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BackgroundSleep duration and quality are associated with physical and mental wellbeing. This paper examines social network effects on individual level change in the sleep quantity and quality from late adolescence to emerging adulthood and its associated factors, including the influence of peers on sleep behavior and the impact of changes in network size.MethodsWe use sleep data from 619 undergraduates at the University of Notre Dame obtained via Fitbit devices as part of the NetHealth project. The data were collected between August 16, 2015 and May 13, 2017. We model trends in sleep behaviors using latent growth-curve models.ResultsControlling for the many factors known to impact sleep quantity and quality, we find two social network effects: increasing network size is associated with less sleep and a student's sleep levels are influenced by his or her peers. While we do not find any consistent decline in sleep quantity over the 637 days, daily fluctuations in sleep quantity are associated with changes in network size and the composition of a student's network. As a student's network gets bigger, s/he sleeps less, and when a student's contacts sleep more (or less) than s/he does, the student becomes more like his or her contacts and sleeps more (or less).ConclusionsSocial networks can and do impact sleep, especially sleep quantity. In contexts where students want to have larger networks, the difficulties of increasing network size and maintaining larger networks negatively impact sleep. Because of peer influence, the effectiveness of interventions designed to improve sleep practices could be increased by leveraging student social networks to help diffuse better sleep habits.

Previous studies of seasonal effects on sleep have yielded unclear results, likely due to methodological differences and limitations in data size and/or quality. We measured the sleep habits of 216 individuals across the U.S. over four seasons for slightly over a year using objective, continuous, and unobtrusive measures of sleep and local weather. In addition, we controlled for demographics and trait-like constructs previously identified to correlate with sleep behavior. We investigated seasonal and weather effects of sleep duration, bedtime, and wake time. We found several small but statistically significant effects of seasonal and weather effects on sleep patterns. We observe the strongest seasonal effects for wake time and sleep duration, especially during the spring season: wake times are earlier, and sleep duration decreases (compared to the reference season winter). Sleep duration also modestly decreases when day lengths get longer (between the winter and summer solstice). Bedtimes and wake times tend to be slightly later as outdoor temperature increases.

Ground-based surveys of three coal fires and airborne surveys of two of the fires were conducted near Sheridan, Wyoming. The fires occur in natural outcrops and in abandoned mines, all containing Paleocene-age subbituminous coals. Diffuse (carbon dioxide (CO(2)) only) and vent (CO(2), carbon monoxide (CO), methane, hydrogen sulfide (H(2)S), and elemental mercury) emission estimates were made for each of the fires. Additionally, gas samples were collected for volatile organic compound (VOC) analysis and showed a large range in variation between vents. The fires produce locally dangerous levels of CO, CO(2), H(2)S, and benzene, among other gases. At one fire in an abandoned coal mine, trends in gas and tar composition followed a change in topography. Total CO(2) fluxes for the fires from airborne, ground-based, and rate of fire advancement estimates ranged from 0.9 to 780mg/s/m(2) and are comparable to other coal fires worldwide. Samples of tar and coal-fire minerals collected from the mouth of vents provided insight into the behavior and formation of the coal fires.

This dissertation develops a new framework for transportation evaluations. Most evaluation techniques fail to adequately assess all factors involved in transportation projects, with qualitative and institutional issues typically receiving less attention than easily quantifiable technical factors. This dissertation uses quantitative decision-theory techniques to develop a flexible approach that allows an analyst to look at all of the myriad issues involved in the evaluation of transportation projects.The research approach focuses on identifying an overall worth, which provides decision-makers with a quantitative measure to compare different system components. The innovative technique developed here integrates the multiple-attribute value function (MAVF) technique with the analytic hierarchy process (AHP). The overall worth of a project may be a combination of its worth under various operational conditions, with subjective relative weights, depending on the decision-makers. A hierarchy of such combinations are possible where the values for individual attributes themselves can be derived from the decision-makers using MAVF schemes. Certain complications arise in the technique, which require the development of a new scaling approach through the use of a universal scaling proxy. The research utilizes a hierarchical approach throughout the analysis while examining a total of four weighting schemes.The methodology is applied to the Anaheim Field Operational Test, a federally funded project, that implemented new traffic control technologies in Anaheim, California's special events area. The research's primary focus is on the city Traffic Engineer's values and preferences over the entire hierarchy. The development of six testing scenarios creates an opportunity to investigate the effects of many evaluation components as well as individual branches within the hierarchy.The evaluation looks at the percentage change in value between the system "before" and "after" implementation across scenarios. While the new system appears to decrease in value for most scenarios, one scenario, the alternate data set, actually shows an overall increase in value. The special event only operations scenario shows improvement over the base case, which indicates the system performs better under these conditions. The evaluation provides valuable insight into the behavior of the system under various conditions and provides guidance for future applications of this evaluation tool.

In order to meet the challenges of sustainable development, our approach to education must be modified to equip students to evaluate alternatives and devise solutions that meet multi-faceted requirements. In 2009, faculty in the Departments of Civil, Industrial and Mechanical Engineering at the University of Texas at Arlington began implementation of a project entitled "Engineering Sustainable Engineers" to infuse the departments' curricula with sustainability. The project, funded by the National Science Foundation, was designed to improve students' awareness of and ability to use sustainability in alternative analysis for engineering decision making. Key outcomes of the project are discussed. These include: (1) course modules for engineering courses that are common to most engineering curricula; (2) a sustainable design checklist, which is a tool that the team designed to facilitate alternative analysis on the basis of sustainability; and (3) models for implementing quality sustainable industry internships and multidisciplinary sustainability-related senior design projects. Engineering Sustainable Engineers is one of the many efforts at UT Arlington to emphasize sustainability, not only as a campus initiative, but also in teaching future engineers to consider the impacts of their design solutions on future generations and on the environment. The modules and tools that have been developed can serve as models for other institutions to implement. (Contains 2 tables and 7 figures.)

Distracted driving existed since the invention of the automobile; however, the emergence of the cell phone and electronic devices created another source of distraction that affected drivers visually, physically, cognitively, and audibly. Many studies investigated factors that influenced saturation flow and startup lost time at a signalized intersection, but the impact of new distractions, such as electronic devices and in-vehicle entertainment systems, remained less investigated. This study aimed to characterize technology's influence on driver behavior at intersections and the impact of distractions on startup lost time through a field test conducted at three intersections in Texas. This study used observational analysis and hypothesis testing to understand distraction behaviors and their impacts on individual and aggregated startup lost time. On average, 15% of drivers experienced distraction during a red indication, and a cell phone distracted more than 60% of these drivers. However, in vehicles located behind a heavy vehicle at an intersection, 20% of drivers were distracted, and 80% used a cell phone. Statistical analysis showed that distraction caused significantly higher headways and total lost times than non-distraction conditions. More importantly, technology-induced distraction, which created significant intersection delay, was more uncertain and varied from event to event more than non-technology-induced delay. This study showed that technology-induced distractions from the prevalent use of cell phones created an impact on startup lost time and saturation flow, which remained critical to properly determine the phase and cycle lengths. [ABSTRACT FROM AUTHOR]