1,373 research outputs found
20 cm VLA Radio-Continuum Study of M31 - Images and Point Source Catalogues DR2: Extraction of a supernova remnant sample
We present Data Release 2 of the Point Source Catalogue created from a series
of previously constructed radio-continuum images of M31 at lambda=20 cm (nu=1.4
GHz) from archived VLA observations. In total, we identify a collection of 916
unique discrete radio sources across the field of M31. Comparing these detected
sources to those listed by Gelfand et al. (2004) at lambda=92 cm, the spectral
index of 98 sources has been derived. The majority (73%) of these sources
exhibit a spectral index of alpha <-0.6, indicating that their emission is
predominantly non-thermal in nature, which is typical for background objects
and Supernova Remnants (SNRs). Additionally, we investigate the presence of
radio counterparts for some 156 SNRs and SNR candidates, finding a total of
only 13 of these object in our images within a 5 arcsec search area. Auxiliary
optical, radio and X-ray catalogs were cross referenced highlighting a small
population of SNR and SNR candidates common to multi-frequency domains
20 cm VLA Radio-Continuum Study of M31 - Images and Point Source Catalogues
We present a series of new high-sensitivity and high-resolution
radio-continuum images of M31 at \lambda=20 cm (\nu=1.4 GHz). These new images
were produced by merging archived 20 cm radio-continuum observations from the
Very Large Array (VLA) telescope. Images presented here are sensitive to rms=60
\mu Jy and feature high angular resolution (<10"). A complete sample of
discrete radio sources have been catalogued and analysed across 17 individual
VLA projects. We identified a total of 864 unique discrete radio sources across
the field of M31. One of the most prominent regions in M31 is the ring feature
for which we estimated total integrated flux of 706 mJy at \lambda=20 cm. We
compare here, detected sources to those listed in Gelfand et al. (2004) at
\lambda=92 cm and find 118 sources in common to both surveys. The majority
(61%) of these sources exhibit a spectral index of \alpha <-0.6 indicating that
their emission is predominantly non-thermal in nature. That is more typical for
background objects.Comment: 28 pages, 25 figures, accepted for publication in the Serbian
Astronomical Journa
"Caring for Insiderness": Phenomenologically informed insights that can guide practice.
Understanding the ‘‘insider’’ perspective has been a pivotal strength of qualitative research. Further than this, within the more applied fields in which the human activity of ‘‘caring’’ takes place, such understanding of ‘‘what it is like’’ for people from within their lifeworlds has also been acknowledged as the foundational starting point in order for ‘‘care’’ to be caring. But we believe that more attention needs to be paid to this foundational generic phenomenon: what it means to understand the ‘‘insiderness’’ of another, but more importantly, how to act on this in caring ways. We call this human phenomenon ‘‘caring for insiderness.’’ Drawing on existing phenomenological studies of marginal caring situations at the limits of caring capability, and through a process of phenomenologically oriented reflection, we interrogated some existential themes implicit in these publications that could lead to deeper insights for both theoretical and applied purposes. The paper provides direction for practices of caring by highlighting some dangers as well as some remedies along this path
The ATLAS 9.0 GHz Survey of the Extended Chandra Deep Field South: The Faint 9.0 GHz Radio Population
We present a new image of the 9.0 GHz radio emission from the extended
Chandra Deep Field South. A total of 181 hours of integration with the
Australia Telescope Compact Array has resulted in a 0.276 square degree image
with a median sensitivity of 20 Jy/beam rms, for a synthesised beam
of 4.0 1.3 arcsec. We present a catalogue of the 9.0 GHz radio
sources, identifying 70 source components and 55 individual radio galaxies.
Source counts derived from this sample are consistent with those reported in
the literature. The observed source counts are also generally consistent with
the source counts from simulations of the faint radio population. Using the
wealth of multiwavelength data available for this region, we classify the faint
9 GHz population and find that 91% are radio loud AGN, 7% are radio quiet AGN
and 2% are star forming galaxies. The 9.0 GHz radio sources were matched to 5.5
and 1.4 GHz sources in the literature and we find a significant fraction of
flat or inverted spectrum sources, with 36% of the 9 GHz sources having
-0.3 (for ). This flat or
inverted population is not well reproduced by current simulations of radio
source populations.Comment: 17 pages, 12 figures. Accepted for publication in MNRA
Radio Galaxy Zoo: Knowledge Transfer Using Rotationally Invariant Self-Organising Maps
With the advent of large scale surveys the manual analysis and classification
of individual radio source morphologies is rendered impossible as existing
approaches do not scale. The analysis of complex morphological features in the
spatial domain is a particularly important task. Here we discuss the challenges
of transferring crowdsourced labels obtained from the Radio Galaxy Zoo project
and introduce a proper transfer mechanism via quantile random forest
regression. By using parallelized rotation and flipping invariant Kohonen-maps,
image cubes of Radio Galaxy Zoo selected galaxies formed from the FIRST radio
continuum and WISE infrared all sky surveys are first projected down to a
two-dimensional embedding in an unsupervised way. This embedding can be seen as
a discretised space of shapes with the coordinates reflecting morphological
features as expressed by the automatically derived prototypes. We find that
these prototypes have reconstructed physically meaningful processes across two
channel images at radio and infrared wavelengths in an unsupervised manner. In
the second step, images are compared with those prototypes to create a
heat-map, which is the morphological fingerprint of each object and the basis
for transferring the user generated labels. These heat-maps have reduced the
feature space by a factor of 248 and are able to be used as the basis for
subsequent ML methods. Using an ensemble of decision trees we achieve upwards
of 85.7% and 80.7% accuracy when predicting the number of components and peaks
in an image, respectively, using these heat-maps. We also question the
currently used discrete classification schema and introduce a continuous scale
that better reflects the uncertainty in transition between two classes, caused
by sensitivity and resolution limits
Dosimetric Evaluation of Tumor Tracking in 4D Radiotherapy
Purpose: In some patients the tumors in lung, pancreas, liver, breast, and other organs move significantly during cardiac and breathing cycles. In this study we have investigated the dosimetric benefits of real-time tumor tracking for patients who were diagnosed with lung cancer.
American Society for Therapeutic Radiation Oncology (ASTRO) 52nd Annual Meeting October 31 - November 4, San Diego, C
Study of a small solar probe /sunblazer/. part ii- spacecraft and payload design progress report, jul. 1, 1964 - jun. 30, 1965
Design considerations for Sunblazer solar probe and payloa
Discovery of magnetic fields along stacked cosmic filaments as revealed by radio and X-ray emission
Diffuse filaments connect galaxy clusters to form the cosmic web. Detecting these filaments could yield information on the magnetic field strength, cosmic ray population and temperature of intercluster gas, yet, the faint and large-scale nature of these bridges makes direct detections very challenging. Using multiple independent all-sky radio and X-ray maps we stack pairs of luminous red galaxies as tracers for cluster pairs. For the first time, we detect an average surface brightness between the clusters from synchrotron (radio) and thermal (X-ray) emission with 73 5\u3c3 significance, on physical scales larger than observed to date ( 653 Mpc). We obtain a synchrotron spectral index of \u3b1 43 -1.0 and estimates of the average magnetic field strength of 30 64 B 64 60 nG, derived from both equipartition and Inverse Compton arguments, implying a 5 to 15 per cent degree of field regularity when compared with Faraday rotation measure estimates. While the X-ray detection is inline with predictions, the average radio signal comes out higher than predicted by cosmological simulations and dark matter annihilation and decay models. This discovery demonstrates that there are connective structures between mass concentrations that are significantly magnetised, and the presence of sufficient cosmic rays to produce detectable synchrotron radiation
Uncertainty and Margin Study for IMRT, VMAT, and Proton Beam Therapy for Treatment After Radical Prostatectomy
Purpose/Objective(s): To compare the uncertainties of 3D dose distributions, caused by the geometrical uncertainty of patient setup, in IMRT, VMAT, and proton plans for post-prostatectomy treatment. To test the effectiveness of a common margin recipe in these three types of treatment plans.
American Society for Therapeutic Radiation Oncology (ASTRO) 52nd Annual Meeting October 31 - November 4, San Diego, C
Characterizing the radio continuum emission from intense starburst galaxies
© 2016 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society.The intrinsic thermal (free-free) and non-thermal (synchrotron) emission components that comprise the radio continuum of galaxies represent unique, dust-free measures of star formation rates (SFR). Such high SFR galaxies will dominate the deepest current and future radio surveys. We disentangle the thermal and non-thermal emission components of the radio continuum of six ultraluminous infrared galaxies (LFIR > 1012.5 L?) at redshifts of 0.2 = z = 0.5 and 22 IR selected galaxies. Radio data over a wide frequency range (0.8 < ? <10 GHz) are fitted with a star-forming galaxy model comprising of thermal and non-thermal components. The luminosities of both radio continuum components are strongly correlated to the 60 µm luminosity across many orders of magnitude (consistent with the far-IR to radio correlation). We demonstrate that the spectral index of the radio continuum spectral energy distribution is a useful proxy for the thermal fraction. We also find that there is an increase in mean and scatter of the thermal fraction with FIR to radio luminosity ratio which could be influenced by different time-scales of the thermal and non-thermal emission mechanisms
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