48 research outputs found
High-Spatial Resolution SED of NGC 1068 from Near-IR to Radio. Disentangling the thermal and non-thermal contributions
We investigate the ideas that a sizable fraction of the interferometrically
unresolved infrared emission of the nucleus of NGC 1068 might originate from
other processes than thermal dust emission from the torus. We examine the
contribution of free-free or synchrotron emissions to the central mid- and
near-IR parsec-scale emitting region of NGC 1068. Each mechanism is constrained
with parsec scale radio data available for NGC 1068 in the 10^9 - 10^11 Hz
regime, and compared to the highest-resolution interferometric data available
in the mid-infrared. It is shown that the unresolved emission in the
interferometric observation (<~1pc) is still dominatedd by dust emission and
not by contributions from synchrotron or free-free emission. As recent studies
suggest, the interferometric observations prefer a clumpy structure of the dust
distribution. Extrapolation of the radio free-free or synchrotron emission to
the IR indicates that their contribution is <20% even for the unresolved
fraction of the interferometric flux. The slope of the available radio data is
consistent with a power law exponent alpha = 0.29 +/- 0.07 which we interprete
in terms of either free-free emission or synchrotron radiation from
quasi-monochromatic electrons. We apply emission models for both mechanisms in
order to obtain physical parameters. (abridged)Comment: 8 pages, 3 figures; accepted by A&
AGN dust tori at low and high luminosities
A cornerstone of AGN unification schemes is the presence of an optically and
geometrically thick dust torus. It provides the obscuration to explain the
difference between type 1 and type 2 AGN. We investigate the influence of the
dust distribution on the Eddington limit of the torus. For smooth dust
distributions, the Eddingtion limit on the dust alone is 5 orders of magnitudes
below the limit for electron scattering in a fully ionized plasma, while a
clumpy dust torus has an Eddington limit slightly larger than the classical
one. We study the behaviour of a clumpy torus at low and high AGN luminosities.
For low luminosities of the order of ~10^42 erg/s, the torus changes its
characteristics and obscuration becomes insufficient. In the high luminosity
regime, the clumpy torus can show a behaviour which is consistent with the
"receding torus" picture. The derived luminosity-dependent fraction of
type-2-objects agrees with recent observational results. Moreover, the
luminosity-dependent covering factor in a clumpy torus may explain the presence
of broad-line AGN with high column densities in X-rays.Comment: 5 pages, 0 figures; Accepted for publication in MNRA
Smoking Prevalence Increases following Canterbury Earthquakes
Background. A magnitude 7.1 earthquake hit Canterbury in September 2010. This earthquake and associated aftershocks took the lives of 185 people and drastically changed residentsâ living, working, and social conditions. Aim. To explore the impact of the earthquakes on smoking status and levels of tobacco consumption in the residents of Christchurch. Methods. Semistructured interviews were carried out in two city malls and the central bus exchange 15 months after the first earthquake. A total of 1001 people were interviewed. Results. In August 2010, prior to any earthquake, 409 (41%) participants had never smoked, 273 (27%) were currently smoking, and 316 (32%) were ex-smokers. Since the September 2010 earthquake, 76 (24%) of the 316 ex-smokers had smoked at least one cigarette and 29 (38.2%) had smoked more than 100 cigarettes. Of the 273 participants who were current smokers in August 2010, 93 (34.1%) had increased consumption following the earthquake, 94 (34.4%) had not changed, and 86 (31.5%) had decreased their consumption. 53 (57%) of the 93 people whose consumption increased reported that the earthquake and subsequent lifestyle changes as a reason to increase smoking. Conclusion. 24% of ex-smokers resumed smoking following the earthquake, resulting in increased smoking prevalence. Tobacco consumption levels increased in around one-third of current smokers
Stakeholdersâ Perspectives on the Quality of End-of-Life Health Care Services for Chronic Obstructive Airways Disease: A Focus Group Study
Introduction: Delivery of end-of-life care for severe chronic obstructive pulmonary disease (COPD) has been hampered by an unpredictable disease trajectory and poor integration of health care and social services. Objective: To critically explore the perspectives, values, and experiences of stakeholders in COPD end-of-life healthcare services in a large district in Aotearoa New Zealand. Design: Focus groups analysed utilising critical theory and Actor-Network Theory. Methods: Stakeholders in end-of-life COPD healthcare services were purposively sampled from a large healthcare network in Canterbury, Aotearoa New Zealand to participate in seven focus groups (bereaved carers, community-based health professionals, non-MÄori, non-Pacific patients, and support people (two groups), MÄori patients, supporters and health professionals, Pacific patients, support people and health professionals, and hospital-based health professionals). Participants discussed end-of-life care services for people with COPD. Transcripts were coded utilising descriptive and structural coding to develop themes related to provision of quality care. Participants were positioned as experts. We considered how the themes arising supported and disrupted the healthcare network for end-of-life COPD. Results: Five themes related to quality of care for end-of-life COPD were identified: compassion, competence, community, commitment, and collaboration. The absence of any of these five themes required for quality care led to power imbalances within healthcare systems. Power inequities created disconnection among stakeholders which then disrupted commitment, community, and collaboration. A dysfunctional healthcare network impeded compassion between stakeholders and did not support their competence, leading to lower quality care. All five themes were identified as essential to delivery of high-quality end-of-life care in COPD. Conclusion: Stakeholdersâ perspectives of end-of-life care for COPD identified of core features of a health system network that enabled or impeded the actions of stakeholders and allocation of resources to provide quality care
The small dispersion of the mid IR -- hard X-ray correlation in AGN
Context: We investigate mid-infrared and X-ray properties of the dusty torus
in unification scenarios for active galactic nuclei.
Aims: We use the relation between mid IR and hard X-ray luminosities to
constrain AGN unification scenarios.
Methods: With VISIR at the VLT, we have obtained the currently highest
angular resolution (0".35 FWHM) narrow-band mid infrared images of the nuclei
of 8 nearby Seyfert galaxies. Combining these observations with X-ray data from
the literature we study the correlation between their mid IR and hard X-ray
luminosities.
Results: We find that the rest frame 12.3 mircon (L_MIR) and 2-10 keV (L_X)
luminosities are correlated at a highly significant level. The best fit
power-law to our data is log L_MIR \propto (1.60 \pm 0.22) log L_X, showing a
much smaller dispersion than earlier studies.
Conclusions: The similarity in the og L_MIR / log L_X ratio between Sy1s and
Sy2s even using high angular resolution MIR data implies that the similarity is
intrinsic to AGN and not caused by contamination from extra-nuclear emission.
This supports clumpy torus models. The exponent of the correlation constrains
the inner geometry of the torus.Comment: 5 pages, 3 figures, accepted for publication in Astronomy &
Astrophysic
Interstellar gas within pc of Sgr A
We seek to obtain a coherent and realistic three-dimensional picture of the
interstellar gas out to about 10 pc of the dynamical center of our Galaxy,
which is supposed to be at Sgr A. We review the existing observational
studies on the different gaseous components that have been identified near Sgr
A, and retain all the information relating to their spatial configuration
and/or physical state. Based on the collected information, we propose a
three-dimensional representation of the interstellar gas, which describes each
component in terms of both its precise location and morphology and its
thermodynamic properties. The interstellar gas near Sgr A can represented
by five basic components, which are, by order of increasing size: (1) a central
cavity with roughly equal amounts of warm ionized and atomic gases, (2) a ring
of mainly molecular gas, (3) a supernova remnant filled with hot ionized gas,
(4) a radio halo of warm ionized gas and relativistic particles, and (5) a belt
of massive molecular clouds. While the halo gas fills of the
studied volume, the molecular components enclose of the
interstellar mass.Comment: 21 pages, 7 figure
Severe COPD and the transition to a palliative approach
Patients with severe chronic obstructive pulmonary disease (COPD) have a chaotic trajectory towards death. Research has focused on identifying a âtransition pointâ that would allow identification of those patients who may benefit from a palliative approach to their care, or referral to a specialist palliative care service. This article aims to outline difficulties in identifying this transition point, summarise current literature on this topic and suggests a model based on clinical milestones.
Educational aims
To outline the difficulties associated with identifying patients with severe COPD who are at risk of dying. To summarise current research on this topic.
Key points
A specific transition point is difficult to identify in severe COPD. Tools are available that may assist the physician in identifying those at risk of dying. It is essential that the patient voice is heard, patients can describe specific events that may be used as a âtriggerâ for a palliative approach. Specialist palliative care services may only be required for a subgroup of patients whose needs cannot be managed by the primary care team