604 research outputs found
Star Formation in Southern Seyfert Galaxies
We have produced radio maps, using the ATCA, of the central regions of six
southern Seyfert 2 galaxies (NGC 1365, 4945, 6221, 6810, 7582, and Circinus)
with circumnuclear star formation, to estimate the relative contribution of
star formation activity compared to activity from the active galactic nucleus
(AGN). The radio morphologies range from extended diffuse structures to compact
nuclear emission, with no evidence, even in the relatively compact sources, for
synchrotron self--absorption. In each case the radio to far--infrared (FIR)
ratio has a value consistent with star formation, and in all but one case the
radio to [FeII] ratio is also consistent with star formation. We derive
supernova rates and conclude that, despite the presence of a Seyfert nucleus in
these galaxies, the radio, FIR, and [FeII] line emission are dominated by
processes associated with the circumnuclear star formation (i.e. supernova
remnants and HII regions) rather than with the AGN.Comment: 26 pages, Latex, 13 figures, submitted to MNRA
Cold gas and star formation in a merging galaxy sequence
We explore the evolution of the cold gas and star-formation activity during
galaxy interactions, using a merging galaxy sequence comprising both pre- and
post-mergers. Data for this study come from the literature but supplemented by
new radio observations presented here. Firstly, we confirm that the
star-formation efficiency (SFE) increases close to nuclear coalescence. At
post-merger stages there is evidence that the SFE declines to values typical of
ellipticals. This trend can be attributed to M(H_2) depletion due to
interaction induced star-formation. However, there is significant scatter,
likely to arise from differences in the interaction details of individual
systems. Secondly, we find that the central molecular hydrogen surface density,
increases close to the final stages of the merging of the two nuclei. Such a
trend is also predicted by numerical simulations. Furthermore, there is
evidence for a decreasing fraction of cold gas mass from early interacting
systems to merger remnants, attributed to gas conversion into other forms. The
evolution of the total-radio to blue-band luminosity ratio, reflecting the
disk+nucleus star-formation activity, is also investigated. Although this ratio
is on average higher than that of isolated spirals, we find a marginal increase
along the merging sequence, attributed to the relative insensitivity of disk
star-formation to interactions. However, a similar result is also obtained for
the nuclear radio emission, although galaxy interactions are believed to
significantly affect the activity in the central galaxy regions. Finally, we
find that the FIR--radio flux ratio distribution of interacting galaxies is
consistent with star-formation being the main energising source.Comment: 18 pages, 17 figures, accepted for publication in MNRA
Radio Observations of Super Star Clusters in Dwarf Starburst Galaxies
We present new radio continuum observations of two dwarf starburst galaxies,
NGC3125 and NGC5408, with observations at 4.80GHz (6cm) and 8.64GHz (3cm),
taken with the Australia Telescope Compact Array (ATCA). Both galaxies show a
complex radio morphology with several emission regions, mostly coincident with
massive young star clusters. The radio spectral indices of these regions are
negative (with alpha ~ -0.5 - -0.7), indicating that the radio emission is
dominated by synchrotron emission associated with supernova activity from the
starburst. One emission region in NGC5408 has a flatter index (alpha ~ -0.1)
indicative of optically thin free-free emission, which could indicate it is a
younger cluster. Consequently, in these galaxies we do not see regions with the
characteristic positive spectral index indicative of optically obscured
star-formation regions, as seen in other dwarf starbursts such as Hen 2-10.Comment: Accepted for publication in MNRA
The complex radio and X-ray structure in the nuclear regions of the active galaxy NGC1365
We present a multiwavelength analysis of the prominent active galaxy NGC1365,
in particular looking at the radio and X-ray properties of the central regions
of the galaxy.
We analyse ROSAT observations of NGC1365, and discuss recent ASCA results. In
addition to a number of point sources in the vicinity of NGC1365, we find a
region of X-ray emission extending along the central bar of the galaxy,
combined with an emission peak near the centre of the galaxy. This X-ray
emission is centred on the optical/radio nucleus, but is spatially extended.
The X-ray spectrum can be well fitted by a thermal plasma model, with
kT=0.6-0.8keV and a low local absorbing column. The thermal spectrum is
suggestive of starburst emission rather than emission from a central
black-hole.
The ATCA radio observations show a number of hotspots, located in a ring
around a weak radio nucleus. Synchrotron emission from electrons accelerated by
supernovae and supernova remnants (SNRs) is the likely origin of these
hotspots. The radio nucleus has a steep spectrum, indicative perhaps of an AGN
or SNRs. The evidence for a jet emanating from the nucleus is at best marginal.
The extent of the radio ring is comparable to the extended central X-ray
source.Comment: 13 pages, 5 figures, to be published in MNRA
The Brain as CEO: Teaching Neuroleadership
Recent advances in the brain sciences have opened a window of opportunity for organizational leadership. For example, neuroscientists have determined that the prefrontal cortex of the brain is closely associated with the highest orders of human functioning such as planning, decision-making, control of attention and self-monitoring. This area of grey matter has also become a vivid metaphor for the primary executive or leadership role in business, the Chief Executive Officer or CEO. The burgeoning discipline of Neuroleadership attempts to apply the findings of relevant brain research to the field of leadership studies. A primary educational challenge is how to best translate the rapidly expanding neuroscience research findings into form and substance that can improve the performance of live human leaders in complex organizational settings. The Managerial Psychology course in Franklin University’s MS in Business Psychology program explores the new Neuroleadership field and offers its students insights, tools, and techniques for immediate application.https://fuse.franklin.edu/ss2018/1061/thumbnail.jp
Leadership Coaching in the Fourth Industrial Revolution
Today’s world of extraordinary change follows a long history of technology-driven industrial revolutions. Author Alvin Toffler eloquently identified, categorized, and named the first three of them: Agricultural, Industrial, and Informational. Likening these revolutions to major waves of change, Toffler also described their impact on the social, political, economic and environmental ethos of the times in which they occurred. Recently, a number of knowledgeable commentators have suggested that we are now on the cusp of a fourth industrial wave. This large-scale transformational groundswell is being propelled by a dramatic acceleration in the rate of change itself. It is characterized by major discoveries in Artificial Intelligence, biology, materials science, and neuroscience. In order to remain effective and viable, Leadership Coaching will need to successfully adapt to this virtual thunderstorm of change. This paper will provide background on the preceding waves of industrial change and provide some preliminary glimpses into the just dawning fourth industrial wave. This work will also delve into the potential impact of the newest wave on the leadership coaching profession, describe a few of the latest techniques being introduced, consider the wave’s possible impact on the important work of coaches, and suggest a set of options for the future
Gemini/GMOS Imaging of Globular Cluster Systems in Five Early-type Galaxies
This paper presents deep high quality photometry of globular cluster (GC)
systems belonging to five early-type galaxies covering a range of mass and
environment. Photometric data were obtained with the Gemini North and Gemini
South telescopes in the filter passbands g', r', and i'. The combination of
these filters with good seeing conditions allows an excellent separation
between GC candidates and unresolved field objects. Bimodal GC colour
distributions are found in all five galaxies. Most of the GC systems appear
bimodal even in the (g' -r') vs (r' -i') plane. A population of
resolved/marginally resolved GC and Ultra Compact Dwarf candidates was found in
all the galaxies. A search for the so-called "blue tilt" in the
colour-magnitude diagrams reveals that NGC 4649 clearly shows that phenomenon
although no conclusive evidence was found for the other galaxies in the sample.
This "blue tilt" translates into a mass-metallicity relation given by Z \propto
M^0.28\pm0.03 . This dependence was found using a new empirical (g' -i') vs
[Z/H] relation which relies on an homogeneous sample of GC colours and
metallicities. This paper also explores the radial trends in both colour and
surface density for the blue (metal-poor) and red (metal-rich) GC
subpopulations. As usual, the red GCs show a steeper radial distribution than
the blue ones. Evidence of galactocentric colour gradients is found in some of
the GC systems, being more significant for the two S0 galaxies in the sample.
Red GC subpopulations show similar colours and gradients to the galaxy halo
stars in their inner region. A GC mean colour-galaxy luminosity relation,
consistent with [Z/H] \propto L_B ^0.26\pm0.08, is present for the red GCs. An
estimate of the total GC populations and specific frequency SN values is
presented for NGC 3115, NGC 3379, NGC 3923 and NGC 4649.Comment: 23 pages, 13 figures and 9 tables. Tables A1 and A2 will be published
in full online only. Accepted for publication in MNRA
Financial Planning: What the Social and Brain Sciences Have to Offer
This paper addresses the potential linkage of the disciplines of financial planning and the social and brain sciences from the combined perspectives of a financial planning expert and a business psychologist. It seeks to offer practical guidance on how to utilize insights from recent research and practice in the social and brain sciences to address the issue of effective financial planning in a time of multiple widespread international crises. The article will review the traditional approach to financial planning, indicate where the profession appears to stand now, describe advances in social and brain science, and provide some practical tools for use by practicing financial planners. The paper will conclude with a summary of its key points
Family carer perspectives of acute hospital care following a diagnosis of motor neuron disease: a qualitative secondary analysis
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