High-resolution friction measurements of cross-country ski bases on snow

Participants in the sport of snow skiing devote considerable effort to reduce sliding friction of the ski. A large industry is devoted to providing products and ski preparation methods with claims of improved ski performance, sometimes at considerable expense. Despite this attention to the topic, there are very little data available to skiers that quantify the effect these products and methods have on reducing ski friction. Determining the coefficient of friction of a ski on snow presents a significant technical challenge. Our approach has been to develop a tribometer incorporating a series of proximity sensors to test commercially available ski equipment and waxes on natural snow. We developed a test protocol that significantly reduces the experimental noise associated with variable environmental conditions enabling us to differentiate the difference in friction between two pairs of skis with a resolution of 0.001. A large body of test data was acquired over a wide range of environmental conditions to quantify the effect of ski wax and base texturing treatments in terms of coefficient of friction in a way that is of practical use to skiers. An exercise physiology power model was used to estimate the ski race time difference that could be expected from changing the coefficient of friction.     

The prevalence of social maladjustment among school-age children

PL 94-142 mandates that students who are seriously emotionally disturbed be provided with a free and appropriate public education. Embedded in the federal definition of serious emotional disturbance is a clause that excludes socially maladjusted students from the diagnostic category. Although socially maladjusted children may therefore not receive special education services, their presence in the schools may have implications for society and particularly for the educational system. However, there is little data concerning the prevalence of socially maladjusted students in the schools. The purpose of this study was to investigate the prevalence of social maladjustment in two rural/suburban school systems in the southeastern United States. Results of the study indicate that the percentage of students reported as exhibiting characteristics of social maladjustment is sufficiently high to indicate that services beyond special education may be necessary to meet their educational and social needs.     

Using Story to Help Student Understanding of Gas Behavior

Students tend to have a poor understanding of the concept of gas pressure. Usually, gas pressure is taught in terms of the various formulaic gas laws. The development of the concept of gas pressure according to the early Greeks did not include the concept of a vacuum. It was not for another 2000 years that Torricelli proposed that a vacuum can exist and that he was able to produce a vacuum above a column of mercury. However, the existence of a vacuum continued to be a contentious issue for at least another 100 years. During this time the behavior of gases was studied by Boyle, Amontons, Gay-Lussac, Daniel Bernouli, Charles, and Dalton. In the 19^th century gas behavior was revisited and studied from the molecular level through the work of Graham, Maxwell, Boltzmann, and van der Waal. The stories of conflicting theories and the development of the concept of gas pressure gives students an increased appreciation for the nature of science and helps them with conceptual understanding of the concept of gas pressure.     

Effects of pretraining on acquisition of novel configural discriminations in human predictive learning

In two experiments, participants acquired one of two target configural discriminations (a biconditional or negative patterning discrimination) in a predictive learning task. In Experiment 1, participants were pretrained with either a configural or an elemental discrimination; in Experiment 2, they were pretrained with a configural discrimination, an elemental discrimination, or a control discrimination that was not expected to bias them toward elemental or configural processing. In both experiments, acquisition of the target configural discriminations was faster after configural pretraining than after elemental pretraining. In addition, the negative patterning discrimination was acquired faster than the biconditional discrimination. Finally, the results of Experiment 2 were more consistent with the notion that elemental pretraining hindered acquisition of the target discriminations than with the notion that configural pretraining enhanced their acquisition. Implications of these findings are discussed.     

Making functional units functional: The role of rhetorical structure in use of scholarly journal articles

Scholars are reading more journal articles than ever, so it is important that they focus on the relevant text within the articles they read. To support this goal, this study explores enhancements to a journal reading system by applying the idea of the functional unit, the smallest information unit with a distinct function within four major components of scholarly journal articles—Introduction, Methods, Results and Discussion. This study examined a set of functional units and their associations with scholarly journal article use tasks through literature analysis and validation surveys. Forty-one typical functional units were found in psychology journal articles, with varying relevance to five tasks requiring use of information in journal articles. The relationships among sets of functional units for particular tasks were also identified. A taxonomy was developed incorporating the relationships between functional units and information use tasks, which can be used to inform system design. Based on this taxonomy, a prototype journal reading environment signalling functional units was designed and implemented for testing.