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Description
The collision between the Indian and Eurasian tectonic plates marked the onset of the rise of the Himalayan-Tibetan orogen, but also brought about profound changes to the Earth's oceans and climate. The exact sequence of events that occurred during this collision is poorly understood, leading to a wide range of estimates of its age. The Indus and Yarlung sutures are generally considered to represent the final collision between India and Eurasia, and together form a mostly continuous belt that can be traced over 2000 km along strike. In the western portions of the orogen the Karakoram Fault introduces a key complexity to the study of timing of collision by offsetting the Indus and Yarlung sutures. Recent work has used the complexities introduced by the Karakoram Fault to suggest that the more northerly Shyok suture, not the Indus suture, represents the India-Eurasia collision zone. Estimates for timing of the India-Eurasia collision fall into one of three groups: 40-34 Ma, 55-50 Ma, and 66-60 Ma. Attempts to reconcile these models have thus far been unsuccessful. In order to provide additional data that might further clarify the timing and location of collision, studies have been performed along the Shyok suture in India and along the Yarlung suture in Tibet at Sangsang. A study along the Shyok suture argues that the suture formed between 92-85 Ma. This timing precludes an interpretation that the Shyok suture marks the location of the India-Eurasia collision. A second study demonstrates the utility of two new geochronometers, (U-Th)/Pb joaquinite and 40Ar/39Ar neptunite, that play an important role in unraveling the tectonic history of the Yarlung suture. A third study is an investigation of the structure and geochronology of the Sangsang ophiolite complex. Here, multiple (U-Th)/Pb and 40Ar/39Ar systems record magmatism and metamorphism spanning ca. 125-52 Ma. By tying these chronometers to tectonic process, a history is reconstructed of the southern margin of Tibet that includes Early Cretaceous to Late Cretaceous forearc rifting associated with mid ocean ridge subduction, Paleocene accretionary wedge uplift and erosion, and finally Eocene metasomatism and collision.
ContributorsBorneman, Nathaniel (Author) / Hodges, Kip (Thesis advisor) / Reynolds, Stephen (Committee member) / Whipple, Kelin (Committee member) / Sharp, Thomas (Committee member) / Tyburczy, James (Committee member) / Arizona State University (Publisher)
Created2016
Description
In 2013, 1.8 million US drivers were responsible for rear-end collisions with other vehicles (NHTSA 2014), for which driver distraction has been identified as the main factor (Campbell, Smith & Najm, 2003; Knipling, Mironer, Hendricks, Tijerina, Everson, Allen & Wilson 1993; Wang, Knipling & Goodman, 1996). The ubiquity of cell phones and their use behind the wheel has played a major role in distracting these drivers. To mitigate this, some manufacturers are equipping vehicles with forward collision warning (FCW) systems.
Generally, warnings that are perceived as being urgent produce lower response times. One technique for increasing perceived urgency of a warning is called looming, where the signal increases in or more dimensions over time. Looming warning signals have been shown to produce low response times, likely because the recipient perceives the signal as a potential approaching threat, prompting defensive reactions (Graziano and Cooke, 2006).
The present study evaluates the effect of veridical (intensity increases at the rate of closure with the lead vehicle) and high urgency (intensity increases at a rate of Time to Collision minus 0.5 seconds) looming FCW, as well as a static FCW, on drivers’ brake reaction times in the presence of a secondary texting task. Participants’ brake reaction times were recorded as they followed a lead car in a driving simulator, encountering multiple sudden-braking events across the five conditions (a control condition as well as four counterbalanced conditions using a secondary texting task). In the four conditions with a secondary task, participants received no FCW, static FCW, veridical FCW, and high-urgency FCW, respectively. Performance data was analyzed using a repeated measures ANOVA, and a series of pairwise comparisons were then made using Bonferroni corrected pairwise t-tests.
The presence of a visually and manually distracting secondary task (texting) seems to diminish the performance of the looming signals as compared to previous studies that did not use a distraction component. While looming FCW do seem to effectively lower BRTs when the driver is distracted, it is recommended that further research investigate the relationship between secondary task types and their respective levels of distraction, and the effectiveness of auditory looming FCW.
Generally, warnings that are perceived as being urgent produce lower response times. One technique for increasing perceived urgency of a warning is called looming, where the signal increases in or more dimensions over time. Looming warning signals have been shown to produce low response times, likely because the recipient perceives the signal as a potential approaching threat, prompting defensive reactions (Graziano and Cooke, 2006).
The present study evaluates the effect of veridical (intensity increases at the rate of closure with the lead vehicle) and high urgency (intensity increases at a rate of Time to Collision minus 0.5 seconds) looming FCW, as well as a static FCW, on drivers’ brake reaction times in the presence of a secondary texting task. Participants’ brake reaction times were recorded as they followed a lead car in a driving simulator, encountering multiple sudden-braking events across the five conditions (a control condition as well as four counterbalanced conditions using a secondary texting task). In the four conditions with a secondary task, participants received no FCW, static FCW, veridical FCW, and high-urgency FCW, respectively. Performance data was analyzed using a repeated measures ANOVA, and a series of pairwise comparisons were then made using Bonferroni corrected pairwise t-tests.
The presence of a visually and manually distracting secondary task (texting) seems to diminish the performance of the looming signals as compared to previous studies that did not use a distraction component. While looming FCW do seem to effectively lower BRTs when the driver is distracted, it is recommended that further research investigate the relationship between secondary task types and their respective levels of distraction, and the effectiveness of auditory looming FCW.
ContributorsBecker, Mike (Author) / Gray, Robert (Thesis advisor) / Branaghan, Russell (Committee member) / Craig, Scotty (Committee member) / Arizona State University (Publisher)
Created2016