59 research outputs found
The Far-infrared Continuum of Quasars
ISO provides a key new far-infrared window through which to observe the
multi-wavelength spectral energy distributions (SEDs) of quasars and active
galactic nuclei (AGN). It allows us, for the first time, to observe a
substantial fraction of the quasar population in the far-IR, and to obtain
simultaneous, multi-wavelength observations from 5--200 microns. With these
data we can study the behavior of the IR continuum in comparison with
expectations from competing thermal and non-thermal models. A key to
determining which mechanism dominates, is the measurement of the peak
wavelength of the emission and the shape of the far-IR--mm turnover. Turnovers
which are steeper than frequency^2.5 indicate thermal dust emission in the
far-IR.
Preliminary results from our ISO data show broad, fairly smooth, IR continuum
emission with far-IR turnovers generally too steep to be explained by
non-thermal synchrotron emission. Assuming thermal emission throughout leads to
a wide inferred temperature range of 50-1000 K. The hotter material, often
called the AGN component, probably originates in dust close to and heated by
the central source, e.g. the ubiquitous molecular torus. The cooler emission is
too strong to be due purely to cool, host galaxy dust, and so indicates either
the presence of a starburst in addition to the AGN or AGN-heated dust covering
a wider range of temperatures than present in the standard, optically thick
torus models.Comment: 4 pages, to be published in the proceedings of "The Universe as Seen
by ISO," ed. M. Kessler. This and related papers can be found at
http://hea-www.harvard.edu/~ehooper/ISOkp/ISOkp.htm
Astro2010: State of the Profession Position Paper: The Value of Observatory-Class Missions
The dramatic success of NASAâs astrophysics science program over the past 20 years has resulted from a series of assets in space ranging from Small Explorers to Observatory-Class
missions. NASAâs Observatory-Class missions, such as the Chandra X-ray Observatory (CXO), the Hubble Space Telescope (HST), and the Spitzer Space Telescope (SST), form the
cornerstone of this program by providing all researchers, regardless of institutional affiliation, a spectrum of science opportunities across programs large and small. These observatories stand out in their breadth of capabilities and consequent diversity of high impact science, their reach within the scientific community, and their proven ability to inspire the nation. Each mission was
designed to address specific scientific imperatives recognized by past Decadal Survey Committees, whether it was to refine the extragalactic distance scale, examine galaxies as they were in the distant past, determine the relationship between black holes and quasars, observe the
ultimate fate of stars in their death throes, or reveal heavily obscured regions of star-formation. These were ambitious goals, as are those envisioned for future Observatory-Class missions, such as the James Webb Space Telescope (JWST)
Healthcare provider experiences of deploying a continuous remote patient monitoring pilot program during the COVID-19 pandemic: a structured qualitative analysis
ObjectiveTo describe the healthcare provider (HCP) experience of launching a COVID-19 remote patient monitoring (CRPM) program during the global COVID-19 pandemic.MethodsWe conducted qualitative, semi-structured interviews with eight HCPs involved in deploying the CRPM pilot program in the Military Health System (MHS) from June to December 2020. Interviews were thematically audio recorded, transcribed, and analyzed using an inductive approach. We then deductively mapped themes from interviews to the updated Consolidated Framework for Implementation Research (CFIR).ResultsWe identified the following main themes mapped to CFIR domains listed in parentheses: external and internal environments (outer and inner settings), processes around implementation (implementation process domain), the right people (individuals domain), and program characteristics (innovation domain). Participants believed that buy-in from leadership and HCPs was critical for successful program implementation. HCP participants showed qualities of clinical champions and believed in the CRPM program.ConclusionThe MHS deployed a successful remote patient monitoring pilot program during the global COVID-19 pandemic. HCPs found the CRPM program and the technology enabling the program to be acceptable, feasible, and usable. HCP participants exhibited characteristics of clinical champions. Leadership engagement was the most often-cited key factor for successful program implementation
The hard X-ray view of bright infrared galaxies
Aims. The synthesis of the cosmic X-ray background (CXB) requires a large
population of Compton-thick active galactic nuclei that have not been detected
so far. We probe whether bright infrared galaxies could harbor a population of
Compton-thick nuclei and if they could contribute significantly. Methods. We
analyzed 112 Msec of INTEGRAL observations obtained on 613 galaxies from the
IRAS Revised Bright Galaxy Sample. We derived the average hard X-ray (18-80
keV) emission of Seyfert and various non Seyfert galaxy subsamples to estimate
their relative contribution to the locally emitted CXB. Results. The Seyfert 1
& 2 are detected at hard X-rays. None of the other galaxy subsamples were
detected. ULIRGs are at least 5 times under-luminous at hard X-rays when
compared to Seyferts. The upper limit obtained for the average non Seyfert
galaxies is as low as 7E-13 erg/s cm2. On average, these galaxies do not
contain active nuclei brighter than 10E41 erg/s at hard X-rays. The total hard
X-ray flux detected from the sample is 4.9E-9 erg/s cm2 (about 1% of the CXB),
and 64% of this originates in absorbed active nuclei. Local non-Seyfert
galaxies contribute for less than 7% and do not harbor the Compton-thick nuclei
assumed to synthesize the locally emitted CXB.Comment: 6 pages, accepted for publication in Astronomy & Astropohysic
Infrared Properties of High Redshift and X-ray Selected AGN Samples
The NASA/ISO Key Project on active galactic nuclei (AGN) seeks to better
understand the broad-band spectral energy distributions (SEDs) of these sources
from radio to X-rays, with particular emphasis on infrared properties. The ISO
sample includes a wide variety of AGN types and spans a large redshift range.
Two subsamples are considered herein: 8 high-redshift (1 < z < 4.7) quasars;
and 22 hard X-ray selected sources.
The X-ray selected AGN show a wide range of IR continuum shapes, extending to
cooler colors than the optical/radio sample of Elvis et al. (1994). Where a
far-IR turnover is clearly observed, the slopes are < 2.5 in all but one case
so that non-thermal emission remains a possibility. The highest redshift
quasars show extremely strong, hot IR continua requiring ~ 100 solar masses of
500 - 1000 Kelvin dust with ~ 100 times weaker optical emission. Possible
explanations for these unusual properties include: reflection of the optical
light from material above/below a torus; strong obscuration of the optical
continuum; or an intrinsic deficit of optical emission.Comment: 8 pages, 3 figures (2 color), to be published in the Springer Lecture
Notes of Physics Series as part of the proceedings for "ISO Surveys of a
Dusty Universe," a workshop held at Ringberg Castle, Germany, November 8 -
12, 1999. Requires latex style files for this series: cl2emult.cls,
cropmark.sty, lnp.sty, sprmindx.sty, subeqnar.sty (included with submission
Camera traps and genetic identification of faecal samples for detection and monitoring of an Endangered ungulate.
Almost all Indochinese ungulates are classified as globally threatened but efforts to assess and monitor population status have been hampered by their rarity, cryptic nature and uncertainty in accurate identification from sightings. An improved approach is urgently needed to gather information about threatened ungulate species in order to effectively conserve them as, a lack of reliable monitoring methods means that basic information such as population sizes, distribution and habitat associations is currently unknown. Here, we used a combination of camera trapping and genetic detection of the Endangered Eldâs deer, Rucervus eldii, to investigate the utility of these methods to infer intensity of site use within a protected Cambodian dry forest. We asked: 1) Are Eld's deer present in our study area?; 2) How is site use influenced by local habitat?; and 3) Do camera traps or genetic detection perform better in terms of detection and monitoring? Camera traps were deployed and faecal samples collected from Chhaeb Wildlife Sanctuary in Northern Cambodia during the 2017 dry season. Faecal samples were identified as Eldâs deer using newly developed species-specific mitochondrial DNA primers. Camera traps recorded 20 Eldâs deer observations across 3905 trap-nights and 44 out of 71 collected faecal samples, identified by fieldworkers as likely to belong to Eldâs deer, were positively identified to be so. Camera trap surveys and genetic detection demonstrated that Eldâs deer were present in Chhaeb Wildlife Sanctuary, although the number of detections relative to sampling effort was low in both methods (detected at 29% and 1% of sample sites, respectively). Occupancy models showed that water level and tree diameter both had positive relationships, whilst human and domestic or feral pig activity had a negative relationship, with the relative intensity of Eldâs deer site use. Overall, our data suggest that both of our methods can prove effective for monitoring Eldâs deer but that repeated sampling is necessary to account for their low detectability in this area. We suggest that faecal samples are collected during future camera trap monitoring visits to maximise efficiency, increase detectability, and provide the most information to support conservation
Physiological deterioration in the Emergency Department: the SNAP40-ED study
Continuous novel ambulatory monitoring may detect deterioration in Emergency Department (ED) patients more rapidly, prompting treatment and preventing adverse events. Single-centre, open-label, prospective, observational cohort study recruiting high/medium acuity (Manchester triage category 2 and 3) participants, aged over 16 years, presenting to ED. Participants were fitted with a novel wearable monitoring device alongside standard clinical care (wired monitoring and/or manual clinical staff vital sign recording) and observed for up to 4 hours in the ED. Primary outcome was time to detection of deterioration. Two-hundred and fifty (250) patients were enrolled. In 82 patients (32.8%) with standard monitoring (wired monitoring and/or manual clinical staff vital sign recording), deterioration in at least one vital sign was noted during their four-hour ED stay. Overall, the novel device detected deterioration a median of 34 minutes earlier than wired monitoring (Q1, Q3 67,194; n=73, mean difference 39.48, p<0.0001). The novel device detected deterioration a median of 24 minutes (Q1, Q3 2,43; n=42) earlier than wired monitoring and 65 minutes (Q1, Q3 28,114; n=31) earlier than manual vital signs. Deterioration in physiology was common in ED patients. ED staff spent a significant amount of time performing observations and responding to alarms, with many not escalated. The novel device detected deterioration significantly earlier than standard care
ASCA observations of two steep soft X-ray quasars
Steep soft X-ray (0.1-2 keV) quasars share several unusual properties: narrow
Balmer lines, strong FeII emission, large and fast X-ray variability, rather
steep 2-10 keV spectrum. These intriguing objects have been suggested to be the
analogs of Galactic black hole candidates in the high, soft state. We present
here results from ASCA observations for two of these quasars: NAB0205+024 and
PG1244+026. Both objects show similar variations (factor of about 2 in 10 ks),
despite a factor of about ten difference in the 0.5-10 keV luminosity (7.3E43
erg/s for PG1244+026 and 6.4E44 erg/s for NAB0205+024, assuming isotropic
emission, H_0 = 50.0 and q_0 = 0.0). The X-ray continuum of the two quasars
flattens by 0.5-1 going from the 0.1-2 keV band toward higher energies,
strengthening recent results on another half dozen steep soft X-ray AGN.
PG1244+026 shows a significant feature in the `1 keV' region, which can be
described by either as a broad emission line centered at 0.95 keV (quasar
frame) or as edge or line absorption at 1.17 (1.22) keV. The line emission
could be due to reflection from an highly ionized accretion disk, in line with
the view that steep soft X-ray quasars are emitting close to the Eddington
luminosity. Photoelectric edge absorption or resonant line absorption could be
produced by gas outflowing at a large velocity (0.3-0.6 c).Comment: Accepted for publication in MNRAS, 10 page
Investigating the complex X-ray spectrum of a broad-line 2MASS red quasar: XMM-Newton observation of FTM 0830+3759
We report results from a 50 ks XMM-Newton observation of the dust-reddened
broad-line quasar FTM 0830+3759 (z=0.413) selected from the FIRST/2MASS Red
Quasar survey. For this AGN, a very short 9 ks Chandra exposure had suggested a
feature-rich X-ray spectrum and HST images revealed a very disturbed host
galaxy morphology. Contrary to classical, optically-selected quasars, the X-ray
properties of red (i.e. with J-Ks> 1.7 and R-Ks> 4) broad line quasars are
still quite unexplored, although there is a growing consensus that, due to
moderate obscuration, these objects can offer a unique view of spectral
components typically swamped by the AGN light in normal, blue quasars. The
XMM-Newton observation discussed here has definitely confirmed the complexity
of the X-ray spectrum revealing the presence of a cold (or mildly-ionized)
absorber with Nh ~10^{22} cm^-2 along the line of sight to the nucleus and a
Compton reflection component accompanied by an intense Fe K emission line in
this quasar with a Lum(2-10) ~5 x 10^{44} erg/s. A soft-excess component is
also required by the data. The match between the column density derived by our
spectral analysis and that expected on the basis of reddening due to the dust
suggests the possibility that both absorptions occur in the same medium. FTM
0830+3759 is characterized by an extinction/absorption-corrected
X-ray-to-optical flux ratio alphaox = -2.3, that is steeper than expected on
the basis of its UV luminosity. These findings indicate that the X-ray
properties of FTM 0830+3759 differs from those typically observed for
optically-selected broad line quasars with comparable hard X-ray luminosity.Comment: Accepted for publication in Ap
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