Phase transitions in epitaxial Ba0.5Sr0.5TiO3 thin films

Ba0.5Sr0.5TiO3 (BST) thin-film capacitor structures with various thicknesses, (50-1200 nm) and different strain conditions (on lanthanum strontium cobalt oxide La0.5Sr0.5CoO3 and strontium ruthenate SrRuO3 buffer layers) were made using pulsed laser deposition, and characterized by x-ray diffraction. The out-of-plane lattice parameter was followed as a function of temperature within the 100-300 K temperature interval. The phase sequence (cubic-tetragonal-orthorhombic-rhombohedral) known to exist in the bulk analog is shown to be strongly affected by both the stress conditions imposed by the buffer layer and the thickness of the BST film itself. Thus, no phase transition was found for the in-plane compressed BST films. On the stress-free BST films, on the contrary, more phase transitions were observed. It appeared that the complexity of structural phase transitions increased as the film thickness in this system was reduced.

Electrically switchable nonreciprocal transmission of plasmonic nanorods with liquid crystal

The electro-optic response of a cell consisting of a thin layer of liquid crystal deposited onto gold nanorods embedded in thin film alumina with a transparent top electrode has been investigated. For p-polarized light incident from the liquid crystal side, the extinction peak associated with the nanorod longitudinal plasmon resonance is completely suppressed. The peak could be recovered by applying an external electric field parallel to the long axis of the nanorods. No extinction peak suppression is observed when the light was incident from the nanorod side of the cell. The effect is explained by polarization properties of liquid crystal.

A Blueprint for Democratic Policing Anywhere in the World? Police Reform, Political Transition and Conflict Resolution in Northern Ireland

This article provides an overview of the police reform process undertaken in Northern Ireland since 1999 as part of a broader program of conflict resolution. It considers the recommendations of the Independent Commission on Policing (ICP), which proposed a number of changes to policing structures and arrangements in Northern Ireland, and it assesses the degree to which these have been operationalized in the 8 years since the ICP published its report. It suggests that although the police reform process in Northern Ireland has been moderately successful and provides a number of international best practice lessons, the overall pace of change has been hindered by difficulties of implementation and, more fundamentally, by developments in the political sphere and civil society.

Chronic child abuse: The characteristics and careers of children caught in the child protection system

The introduction of the Quality Protects initiative in England and the focus on performance management has challenged social services departments to examine the systems, processes and outcomes for children who have their name on a child protection register. Research indicates that approximately one-quarter of the situations in which children are registered could be described as chronic—that is, they remain on the child protection register for significant periods of time, experience more than one period of registration or suffer a further incident of significant harm whilst subject to a child protection plan. In this article, the findings from a research study conducted into this group of vulnerable children are reported, focusing on the characteristics of the children and their families, and their careers in the child protection system. The paper concludes with observations about the weak conceptualization of performance management and the need to recognize the complexity of the factors that influence children’s careers in the child protection system.