Optical and infrared observations of SN 2002dj: some possible common properties of fast-expanding Type Ia supernovae

As part of the European Supernova Collaboration, we obtained extensive photometry and spectroscopy of the Type Ia supernova (SN Ia) SN 2002dj covering epochs from 11 d before to nearly two years after maximum. Detailed optical and near-infrared observations show that this object belongs to the class of the high-velocity gradient events as indicated by Si, S and Ca lines. The light curve shape and velocity evolution of SN 2002dj appear to be nearly identical to SN 2002bo. The only significant difference is observed in the optical to near-infrared colours and a reduced spectral ernission beyond 6500 A. For high-velocity gradient SNe Ia, we tentatively identify a faster rise to maximum, a more pronounced inflection in the V and R light curves after maximum and a brighter, slower declining late-time B light curve as common photometric properties of this class of object. They also seem to be characterized by a different colour and colour evolution with respect to 'normal' SNe Ia. The usual light Curve shape parameters do not distinguish these events. Stronger, more blueshifted absorption features of intermediate-mass elements and lower temperatures are the most prominent spectroscopic features of SNe Ia displaying high-velocity gradients. It appears that these events burn more intermediate-mass elements in the outer layers. Possible connections to the metallicity of the progenitor star are explored.

Expanding DDR: The Transformative Role of Former Prisoners in Community-Based Reintegration in Northern Ireland

This article explores the process of Disarmament, Demobilization and Reintegration (DDR) in Northern Ireland. In particular, it examines the role and experiences of former combatants, who were incarcerated during the Troubles. It is shown that upon release from prison, many of these former combatants have played key roles in the development of community-based initiatives, which have not only facilitated the reintegration of former prisoners, but have also contributed to a broader process of post-conflict regeneration and social development. The author considers the notion of expanding the ‘R’ phase of DDR, and contends that additional attention needs to be paid to both to the specific needs of former combatants/former prisoners and to their involvement in the overall process of reintegration and peacebuilding.

Dynamics of relativistic transparency and optical shuttering in expanding overdense plasmas

Overdense plasmas are usually opaque to laser light. However, when the light is of sufficient intensity to drive electrons in the plasma to near light speeds, the plasma becomes transparent. This process—known as relativistic transparency—takes just a tenth of a picosecond. Yet all studies of relativistic transparency so far have been restricted to measurements collected over timescales much longer than this, limiting our understanding of the dynamics of this process. Here we present time-resolved electric field measurements (with a temporal resolution of ~ 50 fs) of the light, initially reflected from, and subsequently transmitted through, an expanding overdense plasma. Our result provides insight into the dynamics of the transparent-overdense regime of relativistic plasmas, which should be useful in the development of laser-driven particle accelerators, X-ray sources and techniques for controlling the shape and contrast of intense laser pulses.

Direct assembly of three-dimensional mesh plasmonic rolls

A direct-assembly method to construct three-dimensional (3D) plasmonic nanostructures yields porous plasmonic rolls through the strain-induced self-rolling up of two-dimensional metallic nanopore films. This route is scalable to different hole sizes and film thicknesses, and applicable to a variety of materials, providing general routes towards a diverse family of 3D metamaterials with nano-engineerable optical properties. These plasmonic rolls can be dynamically driven by light irradiation, rolling or unrolling with increasing or decreasing light intensity. Such dynamically controllable 3D plasmonic nanostructures offer opportunities both for sensing and feedback in active nano-actuators. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4711923]

TEENAGERS AND ILLICIT DRUG-USE - EXPANDING THE USER VS NONUSER DICHOTOMY

The present study examines proximal and distal factors associated with the use and non-use of illegal substances within a sample of 860 teenagers in North Wales. Arguing that there is predictive utility in expanding the traditional 'users vs non-users' design dichotomy, four groups are identified-resistant and vulnerable non-users and experimental and repeated users. 'Person' variables (life satisfaction, deviance, hopelessness and drug-related attributions) appeared to primarily differentiate the vulnerable group from their resistant counterparts and identify this, as yet non-using group, with user samples. It is suggested that these variables might represent 'risk' factors for illicit substance use and that the group design employed suggests they precede, rather than follow as a consequence of, illicit drug use. Like their resistant counterparts however, the vulnerable group are differentiated from user samples on some lifestyle and context indices. It is argued that these represent 'protective' influences in an otherwise at-risk group of non-users. Variables associated with an escalation of illicit drug use are discussed in considering the differences between the experimental and repeated user groups. Apart from the more proximal factor of drug-related attributions, 'person' variables appeared less involved here. Repeated users did however, tend to use a greater number of drugs, have a greater proportion of friends who also used illegal substances and significantly fewer had a Welsh cultural identity.