Star Formation in Southern Seyfert Galaxies

We have produced radio maps, using the ATCA, of the central regions of six southern Seyfert 2 galaxies (NGC 1365, 4945, 6221, 6810, 7582, and Circinus) with circumnuclear star formation, to estimate the relative contribution of star formation activity compared to activity from the active galactic nucleus (AGN). The radio morphologies range from extended diffuse structures to compact nuclear emission, with no evidence, even in the relatively compact sources, for synchrotron self--absorption. In each case the radio to far--infrared (FIR) ratio has a value consistent with star formation, and in all but one case the radio to [FeII] ratio is also consistent with star formation. We derive supernova rates and conclude that, despite the presence of a Seyfert nucleus in these galaxies, the radio, FIR, and [FeII] line emission are dominated by processes associated with the circumnuclear star formation (i.e. supernova remnants and HII regions) rather than with the AGN.Comment: 26 pages, Latex, 13 figures, submitted to MNRA

Cold gas and star formation in a merging galaxy sequence

We explore the evolution of the cold gas and star-formation activity during galaxy interactions, using a merging galaxy sequence comprising both pre- and post-mergers. Data for this study come from the literature but supplemented by new radio observations presented here. Firstly, we confirm that the star-formation efficiency (SFE) increases close to nuclear coalescence. At post-merger stages there is evidence that the SFE declines to values typical of ellipticals. This trend can be attributed to M(H_2) depletion due to interaction induced star-formation. However, there is significant scatter, likely to arise from differences in the interaction details of individual systems. Secondly, we find that the central molecular hydrogen surface density, increases close to the final stages of the merging of the two nuclei. Such a trend is also predicted by numerical simulations. Furthermore, there is evidence for a decreasing fraction of cold gas mass from early interacting systems to merger remnants, attributed to gas conversion into other forms. The evolution of the total-radio to blue-band luminosity ratio, reflecting the disk+nucleus star-formation activity, is also investigated. Although this ratio is on average higher than that of isolated spirals, we find a marginal increase along the merging sequence, attributed to the relative insensitivity of disk star-formation to interactions. However, a similar result is also obtained for the nuclear radio emission, although galaxy interactions are believed to significantly affect the activity in the central galaxy regions. Finally, we find that the FIR--radio flux ratio distribution of interacting galaxies is consistent with star-formation being the main energising source.Comment: 18 pages, 17 figures, accepted for publication in MNRA

Radio Observations of Super Star Clusters in Dwarf Starburst Galaxies

We present new radio continuum observations of two dwarf starburst galaxies, NGC3125 and NGC5408, with observations at 4.80GHz (6cm) and 8.64GHz (3cm), taken with the Australia Telescope Compact Array (ATCA). Both galaxies show a complex radio morphology with several emission regions, mostly coincident with massive young star clusters. The radio spectral indices of these regions are negative (with alpha ~ -0.5 - -0.7), indicating that the radio emission is dominated by synchrotron emission associated with supernova activity from the starburst. One emission region in NGC5408 has a flatter index (alpha ~ -0.1) indicative of optically thin free-free emission, which could indicate it is a younger cluster. Consequently, in these galaxies we do not see regions with the characteristic positive spectral index indicative of optically obscured star-formation regions, as seen in other dwarf starbursts such as Hen 2-10.Comment: Accepted for publication in MNRA

Musculoskeletal Sarcoidosis and Rheumatoid Factor

Articular manifestations of sarcoidosis were present in 19 of our 60 patients (32%). This correlates with previously reported studies. In all of our cases but one, the articular manifestations subsided in eight weeks. This fact and the absence of hyperuricemia are in contradistinction to other studies for which we have no adequate explanation

The 4d one component lattice ϕ4\phi^4 model in the broken phase revisited

Measurements of various physical quantities in the symmetry broken phase of the one component lattice $\phi^4_4$ with standard action, are shown to be consistent with the critical behavior obtained by renormalization group analyses. This is in contrast to recent conclusions by another group, who further claim that the unconventional scaling behavior they observe, when extended to the complete Higgs sector of the Standard Model, would alter the conventional triviality bound on the mass of the Higgs.Comment: 15 pages, 3 figure

Defining Meyer's loop-temporal lobe resections, visual field deficits and diffusion tensor tractography

Anterior temporal lobe resection is often complicated by superior quadrantic visual field deficits (VFDs). In some cases this can be severe enough to prohibit driving, even if a patient is free of seizures. These deficits are caused by damage to Meyer's loop of the optic radiation, which shows considerable heterogeneity in its anterior extent. This structure cannot be distinguished using clinical magnetic resonance imaging sequences. Diffusion tensor tractography is an advanced magnetic resonance imaging technique that enables the parcellation of white matter. Using seed voxels antero-lateral to the lateral geniculate nucleus, we applied this technique to 20 control subjects, and 21 postoperative patients. All patients had visual fields assessed with Goldmann perimetry at least three months after surgery. We measured the distance from the tip of Meyer's loop to the temporal pole and horn in all subjects. In addition, we measured the size of temporal lobe resection using postoperative T1-weighted images, and quantified VFDs. Nine patients suffered VFDs ranging from 22% to 87% of the contralateral superior quadrant. In patients, the range of distance from the tip of Meyer's loop to the temporal pole was 24–43 mm (mean 34 mm), and the range of distance from the tip of Meyer's loop to the temporal horn was –15 to +9 mm (mean 0 mm). In controls the range of distance from the tip of Meyer's loop to the temporal pole was 24–47 mm (mean 35 mm), and the range of distance from the tip of Meyer's loop to the temporal horn was –11 to +9 mm (mean 0 mm). Both quantitative and qualitative results were in accord with recent dissections of cadaveric brains, and analysis of postoperative VFDs and resection volumes. By applying a linear regression analysis we showed that both distance from the tip of Meyer's loop to the temporal pole and the size of resection were significant predictors of the postoperative VFDs. We conclude that there is considerable variation in the anterior extent of Meyer's loop. In view of this, diffusion tensor tractography of the optic radiation is a potentially useful method to assess an individual patient's risk of postoperative VFDs following anterior temporal lobe resection

Bostonia: The Boston University Alumni Magazine. Volume 20

Founded in 1900, Bostonia magazine is Boston University's main alumni publication, which covers alumni and student life, as well as university activities, events, and programs