Physica: A Computer Environment for Physics Problem-Solving

Physica is an integrated software package designed as part of a course for distance learning students from non-traditional educational backgrounds. It gives students access to an extensive hyperlinked physics glossary, computer algebra and graph-plotting tools. The package aims to give students a framework for solving physics problems and to help them acquire some higher level skills of quantitative problem-solving. This paper outlines rationales underlying various protocols for solving physics problems, and discusses the extent to which frameworks may be useful in helping students develop appropriate strategies for representing problems in formal terms, selecting targets, planning solutions and checking answers. Pedagogical issues underlying the design and implementation of the software are discussed.     

The kinematic differences between accurate and inaccurate squash forehand drives for athletes of different skill levels

ABSTRACT

To maintain the accuracy of squash shots under varying conditions, such as the oncoming ball’s velocity and trajectory, players must adjust their technique. Although differences in technique between skilled and less-skilled players have been studied, it is not yet understood how players vary their technique in a functional manner to maintain accuracy under varying conditions. This study compared 3-dimensional joint and racket kinematics and their variability between accurate and inaccurate squash forehand drives of 9 highly skilled and 9 less-skilled male athletes. During inaccurate shots, less-skilled players hit the ball with a more open racket, demonstrating a difference in this task-relevant parameter. No joint kinematic differences were found for accuracy for either group. Coordinated joint rotations at the elbow and wrist both displayed a “zeroing-in” effect, whereby movement variability was reduced from the initiation of propulsive joint rotation to a higher consistency at ball-impact; potentially highlighting the “functionality” of the variability prior to the impact that enabled consistent task-relevant parameters (racket orientation and velocity) under varying conditions. Further, highly skilled players demonstrated greater consistency of task-relevant parameters at impact than less-skilled players. These findings highlight the superior ability of highly skilled players to adjust their technique to achieve consistent task-relevant parameters and a successful shot.     

Influences on Student Cognitions About Evaluation

Interviews on two occasions with 71 Grade 2, 4 and 6 students in a multi-ethnic setting in Toronto, Canada, found that student cognitions about evaluation mediated the relationship between evaluation and achievement. Parents, peers and student characteristics influenced student cognitions about evaluation. Parents identified the evaluation dimensions their children should attend to, raised student aspirations, stated how well student work attained standards and recommended actions children should take in response to the evaluation. Peer interpretations influenced whether a given performance was viewed as superior or inferior. Older student peers focused attention, to a greater extent than parents, on specific aspects of student performance that could be ameliorated through self-remediation. Children became more sophisticated evaluation consumers as they grew older. Females processed evaluation data more productively than males. There were few cultural differences in response to evaluation. Students responded to traditional and alternate evaluation in very similar ways.     

Efficient distributed selective search

Simulation and analysis have shown that selective search can reduce the cost of large-scale distributed information retrieval. By partitioning the collection into small topical shards, and then using a resource ranking algorithm to choose a subset of shards to search for each query, fewer postings are evaluated. In this paper we extend the study of selective search into new areas using a fine-grained simulation, examining the difference in efficiency when term-based and sample-based resource selection algorithms are used; measuring the effect of two policies for assigning index shards to machines; and exploring the benefits of index-spreading and mirroring as the number of deployed machines is varied. Results obtained for two large datasets and four large query logs confirm that selective search is significantly more efficient than conventional distributed search architectures and can handle higher query rates. Furthermore, we demonstrate that selective search can be tuned to avoid bottlenecks, and thus maximize usage of the underlying computer hardware.     

Do allegations of emotional maltreatment predict developmental outcomes beyond that of other forms of maltreatment?

OBJECTIVES: To understand the features of child abuse/neglect (CA/N) allegations in cases with emotional maltreatment (EMT) allegations, as well as the features of the EMT allegations themselves, and to describe any associations of EMT with distinct impairments of children's behavior, emotion and functioning. METHOD: The sample consisted of 806 high-risk children, 545 with one or more maltreatment reports to CPS. The Maltreatment Classification System was used to record the number and severity levels of maltreatment allegations, which compared cases with and without EMT. Multiple regression analyses were conducted using 10 outcome scales from the Child Behavior Checklist, Vineland Screener, and Trauma Symptom Checklist. Successive blocks of predictor variables included demographics, maltreatment classification variables, maternal and family characteristics, and study site. RESULTS: When there were allegations of EMT as well as CA/N in a CPS case-record (by age 8), the CA/N allegations tended to be either more frequent or less severe than those kinds of allegations in cases without EMT. When neglect was alleged to occur with EMT, neglect allegations outnumbered allegations of EMT. However, when sexual abuse allegations were accompanied by EMT allegations, there were more EMT allegations than sexual abuse allegations in the cases. Higher severity ratings for EMT allegations than for physical abuse occurred when cases included any abuse. Distinctive effects of EMT subtypes were found between problems of safety/restriction and self-reported anger symptoms, and between problems of self-esteem/autonomy and posttraumatic stress. CONCLUSION: Differences exist between the CA/N allegations in cases with and without EMT. Having few cases containing only EMT allegations made it difficult to assess distinctive harm associated with EMT. Certain types of EMT allegations were associated with increases in children's anger and posttraumatic stress.     

Social Engineering in the Information Age

This article explores the relevance of social engineering for the postindustrial epoch. The concept of social engineering has been dormant in recent years, stained by the behavior of police states in the 20th century. Yet stripped of its excesses, social engineering still represents a defensible moral and political enterprise. What is needed for the 21st century, however, is a chastened, deontological theory of social engineering, one that accepts the inviolability of the person while still pursuing ambitious long-term teleological strategies through state action. For its content, progressive information society policy should revisit the ethical norms developed by the left-liberal tradition, as articulated by the late John Rawls and others. The article concludes that the information age offers a new opportunity to engineer a just social order, or, at any rate, that the policymaking community needs to reevaluate the idea of social engineering.