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.     

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.     

E-commerce: protecting purchaser privacy to enforce trust

It has been well documented that lack of trust between commercial entities and purchasers can restrict the potential of e-commerce. This may be because the purchaser is required to provide personal information to the commercial entity, which may then be abused, or because the purchaser may be suspicious that after payment has been processed, the goods purchased will not arrive. The challenge for the researcher is to determine the e-commerce model which maximizes the trust a purchaser has when shopping online.     

Ultrarapid Phase Conversion in β"-Alumina Tubes

β"-Alumina, the electrolyte of choice of sodium/sulfur and sodium/metal chloride batteries and alkali-metal thermal-electric converters, was sintered from precursor phases to high β"-phase purity in less than 15 s from the onset of densification by rapid pass-through rf induction coupled plasma sintering. The maximum instantaneous shrinkage rate was 1.8%/s. The resistivity was measured to be 13.8 ± 1.4 Ω·cm. The rapid conversion found is a significant improvement over conventional processing of β"-alumina, which requires extended postsintering annealing times to obtain high β"-phase purity.     

Contribution of equal-sign instruction beyond word-problem tutoring for third-grade students with mathematics difficulty.

Elementary school students often misinterpret the equal sign (=) as an operational rather than a relational symbol. Such misunderstanding is problematic because solving equations with missing numbers may be important for the development of higher order mathematics skills, including solving word problems. Research indicates equal-sign instruction can alter how typically developing students use the equal sign, but no study has been conducted on the effects of such instruction for students with mathematics difficulty (MD) or how equal-sign instruction contributes to word-problem-solving skill for students with or without MD. In the present study, the authors assessed the efficacy of equal-sign instruction within word-problem tutoring. Third-grade students with MD (n = 80) were assigned to word-problem tutoring, word-problem tutoring plus equal-sign instruction (combined) tutoring, or no-tutoring control. Combined tutoring produced greater improvement on equal sign tasks and open equations than did the other 2 conditions. On certain forms of word problems, combined tutoring, but not word-problem tutoring alone, produced more improvement than did the control condition. When compared at posttest with 3rd-grade students without MD on equal-sign tasks and open equations, only combined tutoring students with MD performed comparably. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Switchgrass selection as a “model” bioenergy crop: A history of the process

A review of several publications of the Oak Ridge National Laboratory's Biofuels Feedstock Development Program and final reports from the herbaceous crop screening trials show that technology, environmental, and funding issues influenced the decision to focus on a single herbaceous “model” crop species. Screening trials funded by the U.S. Department of Energy in the late 1980s to early 1990s assessed thirty-four herbaceous species on a wide range of soil types at thirty-one different sites spread over seven states in crop producing regions of the U.S. Several species, including sorghums, reed canarygrass, wheatgrasses, and other crops, were identified as having merit for further development. Six of the seven institutions performing the screening included switchgrass among the species recommended for further development in their region and all recommended that perennial grasses be given high research priority. Reasons for the selection of switchgrass included demonstration of relatively high, reliable productivity across a wide geographical range, suitability for marginal quality land, low water and nutrient requirements, and other positive environmental attributes. Crop screening results, economic and environmental assessments by the Biofuels Feedstock Development Program staff, and Department of Energy funding limitations all contributed to the decision to further develop only switchgrass as a “model” or “prototype” species in 1991. The following ten year focus on development of switchgrass as a bioenergy crop proved the value of focusing on a single “model” herbaceous crop. The advancements and attention gained were sufficient to give government leaders, policymakers, farmers, and biofuel industry developers the confidence that lignocellulosic crops could support an economically viable and environmentally sustainable biofuel industry in the U.S.     

Epidemic Simulation for Training in Public Health Management

Epidemiological simulation models to be used primarily to augment the teaching of epidemiology to medical students and other individuals concerned with public health and control of epidemics are presented. Interactive simulations are used to expose students to ``realistic' epidemic situations and permit them to experiment with various control strategies. Criteria by which simulations for such teaching purposes may be evaluated are proposed and operating simulations, MEASLES and INFLU, are described in detail. Information is provided regarding user experience with the above simulations.