Galaxy redshift surveys selected by neutral hydrogen using FAST

We discuss the possibility of performing a substantial spectroscopic galaxy redshift survey selected via the 21cm emission from neutral hydrogen using the Five-hundred metre Aperture Spherical Telescope (FAST) to be built in China. We consider issues related to the estimation of the source counts and optimizations of the survey, and discuss the constraints on cosmological models that such a survey could provide. We find that a survey taking around two years could detect ~10^7 galaxies with an average redshift of ~0.15 making the survey complementary to those already carried out at optical wavelengths. These conservative estimates have used the z=0 HI mass function and have ignored the possibility of evolution. The results could be used to constrain Gamma = (Omega_m h) to 5 per cent and the spectral index, n_s, to 7 per cent independent of cosmic microwave background data. If we also use simulated power spectra from the Planck satellite, we can constrain w to be within 5 per cent of -1.Comment: 13 pages, 15 figures, Accepted by MNRAS, minor correction

Analysing Large Scale Structure: I. Weighted Scaling Indices and Constrained Randomisation

The method of constrained randomisation is applied to three-dimensional simulated galaxy distributions. With this technique we generate for a given data set surrogate data sets which have the same linear properties as the original data whereas higher order or nonlinear correlations are not preserved. The analysis of the original and surrogate data sets with measures, which are sensitive to nonlinearities, yields information about the existence of nonlinear correlations in the data. We demonstrate how to generate surrogate data sets from a given point distribution, which have the same linear properties (power spectrum) as well as the same density amplitude distribution. We propose weighted scaling indices as a nonlinear statistical measure to quantify local morphological elements in large scale structure. Using surrogates is is shown that the data sets with the same 2-point correlation functions have slightly different void probability functions and especially a different set of weighted scaling indices. Thus a refined analysis of the large scale structure becomes possible by calculating local scaling properties whereby the method of constrained randomisation yields a vital tool for testing the performance of statistical measures in terms of sensitivity to different topological features and discriminative power.Comment: 10 pages, 5 figures, accepted for publication in MNRA

Interventions that address institutional child maltreatment: an evidence and gap map.

Purpose: This evidence and gap map collates evidence reporting on the effectiveness of interventions aimed to prevent, disclose, respond to, or treat child maltreatment occurring in institutional settings. Methods: A comprehensive and systematic literature search identified primary studies and systematic reviews meeting the review’s eligibility criteria. Literature screening, data extraction and critical appraisals were undertaken independently by multiple reviewers. Data extracted and reported from the included studies included information about the institutional setting, target population, type of maltreatment, intervention type and outcomes. Results: Seventy-three studies were identified, including 11 systematic reviews and 62 primary studies. Overall, the methodological quality of the studies was low to moderate. Most evaluated curriculum-based interventions delivered in educational settings, primarily aimed at preventing sexual abuse. Fewer studies examined other institutional settings or intervention types. Conclusions: This review highlights a need for high-quality studies evaluating a more diverse range of interventions across more varied institutional contexts