Gas Accretion and Star Formation Rates

Cosmological numerical simulations of galaxy evolution show that accretion of metal-poor gas from the cosmic web drives the star formation in galaxy disks. Unfortunately, the observational support for this theoretical prediction is still indirect, and modeling and analysis are required to identify hints as actual signs of star-formation feeding from metal-poor gas accretion. Thus, a meticulous interpretation of the observations is crucial, and this observational review begins with a simple theoretical description of the physical process and the key ingredients it involves, including the properties of the accreted gas and of the star-formation that it induces. A number of observations pointing out the connection between metal-poor gas accretion and star-formation are analyzed, specifically, the short gas consumption time-scale compared to the age of the stellar populations, the fundamental metallicity relationship, the relationship between disk morphology and gas metallicity, the existence of metallicity drops in starbursts of star-forming galaxies, the so-called G dwarf problem, the existence of a minimum metallicity for the star-forming gas in the local universe, the origin of the alpha-enhanced gas forming stars in the local universe, the metallicity of the quiescent BCDs, and the direct measurements of gas accretion onto galaxies. A final section discusses intrinsic difficulties to obtain direct observational evidence, and points out alternative observational pathways to further consolidate the current ideas.Comment: Invited review to appear in Gas Accretion onto Galaxies, Astrophysics and Space Science Library, eds. A. J. Fox & R. Dav\'e, to be published by Springe

Recruiting, retaining and supporting early career teachers for rural schools

The staff of Australia’s rural schools include many early career teachers who are keen to begin their careers in geographically diverse communities. Despite often high levels of motivation to take up a rural position and many well-funded government incentives to do so, recruiting and retaining teachers remains a challenge across Australia. Against this backdrop this chapter explores the key question: How can we better prepare and support the next generation of teachers for our rural schools? The chapter firstly explores the perennial issues of rural staffing and then critically examines a range of incentives for both pre-service and in-service teachers to attract them to rural schools and communities. One of the reasons incentives appear to be failing could be that they do very little to transform the preparation and education of pre-service teachers to better work in and for rural schools and their communities. To date, teacher education providers and schools have put little effort into changing their preparation and induction models. The chapter concludes with possibilities for a ‘system’ change to address the rural staffing ‘crisis’ and raises the need for a new transformative approach to link more meaningfully initial teacher education, professional experience in and with communities and in-service professional learning (including teachers and teacher educators)