Parsec-scale dust distributions in Seyfert galaxies - Results of the MIDI AGN snapshot survey

The emission of warm dust dominates the mid-infrared spectra of active galactic nuclei (AGN). Only interferometric observations provide the necessary angular resolution to resolve the nuclear dust and to study its distribution and properties. The investigation of dust in AGN cores is hence one of the main science goals for the MID-infrared Interferometric instrument MIDI at the VLTI. As the first step, the feasibility of AGN observations was verified and the most promising sources for detailed studies were identified. This was carried out in a "snapshot survey" with MIDI using Guaranteed Time Observations. In the survey, observations were attempted for 13 of the brightest AGN in the mid-infrared which are visible from Paranal. The results of the three brightest, best studied sources have been published in separate papers. Here we present the interferometric observations for the remaining 10, fainter AGN. For 8 of these, interferometric measurements could be carried out. Size estimates or limits on the spatial extent of the AGN-heated dust were derived from the interferometric data of 7 AGN. These indicate that the dust distributions are compact, with sizes on the order of a few parsec. The derived sizes roughly scale with the square root of the luminosity in the mid-infrared, s ~ sqrt(L), with no clear distinction between type 1 and type 2 objects. This is in agreement with a model of nearly optically thick dust structures heated to T ~ 300 K. For three sources, the 10 micron feature due to silicates is tentatively detected either in emission or in absorption. Based on the results for all AGN studied with MIDI so far, we conclude that in the mid-infrared the differences between individual galactic nuclei are greater than the generic differences between type 1 and type 2 objects.Comment: 18 pages, 8 figures, updated to version published in A&A 502, 67-8

The Ursinus Weekly, October 28, 1940

Senator J. A. Ellender holds Willkie temperamentally unfit for president • Importance of \u27but\u27 told by vespers talk • Connor calls news staff to plan for Jr. paper • Republican rally to hear Davis tomorrow evening • Rev. Mr. Faye \u2724, to speak on problems of college students • Prof. Mauchly gives lecture at conference of physicists • Hoosier prophet ventures vote prognostication • Get a mask for Friday! • Results of Berlin-Tokyo axis discussed in IRC panel talks • Meistersingers to sing at Collegeville-Trappe assembly • Minutes before, Huey and I were talking... • Campaigning with Yehudi! • Mules\u27 offensive attack swamps bears by 15-6 • Allison leads \u27Fords against bakermen, 3-0 • Rootin\u27 tootin\u27 bout slated, Nov. 5, Sam\u27s arena • Ursinus hockeyites blank Rosemont • Baker is optimistic on soccer future • English Club admits seven; discusses books for review • Joyce Ward reports plans of women\u27s archery practice • \u27Big sisters\u27 treat freshmen and co-ed transfers at movie • Pre-legals fingerprinted; hear of scientific detectionhttps://digitalcommons.ursinus.edu/weekly/1796/thumbnail.jp

Operationally meaningful representations of physical systems in neural networks

To make progress in science, we often build abstract representations of physical systems that meaningfully encode information about the systems. The representations learnt by most current machine learning techniques reflect statistical structure present in the training data; however, these methods do not allow us to specify explicit and operationally meaningful requirements on the representation. Here, we present a neural network architecture based on the notion that agents dealing with different aspects of a physical system should be able to communicate relevant information as efficiently as possible to one another. This produces representations that separate different parameters which are useful for making statements about the physical system in different experimental settings. We present examples involving both classical and quantum physics. For instance, our architecture finds a compact representation of an arbitrary two-qubit system that separates local parameters from parameters describing quantum correlations. We further show that this method can be combined with reinforcement learning to enable representation learning within interactive scenarios where agents need to explore experimental settings to identify relevant variables.Comment: 24 pages, 13 figure

Emergency revascularization in patients with cardiogenic shock on admission: a report from the SHOCK trial and registry

Aims To determine clinical correlates and optimal treatment strategy in patients with cardiogenic shock (CS) on admission. Methods and results In SHould we emergently revascularize Occluded Coronaries in cardiogenic shocK? (SHOCK) trial and registry patients with left ventricular (LV) dysfunction (n=1053), CS on admission occurred in 26% of directly admitted patients (n=166/627). Time from myocardial infarction to CS was shorter, initial haemodynamic profile poorer, and aggressive treatment less frequent in CS on admission than in delayed CS patients. CS on admission patients constituted a smaller relative proportion (11%) of the transferred (n=48/426) when compared with the directly admitted cohort (P<0.001). In-hospital mortality was higher (75 vs. 56%; P<0.001) with more rapid death (24-h mortality 40 vs. 17%; P<0.001) in CS on admission than in delayed CS patients. Emergency revascularization reduced in-hospital mortality in CS on admission (60 vs. 82%; P=0.001) and in delayed CS patients similarly (46 vs. 62%; P<0.001; interaction P=0.25). After adjustment for clinical differences, CS on admission was an independent predictor of in-hospital mortality (P=0.008). Conclusion CS on admission patients have a worse outcome but benefit equally from emergency revascularization as delayed CS patients, emphasizing the need for rapid and direct access of CS on admission patients to facilities providing this car

Ammonia (J,K) = (1,1) to (4,4) and (6,6) inversion lines detected in the Seyfert 2 galaxy NGC 1068

We present the detection of the ammonia (NH3) (J,K) = (1,1) to (4,4) and (6,6) inversion lines toward the prototypical Seyfert 2 galaxy NGC 1068, made with the Green Bank Telescope (GBT). This is the first detection of ammonia in a Seyfert galaxy. The ortho-to-para-NH3 abundance ratio suggests that the molecule was formed in a warm medium of at least 20 K. For the NH3 column density and fractional abundance, we find (1.09\pm0.23)\times10^14 cm^-2 and (2.9\pm0.6)\times10^-8, respectively, from the inner 1.2 kpc of NGC 1068. The kinetic temperature can be constrained to 80\pm20 K for the bulk of the molecular gas, while some fraction has an even higher temperature of 140\pm30 K.Comment: 5 pages, 3 figures, accepted by A&

Resolving the complex structure of the dust torus in the active nucleus of the Circinus galaxy

To test the dust torus model for active galactic nuclei directly, we study the extent and morphology of the nuclear dust distribution in the Circinus galaxy using high resolution interferometric observations in the mid-infrared with the MIDI instrument at the Very Large Telescope Interferometer. We find that the dust distribution in the nucleus of Circinus can be explained by two components, a dense and warm disk-like component of 0.4 pc size and a slightly cooler, geometrically thick torus component with a size of 2.0 pc. The disk component is oriented perpendicular to the ionisation cone and outflow and seems to show the silicate feature at 10 micron in emission. It coincides with a nuclear maser disk in orientation and size. From the energy needed to heat the dust, we infer a luminosity of the accretion disk corresponding to 20% of the Eddington luminosity of the nuclear black hole. We find that the interferometric data are inconsistent with a simple, smooth and axisymmetric dust emission. The irregular behaviour of the visibilities and the shallow decrease of the dust temperature with radius provide strong evidence for a clumpy or filamentary dust structure. We see no evidence for dust reprocessing, as the silicate absorption profile is consistent with that of standard galactic dust. We argue that the collimation of the ionising radiation must originate in the geometrically thick torus component. Our findings confirm the presence of a geometrically thick, torus-like dust distribution in the nucleus of Circinus, as required in unified schemes of Seyfert galaxies. Several aspects of our data require that this torus is irregular, or "clumpy".Comment: 20 pages, 16 figures, accepted for publication by A&

Gas dynamics of the central few parsec region of NGC 1068 fuelled by the evolving nuclear star cluster

High resolution observations with the NIR adaptive optics integral field spectrograph SINFONI at the VLT proved the existence of massive and young nuclear star clusters in the centres of a sample of Seyfert galaxies. With the help of three-dimensional high resolution hydrodynamical simulations with the Pluto code, we follow the evolution of such clusters, focusing on stellar mass loss. This leads to clumpy or filamentary inflow of gas on large scales (tens of parsec), whereas a turbulent and very dense disc builds up on the parsec scale. In order to capture the relevant physics in the inner region, we treat this disc separately by viscously evolving the radial surface density distribution. This enables us to link the tens of parsec scale region (accessible via SINFONI observations) to the (sub-)parsec scale region (observable with the MIDI instrument and via water maser emission). In this work, we concentrate on the effects of a parametrised turbulent viscosity to generate angular momentum and mass transfer in the disc and additionally take star formation into account. Input parameters are constrained by observations of the nearby Seyfert 2 galaxy NGC 1068. At the current age of its nuclear starburst of 250 Myr, our simulations yield disc sizes of the order of 0.8 to 0.9 pc, gas masses of 1.0e6 solar masses and mass transfer rates of 0.025 solar masses per year through the inner rim of the disc. This shows that our large scale torus model is able to approximately account for the disc size as inferred from interferometric observations in the mid-infrared and compares well to the extent and mass of a rotating disc structure as inferred from water maser observations. Several other observational constraints are discussed as well.Comment: 13 pages, 11 figures, accepted for publication in MNRAS, updated author list and reference

Associations between double-checking and medication administration errors: A direct observational study of paediatric inpatients

Background Double-checking the administration of medications has been standard practice in paediatric hospitals around the world for decades. While the practice is widespread, evidence of its effectiveness in reducing errors or harm is scarce. Objectives To measure the association between double-checking, and the occurrence and potential severity of medication administration errors (MAEs); check duration; and factors associated with double-checking adherence. Methods Direct observational study of 298 nurses, administering 5140 medication doses to 1523 patients, across nine wards, in a paediatric hospital. Independent observers recorded details of administrations and double-checking (independent; primed-one nurse shares information which may influence the checking nurse; incomplete; or none) in real time during weekdays and weekends between 07:00 and 22:00. Observational medication data were compared with patients' medical records by a reviewer (blinded to checking-status), to identify MAEs. MAEs were rated for potential severity. Observations included administrations where double-checking was mandated, or optional. Multivariable regression examined the association between double-checking, MAEs and potential severity; and factors associated with policy adherence. Results For 3563 administrations double-checking was mandated. Of these, 36 (1·0%) received independent double-checks, 3296 (92·5%) primed and 231 (6·5%) no/incomplete double-checks. For 1577 administrations double-checking was not mandatory, but in 26·3% (n=416) nurses chose to double-check. Where double-checking was mandated there was no significant association between double-checking and MAEs (OR 0·89 (0·65-1·21); p=0·44), or potential MAE severity (OR 0·86 (0·65-1·15); p=0·31). Where double-checking was not mandated, but performed, MAEs were less likely to occur (OR 0·71 (0·54-0·95); p=0·02) and had lower potential severity (OR 0·75 (0·57-0·99); p=0·04). Each double-check took an average of 6·4 min (107 hours/1000 administrations). Conclusions Compliance with mandated double-checking was very high, but rarely independent. Primed double-checking was highly prevalent but compared with single-checking conferred no benefit in terms of reduced errors or severity. Our findings raise questions about if, when and how double-checking policies deliver safety benefits and warrant the considerable resource investments required in modern clinical settings