Evidence for a Circumnuclear Disk in 1946+708

A number of extragalactic radio sources which exhibit symmetric jets on parsec scales have now been found to have neutral hydrogen absorption at or near the systemic velocities of their host galaxies. Understanding the spatial distribution and kinematics of the HI detected toward the central parsecs of these sources provides an important test of unified schemes for AGN. We present results of Global VLBI Network observations of the redshifted 21 cm HI line toward the Compact Symmetric Object 1946+708 (z=0.101). We find significant structure in the gas on parsec scales. The peak column density of the HI (N_HI~3x10^23 cm^-2(Ts/8000K)) occurs near the center of activity of the source, as does the highest velocity dispersion (FWHM 350 to 400 km/s). There is also good evidence for a torus of ionized gas with column density 7x10^22 cm^-2}. The jets in 1946+708 exhibit bi-directional motion measurable on timescales of a few years. The resulting unique information about the geometry of the continuum source greatly assists in the interpretation of the gas distribution, which is strongly suggestive of a circumnuclear torus of neutral atomic and ionized material with one or more additional compact clumps of gas along the line of sight to the approaching jet.Comment: 13 pages, 2 b/w figures, 2 color figures, figure quality degraded in the interests of space. To appear in ApJ Letter

‘I’m my own boss…’: Active intermediation and ‘entrepreneurial’ worker agency in the Australian gig-economy

Platform firm in the gig-economy are disrupting work as a social practice, production systems and recasting capital-labour relations. This qualitative study examines worker agency in the Australian food-delivery sector; a segment where platforms actively intermediate both product and labour markets. Within this sector, worker agency poses a potential challenge to platform-organisations; however this study reveals how these platforms’ work organisation and market regulation constrain agency potential. Shaped by the work’s spatio-temporal features, organisational fixes and institutional context, it is shown how food-delivery workers, transiently attached to the labour market, predominantly engage in ‘entrepreneurial agency’ – a low-level agency expression aimed at materially improving individual conditions and aligning with, rather than challenging, platforms’ business models

Consensus report from the 6th International forum for liver MRI using gadoxetic acid

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/108276/1/jmri24419.pd

Interferometric 890 mu m images of high-redshift submillimeter galaxies

We present high-resolution 890 μm images of two 20 mJy submillimeter galaxies, SMM J123711+622212 and MIPS J142824.0+352619, obtained using the Submillimeter Array (SMA). Using submillimeter interferometric observations with an angular resolution of 25, the coordinates of these high-redshift sources are determined with an accuracy of 02. The new SMA data on SMM J123711+622212 reveal an unresolved submillimeter source offset to the east by 08 from an optical galaxy found in deep HST images, suggesting either a large galaxy with a dusty central region or an interacting galaxy system. The SMA image of hyperluminous (LFIR = 3.2 × 1013 L) source MIPS J142824.0+352619 provides a firm upper limit to the source size of 12. This constraint provides evidence that the foreground lens is only weakly affecting the observed high far-infrared luminosity

AMI observations of unmatched Planck ERCSC LFI sources at 15.75 GHz

The Planck Early Release Compact Source Catalogue includes 26 sources with no obvious matches in other radio catalogues (of primarily extragalactic sources). Here we present observations made with the Arcminute Microkelvin Imager Small Array (AMI SA) at 15.75 GHz of the eight of the unmatched sources at declination > +10 degrees. Of the eight, four are detected and are associated with known objects. The other four are not detected with the AMI SA, and are thought to be spurious.Comment: 6 pages, 5 figures, 4 table

Are young radio sources in equipartition?

The knowledge of physical conditions in young radio sources is important for defining the framework of models describing radio source evolution. We investigate whether young radio sources are in equipartition (i.e. minimum energy) conditions by comparing the equipartition magnetic fields of 5 High Frequency Peakers (HFP) with values directly inferred from the spectral peak assumed to be produced by synchrotron self absorption. Multi-frequency VLBA observations of 5 HFPs were carried out in both the optically thick and thin part of the spectrum to determine the spectral shape and angular size of the components for which individual radio spectra were obtained. We find that the magnetic fields measured using observations agree well with those obtained by assuming equipartition, which implies that these sources are in minimum energy condition and the turnover in their spectra is due probably to SSA. In two source components, we found that the peak of the spectrum is caused by absorption of a thermal plasma instead of being due to SSA. The magnetic fields found in the various components range from 10 to 100 mG. In the presence of such high magnetic fields, electron populations with rather low $\gamma$ emit in the GHz-regime. In one source, we detect low-surface brightness extended emission at low frequency located ~30 mas (~50 pc) from the main source. This feature may be related to either an earlier episode of radio activity or a discontinuous start of the radio activity (sputtering). By comparing our data with previous VLBA observations, we estimate the hotspot advance speed to be in the range 0.1-0.7c and kinematic ages of a few hundred years.Comment: 12 pages, 7 figures; accepted for publication in A&

Activation of the heat shock transcription factor Hsf1 is essential for the full virulence of the fungal pathogen Candida albicans

Peer reviewedPublisher PD

Thiosquaramides: pH switchable anion transporters

The transport of anions across cellular membranes is an important biological function governed by specialised proteins. In recent years, many small molecules have emerged that mimick the anion transport behaviour of these proteins, but only a few of these synthetic molecules also display the gating/switching behaviour seen in biological systems. A small series of thiosquar-amides was synthesised and their pH-dependent chloride binding and anion transport behaviour was investigated using 1H NMR titrations, single crystal X-ray diffraction and a variety of vesicle-based techniques. Spectrophotometric titrations and DFT calculations revealed that the thiosquaramides are significantly more acidic than their oxosquaramide analogues, with pKa values between 4.0 and 9.0. This led to the observation that at pH 7.2 the anion transport ability of the thiosquaramides is fully switched OFF due to deprotonation of the receptor, but is completely switched ON at lower pH