The SED of the nearby HI-massive LIRG HIZOA J0836-43: from the NIR to the radio domain

HIZOA J0836-43is one of the most HI-massive galaxies in the local (z<0.1) Universe. Not only are such galaxies extremely rare, but this "coelacanth" galaxy exhibits characteristics -- in particular its active, inside-out stellar disk-building -- that appear more typical of past (z ~ 1) star formation, when large gas fractions were more common. Unlike most local giant HI galaxies, it is actively star forming. Moreover, the strong infrared emission is not induced by a merger event or AGN, as is commonly found in other local LIRGs. The galaxy is suggestive of a scaled-up version of local spiral galaxies; its extended star formation activity likely being fueled by its large gas reservoir and, as such, can aid our understanding of star formation in systems expected to dominate at higher redshifts. The multi-wavelength imaging and spectroscopic observations that have led to these deductions will be presented. These include NIR (J H K) and MIR (Spitzer; 3-24micron) imaging and photometry, MIR spectroscopy, ATCA HI-interferometry and Mopra CO line emission observations. But no optical data, as the galaxy is heavily obscured due to its location in Vela behind the Milky Way.Comment: 5 pages, 3 figures, to appear in the proceedings of IAU Symposium 284, "The Spectral Energy Distribution of Galaxies" (SED2011), 5-9 September 2011, Preston, UK, editors R.J. Tuffs & C.C.Popesc

Recalibrating the Wide-field Infrared Survey Explorer (WISE) W4 Filter

We present a revised effective wavelength and photometric calibration for the Wide-field Infrared Survey Explorer (WISE) W4 band, including tests of empirically motivated modifications to its pre-launch laboratory-measured relative system response curve. We derived these by comparing measured W4 photometry with photometry synthesised from spectra of galaxies and planetary nebulae. The difference between measured and synthesised photometry using the pre-launch laboratory-measured W4 relative system response can be as large as 0.3 mag for galaxies and 1 mag for planetary nebulae. We find the W4 effective wavelength should be revised upward by 3.3%, from 22.1 micron to 22.8 micron, and the W4 AB magnitude of Vega should be revised from m = 6.59 to m = 6.66. In an attempt to reproduce the observed W4 photometry, we tested three modifications to the pre-launch laboratory-measured W4 relative system response curve, all of which have an effective wavelength of 22.8 micron. Of the three relative system response curve models tested, a model that matches the laboratory-measured relative system response curve, but has the wavelengths increased by 3.3% (or 0.73 micron) achieves reasonable agreement between the measured and synthesised photometry.Comment: Accepted for publication in Publications of the Astronomical Society of Australia, 6 pages, 4 figures, 1 tabl

World Health Day focus on HIV and depression - a comorbidity with specific challenges.

Depression is intricately bound with HIV. Depression may elevate risks of HIV acquisition and be triggered by an HIV diagnosis, in people living with HIV or in people receiving treatment. Depression is a key comorbidity in HIV. Mental health is often underserved especially in adult care, and more so for children and adolescents – despite the elevated infection rates, nonadherence and mortality in these age groups

Maternal position during caesarean section for preventing maternal and neonatal complications : a cochrane review

Thesis (MMed)--Stellenbosch University, 2011.ENGLISH ABSTRACT: Background: During caesarean section mothers can be in different positions. Theatre tables could be tilted laterally, upwards, downwards or flexed and wedges or cushions could be used. There is no consensus on the best positioning at present. Objectives: We assessed all available data on positioning of the mother to determine if there is an ideal position during caesarean section that would improve outcomes. Search methods: We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (September 2009), PubMed (1966 to 14 September 2009) and manually searched the references of retrieved articles. Selection criteria: Randomised trials of women undergoing caesarean section comparing different positions. Data collection and analysis: Two authors assessed eligibility, trial quality and extracted data. Results: We identified 17 studies with a total of 683 woman included. We included nine studies and excluded eight studies. Included trials were of variably quality with small sample sizes. Most comparisons had data from single trials. This is a shortcoming and applicability of results is limited. The incidence of air embolism was not affected by head up versus horizontal position (risk ratio (RR) 0.91; 95% confidence interval (CI) 0.65 to 1.26). We found no change in hypotensive episodes when comparing left lateral tilt (RR 0.11; 95% CI 0.01 to 1.94), right lateral tilt (RR 1.25; 95% CI 0.39 to 3.99) and head down tilt (mean difference (MD) -3.00; 95% CI -8.38 to 2.38) with horizontal positions or full lateral tilt with 15-degree tilt (RR 1.20; 95% CI 0.80 to 1.79). Hypotensive episodes were decreased with manual displacers (RR 0.11; 95% CI 0.03 to 0.45), a right lumbar wedge compared to a right pelvic wedge (RR 1.64; 95% CI 1.07 to 2.53) and increased in right lateral tilt (RR 3.30; 95% CI 1.20 to 9.08) versus left lateral tilt. Position did not affect systolic blood pressure when comparing left lateral tilt (MD 2.70; 95% CI -1.47 to 6.87) or head down tilt (RR 1.07; 95% CI 0.81 to 1.42) to horizontal positions, or full lateral tilt with 15-degree tilt (MD -5.00; 95% CI -11.45 to 1.45). Manual displacers showed decreased fall in mean systolic blood pressure compared to left lateral tilt (MD -8.80; 95% CI -13.08 to -4.52). Position did not affect diastolic blood pressures when comparing left lateral tilt versus horizontal positions. (MD-1.90; 95% CI -5.28 to 1.48). The mean diastolic pressure was lower in head down tilt (MD -7.00; 95% CI -12.05 to -1.95) when compared to horizontal positions. There were no statistically significant changes in maternal pulse rate, five-minute Apgars, maternal blood pH or cord blood pH when comparing different positions. Authors' conclusions There is limited evidence to support or clearly disprove the value of the use of tilting or flexing the table, the use of wedges and cushions or the use of mechanical displacers. Larger studies are needed.AFRIKAANSE OPSOMMING: Agtergrond: Tydens keisersnitte kan moeders in verskillende posisies wees. Teater tafels kan lateraal, opwaarts, afwaarts of gebuig word, of 'n wig en kussings kan gebruik word. Op die oomblik is daar geen konsensus oor die beste posisie nie. Doelwitte: Ons het alle beskikbare data oor die plasing van die moeder ondersoek, met die doel om 'n ideale posisie vir 'n verbeterde uitkoms tydens 'n keisersnit vas te stel. Metodes: Ons het die “Cochrane Pregnancy and Childbirth Group's Trials Register“ (September 2009), PubMed (1966 tot 14 September 2009) deursoek en die herwinde artikels se verwysings per hand nagegaan. Keuringskriteria: Gerandomiseerde proewe van vroue wat keisersnitte ondergaan het, is in verskillende posisies vergelyk. Data insameling en analise: Twee outeurs het die kwaliteit, die geskiktheid en data van die studie beoordeel. Resultate: Ons het 17 studies geidentifiseer wat 'n totaal van 683 vroue ingesluit het. Ons het nege studies ingesluit en agt uitgesluit. Die ingeslote studies was van wisselvallige gehalte en die monster groepe was klein. Die meeste vergelykings het data van enkele studies gegee. Dit is 'n tekortkoming en die bruikbaarheid van die resultate is beperk. Die plasing van kop-op teenoor horisontale posisie het die voorkomssyfer van lug embolisme nie geaffekteer nie.(risiko verhouding RR 0.91;95% 95% vertroue interval Cl 0.65 tot 1.26). Daar is geen hipotensiewe veranderinge gevind toe 'n vergelyking gemaak is tussen linker laterale kantel (RR 0.11; 95% Cl 0.01 tot 1.94) regter laterale kantel (RR 1.25; 95% Cl 0.39 tot 3.99) en kop-af kantel (“mean difference” MD -3.00; 95%Cl -8.38 tot 2.38) teenoor horisontale posisies of volle laterale kantel met 'n 15 grade kantel nie (RR 1.20;95% Cl 0.8. tot 1.79). Hipotensiewe episodes het verminder met hand verplasers (RR 0.11; 95% Cl 0.03 tot 0.45), 'n regter lumbale wig in vergelyking met 'n regter bekken wig (RR 1.64; 95% Cl 1.07 tot 2.53) en 'n vermeerdering van die regter laterale kantel (RR3.30; 95% Cl 1.20 tot 9.08) teenoor die linker laterale kantel. In die vergelyking tussen die posisie van linker laterale kantel (MD 2.70; 95% Cl -1.47 tot 6.87) of kop-af kantel (RR 1.07; 95% Cl 0.81 tot 1.42) teenoor horisontale posisies, of volle laterale kantel met 15 grade kantel (MD -5.00; 95% Cl -11.45 tot 1.45) het die posisie nie die sistoliese bloeddruk geaffekteer nie. Hand verplasers het 'n verminderde daling in gemiddelde sistoliese bloeddruk veroorsaak in vergelyking met linker laterale kantel plasing (MD -8.80;95% Cl-13.08 tot -4.52). In die vergelyking tussen linker laterale kantel en horisontale posisie was daar geen effek op die diastoliese bloeddruk nie (MD -1.90; 95% Cl -5.28 tot1.48). Die gemiddelde diastoliese druk was laer in die kop-af kantel (MD -7.00; 95% Cl -12.05 tot -1.95) in vergelyking met horisontale posisies. In die vergelyking tussen die verskillende posisies was daar geen betekenisvolle statistiese veranderinge in die moeder se polstempo, vyf minute Apgartellings, moederlike bloed pH of naelstringbloed pH nie. Outeur se gevolgtrekkings: Daar is beperkte getuienis om die waarde van kantel, buiging van tafel, die gebruik van wieë en kussings of die gebruik van maganiese verplasers te ondersteun of totaal te verwerp. Groter studies is nodig

Observations and modeling of the dust emission from the H_2-bright galaxy-wide shock in Stephan's Quintet

Context. Spitzer Space Telescope observations have detected powerful mid-infrared (mid-IR) H_2 rotational line emission from the X-ray emitting large-scale shock (~15 × 35 kpc^2) associated with a galaxy collision in Stephan's Quintet (SQ). Because H_2 forms on dust grains, the presence of H_2 is physically linked to the survival of dust, and we expect some dust emission to originate in the molecular gas. Aims. To test this interpretation, IR observations and dust modeling are used to identify and characterize the thermal dust emission from the shocked molecular gas. Methods. The spatial distribution of the IR emission allows us to isolate the faint PAH and dust continuum emission associated with the molecular gas in the SQ shock. We model the spectral energy distribution (SED) of this emission, and fit it to Spitzer observations. The radiation field is determined with GALEX UV, HST V-band, and ground-based near-IR observations. We consider two limiting cases for the structure of the H_2 gas: it is either diffuse and penetrated by UV radiation, or fragmented into clouds that are optically thick to UV. Results. Faint PAH and dust continuum emission are detected in the SQ shock, outside star-forming regions. The 12/24 μm flux ratio in the shock is remarkably close to that of the diffuse Galactic interstellar medium, leading to a Galactic PAH/VSG abundance ratio. However, the properties of the shock inferred from the PAH emission spectrum differ from those of the Galaxy, which may be indicative of an enhanced fraction of large and neutrals PAHs. In both models (diffuse or clumpy H_2 gas), the IR SED is consistent with the expected emission from dust associated with the warm (> 150 K) H_2 gas, heated by a UV radiation field of intensity comparable to that of the solar neighborhood. This is in agreement with GALEX UV observations that show that the intensity of the radiation field in the shock is GUV = 1.4±0.2 [Habing units]. Conclusions. The presence of PAHs and dust grains in the high-speed (~1000 km s^(-1)) galaxy collision suggests that dust survives. We propose that the dust that survived destruction was in pre-shock gas at densites higher than a few 0.1 cm^(-3), which was not shocked at velocities larger than ~200 km s^(-1). Our model assumes a Galactic dust-to-gas mass ratio and size distribution, and current data do not allow us to identify any significant deviations of the abundances and size distribution of dust grains from those of the Galaxy. Our model calculations show that far-IR Herschel observations will help in constraining the structure of the molecular gas, and the dust size distribution, and thereby to look for signatures of dust processing in the SQ shock

Kathryns Wheel: A spectacular galaxy collision discovered in the Galactic neighbourhood

We report the discovery of the closest collisional ring galaxy to the Milky Way. Such rare systems occur due to "bulls-eye" encounters between two reasonably matched galaxies. The recessional velocity of about 840 km/s is low enough that it was detected in the AAO/UKST Survey for Galactic H$\alpha$ emission. The distance is only 10.0 Mpc and the main galaxy shows a full ring of star forming knots, 6.1 kpc in diameter surrounding a quiescent disk. The smaller assumed "bullet" galaxy also shows vigorous star formation. The spectacular nature of the object had been overlooked because of its location in the Galactic plane and proximity to a bright star and even though it is the 60$^{\rm th}$ brightest galaxy in the HI Parkes All Sky Survey (HIPASS) HI survey. The overall system has a physical size of $\sim$15 kpc, a total mass of $M_\ast = 6.6\times 10^9$ M$_\odot$ (stars + HI), a metallicity of [O/H]$\sim-0.4$, and a star formation rate of 0.2-0.5 M$_\odot$\,yr$^{-1}$, making it a Magellanic-type system. Collisional ring galaxies therefore extend to much lower galaxy masses than commonly assumed. We derive a space density for such systems of $7 \times 10^{-5}\,\rm Mpc^{-3}$, an order of magnitude higher than previously estimated. This suggests Kathryn's Wheel is the nearest such system. We present discovery images, CTIO 4-m telescope narrow-band follow-up images and spectroscopy for selected emission components. Given its proximity and modest extinction along the line of sight, this spectacular system provides an ideal target for future high spatial resolution studies of such systems and for direct detection of its stellar populations.Comment: 18 pages, 12 figures, accepted for publication in MNRA