Solution of the Stochastic control problem in unbounded domains

Bellman's dynamic programming equation for the optimal index and control law for stochastic control problems is a parabolic or elliptic partial differential equation frequently defined in an unbounded domain. Existing methods of solution require bounded domain approximations, the application of singular perturbation techniques or Monte Carlo simulation procedures.In this paper, using the fact that Poisson impulse noise tends to a Gaussian process under certain limiting conditions, a method which achieves an arbitrarily good approximate solution to the stochastic control problem is given. The method uses the two iterative techniques of successive approximation and quasi-linearization and is inherently more efficient than existing methods of solution.     

Educational practitioners’ beliefs and conceptualisation about the cause of ADHD: A qualitative study

Objectives: Educational practitioners play an important role in the referral and treatment of children with attention-deficit/hyperactivity disorder (ADHD). This study aimed to explore how educational practitioners conceptualise their beliefs about the causes of symptoms of ADHD. Method: Forty-one educational practitioners from schools in the United Kingdom participated in focus groups or individual interviews. Data were analysed using thematic analysis. Results: Practitioners’ beliefs fell into two categories: biological and environmental. Practitioners conceptualised the causes of ADHD in lay-theoretical models: a ‘True’ ADHD model considered that symptoms of ADHD in many cases were due to adverse environments; and a model whereby a biological predisposition is the root of the cause of the child’s symptoms. Conclusion: Differential beliefs about the causes of ADHD may lead to practitioners blaming parents for a child’s behaviour and discounting ADHD as a valid condition. This has implications for the effective support of children with ADHD in schools.     

Rats’ responses to molar and local schedule constraints

Three experiments explored responses to molar and local schedule constraints. Thirsty rats pressed a lever for access to a water spout. In Experiment 1, response totals were unaffected by two local schedule characteristics—the variability of the instrumental requirement and the variability of the magnitude of contingent reward. Experiment 2 manipulated the correlation between the instrumental requirement and the magnitude of reward. This correlation did not affect the behavioral price ratio (presses per lick) at a molar level. At a local level, the positive correlation created a lower mean lick price than did the negative correlation. The rats licked more, and licked less efficiently, under the positive correlation than under the negative correlation. Experiment 3 compared two ways of manipulating the molar presses/lick ratio: The instrumental (contingent) series varied the instrumental (contingent) requirement, but held the other requirement constant. As the ratio increased, total leverpresses increased, and total licks decreased linearly; the two series did not differ significantly. At higher lick prices, the rats licked more efficiently and made more extra licks at the spout as it closed. The results help delimit the applicability of molar models of the organism’s response to schedule constraints.     

Reducing the rate of cesarean birth

This column examines recent research that illustrates the varying perspectives of cesarean birth and vaginal birth.     

Sensory processing disorder in a primate model: evidence from a longitudinal study of prenatal alcohol and prenatal stress effects

Disrupted sensory processing, characterized by over- or underresponsiveness to environmental stimuli, has been reported in children with a variety of developmental disabilities. This study examined the effects of prenatal stress and moderate-level prenatal alcohol exposure on tactile sensitivity and its relationship to striatal dopamine system function in thirty-eight 5- to 7-year-old rhesus monkeys. The monkeys were from four experimental conditions: (a) prenatal alcohol exposed, (b) prenatal stress, (c) prenatal alcohol exposed + prenatal stress, and (d) sucrose controls. Increased D(2) receptor binding in the striatum, evaluated using positron emission tomography neuroimaging, was related to increased withdrawal (aversion) responses to repetitive tactile stimuli and reduced habituation across trials. Moreover, prenatal stress significantly increased overall withdrawal responses to repetitive tactile stimulation compared to no prenatal stress.     

Current studies on two populations: childbearing teens and women with cesarean births

Young women in their teen years and women who have had previous cesarean births are two special groups taught by Lamaze Certified Childbirth Educators. This review includes research related to both groups. Information collected from these studies can help childbirth educators assess their programs and plan appropriate classes that address the particular needs of each group.     

Cartoon embellishments in informative presentations

What effect does the inclusion of cartoon embellishments have on printed and audiovisual presentations? College students read, listened to, or viewed a presentation about the library. Some presentations included cartoons. The results suggest that if comprehension is the only goal, the printed text without cartoons is just as effective as cartoons or audiovisual presentations. If enjoyment is a factor, cartoons or audiovisual presentations should be considered.     

Designing and building an on-line community: The struggle to support sociability in the inquiry learning forum

In this paper we describe the sociotechnical structures of the Inquiry Learning Forum (ILF), a Web-based professional development tool designed to support a community of inservice and preservice mathematics and science teachers creating, sharing, and improving inquiry-based pedagogical practices. Founded in our previous research and consistent with our pedagogical commitment, the technical structures of the ILF have been designed around a “visiting-the-classroom” metaphor. This decision was based on our belief that teachers need to be full participants in, and owners of, their virtual space for meaningful interaction to occur. The hallmark of this environment is that teachers with a broad range of experience and expertise can come together in an on-line environment to observe, discuss, and reflect on pedagogical theory and practice anchored to actual teaching vignettes. The goal of this paper is to share how we instantiated our pedagogical commitments and to describe the challenges we faced during the design, development, implementation, and analysis of the ILF. Toward this end, we walk the reader through our design and implementation process, highlighting our change in focus from usability to sociability issues, and movement from conceiving the ILF as an electronic structure to a sociotechnical interaction network. The ILF Design Team consists of Brian Beatty, Tom Duffy, Geraldine Haas, Chris Keslin, Sun-Myung Lee, Justin Marquis, and Kirk Sluder     

Heuristic literacy development and its relation to mathematical achievements of middle school students

The relationships between heuristic literacy development and mathematical achievements of middle school students were explored during a 5-month classroom experiment in two 8th grade classes (N = 37). By heuristic literacy we refer to an individual’s capacity to use heuristic vocabulary in problem-solving discourse and to approach scholastic mathematical problems by using a variety of heuristics. During the experiment the heuristic constituent of curriculum-determined topics in algebra and geometry was gradually revealed and promoted by means of incorporating heuristic vocabulary in classroom discourse and seizing opportunities to use the same heuristics in different mathematical contexts. Students’ heuristic literacy development was indicated by means of individual thinking-aloud interviews and their mathematical achievements – by means of the Scholastic Aptitude Test. We found that heuristic literacy development and changes in mathematical achievements are correlated yet distributed unequally among the students. In particular, the same students, who progressed with respect to SAT scores, progressed also with respect to their heuristic literacy. Those students, who were weaker with respect to SAT scores at the beginning of the intervention, demonstrated more significant progress regarding both measures.     

Self-guided field trips for students of environments

In many learning institutions around the world, there is a trend towards larger classes, more flexible learning pathways and reduced teaching resources. Experiential learning is often used in the form of site visits or field trips for students studying engineering, natural resource management, geography and similar disciplines. Providing opportunities for students to undertake field trips without the traditional support mechanism is one of the more challenging issues for subject designers. How can large cohorts of students gain practical exposure to various aspects of the natural or built environment? Although this is typically done using traditional site visits and fieldwork with a high staff/student ratio, the goal has been to use action research to design and develop resources to enable small groups (three or four) to make self-guided visits to sites close to campus. Multimedia resources to examine and interpret aspects of the site that relate to their on-campus learning guide the students. One critical issue in the success of these activities has been proper risk assessment and control procedures. The outcome of this research is a framework to provide a safe, active learning experience by way of self-guided field trips that is suitable for implementation with large classes.