TECHNICAL NOTE. A BRIEF REVIEW OF METHODS FOR MEASURING THE PERMEATION PROPERTIES OF CONCRETE IN SITU

Numerous methods are available to measure the permeation properties of concrete, which can be classified in terms of the diffusion, absorption and permeability properties. The results from these tests are generally used to infer 'quality' or relative durability. Some of these tests involve the laboratory assessment of a sample of concrete extracted from the structure. However, this Technical Note concentrates on the alternative methods appropriate for use on site. Guidance is given on the choice of an appropriate test method, which in most practical situations depends on the predominant mechanism acting on the concrete under consideration.

Attention Engagement in Early Infancy

We report a longitudinal study investigating developmental changes in the structure of attention engagement during early infancy. Forty-three infants were observed monthly from 2 to 4 months. Attention engagement was assessed from play interactions with parents, using a coding system developed by Bakeman and Adamson (1984). The results indicated a developmental transition in attention engagement at 3 months: after this age infants engaged for longer periods and in a wider variety of states. Most infants displayed person engagement at 2 months, passive joint engagement at 3 months, and object engagement at 4 months. To address whether emerging abilities of attention engagement allow infants to follow the attention of social partners, we compared attention engagement to performance on an experimental measure of attention control (reported by Perra & Gattis, 2010). Analyses revealed a positive relation between passive joint engagement and checking back, suggesting that changes in passive joint engagement reflect the development in attention control.

Measuring positron-atom binding energies through laser-assisted photorecombination

Described here is a proposed experiment to use laser-assisted photorecombination of positrons from a trap-based beam and metal atoms in the gas phase to measure positron-atom binding energies. Signal rates are estimated, based in part upon experience studying resonant annihilation spectra using a trapbased positron beam. © IOP Publishing Ltd and Deutsche Physikalische Gesellschaft.

Responsible Participation, Community Engagement and Policing in Transitional Societies: Lessons from a Local Crime Survey in Northern Ireland

The new structures of policing in Northern Ireland have been internationally lauded as a success, but the manner in which police-community relations are unfolding in local settings is less clear. In this article we draw on a local crime survey conducted in a Republican area in Belfast to examine residents’ views of policing and to highlight residents’ concerns about police effectiveness in dealing with crime and disorder. Drawing on Habermas’s concept of ‘responsible participation’, we also consider the role that community organisations can play in helping overcome local scepticism and developing positive forms of engagement with the police. © 2012 The Authors