451 research outputs found

    Driving Performance while Engaged in MP-3 Player Interaction: Effects of Practice and Task Difficulty on PRT and Eye Movements

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    The purpose of this study was to examine the effects of iPod interactions on driver performance over several sessions to determine the distraction effect of iPods on driver performance, as well as to see if performance decrements declined with practice. Nineteen younger drivers (mean age = 19.4, range 18 to 22) participated in a seven-session study in the University of Calgary Driving Simulator. Drivers encountered a number of critical events such as pedestrian incursions, lead vehicle braking, and pullout vehicle events, on the roadways. These events were encountered both while driving alone and when performing iPod tasks of varying difficulty. Participants’ hazard response, frequency of collisions and eye movement measures were examined to determine if there were any changes in performance related to iPod distraction and practice effects. Increases in perception response time (PRT) and frequency of collisions were found during the difficult iPod interactions. The number and duration of glances made into the vehicle increased significantly while performing the difficult iPod interactions, reducing the number of glances made to the roadway. Over the course of the sessions, performance improved significantly in all secondary task conditions, but performance decrements still remained in the difficult iPod condition compared to the baseline

    Influence of resource pulses and perennial neighbors on the establishment of an invasive annual grass in the Mojave Desert

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    Invasion by exotic annual grasses is one of the most significant threats to arid ecosystems in the western USA. Current theories of invasibility predict plant communities become more susceptible to invasion whenever there is an increase in the amount of unused resources. The objective of this field study was to examine how resource pulses and temporal variation in resource demand by the native shrub vegetation influences establishment of the invasive annual grass Schismus arabicus. Water and nitrogen were applied as pulses in early spring, mid-spring, or continuously throughout the growing season to plots containing either Atriplex confertifolia or Atriplex parryi shrubs. The effect of resource pulses on Schismus density and biomass was highly dependent on the seasonal timing of the resource pulses and the identity of the neighbor shrub. When resource pulses coincided with high rates of resource capture and growth of the native vegetation, density and biomass of Schismus was reduced. Schismusestablishment was greater under continuous resource supply compared to pulsed resource supply, likely because more soil resources were available at a shallow depth when resources were supplied at a continuous low rate. These results suggest that the establishment of invasive annual grasses in arid systems can be influenced by the magnitude and spatial distribution of resource pulses in addition to the seasonal timing of resource pulses

    Older and Younger Driver Performance at Complex Intersections: Implications for Using Perception-Response Time and Driving Simulation

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    Older drivers are at increased accident risk at intersections for a variety of maneuvers. To examine why, a study was conducted to assess older driver performance at complex intersections in a driving simulator. The University of Calgary Driving Simulator was used to test healthy older drivers (65-83, M = 71.4) and younger drivers (19-22, M = 20.7). Critical scenarios included the sudden appearance of a pedestrian in an intersection, a lastsecond yellow light, an unexpected change during a left, and a vehicle violating a stoplight. Older drivers had significantly higher perception response times (PRT) than younger drivers for the latter three of the four intersection scenarios. Analysis of specific maneuvers also revealed qualitative response differences between young and old groups. In contradiction to expectation, more older drivers ran the yellow light than younger drivers. The capability of older drivers to respond under time constraints is implicated. The utility of driving simulators to assess older driver performance at intersections was limited by the prevalence of simulator sickness

    Do In-Vehicle Advance Signs Benefit Older and Younger Driver Intersection Performance?

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    An experimental study was conducted to determine if intersection behavior of those 18 to 24 and 65+ benefited from advanced in-vehicle signs presented in a head-up display (HUD) format. The University of Calgary Driving Simulator (UCDS) was used to determine whether intersection performance improved in the presence of several advanced signs or whether unwanted adaptive behaviors occurred (e.g., increasing speed to run the light instead of stopping). Invehicle signs facilitated an increase in stopping occurrences for both younger and older drivers at intersections with relatively short yellow onsets. In addition, eye movement analysis revealed significant age effects with regard to vertical and horizontal gaze variablity, with younger drivers showing increases in vertical gaze variability compared to the older drivers. Younger drivers also looked more often and had longer percentage of durations fixating on the HUD compared to the older drivers

    Older and Younger Driver Performance at Complex Intersections: Implications for Using Perception-Response Time and Driving Simulation

    Get PDF
    Older drivers are at increased accident risk at intersections for a variety of maneuvers. To examine why, a study was conducted to assess older driver performance at complex intersections in a driving simulator. The University of Calgary Driving Simulator was used to test healthy older drivers (65-83, M = 71.4) and younger drivers (19-22, M = 20.7). Critical scenarios included the sudden appearance of a pedestrian in an intersection, a lastsecond yellow light, an unexpected change during a left, and a vehicle violating a stoplight. Older drivers had significantly higher perception response times (PRT) than younger drivers for the latter three of the four intersection scenarios. Analysis of specific maneuvers also revealed qualitative response differences between young and old groups. In contradiction to expectation, more older drivers ran the yellow light than younger drivers. The capability of older drivers to respond under time constraints is implicated. The utility of driving simulators to assess older driver performance at intersections was limited by the prevalence of simulator sickness

    'Redlands for Regions': Producer demonstration sites of psyllid-resistant leucaena across north Queensland

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    Leucaena, a tree legume with potential to greatly improve cattle performance, has not been readily adopted in northern Queensland primarily due to prevalence of the psyllid (Heteropsylla cubana) insect in higher rainfall zones. Psyllids reduce edible biomass in leaves by 40–52%, combined with a 46–83% reduction of stem yield (Bray and Woodroffe 1991). Losses to the Central Queensland beef industry due to psyllid impact on animal performance are estimated at $2 M per year (Mullen et al. 1998). Cultivar Redlands is a psyllid-resistant leucaena variety recently developed by Meat and Livestock Australia (MLA) and the University of Queensland

    Effective use of personal health records to support emergency services

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    Smart City systems capture and exchange information with the aim to improve public services. Particularly, healthcare data could help emergency services to plan resources and make life-saving decisions. However, the delivery of healthcare information to emergency bodies must be balanced against the concerns related to citizens’ privacy. Besides, emergency services face challenges in interpreting this data; the heterogeneity of sources and a large amount of information available represent a significant barrier. In this paper, we focus on a case study involving the use of personal health records to support emergency services in the context of a fire building evacuation. We propose a methodology involving a knowledge engineering approach and a common-sense knowledge base to address the problem of deriving useful information from health records and, at the same time, preserve citizens’ privacy. We perform extensive experiments involving a synthetic dataset of health records and a curated gold standard to demonstrate how our approach allows us to identify vulnerable people and interpret their particular needs while avoiding the disclosure of personal information
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