SUMSS: A Wide-Field Radio Imaging Survey of the Southern Sky. I. Science goals, survey design and instrumentation

The Molonglo Observatory Synthesis Telescope, operating at 843 MHz with a 5 square degree field of view, is carrying out a radio imaging survey of the sky south of declination -30 deg. This survey (the Sydney University Molonglo Sky Survey, or SUMSS) produces images with a resolution of 43" x 43" cosec(Dec.) and an rms noise level of about 1 mJy/beam. SUMSS is therefore similar in sensitivity and resolution to the northern NRAO VLA Sky Survey (NVSS; Condon et al. 1998). The survey is progressing at a rate of about 1000 square degrees per year, yielding individual and statistical data for many thousands of weak radio sources. This paper describes the main characteristics of the survey, and presents sample images from the first year of observation.Comment: 27 pages, 12 figures (figures 2, 8, 10 in jpg format); AJ, in pres

Intrapancreatic delivery of human umbilical cord blood aldehyde dehydrogenase-producing cells promotes islet regeneration

Aims/hypothesis We sought to investigate the stimulation of islet regeneration by transplanted human umbilical cord blood (UCB) cells purified according to high aldehyde dehydrogenase (ALDH) activity (ALDHhi), a conserved characteristic of multiple progenitor lineages. We hypothesised that direct intrapancreatic (iPan) delivery of ALDHhi progenitors would augment islet regeneration via timely and localised exposure to islet-regenerative stimuli. Methods Cells were purified from UCB based on flow cytometry for low ALDH activity (ALDHlo) vs ALDHhi. UCB ALDHlo or ALDHhi cells were compared for surface marker expression, as well as haematopoietic, endothelial and multipotent stromal progenitor content in vitro. UCB ALDHlo or ALDHhi cells were i.v. or iPan injected into streptozotocin-treated non-obese diabetic/severe combined immune-deficient mice temporally monitored for blood glucose, serum insulin and glucose tolerance. Human cell recruitment and survival in the pancreas, insulin content, islet-associated cell proliferation and islet vascularisation were documented in situ. Results UCB-derived ALDHhi cells were highly enriched for haematopoietic and endothelial progenitor frequency, and showed increased expression of progenitor and myeloid cell surface markers. Although i.v. transplantation of ALDHhi cells demonstrated low pancreas engraftment and only transient blood glucose lowering capacity, iPan injected ALDHhi cells reversed established hyperglycaemia, increased serum insulin and improved the response to a glucose challenge. iPan injected ALDHhi cells surrounded damaged islets at early time points and increased islet-associated cell proliferation, resulting in the recovery of beta cell mass. Conclusions/interpretation iPan delivery of UCB ALDHhi cells potentiated islet-associated cell proliferation, insulin production and islet revascularisation, resulting in the recovery of host islet function. Elucidation of the progenitor-specific pathways stimulated during islet regeneration may provide new approaches to promote islet expansion during diabetes. © Springer-Verlag 2012

Water diffusion into UV inscripted long period grating in microstructured polymer fibre

A long period grating was photoinscribed step-by-step in microstructured poly(methyl methacrylate) fiber for the first time using a continuous wave HeCd laser at 325 nm, irradiating the fiber with a power of 1 mW. The grating had a length of 2 cm and a period of 1 mm. A series of cladding mode coupling resonances were observed throughout the spectral region studied of 600 to 1100 nm. The resonance wavelengths were shown to be sensitive to the diffusion of water into the fiber

The Molonglo Galactic Plane Survey: I. Overview and Images

The first epoch Molonglo Galactic Plane Survey (MGPS1) is a radio continuum survey made using the Molonglo Observatory Synthesis Telescope (MOST) at 843 MHz with a resolution of 43" X 43" cosec |delta|. The region surveyed is 245 deg < l < 355 deg, |b| < 1.5 deg. The thirteen 9 deg X 3 deg mosaic images presented here are the superposition of over 450 complete synthesis observations, each taking 12 h and covering 70' X 70' cosec |delta|. The root-mean-square sensitivity over much of the mosaiced survey is 1-2 mJy/beam (1 sigma), and the positional accuracy is approximately 1" X 1" cosec |delta| for sources brighter than 20 mJy. The dynamic range is no better than 250:1, and this also constrains the sensitivity in some parts of the images. The survey area of 330 sq deg contains well over 12,000 unresolved or barely resolved objects, almost all of which are extra-galactic sources lying in the Zone of Avoidance. In addition a significant fraction of this area is covered by extended, diffuse emission associated with thermal complexes, discrete H II regions, supernova remnants, and other structures in the Galactic interstellar medium.Comment: Paper with 3 figures and 1 table + Table 2 + 7 jpg grayscales for Fig 4. Astrophysical Journal Supplement (in press) see also http://www.astrop.physics.usyd.edu.au/MGP

The optical-ultraviolet continuum of Seyfert 2 galaxies

This paper aims to understand the continuum of Seyfert 2 galaxies. By fitting the single galaxies in the sample of Heckman et al. (1995) with composite models (shock+ photoionization from the active center), we show that five main components characterize the SED of the continuum. Shocks play an important role since they produce a high temperature zone where soft X-rays are emitted. We show that in the optical-UV range, the slope of the NLR emission reproduces the observed values, and may be the main component of the featureless continuum. The presence of star forming regions cannot be excluded in the circumnuclear region of various Seyfert galaxies. An attempt is made to find their fingerprints in the observed AGN spectra. Finally, it is demonstrated that multi-cloud models are necessary to interpret the spectra of single objects, even in the global investigation of a sample of galaxies.Comment: 26 pages, LaTeX (including 5 Tables) + 17 PostScript figures. To appear in "The Astrophysical Journal

Gas and Dust Emission from the Nuclear Region of the Circinus Galaxy

Simultaneous modeling of the line and continuum emission from the nuclear region of the Circinus galaxy is presented. Composite models which include the combined effect of shocks and photoionization from the active center and from the circumnuclear star forming region are considered. The effects of dust reradiation, bremsstrahlung from the gas and synchrotron radiation are treated consistently. The proposed model accounts for two important observational features. First, the high obscuration of Circinus central source is produced by high velocity and dense clouds with characteristic high dust-to-gas ratios. Their large velocities, up to 1500 km\s, place them very close to the active center. Second, the derived size of the line emitting region is well in agreement with the observed limits for the coronal and narrow line region of Circinus.Comment: 36 pages, LaTex (including 4 Tables and 9 figures), $$ removed from Abstract To appear in "The Astrophysical Journal

The Distribution of H2O Maser Emission in the Nucleus of NGC 4945

We present the first interferometer map of the water maser emission in the active nucleus of NGC 4945. Although the declination of the galaxy is about -49 degrees, we were able to make the observations with the southernmost antennas of the Very Long Baseline Array. Strong maser emission is present in three velocity ranges, one near the systemic velocity and two shifted roughly symmetrically by +/-(100-150) km/s. This is the first detection of highly blue-shifted water emission in NGC 4945. We determined the position of the maser to be RA(B1950)= 13 02 32.28 +/- 0.02 ; Dec(B1950)= -49 12 01.9 +/- 0.1. The uncertainties in earlier estimates are at least several arcseconds. The maser lies within 2'' (36 pc at a distance of 3.7 Mpc) of the peaks in 1.4 GHz continuum and 1.6 micron emission from the nucleus. The mappable maser emission is distributed roughly linearly over about 40 milliarcseconds (0.7 pc) at a position angle of about 45 degrees, which is close to the 43 +/- 2 degree position angle of the galactic disk. The red and blue-shifted emission symmetrically stradle the systemic emission on the sky, which suggests material in edge-on circular motion around a central object. The position-velocity structure indicates a binding mass of about one million Suns, within a volume of radius about 0.3 pc. This implies that the central engine radiates on the order of 10% of its Eddington luminosity.Comment: 18 pages, including 5 Postscript figures. Accepted for publication in ApJ Letter

Developmental trajectory of social influence integration into perceptual decisions in children

The opinions of others have a profound influence on decision making in adults. The impact of social influence appears to change during childhood, but the underlying mechanisms and their development remain unclear. We tested 125 neurotypical children between the ages of 6 and 14 years on a perceptual decision task about 3D-motion figures under informational social influence. In these children, a systematic bias in favor of the response of another person emerged at around 12 years of age, regardless of whether the other person was an age-matched peer or an adult. Drift diffusion modeling indicated that this social influence effect in neurotypical children was due to changes in the integration of sensory information, rather than solely a change in decision behavior. When we tested a smaller cohort of 30 age- and IQ-matched autistic children on the same task, we found some early decision bias to social influence, but no evidence for the development of systematic integration of social influence into sensory processing for any age group. Our results suggest that by the early teens, typical neurodevelopment allows social influence to systematically bias perceptual processes in a visual task previously linked to the dorsal visual stream. That the same bias did not appear to emerge in autistic adolescents in this study may explain some of their difficulties in social interactions