Segmentation and range sensing using a moving-aperture lens

The use of a novel motorized lens to perform segmentation of image sequences is presented in this paper. The lens has the effect of introducing small, repeating movements of the camera center so that objects appear to translate in the image by an amount that depends on the distance from the plane of focus. For a stationary scene, optical flow magnitudes are therefore directly related to three-dimensional object distance from the observer. We describe a segmentation procedure that exploits these controlled observer movements and present experimental results that demonstrate the successful extraction of objects at different depths. Potential applications of our approach include image compositing, teleconferencing, and range estimation.Received: 4 July 2002, Accepted: 16 December 2002, Published online: 23 July 2003 Correspondence to: Amy E. Bell     

Consideration of driver home county prohibition and alcohol-related vehicle crashes

This study examines the characteristics of alcohol-related crashes in wet versus dry counties in the state of Kentucky, USA and incorporates the location of driver residences through use of geographic information system (GIS) analysis. Between 1991 and 1997, 39344 alcohol-related crashes by Kentucky residents on Kentucky State roads were reported. The location of the crash and the home ZIP code from the driver's address were used to consider distance from home in the GIS. Analysis of the crash data revealed that a similar proportion of crashes in wet and dry counties are alcohol-related but that a higher proportion of dry counties residents are involved in an alcohol-related crash. However, when the distance from home variable is considered, several results suggest that dry county residents may be driving further when consuming alcohol. In part due to the rural nature of dry counties, drivers from dry counties have both alcohol-related and non-alcohol related crashes farther from their homes than residents from wet counties. Alcohol-related crashes by dry county residents in wet counties are the greatest average distance from home while crashes by wet county residents in wet counties are the smallest average distance. Drivers from dry counties over 21 years of age have alcohol-related crashes significantly farther from home than those under 21 who would not legally be admitted to drinking establishments in the wet counties. Furthermore, residents from dry counties that do not border wet counties have alcohol-related crashes on average farther from home than the border county residents. These last three results provide circumstantial evidence that some dry county drivers may be driving to wet counties to consume alcohol thus increasing impaired driving exposure. In conclusion, by considering crash location and driver residence, these findings indicate that county-level prohibition is not necessarily effective in improving highway safety.     

What's "up" with God? Vertical space as a representation of the divine.

"God" and "Devil" are abstract concepts often linked to vertical metaphors (e.g., "glory to God in the highest," "the Devil lives down in hell"). It is unknown, however, whether these metaphors simply aid communication or implicate a deeper mode of concept representation. In 6 experiments, the authors examined the extent to which the vertical dimension is used in noncommunication contexts involving God and the Devil. Experiment 1 established that people have implicit associations between God-Devil and up-down. Experiment 2 revealed that people encode God-related concepts faster if presented in a high (vs. low) vertical position. Experiment 3 found that people's memory for the vertical location of God- and Devil-like images showed a metaphor-consistent bias (up for God; down for Devil). Experiments 4, 5a, and 5b revealed that people rated strangers as more likely to believe in God when their images appeared in a high versus low vertical position, and this effect was independent of inferences related to power and likability. These robust results reveal that vertical perceptions are invoked when people access divinity-related cognitions. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Structural collapse analysis of framed structures under impact loads using ASI-Gauss finite element method

The main objective of this study is to devise a technique, which, when implemented into finite-element codes, is efficiently applicable to impact collapse analyses of framed structures. In this study, the formerly developed adaptively shifted integration (ASI) technique for the linear Timoshenko beam element is modified into the ASI-Gauss technique by placing the numerical integration points of the two consecutive elements forming an elastically deformed member in such a way that stresses and strains are evaluated at the Gaussian integration points of the two-element member. On comparison with the ASI technique, the ASI-Gauss technique proves its higher accuracy and efficiency in elastic range. Moreover, instead of applying impact loads in the form of nodal forces, we consider the impact phenomenon by means of contacts between the elements involved and the elemental contact algorithm is verified from the point of conservation of energy. Impact analyses considering member fracture with different sets of parameters are performed using a high-rise framed structure and a small aircraft. From the results obtained, we can observe propagation phenomena of impact loads and shock waves. Also, a proper difference in impact damage is obtained by different sets of parameters. The results also indicate that the mass of the aircraft has a stronger influence on impact damage than its velocity. Moreover, soon after impact, tensile stresses are observed in the columns that were compressed by dead loads before impact.     

CHALLENGING THE COMPUTATIONAL METAPHOR: IMPLICATIONS FOR HOW WE THINK

This paper explores the role of the traditional computational metaphor in our thinking as computer scientists, its influence on epistemological styles, and its implications for our understanding of cognition. It proposes to replace the conventional metaphor a sequence of steps with the notion of a community of interacting entities, and examines the ramifications of such a shift on these various ways in which we think.     

Young people’s digital lives: The impact of interpersonal relationships and digital media use on adolescents’ sense of identity

The current study investigates the joint effects of interpersonal relationships and digital media use on adolescents’ sense of identity. Questionnaires were administered to a sample of 2079 students (57% female) between the ages of 11 and 19 years (M = 15.4 years) attending one of seven secondary schools in Bermuda. Using structural equation modeling, the author found that mothers and friends play an important role in adolescents’ lives, with both relationships contributing in positive ways to respondents’ self-concept clarity. Further, the results showed that mother relationship quality affected adolescents’ self-concept clarity both directly and indirectly, through the positive impact it had on friendship quality. Friends also played a mediating role in relation to aspects of adolescents’ digital media use. Specifically, the negative association detected between online identity expression/exploration and self-concept clarity was mediated partially by low friendship quality. Going online to communicate with one’s friends appeared to play a more positive role in adolescents’ sense of identity. The results showed that online peer communication affected self-concept clarity indirectly through its positive impact on friendship quality.     

Multiscale assessment of green leaf cover in a semi-arid rangeland with a small unmanned aerial vehicle

Spatial variability in green leaf cover of a semi-arid rangeland was studied by comparing field measurements on 50 m crossed transects to aerial and satellite imagery. The normalized difference vegetation index was calculated for 2 cm resolution images collected with a multispectral digital camera mounted on a radio-controlled helicopter, as well as a 30 m resolution Landsat Thematic Mapper image. Variograms of green cover from these two sources show that the range of influence for spatial autocorrelation extended to a distance of approximately 200 m. Field transects that are much smaller than the extent of this spatial autocorrelation are more likely to fall within local deviations from the mean landscape condition. A sampling scheme that exceeds the spatial scale of these localized deviations is shown to reduce sample variance and require fewer sampling locations to reach a given level of measurement uncertainty. The time and cost of more spatially extensive sampling at each location may be less than deploying to a larger number of locations with smaller transects, and unmanned aerial vehicles may be a valuable tool in extending current field sampling strategies for quantifying the health of shrub-dominated rangelands.