MUSE observations of a changing-look AGN I: The re-appearance of the broad emission lines

Optical changing-look Active Galactic Nuclei (AGN) are a class of sources that change type within a short timescale of years or decades. This change is characterised by the appearance or disappearance of broad emission lines, often associated with dramatic AGN continuum flux changes that are orders of magnitude larger than those expected from typical AGN variability. In this work we study for the first time the host galaxy of a changing-look AGN, Mrk 590, using high spatial resolution optical and near-infrared observations. We discover that after ~ 10 yr absence, the optical broad emission lines of Mrk 590 have reappeared. The AGN optical continuum flux however, is still ~ 10 times lower than that observed during the most luminous state in the 1990s. The host galaxy shows a 4.5 kpc radius star-forming ring with knots of ionised and cold molecular gas emission. Extended ionised and warm molecular gas emission are detected in the nucleus, indicating that there is a reservoir of gas as close as 60 pc from the black hole. We observe a nuclear gas spiral between radii r ~ 0.5 - 2 kpc, which has been suggested as a dynamical mechanism able to drive the necessary gas to fuel AGN. We also discover blue-shifted and high velocity dispersion [O III] emission out to a radius of 1 kpc, tracing a nuclear gas outflow. The gas dynamics in Mrk 590 suggest a complex balance between gas inflow and outflow in the nucleus of the galaxy.Comment: Accepted for publication in MNRA

Views from within a narrative : Evaluating long-term human-robot interaction in a naturalistic environment using open-ended scenarios

Open Access This article is distributed under the terms of the Creative Commons Attribution License which permits any use, distribution, and reproduction in any medium, provided the original author(s) and the source are credited. Date of acceptance: 16/06/2014This article describes the prototyping of human–robot interactions in the University of Hertfordshire (UH) Robot House. Twelve participants took part in a long-term study in which they interacted with robots in the UH Robot House once a week for a period of 10 weeks. A prototyping method using the narrative framing technique allowed participants to engage with the robots in episodic interactions that were framed using narrative to convey the impression of a continuous long-term interaction. The goal was to examine how participants responded to the scenarios and the robots as well as specific robot behaviours, such as agent migration and expressive behaviours. Evaluation of the robots and the scenarios were elicited using several measures, including the standardised System Usability Scale, an ad hoc Scenario Acceptance Scale, as well as single-item Likert scales, open-ended questionnaire items and a debriefing interview. Results suggest that participants felt that the use of this prototyping technique allowed them insight into the use of the robot, and that they accepted the use of the robot within the scenarioPeer reviewe

The presence of interstellar scintillation in the 15 GHz interday variability of 1158 OVRO-monitored blazars

We have conducted the first systematic search for interday variability in a large sample of extragalactic radio sources at 15 GHz. From the sample of 1158 radio-selected blazars monitored over an ∼10 yr span by the Owens Valley Radio Observatory 40-m telescope, we identified 20 sources exhibiting significant flux density variations on 4-d time-scales. The sky distribution of the variable sources is strongly dependent on the line-of-sight Galactic H α intensities from the Wisconsin H α Mapper Survey, demonstrating the contribution of interstellar scintillation (ISS) to their interday variability. 21 per cent of sources observed through sightlines with H α intensities larger than 10  rayleighs exhibit significant ISS persistent over the ∼10 yr period. The fraction of scintillators is potentially larger when considering less significant variables missed by our selection criteria, due to ISS intermittency. This study demonstrates that ISS is still important at 15 GHz, particularly through strongly scattered sightlines of the Galaxy. Of the 20 most significant variables, 11 are observed through the Orion–Eridanus superbubble, photoionized by hot stars of the Orion OB1 association. The high-energy neutrino source TXS 0506+056 is observed through this region, so ISS must be considered in any interpretation of its short-term radio variability. J0616−1041 appears to exhibit large ∼20 per cent interday flux density variations, comparable in magnitude to that of the very rare class of extreme, intrahour scintillators that includes PKS0405−385, J1819+3845, and PKS1257−326; this needs to be confirmed by higher cadence follow-up observations

WOOD PLASTIC COMPOSITES MADE FROM CORN HUSK FIBER AND RECYCLED POLYSTYRENE FOAM

This research is a preliminary study on the preparation of wood plastic composites (WPC) from corn husk fiber (CHF) and recycled polystyrene foam (rPS). The effects of fiber content and alkaline treatment on tensile, thermal, water absorption and morphological properties of the composites were investigated. The rPS/CHF composites were prepared using melt compounding and compression moulding processes. The results showed that an increase of fiber content increased the tensile strength, modulus, and thermal stability (Td50%) of composites. However, the water absorption of composites increased vastly as the fiber content increases. The addition of more fiber also caused an earlier thermal degradation to composites. Alkaline treatment has improved the tensile strength, modulus, thermal stability (Td10%), and also reduced water absorption of rPS/CHF composites. The WPS prepared from rPS and treated CHF shows better tensile and thermal properties with lower water absorption

Exposure to solar ultraviolet radiation establishes a novel immune suppressive lipidome in skin-draining lymph nodes

The ability of ultraviolet radiation to suppress the immune system is thought to be central to both its beneficial (protection from autoimmunity) and detrimental (carcinogenic) effects. Previous work revealed a key role for lipids particularly platelet-activating factor and sphingosine-1-phosphate in mediating UV-induced immune suppression. We therefore hypothesized that there may be other UV-induced lipids that have immune regulatory roles. To assess this, mice were exposed to an immune suppressive dose of solar-simulated UV (8 J/cm2). Lipidomic analysis identified 6 lipids (2 acylcarnitines, 2 neutral lipids, and 2 phospholipids) with significantly increased levels in the skin-draining lymph nodes of UV-irradiated mice. Imaging mass spectrometry of the lipids in combination with imaging mass cytometry identification of lymph node cell subsets indicated a preferential location of UV-induced lipids to T cell areas. In vitro co-culture of skin-draining lymph node lipids with lymphocytes showed that lipids derived from UV-exposed mice have no effect on T cell activation but significantly inhibited T cell proliferation, indicating that the lipids play an immune regulatory role. These studies are important first steps in identifying novel lipids that contribute to UV-mediated immune suppression

Removal of fluoride using quaternized palm kernel shell as adsorbents: Equilibrium isotherms and kinetics studies

Palm kernel shell (PKS) core fibers, an agricultural waste, were chemically modified using N-(3-chloro-2-hydroxypropyl) trimethylammonium chloride (CHMAC) as a quaternizing agent. The potential of quaternized palm kernel shell (QPKS) as an adsorbent for fluoride in an aqueous solution was then studied. The quaternized palm kernel shell (QPKS) core fibers were characterized using Fourier transform infrared spectroscopy (FTIR) and a scanning electron microscope (SEM). The effect of various factors on the fluoride sequestration was also investigated. The results showed that with an increase in the adsorbent amount and contact time, the efficiency of fluoride removal was improved. The maximum fluoride uptake was obtained at pH 3 and a contact time of 4 h. The adsorption behavior was further investigated using equilibrium isotherms and kinetics studies. The results from these studies fit well into Freundlich, Redlich-Peterson, and Sips isotherm's with a coefficient of determination (R2) of 0.9716. The maximum fluoride removal was 63%. For kinetics studies, the pseudo-second order was the best fit for fluoride, with an R2 of 0.999. These results suggest that QPKS has the potential to serve as a low-cost adsorbent for fluoride removal from aqueous solutions

A parsec-scale faint jet in the nearby changing-look Seyfert galaxy Mrk 590

Broad Balmer emission lines in active galactic nuclei (AGN) may display dramatic changes in amplitude, even disappearance and re-appearance in some sources. As a nearby galaxy at a redshift of z = 0.0264, Mrk 590 suffered such a cycle of Seyfert type changes between 2006 and 2017. Over the last fifty years, Mrk 590 also underwent a powerful continuum outburst and a slow fading from X-rays to radio wavelengths with a peak bolometric luminosity reaching about ten per cent of the Eddington luminosity. To track its past accretion and ejection activity, we performed very long baseline interferometry (VLBI) observations with the European VLBI Network (EVN) at 1.6 GHz in 2015. The EVN observations reveal a faint (~1.7 mJy) radio jet extending up to ~2.8 mas (projected scale ~1.4 pc) toward north, and probably resulting from the very intensive AGN activity. To date, such a parsec-scale jet is rarely seen in the known changing-look AGN. The finding of the faint jet provides further strong support for variable accretion as the origin of the type changes in Mrk 590.Comment: 5 pages, 1 figure, accepted for publication in MNRAS Letter

The Commensal Real-time ASKAP Fast Transients (CRAFT) survey

We are developing a purely commensal survey experiment for fast (<5s) transient radio sources. Short-timescale transients are associated with the most energetic and brightest single events in the Universe. Our objective is to cover the enormous volume of transients parameter space made available by ASKAP, with an unprecedented combination of sensitivity and field of view. Fast timescale transients open new vistas on the physics of high brightness temperature emission, extreme states of matter and the physics of strong gravitational fields. In addition, the detection of extragalactic objects affords us an entirely new and extremely sensitive probe on the huge reservoir of baryons present in the IGM. We outline here our approach to the considerable challenge involved in detecting fast transients, particularly the development of hardware fast enough to dedisperse and search the ASKAP data stream at or near real-time rates. Through CRAFT, ASKAP will provide the testbed of many of the key technologies and survey modes proposed for high time resolution science with the SKA.Comment: accepted for publication in PAS

Linear ubiquitin chain assembly complex coordinates late thymic T-cell differentiation and regulatory T-cell homeostasis.

The linear ubiquitin chain assembly complex (LUBAC) is essential for innate immunity in mice and humans, yet its role in adaptive immunity is unclear. Here we show that the LUBAC components HOIP, HOIL-1 and SHARPIN have essential roles in late thymocyte differentiation, FOXP3(+) regulatory T (Treg)-cell development and Treg cell homeostasis. LUBAC activity is not required to prevent TNF-induced apoptosis or necroptosis but is necessary for the transcriptional programme of the penultimate stage of thymocyte differentiation. Treg cell-specific ablation of HOIP causes severe Treg cell deficiency and lethal immune pathology, revealing an ongoing requirement of LUBAC activity for Treg cell homeostasis. These data reveal stage-specific requirements for LUBAC in coordinating the signals required for T-cell differentiation