'permanent and disturbing change' and 'fragile person in a scary world', and were each found to possess good internal consistency, test-retest reliability, convergent validity, and discriminative validity. The reliability and validity of these sub-scales was present regardless of whether the measure was completed in the acute phase or several months after a trauma. Scores on these sub-scales did not vary with age. Conclusions: The CPTCI is a reliable and valid measure that is not specific to the type of trauma exposure, and shows considerable promise as a research and clinical tool. The structure of this measure suggests that appraisals concerning the more abstract consequences of a trauma, as well as physical threat and vulnerability, are pertinent factors in trauma-exposed children and adolescents, even prepubescent children

A study of changes in genetic and environmental influences on weight and shape concern across adolescence

The goal of the current study was to examine whether genetic and environmental influences on an important risk factor for disordered eating, weight and shape concern (WSC), remained stable over adolescence. This stability was assessed in two ways: whether new sources of latent variance were introduced over development, and whether the magnitude of variance contributing to the risk factor changed. We examined an 8-item WSC sub-scale derived from the Eating Disorder Examination using telephone interviews with female adolescents. From three waves of data collected from female-female same sex twin pairs from the Australian Twin Registry, a subset of the data (which included 351 pairs at Wave 1) was used to examine three age cohorts: 12-13, 13-15, and 14-16 years. The best fitting model contained genetic and environmental influences, both shared and non-shared. Biometric model fitting indicated that non-shared environmental influences were largely specific to each age cohort, and results suggested that latent shared environmental and genetic influences that were influential at 12-13 years continued to contribute to subsequent age cohorts, with independent sources of both emerging at ages 13-15. The magnitude of all three latent influences could be constrained to be the same across adolescence. Ages 13-15 was indicated as a time of risk for the development of high levels of WSC given that most specific environmental risk factors were significant at this time (e.g., peer teasing about weight, adverse life events), and indications of the emergence of new sources of latent genetic and environmental variance over this period.NHMRC Grants 324715 and 480420

Optical nanoelectromechanical switch based in a III-V material system

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2001.Includes bibliographical references (leaves 58-59).by Reginald Bryant.S.M