Origins of children's helpless and mastery achievement patterns in the family.

An exploratory study examined the origins of children's motivational patterns in the family by observing 3rd-grade children (10 helpless and 11 mastery-oriented) and their mothers performing a series of solvable and insolvable problem-solving tasks. Mothers of mastery children appeared to show sensitivity and responsiveness to their children's ability perceptions and requests for help. They also appeared to support mastery behaviors in their children by increasing task-focused teaching behaviors and maintaining high-positive affect during the insolvable puzzles. Furthermore, in the face of failures, they retrained their children's low-ability attributions and performance-goal statements, while promoting mastery or task-focused behaviors. These findings are consistent with the hypothesis that mothers of mastery children may socialize their children's achievement motivation. However, because of the small sample size and other limitations, the results should be interpreted with caution. Several directions are outlined for future research on the familial origins of helpless and mastery patterns in children. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

New formulation and plots for error probability in the pulse position modulation (PPM) photon counting satellite-to-earth channel

In digital satellite-to-earth transmission the entry of substantial undesired solar radiation into the receiver antenna is sometimes unavoidable. When the signal transmission takes the form of incoherent optical pulse position modulation (PPM) the parameters of signal and consequent intense noise can fall outside the range of routinely available classical numerical results on symbol error probability. This paper presents an alternative system for parametrization of signal and noise in the classical PPM channel, i.e. that characterized by Poisson photon arrival statistics for signal itself, the noise itself, and the signal plus noise. The resulting formulation for error probability, the scheme for probability calculation, and the simple, compact plots of error probability versus newly conceived parameters cover the entire range of signal and noise intensities, from weakest to strongest. Of course, when properly interpreted the new results agree entirely with classically available numerical results within the parametric range of the former.     

The miniwid-coater: I. design and evaluation of a temperature-controlled miniature fluid-bed pan coater

A novel miniature laboratory-scale pan coater has been developed. Small batches of 50 to 100 g of pellets, granules, large crystalls and small tablets allow the formulation development with minimal quantities of valuable drugs and new active ingredients. Although originally it is a pan coater, the core bed will be slightly fluidized by the inlet air flow due to the small dimensions of the coating pan. This allows a rapid drying and the loss of coating materials will be negligible.

A computer was used to control the core bed temperature during the coating process by varying the spraying rate of an analytical dosing pump. Additionally, the drying air temperature can be adopted. It was possible to change the parameters during the process to optimize the operation conditions within one run. The computer program described in this article provides a constant bed temperature with a precision of ± 0.3 °C.

In the MiniWiD-Coater, neutral pellets have been loaded with bisacodyl and then enteric-coated with aqueous dispersions of Eudragit L 30 D. Batch homogeneity and reproducibility were excellent. Friability of the cores and abrasion of the coat remained low. The loss of coating material during operation was always below 5 %.     

Mathematics self-efficacy and mathematics performances: The need for specificity of assessment.

In this study, 391 students were asked to provide 3 types of mathematics self-efficacy judgments: confidence to solve mathematics problems, confidence to succeed in math-related courses, and confidence to perform math-related tasks. Criterial tasks were solution of math problems and choice of math-related majors. As hypothesized, students' reported confidence to solve the problems they were later asked to solve was a more powerful predictor of that performance than was either their confidence to perform math-related tasks or to succeed in math-related courses. Similarly, confidence to succeed in math-related courses was a stronger predictor of choice of math-related majors than was either confidence to solve problems or to perform math-related tasks. Results support A. Bandura's (1986) contention that, because judgments of self-efficacy are task specific, measures of self-efficacy should be tailored to the criterial task being assessed and the domain of functioning being analyzed to increase prediction. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Book reviews

Book reviewed in this article:
The Information Economy and American Cities. Matthew P. Drennan.
Transportation Networks and the Optimal Location of Human Activities: A Numerical Geography Approach. (Transport Economics, Management and Policy Series.)
Travel Behaviour: Spatial Patterns, Congestion and Modelling. E. Stern, I. Salomon, P.H.I. Bovy (eds).
Input-Output Analysis: Frontiers and Extensions. Michael L. Lahr and Erik Dietzenbacher (eds).     

Robust Practical Point Stabilization of a Nonholonomic Mobile Robot Using Neural Networks

A control structure that makes possible the integration of a kinematiccontroller and a neural network (NN) computed-torque controller fornonholonomic mobile robots is presented. A combined kinematic/torque controllaw is developed and stability is guaranteed by Lyapunov theory. Thiscontrol algorithm is applied to the practical point stabilization problemi.e., stabilization to a small neighborhood of the origin. The NN controllercan deal with unmodeled bounded disturbances and/or unstructured unmodeleddynamics in the vehicle. On-line NN weight tuning algorithms that do notrequire off-line learning yet guarantee small tracking errors and boundedcontrol signals are utilized.     

Ferromagnetic Resonance in Ga1−x Mn x As

We report on ferromagnetic resonance measurements of Ga_1?x Mn _x As thin films with Mn contents 0.022 ≤ x ≤ 0.051. For x ≥ 0.036 and the external magnetic field normal to the thin film, we observe several resonances, which we identify as spin wave resonances. The non-quadratic mode spacing can be consistently explained by a linear gradient in the magnetic properties of the films. From the measurements, the exchange constant A can be deduced for different Mn contents x.