Quantifying stability and change in ethnic group

nine per cent of those recorded in an Asian group in 1991 have changed to a different group by 2001; 23 per cent of each of the Caribbean and African groups have changed. We quantify the separate influences of question unreliability, changes in categories, and conscious change of affiliation, finding that the latter contributes little instability over the period 1991–2001. The unreliability of the question is significant, due partly to the ambiguity of the categories for some people, and partly to imprecise imputation of missing values. We report the best correspondence between the different classifications used in 1991 and 2001 using empirical measures of fit. Key words: Race; reliability; longitudinal; census. 1

Error in official age-specific population estimates over place and time

Population estimates for sub-national areas underpin resource targeting for public and private expenditure. We quantify the success of the Office for National Statistics Small Area Population Estimates (ONS SAPE) in England (2011) using census-based population estimates as a comparative gold standard. We model the accuracy (% absolute error) of the ONS SAPE for Lower Super Output areas according to place characteristics and broad age groups. We compare the modelled accuracy to similar small area population estimates developed by local planners in 1991 and also to simple methods (2011) that might be used with less investment in estimation. Our results show that the ONS SAPE is of comparable accuracy to locally conducted censuses that provided the most accurate results in 1991. We find no combination of area characteristic or age group in which simpler methods of population estimation (in 1991 or 2001) outperform the ONS SAPE. The ONS SAPE is least accurate for young adult ages and areas that are experiencing high unemployment or in-migration. For such areas and groups local censuses may be used to resolve disputes over population estimates and are where attention might be focussed in order to improve the accuracy of small area population estimates.</p

PCP-B class pollen coat proteins are key regulators of the hydration checkpoint in Arabidopsis thaliana pollen-stigma interactions

The establishment of pollen–pistil compatibility is strictly regulated by factors derived from both male and female reproductive structures. Highly diverse small cysteine-rich proteins (CRPs) have been found to play multiple roles in plant reproduction, including the earliest stages of the pollen–stigma interaction. Secreted CRPs found in the pollen coat of members of the Brassicaceae, the pollen coat proteins (PCPs), are emerging as important signalling molecules that regulate the pollen–stigma interaction. Using a combination of protein characterization, expression and phylogenetic analyses we identified a novel class of Arabidopsis thaliana pollen-borne CRPs, the PCP-Bs (for pollen coat protein B-class) that are related to embryo surrounding factor (ESF1) developmental regulators. Single and multiple PCP-B mutant lines were utilized in bioassays to assess effects on pollen hydration, adhesion and pollen tube growth. Our results revealed that pollen hydration is severely impaired when multiple PCP-Bs are lost from the pollen coat. The hydration defect also resulted in reduced pollen adhesion and delayed pollen tube growth in all mutants studied. These results demonstrate that AtPCP-Bs are key regulators of the hydration ‘checkpoint’ in establishment of pollen–stigma compatibility. In addition, we propose that interspecies diversity of PCP-Bs may contribute to reproductive barriers in the Brassicaceae