Exploring connected learning spaces in teacher education

© 2013 Rachel Perry, Kimberley Pressick-Kilborn, Matthew Kearney. This paper reports on outcomes from a study that explored how connected learning spaces, mediated by videoconference technology, enabled real-world engagement in pre-service teacher education. Student teachers in drama and science education participated in the study, which involved varied connections with school children and their classroom teachers. Key themes that emerged were underpinned by a consideration of authentic learning: student teachers’ observations of teacher practices; enactment of multiple roles; and exposure to diverse and timely feedback. Implications for the design of discipline specific on-campus activities are considered in relation to how they inform effective integration of videoconference technology for real-world, professional engagement in teacher education

The z<=0.1 Surface Brightness Distribution

The surface brightness distribution (SBD) function describes the number density of galaxies as measured against their central surface brightness. Because detecting galaxies with low central surface brightnesses is both time-consuming and complicated, determining the shape of this distribution function can be difficult. In a recent paper Cross, et al. suggested a bell-shaped SBD disk-galaxy function which peaks near the canonical Freeman value of 21.7 and then falls off significantly by 23.5 B mag arcsec-2. This is in contradiction to previous studies which have typically found flat (slope=0) SBD functions out to 24 - 25 B mag arcsec^-2 (the survey limits). Here we take advantage of a recent surface-brightness limited survey by Andreon & Cuillandre which reaches considerably fainter magnitudes than the Cross, et.al sample (M_B reaches fainter than -12 for Andreon & Cuillandre while the Cross, et.al sample is limited to M_B < -16) to re-evaluate both the SBD function as found by their data and the SBD for a wide variety of galaxy surveys, including the Cross, et al. data. The result is a SBD function with a flat slope out through the survey limits of 24.5 B mag arcsec^-2, with high confidence limits.Comment: 5 pages including 5 figures. accepted by A&A

Primary Connections: Linking science with literacy Stage 6 research evaluation final report

This report presents findings from the External Independent Evaluation and Research for Primary Connections Stage 6 (2014–2018) conducted by a research team from the University of Technology Sydney (UTS)

The effects of an ionizing background on the HI column density distribution in the local Universe

Using data on the HI column density distribution in the local Universe, f(N_{HI}), we show how to determine g(N_{H}), the distribution of the total gas (HI+HII) column density. A simple power law fit to f(N_{HI}) fails due to bendings in the distributions when N_{HI}<10^{20} cm^{-2} and H is no longer fully neutral. If an ultraviolet background is responsible for the gas ionization, and g(N_{H}) is proportional N_{H}^{-alpha}, we find the values of alpha and of the intensity of the background radiation which are compatible with the present data. These best fitting values, however, depend upon the scaling law of the the gas volume densities with N_{H} and cannot be determined unambiguously. We examine in detail two models: one in which the average gas volume density decreases steadily with N_H, while in the other it stays constant at low column densities. The former model leads to a steep power law fit for g(N_{H}), with alpha of order 3.3 +- 0.4 and requires an ultraviolet flux larger than what the QSOs alone produce at z=0. For the latter alpha is 1.5 +- 0.1 and a lower ionizing flux is required. The ambiguities about the modelling and the resulting steep or shallow N_{H} distribution can be resolved only if new 21-cm observations and QSOs Lyman limit absorbers searches will provide more data in the HI-HII transition region at low redshifts. Using the best fit obtained for higher redshift data we outline two possible scenarios for the evolution of gaseous structures, compatible with the available data at z=0.Comment: 12 pages, 2 figures, ApJ in press (2002, vol. 567

An HI survey of the Centaurus and Sculptor Groups - Constraints on the space density of low mass galaxies

We present results of two 21-cm HI surveys performed with the Australia Telescope Compact Array in the nearby Centaurus A and Sculptor galaxy groups. These surveys are sensitive to compact HI clouds and galaxies with HI masses as low as 3E+06 Msun, and are therefore among the most sensitive extragalactic HI surveys to date. The surveys consist of sparsely spaced pointings that sample approximately 2% of the groups' area on the sky. We detected previously known group members, but we found no new HI clouds or galaxies down to the sensitivity limit of the surveys. If the HI mass function had a faint end slope of alpha = 1.5 below M_{HI} = 10^{7.5} Msun in these groups, we would have expected ~3 new objects. Cold dark matter theories of galaxy formation predict the existence of a large number low mass DM sub-halos that might appear as tiny satellites in galaxy groups. Our results support and extend similar conclusions derived from previous HI surveys that a HI rich population of these satellites does not exist.Comment: Accepted for publication in A&