Model Checking CTL is Almost Always Inherently Sequential

The model checking problem for CTL is known to be P-complete (Clarke, Emerson, and Sistla (1986), see Schnoebelen (2002)). We consider fragments of CTL obtained by restricting the use of temporal modalities or the use of negations---restrictions already studied for LTL by Sistla and Clarke (1985) and Markey (2004). For all these fragments, except for the trivial case without any temporal operator, we systematically prove model checking to be either inherently sequential (P-complete) or very efficiently parallelizable (LOGCFL-complete). For most fragments, however, model checking for CTL is already P-complete. Hence our results indicate that, in cases where the combined complexity is of relevance, approaching CTL model checking by parallelism cannot be expected to result in any significant speedup. We also completely determine the complexity of the model checking problem for all fragments of the extensions ECTL, CTL+, and ECTL+

Prevalence of childhood disability and the characteristics and circumstances of disabled children in the UK : secondary analysis of the Family Resources Survey

Background: Robust data on the prevalence of childhood disability and the circumstances and characteristics of disabled children is crucial to understanding the relationship between impairment and social disadvantage. It is also crucial for public policy development aimed at reducing the prevalence of childhood disability and providing appropriate and timely service provision. This paper reports prevalence rates for childhood disability in the United Kingdom (UK) and describes the social and household circumstances of disabled children, comparing these where appropriate to those of non-disabled children. Methods: Data were generated from secondary analysis of the Family Resources Survey, a national UK cross-sectional survey, (2004/5) which had data on 16,012 children aged 0-18 years. Children were defined as disabled if they met the Disability Discrimination Act (DDA) definition (1995 and 2005). Frequency distributions and cross-tabulations were run to establish prevalence estimates, and describe the circumstances of disabled children. To establish the association between individual social and material factors and childhood disability when other factors were controlled for, logistic regression models were fitted on the dependent variable 'DDA defined disability'. Results: 7.3% (CI 6.9, 7.7) of UK children were reported by as disabled according to the DDA definition. Patterns of disability differed between sexes with boys having a higher rate overall and more likely than girls to experience difficulties with physical coordination; memory, concentration and learning; communication. Disabled children lived in different personal situations from their non-disabled counterparts, and were more likely to live with low-income, deprivation, debt and poor housing. This was particularly the case for disabled children from black/minority ethnic/ mixed parentage groups and lone-parent households. Childhood disability was associated with lone parenthood and parental disability and these associations persisted when social disadvantage was controlled for. Conclusion: These analyses suggest that UK disabled children experience higher levels of poverty and personal and social disadvantage than other children. Further research is required to establish accurate prevalence estimates of childhood disability among different black and minority ethnic groups and to understand the associations between childhood disability and lone parenthood and the higher rates of sibling and parental disability in households with disabled children

Poverty, socio-economic position, social capital and the health of children and adolescents with intellectual disabilities in Britain: a replication

Background When compared with their nonintellectually disabled peers, people with intellectual disabilities (IDs) have poorer health and are more likely to be exposed to poverty during childhood. Given that exposure to child poverty has been linked to poorer health outcomes, we attempted to estimate the extent to which the health inequalities faced by children and adolescents with IDs may be accounted for by their more disadvantaged socio-economic position. Methods Secondary analysis of data on a nationally representative sample of 12 160 British children aged under 17 years extracted from the Department of Work and Pensions' Families and Children Study. Results After controlling for age and sex, children with IDs were significantly more likely (corrected odds ratio = 2.49) to be reported to have less than good health than their nonintellectually disabled peers. However, 31% of the elevated risk for poorer health was accounted for by between-group differences in socio-economic position and social capital. Conclusions A socially and statistically significant proportion of the increased risk of poorer health among children and adolescents with IDs may be attributed to their increased risk of socio-economic disadvantage

Cross-sector collaborations in Aboriginal and Torres Strait Islander childhood disability : a systematic integrative review and theory-based synthesis

Introduction: Aboriginal and Torres Strait Islander children in Australia experience a higher prevalence of disability and socio-economic disadvantage than other Australian children. Early intervention is vital for improved health outcomes, but complex and fragmented service provision impedes access. There have been international and national policy shifts towards inter-sector collaborative responses to disability, but more needs to be known about how collaboration works in practice. Methods: A systematic integrative literature review using a narrative synthesis of peer-reviewed and grey literature was undertaken to describe components of inter- and intra-sector collaborations among services to Aboriginal and Torres Strait Islander children with a disability and their families. The findings were synthesized using the conceptual model of the ecological framework. Results: Thirteen articles published in a peer-reviewed journal and 18 articles from the grey literature met inclusion criteria. Important factors in inter- and intra-sector collaborations identified included: structure of government departments and agencies, and policies at the macro- (government) system level; communication, financial and human resources, and service delivery setting at the exo-(organizational) system level; and relationships and inter- and intra-professional learning at the meso- (provider) system level. Conclusions: The policy shift towards inter-sector collaborative approaches represents an opportunity for the health, education and social service sectors and their providers to work collaboratively in innovative ways to improve service access for Aboriginal and Torres Strait Islander children with a disability and their families. The findings of this review depict a national snapshot of collaboration, but as each community is unique, further research into collaboration within local contexts is required to ensure collaborative solutions to improve service access are responsive to local needs and sustainable