433 research outputs found
Radio Polarization of the Young High-Magnetic-Field Pulsar PSR J1119-6127
We have investigated the radio polarization properties of PSR J1119-6127, a
recently discovered young radio pulsar with a large magnetic field. Using
pulsar-gated radio imaging data taken at a center frequency of 2496 MHz with
the Australia Telescope Compact Array, we have determined a rotation measure
for the pulsar of +842 +/- 23 rad m^-2. These data, combined with archival
polarimetry data taken at a center frequency of 1366 MHz with the Parkes
telescope, were used to determine the polarization characteristics of PSR
J1119-6127 at both frequencies. The pulsar has a fractional linear polarization
of ~75% and ~55% at 1366 and 2496 MHz, respectively, and the profile consists
of a single, wide component. This pulse morphology and high degree of linear
polarization are in agreement with previously noticed trends for young pulsars
(e.g., PSR J1513-5908). A rotating-vector (RV) model fit of the position angle
(PA) of linear polarization over pulse phase using the Parkes data suggests
that the radio emission comes from the leading edge of a conal beam. We discuss
PSR J1119-6127 in the context of a recent theoretical model of pulsar spin-down
which can in principle be tested with polarization and timing data from this
pulsar. Geometric constraints from the RV fit are currently insufficient to
test this model with statistical significance, but additional data may allow
such a test in the future.Comment: 9 pages, including 6 figures and 1 table. Accepted for publication in
Ap
Discovery of circularly polarised radio emission from SS 433
We report the discovery of circularly polarised radio emission from the
radio-jet X-ray binary SS 433 with the Australia Telescope Compact Array. The
flux density spectrum of the circular polarization, clearly detected at four
frequencies between 1 - 9 GHz, has a spectral index of (-0.9 +/- 0.1). Multiple
components in the source and a lack of very high spatial resolution do not
allow a unique determination of the origin of the circular polarization, nor of
the spectrum of fractional polarization. However, we argue that the emission is
likely to arise in the inner regions of the binary, possibly via
propagation-induced conversion of linear to circular polarization, and the
fractional circular polarization of these regions may be as high as 10%.
Observations such as these have the potential to investigate the composition,
whether pairs or baryonic, of the ejecta from X-ray binaries.Comment: Accepted for publication in ApJ Letter
Controlling the quality factor of a tuning-fork resonance between 9 K and 300 K for scanning-probe microscopy
We study the dynamic response of a mechanical quartz tuning fork in the
temperature range from 9 K to 300 K. Since the quality factor Q of the
resonance strongly depends on temperature, we implement a procedure to control
the quality factor of the resonance. We show that we are able to dynamically
change the quality factor and keep it constant over the whole temperature
range. This procedure is suitable for applications in scanning probe
microscopy.Comment: 5 pages, 6 figure
Characterisation of the Mopra Radio Telescope at 16--50 GHz
We present the results of a programme of scanning and mapping observations of
astronomical masers and Jupiter designed to characterise the performance of the
Mopra Radio Telescope at frequencies between 16-50 GHz using the 12-mm and 7-mm
receivers. We use these observations to determine the telescope beam size, beam
shape and overall telescope beam efficiency as a function of frequency. We find
that the beam size is well fit by / over the frequency range with a
correlation coefficient of ~90%. We determine the telescope main beam
efficiencies are between ~48-64% for the 12-mm receiver and reasonably flat at
~50% for the 7-mm receiver. Beam maps of strong HO (22 GHz) and SiO masers
(43 GHz) provide a means to examine the radial beam pattern of the telescope.
At both frequencies the radial beam pattern reveals the presence of three
components, a central `core', which is well fit by a Gaussian and constitutes
the telescopes main beam, and inner and outer error beams. At both frequencies
the inner and outer error beams extend out to approximately 2 and 3.4 times the
full-width half maximum of the main beam respectively. Sources with angular
sizes a factor of two or more larger than the telescope main beam will couple
to the main and error beams, and therefore the power contributed by the error
beams needs to be considered. From measurements of the radial beam power
pattern we estimate the amount of power contained in the inner and outer error
beams is of order one-fifth at 22 GHz rising slightly to one-third at 43 GHz.Comment: Accepted for publication in PAS
Polarization observations in a low synchrotron emission field at 1.4 GHz
We present the first observation of the diffuse polarized synchrotron
radiation of a patch () in the BOOMERanG field,
one of the areas with the lowest CMB foreground emission. The work has been
carried out with the Australia Telescope Compact Array at 1.4 GHz with 3.4
arcmin resolution and sensitivity of mJy beam. The mean
polarized signal has been found to be mK, nearly one order of magnitude below than in the Galactic
Plane.
Extrapolations to frequencies of interest for cosmological investigations
suggest that polarized synchrotron foreground noise should allow the detection
of the CMB Polarization --mode already at 32 GHz and make us confident that,
at 90 GHz, it is accessible with no relevant foreground contamination. Last but
not least, even the --mode detection for is not ruled out in
such a low emission patch.Comment: Uses emulateapj.sty, onecolfloat.sty, 5 pages 4 fig., accepted for
publication in ApJ
A radio supernova remnant associated with the young pulsar J1119-6127
We report on Australia Telescope Compact Array observations in the direction
of the young high magnetic-field pulsar J1119-6127. In the resulting images we
identify a non-thermal radio shell of diameter 15', which we classify as a
previously uncatalogued young supernova remnant, G292.2-0.5. This supernova
remnant is positionally coincident with PSR J1119-6127, and we conclude that
the two objects are physically associated. No radio emission is detected from
any pulsar wind nebula (PWN) associated with the pulsar; our observed upper
limits are consistent with the expectation that high magnetic-field pulsars
produce radio nebulae which fade rapidly. This system suggests a possible
explanation for the lack of an associated radio pulsar and/or PWN in many
supernova remnants.Comment: 13 pages, 6 embedded eps figures. Accepted to Ap
Radio Emission from GRO J1655-40 during the 1994 Jet Ejection Episodes
We report multifrequency radio observations of GRO J1655-40 obtained with the
Australia Telescope Compact Array, the Molonglo Observatory Synthesis Telescope
and the Hartebeesthoek Radio Astronomy Observatory at the time of the major
hard X-ray and radio outbursts in 1994 August-September. The radio emission
reached levels of the order of a few Jy and was found to be linearly polarized
by up to 10%, indicating a synchrotron origin. The light curves are in good
agreement with those measured with the VLA, but our closer time sampling has
revealed two new short-lived events and significant deviations from a simple
exponential decay. The polarization data show that the magnetic field is well
ordered and aligned at right angles to the radio jets for most of the
monitoring period. The time evolution of the polarization cannot be explained
solely in terms of a simple synchrotron bubble model, and we invoke a hybrid
`core-lobe' model with a core which contributes both synchrotron and free-free
emission and `lobes' which are classical synchrotron emitters.Comment: 36 pages, 5 tables, 9 figures; accepted for publication in Ap
Motivational Interviewing training for physiotherapy and occupational therapy students: Effect on confidence, knowledge and skills.
Copyright © 2019 The Authors. Objective: To examine the effectiveness of a three-day training programme on knowledge, confidence and
fidelity to Motivational Interviewing (MI) delivery in an undergraduate occupational therapy and
physiotherapy cohort (n = 25).
Methods: Training outcomes were assessed pre-training, post-training and following a subsequent
clinical placement. The Motivational Interviewing Knowledge and Attitudes Test (MIKAT) and an 8-item
survey assessed knowledge, attitudes and confidence respectively. MI fidelity was evaluated by a
simulated patient interview rated with the Motivational Interviewing Treatment Integrity scale (MITI).
Analysis was by one-way repeated measures ANOVA.
Results: Self-report measurements indicated increased confidence but no effect on knowledge or attitude.
MITI analysis showed superior performance in all four global criteria and an increased frequency of MI
adherent behaviours post-training. Positive changes were maintained following clinical placement. MITI
summary scores indicated an improvement in question to reflection ratio in line with beginner
competency.
Conclusion(s): Participation in a three-day MI training programme significantly improved student
confidence and MI skilfulness.
Practice Implications: Where feasible, MI training should be embedded within the curriculum. Further
research is needed elucidate the best practices to incorporate teaching this skill set within the curriculum
in order to best prepare students to counsel clients in behaviour change in their applied settings.Health Education England North West Londo
High Galactic latitude polarized emission at 1.4 GHz and implications for cosmic microwave background observations
We analyse the polarized emission at 1.4 GHz in a 3x3 deg^2 area at high
Galactic latitude (b ~ -40deg). The region, centred in (RA=5h, Dec=-49deg), was
observed with the Australia Telescope Compact Array radio-interferometer, whose
3-30 arcmin angular sensitivity range allows the study of scales appropriate
for CMB Polarization (CMBP) investigations. The angular behavior of the diffuse
emission is analysed through the E- and B-mode power spectra. These follow a
power law with slopes \beta_E = -1.97 \pm 0.08 and
\beta_B = -1.98 \pm 0.07. The emission is found to be about a factor 25 fainter
than in Galactic plane regions. The comparison of the power spectra with other
surveys indicates that this area is intermediate between strong and negligible
Faraday rotation effects. A similar conclusion can be reached by analysing both
the frequency and Galactic latitude behaviors of the diffuse Galactic emission
of the 408-1411 MHz Leiden survey data. We present an analysis of the Faraday
rotation effects on the polarized power spectra, and find that the observed
power spectra can be enhanced by a transfer of power from large to small
angular scales. The extrapolation of the spectra to 32 and 90GHz of the CMB
window suggests that Galactic synchrotron emission leaves the CMBP E-mode
uncontaminated at 32GHz. The level of the contamination at 90GHz is expected to
be more than 4 orders of magnitude below the CMBP spectrum. Extrapolating to
the relevant angular scales, this region also appears adequate for
investigation of the CMBP B-modes for models with tensor/scalar fluctuation
power ratio T/S>0.01. We also identify polarized point sources in the field,
providing a 9 object list which is complete down to the polarized flux limit of
S^p_lim = 2 mJy.Comment: 13 pages, 11 figures, accepted for publication in MNRA
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