Manipulating and protecting entanglement by means of spin environments

We study the dynamical behavior of two initially entangled qubits, each locally coupled to an environment embodied by an interacting spin chain. We consider energy-exchange qubit-environment couplings resulting in rich and highly non-trivial entanglement dynamics. We obtain exact results for the time evolution of the concurrence between the two qubits and find that, by tuning the interaction parameters, one can freeze the dynamics of entanglement, therefore inhibiting their relaxation into the spin environments, as well as activate a sudden-death phenomenon. We also discuss the effects of an environmental quantum phase transition on the features of the two-qubit entanglement dynamics.

From rhetoric to reality: advancing literacy by cross-curricular means

Cross-curricularity, literacy and critical literacy are currently promoted as components of a curriculum appropriate for the 21st century. The first two in particular are prescribed elements of classroom experience in Northern Ireland, which is the immediate context of this article, but also more widely in the UK. Teachers are implementing cross-curricular and inter-disciplinary initiatives, but rhetorical imperatives can translate into superficial realities. The reasons for this are explored, as are the reasons why inter-disciplinary studies, literacy across the curriculum and critical literacy are deemed to be of significance for education at the present time. The ‘Making Science: Making News’ project is described, in which Key Stage 3 Science and English classes worked together, with input from a research scientist and a journalist, to produce articles on space science which were published in local newspapers. The outcomes of the project are discussed from the perspectives of both teachers and learners. It is argued that this project is an example of genuine inter-disciplinary activity; that it went beyond literacy skills to a deeper development of scientific discourse; and that, through its media connection, there was potential for building an ongoing awareness in pupils of critical literacy and scientific literacy.

The rhetoric of acculturation: When integration means assimilation

Viewing traditional acculturation literature through a social constructionist lens, the present paper identifies a number of limitations with this research. A discourse analytic approach to acculturation is offered as a means of addressing some of these issues. Drawing on examples taken from British print media debate surrounding the issue of faith schooling in the UK, an analysis is presented which illustrates the manner in which, though optimally positioned within acculturative moral hierarchies directed towards the legitimization of both pro- and anti-faith schooling debates, integration rhetoric often conceals the (re-)production of a more implicit assimilationism. Findings are discussed in terms of their implications for hegemonically structured acculturative power relations. This exploratory analysis provides the basis for reflection on the benefits of a discursive approach to acculturation. Moreover, the dependence of integrationist discourse on a series of socio-spatial resources is considered and, following on from Dixon and Durrheim's (2000) discursive re-conceptualization of place-identity, is taken to signify the need for a more environmentally 'grounded' approach to acculturation.

A pseudo-transient solution strategy for the analysis of delamination by means of interface elements

Recent efforts in the finite element modelling of delamination have concentrated on the development of cohesive interface elements. These are characterised by a bilinear constitutive law, where there is an initial high positive stiffness until a threshold stress level is reached, followed by a negative tangent stiffness representing softening (or damage evolution). Complete decohesion occurs when the amount of work done per unit area of crack surface is equal to a critical strain energy release rate. It is difficult to achieve a stable, oscillation-free solution beyond the onset of damage, using standard implicit quasi-static methods, unless a very refined mesh is used. In the present paper, a new solution strategy is proposed based on a pseudo-transient formulation and demonstrated through the modelling of a double cantilever beam undergoing Mode I delamination. A detailed analysis into the sensitivity of the user-defined parameters is also presented. Comparisons with other published solutions using a quasi-static formulation show that the pseudo-transient formulation gives improved accuracy and oscillation-free results with coarser meshes

TlCu1.73Fe0.27Se2 studied by means of Mössbauer spectroscopy and SQUID magnetometry

TlCu2-xFexSe2 is a p-type metal for x < 0.5 which crystallizes in a body-centred tetragonal structure. The metal atoms are situated in ab-planes, similar to 7 angstrom apart, while the metal - metal distance within the plane is similar to 2.75 angstrom. Due to the large difference in cation distances, the solid solutions show magnetic properties of mainly two-dimensional character. The SQUID measurements performed for x = 0.27 give the c-axis as the easy axis of magnetization, but also show clear hysteresis effects at 10 K, indicating a partly ferromagnetic coupling. The magnetic ordering temperature T-c is 55( 5) K as found from both SQUID and Mossbauer spectra. At T << Tc the magnetic hyperfine fields are distributed with a maximum at about 30 T, which are compared to the measured magnetic moment per iron atom, which is 0.97 mu(B)/Fe as found from SQUID measurements. The experimental results are compared to results using other methods on isostructural Tl selenides.