The centrality of groups and classes

This paper extends the standard network centrality measures of degree, closeness and betweenness to apply to groups and classes as well as individuals. The group centrality measures will enable researchers to answer such questions as ‘how central is the engineering department in the informal influence network of this company?’ or ‘among middle managers in a given organization, which are more central, the men or the women?’ With these measures we can also solve the inverse problem: given the network of ties among organization members, how can we form a team that is maximally central? The measures are illustrated using two classic network data sets. We also formalize a measure of group centrality efficiency, which indicates the extent to which a group's centrality is principally due to a small subset of its members.

Micro-mechanical parameterisations for continuum modelling of granular material using the discrete element method

The present work uses the discrete element method (DEM) to describe assemblies of particulate bulk materials. Working numerical descriptions of entire processes using this scheme are infeasible because of the very large number of elements (1012 or more in a moderately sized industrial silo). However it is possible to capture much of the essential bulk mechanics through selective DEM on important regions of an assembly, thereafter using the information in continuum numerical descriptions of particulate processes. The continuum numerical model uses population balances of the various components in bulk solid mixtures. It depends on constitutive relationships for the internal transfer, creation and/or destruction of components within the mixture. In this paper we show the means of generating such relationships for two important flow phenomena – segregation whereby particles differing in some important property (often size) separate into discrete phases, and degradation, whereby particles break into sub-elements, through impact on each other or shearing. We perform DEM simulations under a range of representative conditions, extracting the important parameters for the relevant transfer, creation and/or destruction of particles in certain classes within the assembly over time. Continuum predictions of segregation and degradation using this scheme are currently being successfully validated against bulk experimental data and are beginning to be used in schemes to improve the design and operation of bulk solids process plant.

Absence makes the professional try harder? Meeting the needs of socially excluded young men who become fathers

Research on socially excluded young fathers has been minimally addressed in the literature (SEU 1999, 2004). Indeed, research on young parents which informs health and social care professionals is often presented ‘through the eyes of the mother’ (Reeves 2006). Young parents in general and young fathers in particular are notoriously difficult to gain access to and engage with (Tyrer et al 2005) particularly if they have had previous negative involvement with the statutory services. Moreover, as Daniel and Taylor (1999, 2001, 2003) point out, professionals working in the health and care services often have an intense ‘maternal’ focus and this often excludes fathers from discussion and decisions about their children. The focus of this paper, drawing on two narrative studies of young fathers aged between 15-24 from the US and USA, is to evaluate the features of professional relationships that young fathers describe as finding helpful. Indeed, the findings discuss moving away from a culture of parenting classes, which all the young men interviewed described as finding problematical and in some cases embarrassing, to a culture of support which actively draws on their strengths and helps them become providers for their new families.

Keeping it together: a guide for support staff working with people whose behaviour is challenging

This guide has been written for support staff, working with people with learning disabilities, who are new to challenging behaviour or facing it for the first time. It is a self-help guide and provides practical and realistic information on how direct care staff can develop strageties to support people whose behaviour is challenging and develop their skills in this area.