4,095 research outputs found
Mid-infrared observations of the ultraluminous galaxies IRAS14348-1447, IRAS19254-7245, and IRAS23128-5919
We present a study of the three ultraluminous infrared galaxies
IRAS14348-1447, IRAS19254-7245, and IRAS23128-5919, based on mid-infrared (MIR)
spectro-imaging (5-18microns) observations performed with ISOCAM. We find that
the MIR emission from each system, which consists of a pair of interacting late
type galaxies, is principally confined to the nuclear regions with diameters of
1-2kpc and can account for more than 95% of their IRAS 12micron flux. In each
interacting system, the galaxy hosting an active galactic nucleus (AGN)
dominates the total spectrum and shows stronger dust continuum (12-16microns)
relative to the Unidentified Infrared Band (UIB) emission (6-9microns),
suggestive of its enhanced radiation field. The MIR dominant galaxy also
exhibits elevated 15micron/Halpha and 15micron/K ratios which trace the high
extinction due to the large quantities of molecular gas and dust present in its
central regions. Using only diagnostics based on our mid-infrared spectra, we
can establish that the Seyfert galaxy IRAS19254-7245 exhibits MIR spectral
features of an AGN while the MIR spectrum of the Seyfert (or LINER) member of
IRAS23128-5919 is characteristic of dust emission principally heated by star
forming regions.Comment: Accepted for publication in Astronomy & Astrophysics, 13 pages, 9
figure
Linking dust emission to fundamental properties in galaxies: The low-metallicity picture
In this work, we aim at providing a consistent analysis of the dust
properties from metal-poor to metal-rich environments by linking them to
fundamental galactic parameters. We consider two samples of galaxies: the Dwarf
Galaxy Survey (DGS) and KINGFISH, totalling 109 galaxies, spanning almost 2 dex
in metallicity. We collect infrared (IR) to submillimetre (submm) data for both
samples and present the complete data set for the DGS sample. We model the
observed spectral energy distributions (SED) with a physically-motivated dust
model to access the dust properties. Using a different SED model (modified
blackbody), dust composition (amorphous carbon), or wavelength coverage at
submm wavelengths results in differences in the dust mass estimate of a factor
two to three, showing that this parameter is subject to non-negligible
systematic modelling uncertainties. For eight galaxies in our sample, we find a
rather small excess at 500 microns (< 1.5 sigma). We find that the dust SED of
low-metallicity galaxies is broader and peaks at shorter wavelengths compared
to more metal-rich systems, a sign of a clumpier medium in dwarf galaxies. The
PAH mass fraction and the dust temperature distribution are found to be driven
mostly by the specific star-formation rate, SSFR, with secondary effects from
metallicity. The correlations between metallicity and dust mass or total-IR
luminosity are direct consequences of the stellar mass-metallicity relation.
The dust-to-stellar mass ratios of metal-rich sources follow the well-studied
trend of decreasing ratio for decreasing SSFR. The relation is more complex for
highly star-forming low-metallicity galaxies and depends on the chemical
evolutionary stage of the source (i.e., gas-to-dust mass ratio). Dust growth
processes in the ISM play a key role in the dust mass build-up with respect to
the stellar content at high SSFR and low metallicity. (abridged)Comment: 44 pages (20 pages main body plus 5 Appendices), 11 figures, 9
tables, accepted for publication in A&
The physical characteristics of the gas in the disk of Centaurus A using the Herschel Space Observatory
We search for variations in the disk of Centaurus A of the emission from
atomic fine structure lines using Herschel PACS and SPIRE spectroscopy. In
particular we observe the [C II](158 m), [N II](122 and 205 m), [O
I](63 and 145 m) and [O III](88 m) lines, which all play an important
role in cooling the gas in photo-ionized and photodissociation regions. We
determine that the ([C II]+[O I])/ line ratio, a proxy for the
heating efficiency of the gas, shows no significant radial trend across the
observed region, in contrast to observations of other nearby galaxies. We
determine that 10 - 20% of the observed [C II] emission originates in ionized
gas. Comparison between our observations and a PDR model shows that the
strength of the far-ultraviolet radiation field, , varies between
and and the hydrogen nucleus density varies between
and cm, with no significant radial trend in
either property. In the context of the emission line properties of the
grand-design spiral galaxy M51 and the elliptical galaxy NGC 4125, the gas in
Cen A appears more characteristic of that in typical disk galaxies rather than
elliptical galaxies.Comment: Accepted for publication in the Astrophysical Journal. 22 pages, 10
figures, 5 table
Patient Satisfaction with a Pilot Chronic Pain Management Programme in Cape Town, South Africa
Background: The goals of a chronic pain management clinic includeincreasing patient knowledge about pain, developing pain management skillsand increasing patients’ confidence in their pain management abilities.A Chronic Pain Management Programme (CPMP) based on evidence basedguidelines was developed at a chronic pain management clinic to facilitatepatient discharge to a primary healthcare level. Aim: The aim of this study was to explore patient satisfaction with, acceptability of and the perceived success which could be due to the CPMP developed at the Chronic Pain Management Clinic of Groote Schuur Hospital,Cape Town.Methods: Patients (n=14) were referred to the pilot study from the Chronic Pain Management Clinic. A s a pilot, four courses were run over a period ofone year. In order to reach the research aim, an eleven-question, structuredopen-ended interview was conducted with all participants. Results: Fourteen patients enrolled in the CPMP. Responses were favourable with participants emphasising the roleof increased knowledge about pain, the role of exercise and of stress management techniques. Participants also recog-nised a positive change in behaviours and attitudes following participation in the CPMP.Conclusions: Findings suggest that participants found the format of the course acceptable as regards course content,structure and delivery. Participant responses suggest that the course was acceptable and perceived as useful. However,future courses would benefit from refresher courses or structured support groups
Herschel and JCMT observations of the early-type dwarf galaxy NGC 205
We present Herschel dust continuum, James Clerk Maxwell Telescope CO(3-2)
observations and a search for [CII] 158 micron and [OI] 63 micron spectral line
emission for the brightest early-type dwarf satellite of Andromeda, NGC 205.
While direct gas measurements (Mgas ~ 1.5e+6 Msun, HI + CO(1-0)) have proven to
be inconsistent with theoretical predictions of the current gas reservoir in
NGC 205 (> 1e+7 Msun), we revise the missing interstellar medium mass problem
based on new gas mass estimates (CO(3-2), [CII], [OI]) and indirect
measurements of the interstellar medium content through dust continuum
emission. Based on Herschel observations, covering a wide wavelength range from
70 to 500 micron, we are able to probe the entire dust content in NGC 205
(Mdust ~ 1.1-1.8e+4 Msun at Tdust ~ 18-22 K) and rule out the presence of a
massive cold dust component (Mdust ~ 5e+5 Msun, Tdust ~ 12 K), which was
suggested based on millimeter observations from the inner 18.4 arcsec. Assuming
a reasonable gas-to-dust ratio of ~ 400, the dust mass in NGC 205 translates
into a gas mass Mgas ~ 4-7e+6 Msun. The non-detection of [OI] and the low
L_[CII]-to-L_CO(1-0) line intensity ratio (~ 1850) imply that the molecular gas
phase is well traced by CO molecules in NGC 205. We estimate an atomic gas mass
of 1.5e+4 Msun associated with the [CII] emitting PDR regions in NGC 205. From
the partial CO(3-2) map of the northern region in NGC 205, we derive a
molecular gas mass of M_H2 ~ 1.3e+5 Msun. [abridged]Comment: 16 pages, 7 figures, accepted for publication in MNRA
DSM-IV defined conduct disorder and oppositional defiant disorder: An investigation of shared liability in female twins
BACKGROUND: DSM-IV specifies a hierarchal diagnostic structure such that an ODD diagnosis is applied only if criteria are not met for CD. Genetic studies of ODD and CD support a combination of shared genetic and environmental influences, but largely ignore the imposed diagnostic structure. METHODS: We examined whether ODD and CD share an underlying etiology while accounting for DSM-IV diagnostic specifications. Data from 1446 female twin pairs, aged 11–19, were fitted to two-stage models adhering to the DSM-IV diagnostic hierarchy. RESULTS: Models suggested that DSM-IV ODD-CD covariation is attributed largely to shared genetic influences. CONCLUSIONS: This is the first study, to our knowledge, to examine genetic and environmental overlap among these disorders while maintaining DSM-IV hierarchical structure. Findings reflect primarily shared genetic influences and specific (i.e., uncorrelated) shared/familial environmental effects on these DSM-IV defined behaviors. These results have implications for how best to define CD and ODD for future genetically-informed analyses
Circulating endothelial microparticles reduce in concentration following an exercise programme in women with polycystic ovary syndrome
Purpose: Endothelial dysfunction is a known comorbidity in women with polycystic ovary syndrome (PCOS). The aim was to assess if supervised, moderate intensity exercise could potentially impact markers of endothelial disruption; endothelial cell derived microparticles (EMP). Methods: The current study investigated the effects of a supervised 8-week moderate intensity exercise programme on EMP in women with PCOS (n=11) and control women free from any known disease (n=10). EMP were enumerated via specific antibody (CD105, CD106) labelling and flow cytometry.Results: CD105+MP significantly reduced in women with PCOS from pre to post exercise programme, with CD105+ MP reducing from 2114 CD105+ MP per µl platelet free plasma (PFP) to 424 CD105+ MP per µl PFP (p = 0.025). Control women showed no significant change in CD105+ MP (p = 0.25) after completing the same exercise programme. CD106+ MP showed no change in either PCOS (p = 0.95) or control groups (p = 0.99). No significant correlations existed with the changes in endothelial microparticles (EMP) compared to body composition changes as a result of exercise. Conclusion: Supervised, moderate intensity exercise independent of substantial weight loss reduced circulating CD105+MP, likely reflecting an improvement in endothelial function in women with PCOS compared to healthy control women. Additionally, EMP may be a useful marker for physical improvement in exercise programmes for clinical populations
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