Long-term natural ageing of a dissociated dislocation in a Cu-13.43 at.% Al alloy

The nature of impurity-dislocation interactions is one of the key questions governing the strength and plasticity of solid-solution materials. To investigate the influence of impurities on the mechanical properties of intermetallic NiAl, the electronic structure and energy of NiAl with a <100>{010} edge dislocation and transition-metal impurities was calculated using the real-space tight-binding linear muffin-tin orbital method. The localized electronic states, appearing in the core of the dislocation, are found to lead to strong impurity-dislocation interactions via two mechanisms: firstly, chemical locking, due to strong hybridization between impurity electronic states and dislocation localized states; secondly, electrostatic locking, due to long-range charge oscillations caused by the electron localization in the dislocation core. The results obtained explain qualitatively why the solid-solution hardening effect in NiAl correlates with the electronic structure of impurities rather than with size misfit, as expected according to traditional views.     

The effects of age,enactment, and cue-action relatedness on memory for intentions in the Virtual Week task

ABSTRACT

The current study investigated the influence of encoding modality and cue-action relatedness on prospective memory (PM) performance in young and older adults using a modified version of the Virtual Week task. Participants encoded regular and irregular intentions either verbally or by physically performing the action during encoding. For half of the intentions there was a close semantic relation between the retrieval cue and the intended action, while for the remaining intentions the cue and action were semantically unrelated. For irregular tasks, both age groups showed superior PM for related intentions compared to unrelated intentions in both encoding conditions. While older adults retrieved fewer irregular intentions than young adults after verbal encoding, there was no age difference following enactment. Possible mechanisms of enactment and relatedness effects are discussed in the context of current theories of event-based PM.     

Inhibiting children's memory of an interactive event: the effectiveness of a cover‐up

Children are generally more susceptible than adults to suggestive interview techniques. Children's memories of an event can be altered and added to by presenting post‐event information (PEI). What is not known is whether embedding silence about a particular scene within the PEI makes that scene less likely to be reported. Children aged 5–6 years made cakes with an agent ‘Mrs Flour’. The following day they received PEI in which a target scene from the original event was omitted, resulting in children reporting the target scene significantly less often than did controls (control= 57% and omit= 23% correct responses). There was direct evidence from the children's language that the omission led to a detriment in memory for the original scene itself. Allowing children to draw during the interview did not reduce the effect. Implications are discussed in terms of child victims and witnesses particularly regarding child sexual abuse. Copyright © 2002 John Wiley & Sons, Ltd.     

Blockade of GABAA Receptors in the Interpositus Nucleus Modulates Expression of Conditioned Excitation but not Conditioned Inhibition of the Eyeblink Response

The cerebellum and related brainstem structures are essential for excitatory eyeblink conditioning. Recent evidence indicates that the cerebellar interpositus and lateral pontine nuclei may also play critical roles in conditioned inhibition (CI) of the eyeblink response. The current study examined the role of GABAergic inhibition of the interpositus nucleus in retention of CI. Male Long-Evans rats were implanted with a cannula positioned just above or in the anterior interpositus nucleus before training. The rats were trained with two different tones and a light as conditioned stimuli, and a periorbital shock as the unconditioned stimulus. CI training consisted of four phases: 1) excitatory conditioning (8 kHz tone paired with shock); 2) feature-negative discrimination (2 kHz tone paired with shock or 2 kHz tone concurrent with light); 3) summation test (8 kHz tone or 8 kHz tone concurrent with light); and 4) retardation test (light paired with shock). After reaching a criterion level of performance on the feature-negative discrimination (40% discrimination), 0.5 microl picrotoxin (a GABAA receptor antagonist) was infused at one of four concentrations, each concentration infused during separate test sessions. Picrotoxin transiently impaired conditioned responses during trials with the excitatory stimulus (tone) in a dose-dependent manner, but did not significantly impact responding to the inhibitory compound stimulus (tone-light). The results suggest that expression of conditioned inhibition of the eyeblink conditioned response does not require GABAergic inhibition of neurons in the anterior interpositus nucleus.     

Orientation of the diamond and the square revisited

Below the age of 7 or 8, children find it very difficult to reproduce a diamond compared with a square. They are also highly sensitive to contextual alignment cues from the age of three years. It is shown here that over the brief age-span of 4-6 years (inclusive), children come to control the weight they give to contextual cues. It is argued that this is a more likely precursor of the older child's ability to cope with obliques, than is the converse process of learning to specify targets and thence to prevent themselves from responding inappropriately to the context. Of course, both target-specification and contextual-responsiveness are manifest at all the ages, but the latter seems to have the leading edge in early development.     

ARTICULATION TRAINING OF TWO HEARING-IMPAIRED GIRLS1

Two 4-yr-old hearing-impaired girls were trained to articulate correctly /f/ and /sh/ phonemes in the initial position of words in response to pictures. They were first trained to imitate, and then to respond on demand of “what's this?” As a result, both girls generalized correct articulation to words requiring both phonemes in the initial and final positions.     

Agency,communion and entitlement

In this study, the relationship between agency, communion, and the active, passive, and revenge forms of entitlement is examined. Results indicate that active entitlement was positively related to agency, negatively to communion (Study 1), and unrelated to unmitigated agency and communion (Study 2). Passive entitlement was positively related to communion (in regular and unmitigated forms) and negatively related to agency (in both forms). Revenge entitlement was positively related to agency (unmitigated and regular), and negatively related to both regular and unmitigated communal orientations. Detected relationships were independent from self‐esteem (Study 1). The findings are discussed in relation to distinctions between narcissistic and healthy entitlement, and within the context of the three‐dimensional model of entitlement.