87 research outputs found
SN 2009E: a faint clone of SN 1987A
In this paper we investigate the properties of SN 2009E, which exploded in a
relatively nearby spiral galaxy (NGC 4141) and that is probably the faintest
1987A-like supernova discovered so far. Spectroscopic observations which
started about 2 months after the supernova explosion, highlight significant
differences between SN 2009E and the prototypical SN 1987A. Modelling the data
of SN 2009E allows us to constrain the explosion parameters and the properties
of the progenitor star, and compare the inferred estimates with those available
for the similar SNe 1987A and 1998A. The light curve of SN 2009E is less
luminous than that of SN 1987A and the other members of this class, and the
maximum light curve peak is reached at a slightly later epoch than in SN 1987A.
Late-time photometric observations suggest that SN 2009E ejected about 0.04
solar masses of 56Ni, which is the smallest 56Ni mass in our sample of
1987A-like events. Modelling the observations with a radiation hydrodynamics
code, we infer for SN 2009E a kinetic plus thermal energy of about 0.6 foe, an
initial radius of ~7 x 10^12 cm and an ejected mass of ~19 solar masses. The
photospheric spectra show a number of narrow (v~1800 km/s) metal lines, with
unusually strong Ba II lines. The nebular spectrum displays narrow emission
lines of H, Na I, [Ca II] and [O I], with the [O I] feature being relatively
strong compared to the [Ca II] doublet. The overall spectroscopic evolution is
reminiscent of that of the faint 56Ni-poor type II-plateau supernovae. This
suggests that SN 2009E belongs to the low-luminosity, low 56Ni mass, low-energy
tail in the distribution of the 1987A-like objects in the same manner as SN
1997D and similar events represent the faint tail in the distribution of
physical properties for normal type II-plateau supernovae.Comment: 19 pages, 9 figures (+7 in appendix); accepted for publication in A&A
on 3 November 201
The Australia Telescope 20 GHz Survey: The Source Catalogue
We present the full source catalogue from the Australia Telescope 20 GHz
(AT20G) Survey. The AT20G is a blind radio survey carried out at 20 GHz with
the Australia Telescope Compact Array (ATCA) from 2004 to 2008, and covers the
whole sky south of declination 0 deg. The AT20G source catalogue presented here
is an order of magnitude larger than any previous catalogue of high-frequency
radio sources, and includes 5890 sources above a 20 GHz flux-density limit of
40 mJy. All AT20G sources have total intensity and polarisation measured at 20
GHz, and most sources south of declination -15 deg also have near-simultaneous
flux-density measurements at 5 and 8 GHz. A total of 1559 sources were detected
in polarised total intensity at one or more of the three frequencies. We detect
a small but significant population of non-thermal sources that are either
undetected or have only weak detections in low-frequency catalogues. We
introduce the term Ultra-Inverted Spectrum (UIS) to describe these radio
sources, which have a spectral index alpha(5, 20) > +0.7 and which constitute
roughly 1.2 per cent of the AT20G sample. The 20 GHz flux densities measured
for the strongest AT20G sources are in excellent agreement with the WMAP 5-year
source catalogue of Wright et al. (2009), and we find that the WMAP source
catalogue is close to complete for sources stronger than 1.5 Jy at 23 GHz.Comment: 21 pages, accepted for publication in MNRA
Adaptive optics imaging and optical spectroscopy of a multiple merger in a luminous infrared galaxy
(abridged) We present near-infrared (NIR) adaptive optics imaging obtained
with VLT/NACO and optical spectroscopy from the Southern African Large
Telescope (SALT) of a luminous infrared galaxy (LIRG) IRAS 19115-2124. These
data are combined with archival HST imaging and Spitzer imaging and
spectroscopy, allowing us to study this disturbed interacting/merging galaxy,
dubbed the Bird, in extraordinary detail. In particular, the data reveal a
triple system where the LIRG phenomenon is dominated by the smallest of the
components.
One nucleus is a regular barred spiral with significant rotation, while
another is highly disturbed with a surface brightness distribution intermediate
to that of disk and bulge systems, and hints of remaining arm/bar structure. We
derive dynamical masses in the range 3-7x10^10 M_solar for both. The third
component appears to be a 1-2x10^10 M_solar mass irregular galaxy. The total
system exhibits HII galaxy-like optical line ratios and strengths, and no
evidence for AGN activity is found from optical or mid-infrared data. The star
formation rate is estimated to be 190 M_solar/yr. We search for SNe, super star
clusters, and detect 100-300 km/s outflowing gas from the Bird. Overall, the
Bird shows kinematic, dynamical, and emission line properties typical for cool
ultra luminous IR galaxies. However, the interesting features setting it apart
for future studies are its triple merger nature, and the location of its star
formation peak - the strongest star formation does not come from the two major
K-band nuclei, but from the third irregular component. Aided by simulations, we
discuss scenarios where the irregular component is on its first high-speed
encounter with the more massive components.Comment: 24 pages, 16 figures. Accepted MNRAS version, minor corrections only,
references added. Higher resolution version (1.3MB) is available from
http://www.saao.ac.za/~petri/bird/ulirg_bird_highres_vaisanen_v2.pd
An optimal trauma-informed pathway for PTSD, complex PTSD and other mental health and psychosocial impacts of trauma in prisons: an expert consensus statement
People in prisons have high levels of trauma exposure throughout their lives. Presentations are often complex, with a high prevalence of PTSD and CPTSD and other mental health comorbidities. Prisons themselves can be stressful and traumatising environments. There are challenges in the delivery of effective treatments for PTSD and CPTSD. There is a need for the development of effective clinical pathways for these conditions that are embedded within trauma-informed organisational approaches. Responding to this need, this report is the result of a multidisciplinary expert consensus meeting and review of the research literature on PTSD, CPTSD, associated comorbidities and optimal approaches to trauma-informed practice. The group consisted of 24 expert representatives from psychology, psychiatry, healthcare, academia, social care and Welsh Government. The meeting commenced with presentations on various aspects of the clinical pathway for PTSD and complex PTSD in prisons, and of applications of trauma-informed practice within prisons. Small sub-groups then provided practical recommendations and solutions relevant to their assigned topic. Findings were presented to all meeting attendees for another round of discussion and debate, until consensus was reached. The resulting recommendations provide guidance to improve identification, treatment and support for people living in prison who have experienced trauma
A novel ruthenium(II)–cobaloxime supramolecular complex for photocatalytic H_2 evolution: synthesis, characterisation and mechanistic studies
We report the synthesis and characterization of novel mixed-metal binuclear ruthenium(II)–cobalt(II) photocatalysts for hydrogen evolution in acidic acetonitrile. First, 2-(2′-pyridyl)benzothiazole (pbt), 1, was reacted with RuCl_(3)·xH_(2)O to produce [Ru(pbt)_(2)Cl_2]·0.25CH_(3)COCH_3, 2, which was then reacted with 1,10-phenanthroline-5,6-dione (phendione), 3, in order to produce [Ru(pbt)_(2)(phendione)](PF_(6))_2·4H_(2)O, 4. Compound 4 was then reacted with 4-pyridinecarboxaldehyde in order to produce [Ru(pbt)_(2)(L-pyr)](PF_6)_(2)·9.5H_(2)O, 5 (where L-pyr = (4-pyridine)oxazolo[4,5-f]phenanthroline). Compound 5 was then reacted with [Co(dmgBF_2)_(2)(H_(2)O)_2] (where dmgBF_(2) = difluoroboryldimethylglyoximato) in order to produce the mixed-metal binuclear complex, [Ru(pbt)_(2)(L-pyr)Co(dmgBF_(2))_(2)(H_(2)O)](PF_(6))_2·11H_(2)O·1.5CH_(3)COCH_3, 6. [Ru(Me_(2)bpy)_2(L-pyr)Co(dmgBF_2)_(2)(OH_2)](PF_6)_(2), 7 (where Me_(2)bpy = 1,10-phenanthroline, 4,4′-dimethyl-2,2′-bipyridine) and [Ru(phen)_(2)(L-pyr)Co(dmgBF_2)_(2)(OH_2)](PF_(6))_2, 8 were also synthesised. All complexes were characterized by elemental analysis, ESI MS, HRMS, UV-visible absorption, ^(11)B, ^(19)F, and ^(59)Co NMR, ESR spectroscopy, and cyclic voltammetry, where appropriate. Photocatalytic studies carried out in acidified acetonitrile demonstrated constant hydrogen generation longer than a 42 hour period as detected by gas chromatography. Time resolved spectroscopic measurements were performed on compound 6, which proved an intramolecular electron transfer from an excited Ru(II) metal centre to the Co(II) metal centre via the bridging L-pyr ligand. This resulted in the formation of a cobalt(I)-containing species that is essential for the production of H_2 gas in the presence of H^+ ions. A proposed mechanism for the generation of hydrogen is presented
Real-Time Self-Regulation of Emotion Networks in Patients with Depression
Many patients show no or incomplete responses to current pharmacological or psychological therapies for depression. Here we explored the feasibility of a new brain self-regulation technique that integrates psychological and neurobiological approaches through neurofeedback with functional magnetic resonance imaging (fMRI). In a proof-of-concept study, eight patients with depression learned to upregulate brain areas involved in the generation of positive emotions (such as the ventrolateral prefrontal cortex (VLPFC) and insula) during four neurofeedback sessions. Their clinical symptoms, as assessed with the 17-item Hamilton Rating Scale for Depression (HDRS), improved significantly. A control group that underwent a training procedure with the same cognitive strategies but without neurofeedback did not improve clinically. Randomised blinded clinical trials are now needed to exclude possible placebo effects and to determine whether fMRI-based neurofeedback might become a useful adjunct to current therapies for depression
PKS 2250−351: A Giant Radio Galaxy in Abell 3936
We present a detailed analysis of the radio galaxy PKS , a giant of 1.2 Mpc projected size, its host galaxy, and its environment. We use radio data from the Murchison Widefield Array, the upgraded Giant Metre-wavelength Radio Telescope, the Australian Square Kilometre Array Pathfinder, and the Australia Telescope Compact Array to model the jet power and age. Optical and IR data come from the Galaxy And Mass Assembly (GAMA) survey and provide information on the host galaxy and environment
Evidence-based Kernels: Fundamental Units of Behavioral Influence
This paper describes evidence-based kernels, fundamental units of behavioral influence that appear to underlie effective prevention and treatment for children, adults, and families. A kernel is a behavior–influence procedure shown through experimental analysis to affect a specific behavior and that is indivisible in the sense that removing any of its components would render it inert. Existing evidence shows that a variety of kernels can influence behavior in context, and some evidence suggests that frequent use or sufficient use of some kernels may produce longer lasting behavioral shifts. The analysis of kernels could contribute to an empirically based theory of behavioral influence, augment existing prevention or treatment efforts, facilitate the dissemination of effective prevention and treatment practices, clarify the active ingredients in existing interventions, and contribute to efficiently developing interventions that are more effective. Kernels involve one or more of the following mechanisms of behavior influence: reinforcement, altering antecedents, changing verbal relational responding, or changing physiological states directly. The paper describes 52 of these kernels, and details practical, theoretical, and research implications, including calling for a national database of kernels that influence human behavior
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