Onset of plasticity in a Σ = 5 GaAs compliant structure

Compliant structures have been fabricated in which a thin GaAs layer (thickness between 10 and 20nm) was bonded on top of a GaAs substrate with a large twist angle (about 37). This twist angle value was chosen so that the energy of the boundary (coincident boundary of type =5 (001)) was minimized. The structure of the interface was characterized and the onset of plasticity in such a compliant substructure was investigated using nanoindentation that allowed the low-load deformation regime to be observed. The results are compared with those obtained under the same conditions on a GaAs bulk substrate alone. No plastic zone was observed by transmission electron microscopy in the compliant structure under loads below 0.25mN while, under the same loads, plastic deformation was observed in the bulk substrate. For higher loads (2mN), plastic-flow enhancement was observed in the compliant structure. The results are discussed in the light of the arrangement of dislocations observed in the plastic zones.     

Plastic behaviour of an AlAs/GaAs superlattice with a short period

Nanoindentation has been used to investigate the plastic behaviour of an AlAs/GaAs superlattice with a short period. The sample was grown on a (001) surface of a GaAs single crystal by metal-organic vapour-phase epitaxy. The mechanical response of the superlattice to nanoindentation testing was compared with that of a (001) surface of bulk GaAs. The indents formed were observed by transmission electron microscopy. The plastic zone size associated with each indent was measured as a function of the maximum load. Finally the arrangement of the dislocations generated by the indenter has been analysed and compared with the arrangement observed in deformed bulk GaAs.     

Temporal considerations in the study of family firms: Reflections on “the study of organizational behaviour in family business”

We complement the work of Gagné et al. by discussing how an extended time dimension shapes organizational behaviour in family firms. Using insights from family dynamics, identity theory, and social identity theory, we show how early formative experiences in the family can influence commitment, conflict, and motivation in family firms. Then we examine how a family's intention to pass on the firm to later generations can impact leadership, human-resources practices, and corporate cultures.     

Mixed emotions: Holistic and analytic perception of facial expressions

In the face literature, it is debated whether the identification of facial expressions requires holistic (i.e., whole face) or analytic (i.e., parts-based) information. In this study, happy and angry composite expressions were created in which the top and bottom face halves formed either an incongruent (e.g., angry top + happy bottom) or congruent composite expression (e.g., happy top + happy bottom). Participants reported the expression in the target top or bottom half of the face. In Experiment 1, the target half in the incongruent condition was identified less accurately and more slowly relative to the baseline isolated expression or neutral face conditions. In contrast, no differences were found between congruent and the baseline conditions. In Experiment 2, the effects of exposure duration were tested by presenting faces for 20, 60, 100 and 120 ms. Interference effects for the incongruent faces appeared at the earliest 20 ms interval and persisted for the 60, 100 and 120 ms intervals. In contrast, no differences were found between the congruent and baseline face conditions at any exposure interval. In Experiment 3, it was found that spatial alignment impaired the recognition of incongruent expressions, but had no effect on congruent expressions. These results are discussed in terms of holistic and analytic processing of facial expressions.     

What aspects of face processing are impaired in developmental prosopagnosia?

Developmental prosopagnosia (DP) is a severe impairment in identifying faces that is present from early in life and that occurs despite no apparent brain damage and intact visual and intellectual function. Here, we investigated what aspects of face processing are impaired/spared in developmental prosopagnosia by examining a relatively large group of individuals with DP (n = 8) using an extensive battery of well-established tasks. The tasks included measures of sensitivity to global motion and to global form, detection that a stimulus is a face, determination of its sex, holistic face processing, processing of face identity based on features, contour, and the spacing of features, and judgments of attractiveness. The DP cases showed normal sensitivity to global motion and global form and performed normally on our tests of face detection and holistic processing. On the other tasks, many DP cases were impaired but there was no systematic pattern. At least half showed deficits in processing of facial identity based on either the outer contour or spacing of the internal features, and/or on judgments of attractiveness. Three of the eight were impaired in processing facial identify based on the shape of internal features. The results show that DP is a heterogeneous condition and that impairment in recognizing faces cannot be predicted by poor performance on any one measure of face processing.     

Correcting for indirect range restriction in meta-analysis: testing a new meta-analytic procedure

Using computer simulation, the authors assessed the accuracy of J. E. Hunter, F. L. Schmidt, and H. Le's (2006) procedure for correcting for indirect range restriction, the most common type of range restriction, in comparison with the conventional practice of applying the Thorndike Case II correction for direct range restriction. Hunter et al.'s procedure produced more accurate estimates of both the mean and standard deviation in meta-analysis than the conventional procedure. Even when its key assumption that the effect of selection on a 3rd variable is fully mediated by the independent variable was violated, Hunter et al.'s procedure was still relatively more accurate than the conventional procedure. When applied to data from a previously published meta-analysis, the new procedure yielded results that led to different substantive conclusions.     

Pocket-sized psychology studies: Exploring daily diary software for Palm Pilots

Daily dairies, also known as experience sampling methods (ESM) or everyday experience methods, are a common methodology utilized to provide insight into momentary psychological processes. Traditionally, such studies often have utilized paper-and-pencil surveys administered several times each day over a span of several days or weeks. However, advances in technology now allow these studies to be conducted using palmtop computers (i.e., personal digital assistants; PDAs). Three software packages for running these studies on the Palm operating system were explored and compared on a number of features. Specifically, ESP (Experience Sampling Program, by Feldman Barrett & Barrett, 2001), iESP Version 3.2 (Intel Experience Sampling Program, by Intel Research Seattle & the University of Washington Computer Science and Engineering Department), and PMAT Version 2.0 (Purdue Momentary Assessment Tool, by the Military Family Research Institute at Purdue University) were examined, with their key features compared. These advances in software for running diary studies include a number of features that provide researchers with methods and information previously unavailable in diary studies and may expand the range of possibilities in diary study designs.     

Influence of education on the pattern of cognitive deterioration in AD patients: the cognitive reserve hypothesis

The cognitive reserve hypothesis proposes that a high educational level could delay the clinical expression of Alzheimer's disease (AD) although neuropathologic changes develop in the brain. Therefore, some studies have reported that when the clinical signs of the disease emerge, high-educated patients may decline more rapidly than low-educated patients because the neuropathology is more advanced. However, these studies have only investigated the decline of global cognition or an isolated cognitive process. To study the differential deterioration pattern of several cognitive processes according to education, the performance of 20 AD patients with a high educational level and a low educational level were compared with the performance of 20 control subjects on a neuropsychological battery. The results showed that cognitive deterioration of AD patients is different according to education, although the global performance was similar in AD patients. The high-educated patients exhibited greater impairment of abstract thinking whereas the low-educated patients showed greater impairment of memory and attentional function. This confirms that some cognitive processes, such as abstract thinking, decline more rapidly in high-educated patients whereas others seem to evolve more slowly if compared to low-educated patients. In this latter case, high-educated patients may still benefit from cognitive reserve after the diagnosis of the dementia.