The OU goes digital

Describes how the Open University is embedding electronic library resources and services into e-learning

Share Manager User Guide

This user guide outlines the functionality of the new Share Manager

Exact density-functional potentials for time-dependent quasiparticles

We calculate the exact Kohn-Sham potential that describes, within time-dependent density-functional theory, the propagation of an electron quasiparticle wavepacket of non-zero crystal momentum added to a ground-state model semiconductor. The potential is observed to have a highly nonlocal functional dependence on the charge density, in both space and time, giving rise to features entirely lacking in local or adiabatic approximations. The dependence of the non-equilibrium part of the Kohn-Sham electric field on the local current and charge density is identified as a key element of the correct Kohn-Sham functional.Comment: 4 pages, 3 figure

Intrinsic exchange-correlation magnetic fields in exact current-density functional theory for degenerate systems

We calculate the exact Kohn-Sham (KS) scalar and vector potentials that reproduce, within current-density functional theory, the steady-state density and current density corresponding to an electron quasiparticle added to the ground state of a model quantum wire. Our results show that, even in the absence of an external magnetic field, a KS description of a steady-state system in general requires a non-zero exchange-correlation magnetic field that is purely mechanical in origin. The KS paramagnetic current density is not, in general, that of the interacting system in any gauge.Comment: 6 pages, 2 figure

Applying ethnographic methods to library research

Bryony Ramsden of the University of Huddersfield explains why methods more commonly used in ethnography can be usefully applied to research in libraries

Severity of specific language impairment predicts delayed development in number skills

The extent to which mathematical development is dependent upon language is controversial. This longitudinal study investigates the role of language ability in children's development of number skills. Participants were 229 children with specific language impairment (SLI) who were assessed initially at age 7 and again 1 year later. All participants completed measures of psycholinguistic development (expressive and receptive), performance IQ, and the Basic Number Skills subtest of the British Ability Scales. Number skills data for this sample were compared with normative population data. Consistent with predictions that language impairment would impact on numerical development, average standard scores were more than 1 SD below the population mean at both ages. Although the children showed improvements in raw scores at the second wave of the study, the discrepancy between their scores and the population data nonetheless increased over time. Regression analyses showed that, after controlling for the effect of PIQ, language skills explained an additional 19 and 17% of the variance in number skills for ages 7 and 8, respectively. Furthermore, logistic regression analyses revealed that less improvement in the child's language ability over the course of the year was associated with a greater odds of a drop in performance in basic number skills from 7 to 8 years. The results are discussed in relation to the interaction of linguistic and cognitive factors in numerical development and the implications for mathematical education

Narrative in adolescent specific language impairment (SLI): a comparison with peers across two different narrative genres

Background: Narrative may provide a useful way in which to assess the language ability of adolescents with specific language impairment and may be more ecologically valid than standardized tests. However, the language of this age group is seldom studied and, furthermore, the effect of narrative genre has not been explored in detail. Methods & Procedures: A total of 99 typically developing adolescents and 19 peers with specific language impairment were given two different types of narrative task: a story-telling condition and a conversational condition. Four areas of narrative (productivity, syntactic complexity, syntactic errors and performance) were assessed. Outcomes & Results: The group with specific language impairment was poorer on most aspects of narrative confirming recent research that specific language impairment is a long-term disorder. A number of measures also showed interactions between group and genre, with story-telling proving to be a disproportionately more difficult task for the specific language impairment group. Error analysis also suggested that the specific language impairment group was making qualitatively different errors to the typically developing group, even within a genre. Conclusions: Adolescents with specific language impairment are not only poorer at both types of narrative than peers, but also show different patterns of competence and error, and require more support from the narrative-partner. Clinical Implications: Assessments of adolescents are less frequent than at younger ages. This is partly because of the sparsity of tests available in this age range. Qualitative analysis of narrative might prove a useful alternative. The findings suggest that in every-day conversation, young people with specific language impairment manage their difficulties more discreetly and this might make them harder to identify in a mainstream setting