Dissecting the active galactic nucleus in Circinus -- I. Peculiar mid-IR morphology explained by a dusty hollow cone

Recent high angular resolution observations resolved for the first time the mid-infrared (MIR) structure of nearby active galactic nuclei (AGN). Surprisingly, they revealed that a major fraction of their MIR emission comes from the polar regions. This is at odds with the expectation based on AGN unification, which postulates a dusty torus in the equatorial region. The nearby, archetypical AGN in the Circinus galaxy offers one of the best opportunities to study the MIR emission in greater detail. New, high quality MIR images obtained with the upgraded VISIR instrument at the Very Large Telescope show that the previously detected bar-like structure extends up to at least 40 pc on both sides of the nucleus along the edges of the ionization cone. Motivated by observations across a wide wavelength range and on different spatial scales, we propose a phenomenological dust emission model for the AGN in the Circinus galaxy consisting of a compact dusty disk and a large-scale dusty cone shell, illuminated by a tilted accretion disk with an anisotropic emission pattern. Undertaking detailed radiative transfer simulations, we demonstrate that such a model is able to explain the peculiar MIR morphology and account for the entire IR spectral energy distribution. Our results call for caution when attributing dust emission of unresolved sources entirely to the torus and warrant further investigation of the MIR emission in the polar regions of AGN.Comment: Accepted to MNRAS. Version 2: typos correcte

Dissecting the active galactic nucleus in Circinus -- II. A thin dusty disc and a polar outflow on parsec scales

Recent observations which resolved the mid-infrared (MIR) emission of nearby active galactic nuclei (AGN), surprisingly revealed that their dust emission appears prominently extended in the polar direction, at odds with the expectations from the canonical dusty torus. This polar dust, tentatively associated with dusty winds driven by radiation pressure, is found to have a major contribution to the MIR flux from scales of a few to hundreds of parsecs. When facing a potential change of paradigm, case studies of objects with the best intrinsic resolution are essential. One such source with a clear detection of polar dust is a nearby, well-known AGN in the Circinus galaxy. In the first paper, we successfully explained the peculiar MIR morphology of Circinus observed on large, tens of parsec scales with a model consisting of a compact dusty disc and an extended hollow dusty cone. In this work, we further refine the model on smaller, parsecs scales to test whether it can also explain the MIR interferometric data. We find that a model composed of a thin dusty disc seen almost edge-on and a polar outflow in the form of a hyperboloid shell can reproduce well the VLTI/MIDI observations at all wavelengths, baselines and position angles. In contrast, while providing a good fit to the integrated MIR spectrum, the dusty torus model fails to reproduce the spatially resolved interferometric data. We put forth the disc$+$hyperboloid wind model of Circinus AGN as a prototype for the dust structure in the AGN population with polar dust.Comment: MNRAS accepte

The 20 GHz solid state transmitter design, impatt diode development and reliability assessment

A single drift gallium arsenide (GaAs) Schottky barrier IMPATT diode and related components were developed. The IMPATT diode reliability was assessed. A proof of concept solid state transmitter design and a technology assessment study were performed. The transmitter design utilizes technology which, upon implementation, will demonstrate readiness for development of a POC model within the 1982 time frame and will provide an information base for flight hardware capable of deployment in a 1985 to 1990 demonstrational 30/20 GHz satellite communication system. Life test data for Schottky barrier GaAs diodes and grown junction GaAs diodes are described. The results demonstrate the viability of GaAs IMPATTs as high performance, reliable RF power sources which, based on the recommendation made herein, will surpass device reliability requirements consistent with a ten year spaceborne solid state power amplifier mission

NGC 1068: No change in the mid-IR torus structure despite X-ray variability

Context. Recent NuSTAR observations revealed a somewhat unexpected increase in the X-ray flux of the nucleus of NGC 1068. We expect the infrared emission of the dusty torus to react on the intrinsic changes of the accretion disk. Aims. We aim to investigate the origin of the X-ray variation by investigating the response of the mid-infrared environment. Methods. We obtained single-aperture and interferometric mid-infrared measurements and directly compared the measurements observed before and immediately after the X-ray variations. The average correlated and single-aperture fluxes as well as the differential phases were directly compared to detect a possible change in the structure of the nuclear emission on scales of $\sim$ 2 pc. Results. The flux densities and differential phases of the observations before and during the X-ray variation show no significant change over a period of ten years. Possible minor variations in the infrared emission are $\lesssim$ 8 %. Conclusions. Our results suggest that the mid-infrared environment of NGC 1068 has remained unchanged for a decade. The recent transient change in the X-rays did not cause a significant variation in the infrared emission. This independent study supports previous conclusions that stated that the X-ray variation detected by NuSTAR observations is due to X-ray emission piercing through a patchy section of the dusty region.Comment: 6 pages, 5 figures, 3 tables. Accepted for publication on A&

Changing the Paradigm for Pesticide Resistance Management

Collaborative action on the part of all stakeholders in pest management is essential to effectively address the challenges of pesticide resistance. The US Environmental Protection Agency, through its Pesticide Program Dialogue Committee, recently posted a report on pesticide resistance management and the role the Agency can play in these efforts. In this perspectives piece, we commend the Agency for acknowledging these needs, and encourage implementation of the recommendations. We urge all stakeholders to follow the example set by EPA to engage openly, listen to other stakeholders, and determine their role as part of the broader community that is needed to address the challenges of resistance. Our contention is that pesticide resistance will continue to escalate until all stakeholders evaluate their roles in resistance management and work together as a community to influence effective management

Geological Evolution of the Brazilian Continental Margin

This article reviews the major findings of an intensive geological and geophysical study of the Brazilian margin and adjacent oceanic and continental areas. Most of the data fits well with standard plate models for Atlantic-type margins, with clearly recognizeable pre-rift, rift, proto-oceanic and oceanic stages. However there are significant problems regarding the nature of the crust beneath the margin and the position of the boundary between oceanic and continental crust

Detection of fractures of hand and forearm in whole-body CT for suspected polytrauma in intubated patients

Background: The aim of this study was to evaluate the potential of whole-body CT for diagnosis of hand and forearm fractures in intubated patients with suspected polytrauma. Methods: We performed a retrospective analysis on data collected from two trauma centres in Germany, including demographics, ISS, clinical symptoms, depiction in whole-body CT, and time to diagnosis. Results: Out of 426 patients included in the study, 66 (15.5%) suffered a hand or forearm fracture. The total number of fractures was 132, the whole-body CT report mentioned 98 (74.2%). 16 (12,1%) fractures of 12 patients were diagnosed later than 24 h after admission. Late diagnoses of fractures of the hand occurred more often if the hand was not fully included in the CT scan field. The sensitivity of whole-body CT for cases with fractures of hand and/or forearm with full inclusion of the corresponding area in the scan field was 80.2%. Conclusions: This study shows that whole-body CT is a valuable diagnostic tool for hand fractures in polytrauma patients. Hands should be evaluated regardless of clinical presentation in intubated patients after suspected polytrauma if they are included in the whole-body CT. © 2020 The Author(s)