Grain orientation effects on dynamic strength of FCC multicrystals at low shock pressures: a hydrodynamic instability study

Variability in local dynamic plasticity due to material anisotropy in polycrystalline metals is likely to be important on damage nucleation and growth at low pressures. Hydrodynamic instabilities could be used to study these plasticity effects by correlating measured changes in perturbation amplitudes at free surfaces to local plastic behaviour and grain orientation, but amplitude changes are typically too small to be measured reliably at low pressures using conventional diagnostics. Correlations between strength at low shock pressures and grain orientation were studied in copper (grain size?≈?800 μm) using the Richtmyer–Meshkov instability with a square-wave surface perturbation (wavelength = 150 μm, amplitude = 5 μm), shocked at 2.7 GPa using symmetric plate impacts. A Plexiglas window was pressed against the peaks of the perturbation, keeping valleys as free surfaces. This produced perturbation amplitude changes much larger than those predicted without the window. Amplitude reductions from 64 to 88% were measured in recovered samples and grains oriented close to 〈0 0 1〉 parallel to the shock had the largest final amplitude, whereas grains with shocks directions close to 〈1 0 1〉 had the lowest. Finite element simulations were performed with elastic-perfectly plastic models to estimate yield strengths leading lead to those final amplitudes. Anisotropic elasticity and these yield strengths were used to calculate the resolved shear stresses at yielding for the two orientations. Results are compared with reports on orientation dependence of dynamic yielding in Cu single crystals and the higher values obtained suggest that strength estimations via hydrodynamic instabilities are sensitive to strain hardening and strain rate effects.     

Functional equivalence of spatial images from touch and vision: evidence from spatial updating in blind and sighted individuals

This research examined whether visual and haptic map learning yield functionally equivalent spatial images in working memory, as evidenced by similar encoding bias and updating performance. In 3 experiments, participants learned 4-point routes either by seeing or feeling the maps. At test, blindfolded participants made spatial judgments about the maps from imagined perspectives that were either aligned or misaligned with the maps as represented in working memory. Results from Experiments 1 and 2 revealed a highly similar pattern of latencies and errors between visual and haptic conditions. These findings extend the well-known alignment biases for visual map learning to haptic map learning, provide further evidence of haptic updating, and most important, show that learning from the 2 modalities yields very similar performance across all conditions. Experiment 3 found the same encoding biases and updating performance with blind individuals, demonstrating that functional equivalence cannot be due to visual recoding and is consistent with an amodal hypothesis of spatial images.     

Analysis of tactile and visual confusion matrices

Confusion matrices were compiled for uppercase letters and for braille characters presented to observers in two ways: as raised touch stimuli and as visual stimuli that had been optically filtered of their higher spatial frequencies. These and other existing matrices were subjected to a number of analyses, including the choice model and hierarchical clustering. The strong similarity of the visual and tactile matrices from this study lends additional support to the claim that visual recognition of low-pass filtered characters, to a first approximation, can be taken as a model of tactile recognition of small two-dimensional raised patterns. Besides this, the analysis questions the widely held assumption that response bias contributes significantly to the stimulus-response contingencies in a character-recognition task.     

Reviews of current books

Pastoral Psychology -     

Haptic identification of objects and their depictions

Haptic identification of real objects is superior to that of raised two-dimensional (2-D) depictions. Three explanations of real-object superiority were investigated: contribution of material information, contribution of 3-D shape and size, and greater potential for integration across the fingers. In Experiment 1, subjects, while wearing gloves that gently attenuated material information, haptically identified real objects that provided reduced cues to compliance, mass, and part motion. The gloves permitted exploration with free hand movement, a single outstretched finger, or five outstretched fingers. Performance decreased over these three conditions but was superior to identification of pictures of the same objects in all cases, indicating the contribution of 3-D structure and integration across the fingers. Picture performance was also better with five fingers than with one. In Experiment 2, the subjects wore open-fingered gloves, which provided them with material information. Consequently, the effect of type of exploration was substantially reduced but not eliminated. Material compensates somewhat for limited access to object structure but is not the primary basis for haptic object identification.     

The Better Beginnings,Better Futures Project: Long‐term Parent,Family, and Community Outcomes of a Universal,Comprehensive, Community‐Based Prevention Approach for Primary School Children and their Families

Better Beginnings, Better Futures is a large‐scale, multi‐year, longitudinal research‐demonstration project designed to reduce children's problems, promote healthy child development, and enhance family and community environments in three economically disadvantaged communities in the province of Ontario, Canada. The initial intervention was implemented from 1993 to 1997 and focused on families with children from 4 to 8 years of age in their first 4 years of schooling (from Junior Kindergarten to Grade 2). This study examined the long‐term parent, family and community programme outcomes, 15 years after the start of the intervention, when the young people who had participated in the intervention as young children were 18 to 19 years of age. Comparison of intervention communities with matched non‐intervention communities showed a mix of outcomes. Although few significant differences between intervention and comparison communities were found with regard to parents' health and family outcomes, there was evidence that parents in the intervention communities were engaging in fewer risk behaviours, had lower levels of depression and had more community involvement than parents in the comparison communities. These results suggest that the intervention did have some positive long‐term effects on youths' parents and on their community environments. Results are discussed with respect to the importance of considering family and neighbourhood contexts in the development and evaluation of prevention programmes. Copyright © 2012 John Wiley & Sons, Ltd.     

Spatial updating of multiple targets: Comparison of younger and older adults

When walking without vision, people mentally keep track of the directions and distances of previously viewed objects, a process called spatial updating. The current experiment indicates that while people across a large age range are able to update multiple targets in memory without perceptual support, aging negatively affects accuracy, precision, and decision time. Participants (20 to 80 years of age) viewed one, three, or six targets (colored lights) on the floor of a dimly lit room. Then, without vision, they walked to a target designated by color, either directly or indirectly (via a forward turning point). The younger adults’ final stopping points were both accurate (near target) and precise (narrowly dispersed), but updating performance did degrade slightly with the number of targets. Older adults’ performance was consistently worse than the younger group, but the lack of interaction between age and memory load indicates that the effect of age on performance was not further exacerbated by a greater number of targets. The number of targets also significantly increased the latency required to turn toward the designated target for both age groups. Taken together, results extend previous work showing impressive updating performance by younger adults, with novel findings showing that older adults manifest small but consistent degradation of updating performance of multitarget arrays.