A construction set for multimedia applications

The authors describe an interface system called Athena Muse. Muse is an experiment kit for the construction of multimedia learning environments. Learning environments developed with Muse offer a diverse set of complementary interaction techniques, styles, and devices. An interface developer can choose from four representation approaches: directed graphs, multidimensional spatial frameworks, declarative constraints, and procedural languages     

Transient overvoltages in low-voltage systems-a field study inGermany

The “Overvoltage Measurements” field study was undertaken with the aim of establishing regulatory measures based on information from metered transient overvoltages occurring in low-voltage networks, installations, and telecommunication lines. Some 40 companies and institutions from industry and the power-utility, insurance, telecommunications, and research sectors contributed to the study. The overvoltages occurring between phase conductors and protective conductors were also measured     

Children's use of the common ground in interpreting ambiguous referential utterances.

Common ground is contextual information shared by a listener and speaker that enables the listener to convert an ambiguous utterance to an informative communication. Four experiments examined young children's understanding of the common ground in interpreting ambiguous referential utterances. Kindergarten and 2nd-grade children and college students were read short vignettes containing statement, joint activity, status common ground, and an ambiguous or informative utterance about a display of 4–6 object drawings. The subjects were asked (a) whether the listener knew which object to pick (Experiment 1), (b) to pick an object themselves or choose "none" (Experiment 2), (c) the source of the listener's knowledge in the context or utterance (Experiment 3), and (d) whether a designated object was the "right one," the one the speaker "meant," or the one the speaker "could have meant" (Experiment 4). Even the kindergarten children used statement information effectively in interpreting ambiguous utterances, and all groups had difficulty using status information. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Therelations between cluster indexes of risk and promotion and the problem behaviors of 6- and 7- year old children from economically disadvantaged families.

This study examined the relations between alternative explanations of poverty cofactors and promotion processes and teacher reports of the problem behaviors of 6- and 7-yr old children from economically disadvantaged families (N?=?159). The results showed that single index representations of risk and promotion variables predicted child aggressive behaviors but not child anxious/depressed behaviors. An addictive model of individual risk indicators performed similarly. Similar indexes representing clusters of parent adjustment variables and family instability variables, however, differentially predicted aggressive and anxious/depressed behaviors, respectively. The results suggest the importance of promotion processes and representing environmental adversity at varying levels of specificity for children from economically disadvantaged families. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Modeling Storm Water Mass Emissions to the Southern California Bight

Storm water runoff is perceived as a major source of pollutants that results in adverse environmental effects, but large-scale assessments are rarely conducted. The problem is particularly pronounced in southern California where 17 million people have rapidly developed coastal watersheds. The goal of this study was to make regionwide estimates of mass emissions, assess the relative contribution from urbanized watersheds, and compare pollutant flux from different land uses. A geographic information system-based storm water runoff model was used to estimate pollutant mass emissions based on land use, rainfall, runoff volume, and local water-quality information. Local monitoring data were used to derive runoff coefficients; over 1,700 storm water sampling events were used to calibrate and validate annual loadings. An average rainfall year produced 1,073×109?L of runoff, 118,000 metric tons (MT) of suspended solids, 1,940 MT of nitrate-N, 108 MT of zinc, and 15 kg of diazinon. The majority of mass emissions were from urbanized watersheds except for suspended solids, total DDT, and chlorpyrifos. Agricultural areas had the greatest fluxes for pesticides, including total DDT and chlorpyrifos while open areas typically had the smallest.     

Predicting individual differences in complex skill acquisition: Dynamics of ability determinants.

Addresses the controvervesy about ability determinants of individual differences in performance during and subsequent to skill acquisition. An information-processing examination of ability–performance relations during complex task acquisition is described. Included are ability testing (including general, reasoning, spatial, perceptual speed, and perceptual/psychomotor abilities) and skill acquisition over practice on the terminal radar approach controller simulation. Results validate and extend P. L. Ackerman's (1988) theory of cognitive ability determinants of individual differences in skill acquisition. Benefits of ability component and task component analyses over global analyses of ability–skill relations are demonstrated. Implications are discussed for selection instruments to predict air traffic controller success and for other tasks with inconsistent information-processing demands. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Simplified model for droplet combustion in a slow convective flow

An idealized model for droplet vaporization or combustion in the Burke-Schumann reaction-sheet approximation is analyzed in terms of a Peclet number based on the Stefan velocity, taken to be of order unity, for Lewis numbers of unity and for small values of a parameter ?, defined as the ratio of the convective velocity far from the droplet to the Stefan velocity at its surface. Asymptotic solutions for the velocity, pressure, and mixture-fraction fields are obtained through second order in ?. The results are employed to calculate the effects of convection on the burning rate and on the flame shape. The prediction that the burning-rate constant increases linearly with ? for small values of ? is shown to be consistent with available experimental data. It is demonstrated that reasonable values of diffusivities provide approximate agreement of predicted burning rates and flame shapes with results of measurements.     

Bird mercury concentrations change rapidly as chicks age: toxicological risk is highest at hatching and fledging

Toxicological risk of methylmercury exposure to juvenile birds is complex due to the highly transient nature of mercury concentrations as chicks age. We examined total mercury and methylmercury concentrations in blood, liver, kidney, muscle, and feathers of 111 Forster's tern (Sterna forsteri), 69 black-necked stilt (Himantopus mexicanus), and 43 American avocet (Recurvirostra americana) chicks as they aged from hatching through postfledging at wetlands that had either low or high mercury contamination in San Francisco Bay, California. For each waterbird species, internal tissue, and wetland, total mercury and methylmercury concentrations changed rapidly as chicks aged and exhibited a quadratic, U-shaped pattern from hatching through postfledging. Mercury concentrations were highest immediately after hatching, due to maternally deposited mercury in eggs, then rapidly declined as chicks aged and diluted their mercury body burden through growth in size and mercury depuration into growing feathers. Mercury concentrations then increased during fledging when mass gain and feather growth slowed, while chicks continued to acquire dietary mercury. In contrast to mercury in internal tissues, mercury concentrations in chick feathers were highly variable and declined linearly with age. For 58 recaptured Forster's tern chicks, the proportional change in blood mercury concentration was negatively related to the proportional change in body mass, but not to the amount of feathers or wing length. Thus, mercury concentrations declined more in chicks that gained more mass between sampling events. The U-shaped pattern of mercury concentrations from hatching to fledging indicates that juvenile birds may be at highest risk to methylmercury toxicity shortly after hatching when maternally deposited mercury concentrations are still high and again after fledging when opportunities for mass dilution and mercury excretion into feathers are limited.     

A correlational analysis of skill specificity: Learning, abilities, and individual differences.

Skill specificity, the notion that task performance is based on unique underlying information-processing components at skilled levels of performance, is examined from the perspective of the ability determinants of individual differences in task performance during skill acquisition. The current investigation uses a dynamic ability-skill theoretical perspective to evaluate how individual differences in procedural learning for a complex criterion task relate to learning of procedures for other more basic tasks such as choice and simple reaction time (RT). An experiment with 86 college students was performed using a simulated Air Traffic Controller (ATC) task for assessment of procedural learning, along with practice on several perceptual speed measures and assessment of reference abilities. When Ss are allowed to practice tests of perceptual speed and psychomotor ability, some measures increase in their power to predict skilled performance on the complex ATC criterion task, a direct disconfirmation of the skill-specificity thesis. Discussion is devoted to the use of individual-differences approaches to address general transfer and skill specificity issues. (PsycINFO Database Record (c) 2010 APA, all rights reserved)