Eddington limited starbursts in the central 10pc of AGN, and the Torus in NGC1068

We present results from a survey of nearby AGN using the near infrared adaptive optics integral field spectrograph SINFONI. These data enable us to probe the distribution and kinematics of the gas and stars at spatial resolutions as small as 0.085arcsec. We find strong evidence for recent but short lived starbursts residing in very dense nuclear disks. On scales of less than 10pc these would have reached Eddington-limited luminosities when active, perhaps accounting for their short duration. In addition, for NGC1068 at a resolution of 6pc, we present direct observations of molecular gas close around the AGN which we identify with the obscuring torus.Comment: Conference proceedings to appear in "The Central Engine of Active Galactic Nuclei", ed. L. C. Ho and J.-M. Wang (San Francisco: ASP

Contextualising teaching. Teaching practice developed by expert teacher educators

This article examines the way a group of expert teachers\u2019 educators contextualises their teaching. To this end, a qualitative phenomenological approach was employed to collect and analyse data from 30 expert teachers\u2019 educators. Grounded theory was used to conceptualise and categorise evidences emerged from the analysis of texts while stories of practices were created for each category emerged for illustration. In general, three teaching strategies emerged as means of contextualising teaching: connecting teaching to authentic experiences, aligning practices in teacher education to secondary school teaching and contextualising teaching to students\u2019 level of understanding. Lastly, the lesson each university could draw from one another and implications of the study are highlighted

The Molecular Gas in the Circumnuclear Region of Seyfert Galaxies

Sub-arcsecond IRAM Plateau de Bure mm-interferometric observations of the 12CO (2-1) line emission in the Seyfert~1 NGC 3227 and the Seyfert~2 NGC 1068 have revealed complex kinematic systems in the inner 100 pc to 300 pc that are not consistent with pure circular motion in the host galaxies. Modeling of these kinematic systems with elliptical orbits in the plane of the host galaxy (representing gas motion in a bar potential) is a possible solution but does not reproduce all features observed. A better description of the complex kinematics is achieved by circular orbits which are tilted out of the plane of the host galaxy. This could indicate that the thin circumnuclear gas disk is warped. In the case of NGC 1068 the warp model suggests that at a radius of about 70 pc, the gas disk is oriented edge-on providing material for the obscuration of the AGN nucleus. The position-velocity diagrams show rising rotation curves at r 2 x 10^7 M_solar for NGC 3227 and > 10^8 M_solar for NGC 1068 within the central 25 pc.Comment: 14 pages, Ap.J. letter, accepte

Dense Molecular Gas and the Role of Star Formation in the Host Galaxies of Quasi-Stellar Objects

New millimeter-wave CO and HCN observations of the host galaxies of infrared-excess Palomar Green quasi-stellar objects (PG QSOs) previously detected in CO are presented. These observations are designed to assess the validity of using the infrared luminosity to estimate star formation rates of luminous AGN by determining the relative significance of dust-heating by young, massive stars and active galactic nuclei (AGN) in QSO hosts and IRAS galaxies with warm, AGN-like infrared colors. The HCN data show the PG QSO host IZw1 and most of the warm IRAS galaxies to have high L_IR / L'_HCN (>1600) relative to the cool IRAS galaxy population for which the median L_IR / L'_HCN ~ 890(+440,-470). If the assumption is made that the infrared emission from cool IRAS galaxies is reprocessed light from embedded star-forming regions, then high values of L_IR / L'_HCN are likely the result of dust heating by the AGN. Further, if the median ratio of L'_HCN / L'_CO ~ 0.06 observed for Seyfert galaxies and IZw1 is applied to the PG QSOs not detected in HCN, then the derived L_IR / L'_HCN correspond to a stellar contribution to the production of L_IR of ~ 7-39%, and star formation rates ~ 2-37 M_sun/yr are derived for the QSO hosts. Alternatively, if the far-infrared is adopted as the star formation component of the total infrared in cool galaxies, the stellar contributions in QSO hosts to their L_FIR are up to 35% higher than the percentages derived for L_IR. This raises the possibility that the L_FIR in several of the PG QSO hosts, including IZw1, could be due entirely to dust heated by young, massive stars. Finally, there is no evidence that the global HCN emission is enhanced relative to CO in galaxies hosting luminous AGN.Comment: LaTex, 31 pages, including 9 postscript figures, AJ, in press (December 2006

Modelling the Molecular Gas in NGC 6240

We present the first observations of H$^{13}$CN$(1-0)$, H$^{13}$CO$^+(1-0)$ and SiO$(2-1)$ in NGC\,6240, obtained with the IRAM PdBI. Combining a Markov Chain Monte Carlo (MCMC) code with Large Velocity Gradient (LVG) modelling, and with additional data from the literature, we simultaneously fit three gas phases and six molecular species to constrain the physical condition of the molecular gas, including mass$-$luminosity conversion factors. We find $\sim10^{10}M_\odot$ of dense molecular gas in cold, dense clouds ($T_{\rm k}\sim10$\,K, $n_{{\rm H}_2}\sim10^6$\,cm$^{-3}$) with a volume filling factor $<0.002$, embedded in a shock heated molecular medium ($T_{\rm k}\sim2000$\,K, $n_{{\rm H}_2}\sim10^{3.6}$\,cm$^{-3}$), both surrounded by an extended diffuse phase ($T_{\rm k}\sim200$\,K, $n_{{\rm H}_2}\sim10^{2.5}$\,cm$^{-3}$). We derive a global $\alpha_{\rm CO}=1.5^{7.1}_{1.1}$ with gas masses $\log_{10}\left(M / [M_\odot]\right)=10.1_{10.0}^{10.8}$, dominated by the dense gas. We also find $\alpha_{\rm HCN} = 32^{89}_{13}$, which traces the cold, dense gas. The [$^{12}$C]/[$^{13}$C] ratio is only slightly elevated ($98^{230}_{65}$), contrary to the very high [CO]/[$^{13}$CO] ratio (300-500) reported in the literature. However, we find very high [HCN]/[H$^{13}$CN] and [HCO$^+$]/[H$^{13}$CO$^+$] abundance ratios $(300^{500}_{200})$ which we attribute to isotope fractionation in the cold, dense clouds.Comment: 27 pages, 17 figures, 9 tables. Accepted in Ap

Talc pleurodesis for malignant pleural effusion: efficacy and factors predicting recurrence

Objectives: To identify potential factors predicting recurrence after talc pleurodesis for malignant pleural effusion. Methods: Retrospective study of two cohorts of consecutive patients undergoing surgery for malignant pleural effusion (T VATS/talc pleurodesis number of procedures n = 41, IPC VATS/indwelling pleural catheter n = 41). Data analysed: ASA, performance status, underlying histology, amount of effusion drained at initial procedure, morbidity, recurrence of effusion (RecEff), redo surgery due to recurrence. The definition of RecEff was based on imaging (at least CxR) and related report issued by a senior radiologist. Median radiological follow-up of both groups was identical (8 months). Statistical analysis was done through SPSS ver 21. Results: The RecEff rate was 20% in the IPC group and 32% in the T group. Fifty percent (4/8) of patients with failed pleurodesis in the IPC group required redo surgery compared to 92% (12/13) in the T group, which was significant. Median time to recurrence in the IPC group was 9 months, in the T group 4 months. In the T group the only relevant factor associated with recurrence was lung cancer histology (P = 0.055). The statistical significance of ASA score >2 (P = 0.042) and performance status 2 (P = 0.019) in this context is difficult to interpret. There were no significant differences between cohorts in age (69.5 years [60-78.2]), gender (41 males and 41 females), ASA (3 [2-3]), performance status (1 [1-2]), millilitres of effusion drained (1600 [1000-2550]), site of primary (mesothelioma 32% of patients, lung Ca 21%) and morbidity (7%). Conclusions: The recurrence rate after talc pleurodesis was notably higher compared to the IPC group in our study and a significant number of patients affected required redo surgery. Lung cancer histology was the only clinically relevant predictor of recurrence in the talc group, potentially favouring the choice of a primary IPC insertion for these patients rather than chemical pleurodesis