Fourier analysis of luminosity-dependent galaxy clustering

We extend the Fourier transform based method for the analysis of galaxy redshift surveys of Feldman, Kaiser & Peacock (1994: FKP) to model luminosity-dependent clustering. In a magnitude limited survey, galaxies at high redshift are more luminous on average than galaxies at low redshift. Galaxy clustering is observed to increase with luminosity, so the inferred density field is effectively multiplied by an increasing function of radius. This has the potential to distort the shape of the recovered power spectrum. In this paper we present an extension of the FKP analysis method to incorporate this effect, and present revised optimal weights to maximize the precision of such an analysis. The method is tested and its accuracy assessed using mock catalogues of the 2-degree field galaxy redshift survey (2dFGRS). We also show that the systematic effect caused by ignoring luminosity-dependent bias was negligible for the initial analysis of the 2dFGRS of Percival et al. (2001). However, future surveys, sensitive to larger scales, or covering a wider range of galaxy luminosities will benefit from this refined method.Comment: 9 pages, 4 figures, accepted for publication in MNRA

Older people's experiences of their kitchens: 2000 to 2010

Purpose – This paper aims to present the quantitative results based on a comparison and evaluation of older people's experiences, needs and wants from their current kitchens, combining and comparing the results obtained from two studies conducted in 2000 and 2010 to see what progress has been made. Design/methodology/approach – A study in 2010 investigated the life-long and contemporary experiences of kitchens of 48 people aged over 60 years of age. The research included detailed questionnaire interviews asking people about their experiences of living in their current kitchen. A previous study, conducted in 2000, asked many of the same questions of 22 people in the same age group. Findings – By combining and comparing the two sets of data it seems that only limited progress has been made in terms of kitchen design meeting the needs of older people between 2000 and 2010. Research limitations/implications – Owing to the small sizes of the samples it is not possible to compare the figures statistically or present them as fully representative of the British older population but while the two samples are limited both had similar characteristics of age and gender, so differences do show potential trends over time. Practical implications – The research refers to guidance and a computer based design tool and identifies a number of practical implications for design. Social implications – As people age their abilities and needs can change and their kitchen may no longer be as accessible or appropriate to their needs. Originality/value – This paper adds to the relevant guidance for designers, developers and managers of buildings where the continued personal use of a kitchen is important for continuing independence of older people