Design and Development of the Clementine Spacecraft Sensor Bench

The Clementine spacecraft was developed to demonstrate the performance of BMDO\u27s lightweight sensor suite. The suite consisted of five different sensors (Star Trackers, UV/Vis, HiRes, NIR, LWIR) and a UDAR (Laser Impulse Detection And Ranging) system. The worst-case sensor operating requirements for the Clementine mission were: interface temperature with -20 to 2° C, alignment to +/- 100µRad, and jitter kept below 40 Rad in 40msec. The average hear dissipation of the suite was over 100 Watts while operating for two of the five hour lunar orbit. To accomplish the mission the sensor suite was integrated onto a single-substrate sensor bench within the spacecraft. The bench met the stringent thermal, alignment, and jitter requirements of the sensors, and concurrently isolated the sensors from outside spacecraft contamination, as well as thermal and structural flexure. Also taken into account were the mission design drivers of hot thermal environment in lunar orbit, limited volume in the spacecraft, minimal weight, limited budget, and a six month schedule from concept to delivery of a flight bench. The design and development of the sensor bench will be discussed. Three different types of heat pipes were used to transport the heat of the sensors to radiators located on the side of the spacecraft. A beryllium metal block was used as a thermal capacitor during peak heat loads. Thermal straps connected sensors to heat pipes to keep thermal gradients as little as 3° C per inch across the interface. The bench was fastened in a quasi-kinematic fashion to eliminate the transfer of spacecraft structural loads and thermal flexing, and yet was rigid enough to keep alignment through launch. The bench substrate itself was made out of aluminum honeycomb. The alignment mechanism consisted of a nut-on-nut method to attain and keep the 100µRad requirement. Volume and alignment constraints dictated sensor location on the bench. Development of the bench involved rigorous testing to insure requirements were met. These tests involved development alignment checks, vibration testing at the sensor bench level, system level qual vibes and TDVT, system level jitter testing, as well as the flight system vibe, TV AC and functional. Lessons learned will be discussed

Mutant Tau knock-in mice display frontotemporal dementia relevant behaviour and histopathology

Peer reviewedPostprin

Investigating the evolution of the dual AGN system ESO~509-IG066

We analyze the evolution of the dual AGN in ESO 509-IG066, a galaxy pair located at z=0.034 whose nuclei are separated by 11 kpc. Previous observations with XMM-Newton on this dual AGN found evidence for two moderately obscured ($N_H\sim10^{22}$ cm$^{-2}$) X-ray luminous ($L_X\sim10^{43}$ erg/s) nuclear sources. We present an analysis of subsequent Chandra, NuSTAR and Swift/XRT observations that show one source has dropped in flux by a factor of 10 between 2004 and 2011, which could be explained by either an increase in the absorbing column or an intrinsic fading of the central engine possibly due to a decrease in mass accretion. Both of these scenarios are predicted by galaxy merger simulations. The source which has dropped in flux is not detected by NuSTAR, which argues against absorption, unless it is extreme. However, new Keck/LRIS optical spectroscopy reveals a previously unreported broad H-alpha line which is highly unlikely to be visible under the extreme absorption scenario. We therefore conclude that the black hole in this nucleus has undergone a dramatic drop in accretion rate. From AO-assisted near-infrared integral-field spectroscopy of the other nucleus, we find evidence that the galaxy merger is having a direct effect on the kinematics of the gas close to the nucleus of the galaxy, providing a direct observational link between the galaxy merger and the mass accretion rate on to the black hole.Comment: Accepted for publication in Ap

Broadband X-ray spectral analysis of the Seyfert 1 galaxy GRS 1734-292

We discuss the broadband X-ray spectrum of GRS 1734-292 obtained from non-simultaneous XMM-Newton and NuSTAR observations, performed in 2009 and 2014, respectively. GRS1734-292 is a Seyfert 1 galaxy, located near the Galactic plane at $z=0.0214$. The NuSTAR spectrum ($3-80$ keV) is dominated by a primary power-law continuum with $\Gamma=1.65 \pm 0.05$ and a high-energy cutoff $E_c=53^{+11}_{-8}$ keV, one of the lowest measured by NuSTAR in a Seyfert galaxy. Comptonization models show a temperature of the coronal plasma of $kT_e=11.9^{+1.2}_{-0.9}$ keV and an optical depth, assuming a slab geometry, $\tau=2.98^{+0.16}_{-0.19}$ or a similar temperature and $\tau=6.7^{+0.3}_{-0.4}$ assuming a spherical geometry. The 2009 XMM-Newton spectrum is well described by a flatter intrinsic continuum ($\Gamma=1.47^{+0.07}_{-0.03}$) and one absorption line due to Fe\textsc{XXV} K$\alpha$ produced by a warm absorber. Both data sets show a modest iron K$\alpha$ emission line at $6.4$ keV and the associated Compton reflection, due to reprocessing from neutral circumnuclear material

A Hard Look at NGC 5347: Revealing a Nearby Compton-thick AGN

Current measurements show that the observed fraction of Compton-thick (CT) active galactic nuclei (AGN) is smaller than the expected values needed to explain the cosmic X-ray background. Prior fits to the X-ray spectrum of the nearby Seyfert-2 galaxy NGC 5347 (z = 0.00792, D = 35.5 Mpc ) have alternately suggested a CT and Compton-thin source. Combining archival data from Suzaku, Chandra, and—most importantly—new data from NuSTAR, ... See full text for complete abstrac

X-ray bolometric corrections for Compton-thick active galactic nuclei

We present X-ray bolometric correction factors, $\kappa_{Bol}$ ($\equiv L_{Bol}/L_X$), for Compton-thick (CT) active galactic nuclei (AGN) with the aim of testing AGN torus models, probing orientation effects, and estimating the bolometric output of the most obscured AGN. We adopt bolometric luminosities, $L_{Bol}$, from literature infrared (IR) torus modeling and compile published intrinsic 2--10 keV X-ray luminosities, $L_{X}$, from X-ray torus modeling of NuSTAR data. Our sample consists of 10 local CT AGN where both of these estimates are available. We test for systematic differences in $\kappa_{Bol}$ values produced when using two widely used IR torus models and two widely used X-ray torus models, finding consistency within the uncertainties. We find that the mean $\kappa_{Bol}$ of our sample in the range $L_{Bol}\approx10^{42}-10^{45}$ erg/s is log$_{10}\kappa_{Bol}=1.44\pm0.12$ with an intrinsic scatter of $\sim0.2$ dex, and that our derived $\kappa_{Bol}$ values are consistent with previously established relationships between $\kappa_{Bol}$ and $L_{Bol}$ and $\kappa_{Bol}$ and Eddington ratio. We investigate if $\kappa_{Bol}$ is dependent on $N_H$ by comparing our results on CT AGN to published results on less-obscured AGN, finding no significant dependence. Since many of our sample are megamaser AGN, known to be viewed edge-on, and furthermore under the assumptions of AGN unification whereby unobscured AGN are viewed face-on, our result implies that the X-ray emitting corona is not strongly anisotropic. Finally, we present $\kappa_{Bol}$ values for CT AGN identified in X-ray surveys as a function of their observed $L_X$, where an estimate of their intrinsic $L_{X}$ is not available, and redshift, useful for estimating the bolometric output of the most obscured AGN across cosmic time.Comment: Accepted for publication in Ap

On the relation of optical obscuration and X-ray absorption in Seyfert galaxies

The optical classification of a Seyfert galaxy and whether it is considered X-ray absorbed are often used interchangeably. But there are many borderline cases and also numerous examples where the optical and X-ray classifications appear to be in conflict. In this article we re-visit the relation between optical obscuration and X-ray absorption in AGNs. We make use of our "dust color" method (Burtscher et al. 2015) to derive the optical obscuration A_V and consistently estimated X-ray absorbing columns using 0.3--150 keV spectral energy distributions. We also take into account the variable nature of the neutral gas column N_H and derive the Seyfert sub-classes of all our objects in a consistent way. We show in a sample of 25 local, hard-X-ray detected Seyfert galaxies (log L_X / (erg/s) ~ 41.5 - 43.5) that there can actually be a good agreement between optical and X-ray classification. If Seyfert types 1.8 and 1.9 are considered unobscured, the threshold between X-ray unabsorbed and absorbed should be chosen at a column N_H = 10^22.3 / cm^2 to be consistent with the optical classification. We find that N_H is related to A_V and that the N_H/A_V ratio is approximately Galactic or higher in all sources, as indicated previously. But in several objects we also see that deviations from the Galactic ratio are only due to a variable X-ray column, showing that (1) deviations from the Galactic N_H/A_V can simply be explained by dust-free neutral gas within the broad line region in some sources, that (2) the dust properties in AGNs can be similar to Galactic dust and that (3) the dust color method is a robust way to estimate the optical extinction towards the sublimation radius in all but the most obscured AGNs.Comment: 7 pages, 3 figures, accepted for publication by A&A; updated PDF to include abstrac

Surgical smoke: modern mobile smoke evacuation systems improve occupational safety in the operating theatre.

OBJECTIVES Evaluation of smoke capture efficiency of different mobile smoke evacuation devices with respect to volatile organic compounds and their noise emission. METHODS Electrosurgical incisions were performed on fresh porcine liver in an operating room with vertical laminar flow. The generated surgical smoke was analysed with proton-transfer-reaction mass spectrometry with and without the use of a mobile smoke evacuation system consisting of a smoke evacuator machine, a suction hose and a handpiece. The inlet of the mass spectrometer was positioned 40 cm above the specimen. Various devices were compared: a hard plastic funnel, a flexible foam funnel, an on-tip integrated aspirator of an electrosurgical knife and a standard secretion suction (Yankauer). Also, sound levels were measured at a distance of 40 cm from the handpieces' inlet. RESULTS The smoke capture efficiency of the secretion suction was only 53%, while foam funnel, plastic funnel and integrated aspirator were all significantly more effective with a clearance of 95%, 91% and 91%, respectively. The mean sound levels were 68 and 59 A-weighted decibels with the plastic and foam funnel, respectively, 66 A-weighted decibels with the integrated aspirator and 63 A-weighted decibels with the secretion suction. CONCLUSIONS Carcinogenic, mutagenic and reprotoxic volatile organic compounds in surgical smoke can be efficiently reduced by mobile smoke evacuation system, providing improved protection for medical personnel. Devices specifically designed for smoke evacuation are more efficient than standard suction tools. Noise exposure for the surgeon was lowest with the flexible foam funnel and higher with the other handpieces tested