Macquarie University

About: Macquarie University is a education organization based out in Sydney, New South Wales, Australia. It is known for research contribution in the topics: Population & Context (language use). The organization has 14075 authors who have published 47673 publications receiving 1416184 citations. The organization is also known as: Macquarie uni.

The 6dF Galaxy Survey: z≈ 0 measurements of the growth rate and σ 8

Abstract: We present a detailed analysis of redshift-space distortions in the two-point correlation function of the 6dF Galaxy Survey (6dFGS). The K-band selected subsample which we employ in this study contains 81 971 galaxies distributed over 17 000 degree2 with an effective redshift zeff= 0.067. By modelling the 2D galaxy correlation function, , we measure the parameter combination f(zeff)σ8(zeff) = 0.423 ± 0.055, where is the growth rate of cosmic structure and σ8 is the rms of matter fluctuations in 8 h−1 Mpc spheres. Alternatively, by assuming standard gravity we can break the degeneracy between σ8 and the galaxy bias parameter b. Combining our data with the Hubble constant prior from Riess et al., we measure σ8= 0.76 ± 0.11 and Ωm= 0.250 ± 0.022, consistent with constraints from other galaxy surveys and the cosmic microwave background data from Wilkinson Microwave Anisotropy Probe 7 (WMAP7). Combining our measurement of fσ8 with WMAP7 allows us to test the cosmic growth history and the relationship between matter and gravity on cosmic scales by constraining the growth index of density fluctuations, γ. Using only 6dFGS and WMAP7 data we find γ= 0.547 ± 0.088, consistent with the prediction of General Relativity. We note that because of the low effective redshift of the 6dFGS our measurement of the growth rate is independent of the fiducial cosmological model (Alcock–Paczynski effect). We also show that our conclusions are not sensitive to the model adopted for non-linear redshift-space distortions. Using a Fisher matrix analysis we report predictions for constraints on fσ8 for the Wide-field Australian SKA Pathfinder telescope L-band Legacy All-sky Blind surveY (WALLABY) and the proposed Transforming Astronomical Imaging surveys through Polychromatic Analysis of Nebulae (TAIPAN) survey. The WALLABY survey will be able to measure fσ8 with a precision of 4–10 per cent, depending on the modelling of non-linear structure formation. This is comparable to the predicted precision for the best redshift bins of the Baryon Oscillation Spectroscopic Survey, demonstrating that low-redshift surveys have a significant role to play in future tests of dark energy and modified gravity.

N-Watch: A program for deriving neighborhood size and other psycholinguistic statistics

Abstract: This article describes a Windows program that enables users to obtain a broad range of statistics concerning the properties of word and nonword stimuli, including measures of word frequency, orthographic similarity, orthographic and phonological structure, age of acquisition, and imageability. It is designed for use by researchers in psycholinguistics, particularly those concerned with recognition of isolated words. The program computes measures of orthographic similarity on line, either with respect to a default vocabulary of 30,605 words or to a vocabulary specified by the user. In addition to providing standard orthographic neighborhood measures, the program can be used to obtain information about other forms of orthographic similarity, such as transposed-letter similarity and embedded-word similarity. It is available, free of charge, from the following Web site: http://www.maccs.mq.edu.au/≈colin/N-Watch/.