Constraints on hot metals in the Vicinity of the Galaxy

We have searched for evidence of soft X-ray absorption by hot metals in the vicinity of the Galaxy in the spectra of a small sample of fifteen Type I AGN observed with the high resolution X-ray gratings on board Chandra. This is an extension of our previous survey of hot OVII and OVIII absorbing gas in the vicinity of the Galaxy. The strongest absorption signatures within a few hundred km/s of their rest-frame energies are most likely due to warm absorbing outflows from the nearest AGN, which are back-lighting the local hot gas. We emphasize that absorption signatures in the spectra of some distant AGN that are kinematically consistent with the recessional velocity of the AGN are most likely to be due to hot local gas. Along the sightline towards PG 1211+143, PDS 456 and MCG-6-30-15 there is a very large absorbing Fe column density which is kinematically consistent with absorption by hot, local Fe. The sightlines to these three AGN pass through the limb of the Northern Polar Spur (NPS), a local bubble formed from several supernovae which, if rich in Fe, may account for a large local Fe column. We obtain limits on the column density of local, highly ionized N, Ne, Mg, Si along all of the sightlines in our sample. We correlate the column density limits with those of highly ionized O along the same sightlines. Assuming the hot local gas is in collisionally ionized equilibrium, we obtain limits on the temperature and relative abundances of the metals in the hot local gas. Our limits on the ionic column densities in the local hot gas seem to be consistent with those observed in the hot halo gas of edge-on normal spiral galaxies.Comment: 9 pages,2 figures, MNRAS (accepted

Black Hole Mass, Host galaxy classification and AGN activity

We investigate the role of host galaxy classification and black hole mass in a heterogeneous sample of 276 mostly nearby (z<0.1) X-ray and IR selected AGN. Around 90% of Seyfert 1 AGN in bulge-dominated host galaxies (without disk contamination) span a very narrow range in the observed 12um to 2-10keV luminosity ratio (1<R_{IR/X}<7). This narrow dispersion incorporates all possible variations among AGN central engines, including accretion mechanism and efficiency, disk opening angle, orientation to sightline, covering fraction of absorbing material, patchiness of X-ray corona and measured variability. As a result, all models of X-ray and IR production in AGN are very strongly constrained. Among Seyfert 1 AGN, median X-ray and IR luminosities increase with black hole mass at >99% confidence. Using ring morphology of the host galaxy as a proxy for lack of tidal interaction, we find that AGN luminosity in host galaxies within 70Mpc is independent of host galaxy interaction for $\sim$ Gyrs, suggesting that the timescale of AGN activity due to secular evolution is much shorter than that due to tidal interactions. We find that LINER hosts have lower 12um luminosity than the median 12um luminosity of normal disk- and bulge-dominated galaxies which may represent observational evidence for past epochs of feedback that supressed star formation in LINER host galaxies. We propose that nuclear ULXs may account for the X-ray emission from LINER 2s without flat-spectrum, compact radio cores. We confirmed the robustness of our results in X-rays by comparing them with the 14-195keV 22-month BAT survey of AGN, which is all-sky and unbiased by photoelectric absorption.Comment: MNRAS accepted. 14 pages, 11 figures, complete Table 1 in online journa

Spin injection from perpendicular magnetized ferromagnetic δ\delta-MnGa into (Al,Ga)As heterostructures

Electrical spin injection from ferromagnetic $\delta$-MnGa into an (Al,Ga)As p-i-n light emitting diode (LED) is demonstrated. The $\delta$-MnGa layers show strong perpendicular magnetocrystalline anisotropy, enabling detection of spin injection at remanence without an applied magnetic field. The bias and temperature dependence of the spin injection are found to be qualitatively similar to Fe-based spin LED devices. A Hanle effect is observed and demonstrates complete depolarization of spins in the semiconductor in a transverse magnetic field.Comment: 4 pages, 3 figure

Fabrication of lanthanide-doped glasses and their possible application as UV detectors

This work describes the preparation of lanthanide-doped glasses and examines the performance potential of these glasses as UV detectors. All presently available UV detection systems are extremely expensive and most are unstable to some degree. A number of the lanthanides fluoresce within the spectral response region of commercial photomultiplier tubes and glass is a suitable material for use in vacuum systems. Rare earth ions are readily incorporated into a glass matrix and the manufacturing costs of such detectors could be comparatively low. The lanthanides were prepared in two types of glass matrices i.e. borate and silicate systems.The borate is of interest as the composition used has not been reported in the available literature.The silicate matrix used is a well established commercial composition. The prepared glasses were characterised using a range of techniques including X-ray diffraction,infrared spectroscopy,absorbance and luminescence measurements. Measurements on the glasses in the UV region 200-300nm were made using a normal incidence monochromator and a deuterium lamp source. Studies were undertaken of the comparative responses from the doped glasses and other detector systems.In particular, comparison was made with sodium salicylate-a phosphor commonly used in XUV/VUV detection systems- as well as with plastic scintillators. Glass absorbs strongly in the UV and the possibility of energy transfer from the host glasses to the dopant ions is discussed. The 4f electron behaviour of the lanthanides is cited with the view to explaining the effects observed. Further possible developments of the project are discussed

Evaluation of an inflammation-based prognostic score in patients with inoperable gastro-oesophageal cancer

There is increasing evidence that the presence of an ongoing systemic inflammatory response is associated with poor outcome in patients with advanced cancer. The aim of the present study was to examine whether an inflammation-based prognostic score (Glasgow Prognostic score, GPS) was associated with survival, in patients with inoperable gastro-oesophageal cancer. Patients diagnosed with inoperable gastro-oesophageal carcinoma and who had measurement of albumin and C-reactive protein concentrations, at the time of diagnosis, were studied (n=258). Clinical information was obtained from a gastro-oesophageal cancer database and analysis of the case notes. Patients with both an elevated C-reactive protein (>10 mg l−1) and hypoalbuminaemia (<35 g l−1) were allocated a GPS score of 2. Patients in whom only one of these biochemical abnormalities was present were allocated a GPS score of 1, and patients with a normal C-reactive protein and albumin were allocated a score of 0. On multivariate survival analysis, age (hazard ratio (HR) 1.22, 95% CI 1.02–1.46, P<0.05), stage (HR 1.55, 95% CI 1.30–1.83, P<0.001), the GPS (HR 1.51, 95% CI 1.22–1.86, P<0.001) and treatment (HR 2.53, 95% CI 1.80–3.56, P<0.001) were significant independent predictors of cancer survival. A 12-month cancer-specific survival in patients with stage I/II disease receiving active treatment was 67 and 60% for a GPS of 0 and 1, respectively. For stage III/IV disease, 12 months cancer-specific survival was 57, 25 and 12% for a GPS of 0, 1 and 2, respectively. In the present study, the GPS predicted cancer-specific survival, independent of stage and treatment received, in patients with inoperable gastro-oesophageal cancer. Moreover, the GPS may be used in combination with conventional staging techniques to improve the prediction of survival in patients with inoperable gastro-oesophageal cancer

Frying Doughnuts: What can the reprocessing of X-rays to IR tell us about the AGN environment?

Active galactic nuclei (AGN) produce vast amounts of high energy radiation deep in their central engines. X-rays either escape the AGN or are absorbed and re-emitted mostly as IR. By studying the dispersion in the ratio of observed mid-IR luminosity to observed 2-10keV X-ray luminosity (R_{ir/x}) in AGN we can investigate the reprocessing material (possibly a torus or donut of dust) in the AGN central engine, independent of model assumptions. We studied the ratio of observed mid-IR and 2-10keV X-ray luminosities in a heterogeneous sample of 245 AGN from the literature. We found that when we removed AGN with prominent jets, ~90% of Type I AGN lay within a very tight dispersion in luminosity ratio (1<R_{ir/x}<30). This implies that the AGN central engine is extremely uniform and models of the physical AGN environment (e.g. cloud cover, turbulent disk, opening angle of absorbing structures such as dusty tori) must span a very narrow range of parameters. We also found that the far-IR(100um) to mid-IR (12um) observed luminosity ratio is an effective descriminator between heavily obscured AGN and relatively unobscured AGN.Comment: 12 pages, MNRAS accepte

Occultation Mapping of the Central Engine in the Active Galaxy MCG -6-30-15

The colossal power output of active galactic nuclei (AGN) is believed to be fueled by the accretion of matter onto a supermassive black hole. This central accreting region of AGN has hitherto been spatially unresolved and its structure therefore unknown. Here we propose that a previously reported `deep minimum' in the X-ray intensity of the AGN MCG-6-30-15, was due to a unique X-ray occultation event and that it probes structure of the central engine on scales < 1e14 cm, or 1.4e-7 arcseconds. The data are consistent with a bright central source surrounded by a less intense ring, which we identify with the inner edge of an accretion disk. These may be the first direct measurements of the spatial structure and geometry of the accreting black-hole system in an active galaxy.If the ring of X-ray emission is identified with the inner edge of an accretion disk, upper limits on the BH mass can be derived. Our occultation interpretation is controversial in the sense that X-ray variability in AGNs is normally attributed to intrinsic physical changes in the X-ray emission region, such as disk or coronal instabilities.Comment: 15 pages, 2 Figures. Latex with separate postscript figure files. Accepted for publication in ApJ Letter

Application of Active Learning Strategies for Online Delivery in an Occupational Therapy Assistant Program

The COVID-19 pandemic had a significant impact worldwide in every aspect of society including occupational therapy assistant students enrolled in academic coursework. This manuscript examines the unique experience of occupational therapy assistant faculty in a northeast state who were able to quickly modify classroom and lab teaching-learning strategies to a fully online virtual format for two semesters. Since no available information on strategies for online delivery of occupational therapy assistant education were found in the literature, their experiences implementing active learning strategies are described and discussed. Strategies covered include: the flipped classroom model; think-pair-share and jigsaw technique using breakout rooms; polling and student response systems; muddiest point via chat box; lab kits; one-minute paper using discussion forums; and student-generated videos. Twenty students provided feedback through a survey about the helpfulness of each strategy. The breakout room and chat box feature of the synchronous virtual classroom as well as lab kits were perceived as most helpful, whereas student-generated videos and one-minute papers were perceived as least helpful. Implications for continued incorporation of online learning in occupational therapy assistant curricula are outlined

O VII and O VIII absorption by hot gas in the vicinity of the Galaxy

(abridged) We searched for evidence of soft X-ray absorption by hot gas in the vicinity of the Galaxy in a small sample of fifteen type I AGN observed with the high resolution X-ray gratings on board Chandra. We find that around half of the sight lines in our sample exhibit absorption due to local H- or He-like Oxygen (or both) at confidence levels ranging from >90% to >3sigma. Depending on the sight line, the absorption can be identified with hot gas in particular local structures, the Local Group (LG) or the putative local hot intergalactic medium (IGM). Several sight lines in our sample coincide with sight lines in a study of O VI absorption by local gas, so an assumption of collisional ionization equilibrium (CIE) allows us to constrain the temperature of the local hot gas. We show that some portion of the hot absorbing outflows apparently detected in the spectra of NGC 4051, PDS 456 and PG 1211+143 respectively could actually correspond to absorption by hot local gas since the outflow velocity from each of these AGN coincides with the respective cosmological recession velocity of the AGN.Comment: 8 pages. Modified discussion of Fe-K band absorption features in PDS 456 and PG 1211+14