160 research outputs found
Being in Another World: Transcultural Student Experiences Using Service Learning With Families Who Are Homeless
Developing skills in cultural competence is a recognized theoretical strategy in schools of nursing. Nursing faculty know that students need to be sensitized to the concept of diversity; however, many are struggling with the best way to teach cultural competence. This article describes transcultural experiences from service learning clinical rotations at a family homeless shelter, described by students as being in another world. Student narratives provide valuable information about structuring clinical learning activities to promote understanding of cultural differences and similarities. Clinical experiences using a traditional model versus those using service learning, the role of reflection, and teaching strategies promoting transcultural learning through service learning are explored
Discovery of Five New Pulsars in Archival Data
Reprocessing of the Parkes Multibeam Pulsar Survey has resulted in the
discovery of five previously unknown pulsars and several as-yet-unconfirmed
candidates. PSR J0922-52 has a period of 9.68 ms and a DM of 122.4 pc cm^-3.
PSR J1147-66 has a period of 3.72 ms and a DM of 133.8 pc cm^-3. PSR J1227-6208
has a period of 34.53 ms, a DM of 362.6 pc cm^-3, is in a 6.7 day binary orbit,
and was independently detected in an ongoing high-resolution Parkes survey by
Thornton et al. and also in independent processing by Einstein@Home volunteers.
PSR J1546-59 has a period of 7.80 ms and a DM of 168.3 pc cm^-3. PSR J1725-3853
is an isolated 4.79-ms pulsar with a DM of 158.2 pc cm^-3. These pulsars were
likely missed in earlier processing efforts due to their high DMs and short
periods and the large number of candidates that needed to be looked through.
These discoveries suggest that further pulsars are awaiting discovery in the
multibeam survey data.Comment: 12 pages, 2 figures, 2 tables, accepted to Ap
A Pilot Study of Nulling in 22 Pulsars Using Mixture Modeling
The phenomenon of pulsar nulling, observed as the temporary inactivity of a
pulsar, remains poorly understood both observationally and theoretically. Most
observational studies that quantify nulling employ a variant of Ritchings
(1976)'s algorithm which can suffer significant biases for pulsars where the
emission is weak. Using a more robust mixture model method, we study pulsar
nulling in a sample of 22 recently discovered pulsars, for which we publish the
nulling fractions for the first time. These data clearly demonstrate biases of
the former approach and show how an otherwise non-nulling pulsar can be
classified as having significant nulls. We show that the population-wide
studies that find a positive correlation of nulling with pulsar
period/characteristic age can similarly be biased because of the bias in
estimating the nulling fraction. We use our probabilistic approach to find the
evidence for periodicity in the nulls in a subset of three pulsars in our
sample. In addition, we also provide improved timing parameters for 17 of the
22 pulsars that had no prior follow-up.Comment: Accepted for publication in the Astrophysical Journal (ApJ
The International Pulsar Timing Array: First Data Release
The highly stable spin of neutron stars can be exploited for a variety of (astro)physical investigations. In particular, arrays of pulsars with rotational periods of the order of milliseconds can be used to detect correlated signals such as those caused by gravitational waves. Three such \u27pulsar timing arrays\u27 (PTAs) have been set up around the world over the past decades and collectively form the \u27International\u27 PTA (IPTA). In this paper, we describe the first joint analysis of the data from the three regional PTAs, i.e. of the first IPTA data set. We describe the available PTA data, the approach presently followed for its combination and suggest improvements for future PTA research. Particular attention is paid to subtle details (such as underestimation of measurement uncertainty and long-period noise) that have often been ignored but which become important in this unprecedentedly large and inhomogeneous data set. We identify and describe in detail several factors that complicate IPTA research and provide recommendations for future pulsar timing efforts. The first IPTA data release presented here (and available on-line) is used to demonstrate the IPTA\u27s potential of improving upon gravitational-wave limit
The PALFA Survey: Going to great depths to find radio pulsars
The on-going PALFA survey is searching the Galactic plane (|b| < 5 deg., 32 <
l < 77 deg. and 168 < l < 214 deg.) for radio pulsars at 1.4 GHz using ALFA,
the 7-beam receiver installed at the Arecibo Observatory. By the end of August
2012, the PALFA survey has discovered 100 pulsars, including 17 millisecond
pulsars (P < 30 ms). Many of these discoveries are among the pulsars with the
largest DM/P ratios, proving that the PALFA survey is capable of probing the
Galactic plane for millisecond pulsars to a much greater depth than any
previous survey. This is due to the survey's high sensitivity, relatively high
observing frequency, and its high time and frequency resolution. Recently the
rate of discoveries has increased, due to a new more sensitive spectrometer,
two updated complementary search pipelines, the development of online
collaborative tools, and access to new computing resources. Looking forward,
focus has shifted to the application of artificial intelligence systems to
identify pulsar-like candidates, and the development of an improved
full-resolution pipeline incorporating more sophisticated radio interference
rejection. The new pipeline will be used in a complete second analysis of data
already taken, and will be applied to future survey observations. An overview
of recent developments, and highlights of exciting discoveries will be
presented.Comment: Proceedings of IAUS 291 "Neutron Stars and Pulsars: Challenges and
Opportunities after 80 years", J. van Leeuwen (ed.); 6 pages, 4 figure
Fast Radio Burst Discovered in the Arecibo Pulsar ALFA Survey
Recent work has exploited pulsar survey data to identify temporally isolated,
millisecond-duration radio bursts with large dispersion measures (DMs). These
bursts have been interpreted as arising from a population of extragalactic
sources, in which case they would provide unprecedented opportunities for
probing the intergalactic medium; they may also be linked to new source
classes. Until now, however, all so-called fast radio bursts (FRBs) have been
detected with the Parkes radio telescope and its 13-beam receiver, casting some
concern about the astrophysical nature of these signals. Here we present FRB
121102, the first FRB discovery from a geographic location other than Parkes.
FRB 121102 was found in the Galactic anti-center region in the 1.4-GHz Pulsar
ALFA survey with the Arecibo Observatory with a DM = 557.4 3 pc
cm, pulse width of ms, and no evidence of interstellar
scattering. The observed delay of the signal arrival time with frequency agrees
precisely with the expectation of dispersion through an ionized medium. Despite
its low Galactic latitude (), the burst has three times the
maximum Galactic DM expected along this particular line-of-sight, suggesting an
extragalactic origin. A peculiar aspect of the signal is an inverted spectrum;
we interpret this as a consequence of being detected in a sidelobe of the ALFA
receiver. FRB 121102's brightness, duration, and the inferred event rate are
all consistent with the properties of the previously detected Parkes bursts.Comment: 9 pages, 3 figures, submitted to Ap
The Green Bank North Celestial Cap Pulsar Survey. IV: Four New Timing Solutions
We present timing solutions for four pulsars discovered in the Green Bank
Northern Celestial Cap (GBNCC) survey. All four pulsars are isolated with spin
periods between 0.26s and 1.84s. PSR J00382501 has a 0.26s
period and a period derivative of ,
which is unusually low for isolated pulsars with similar periods. This low
period derivative may be simply an extreme value for an isolated pulsar or it
could indicate an unusual evolution path for PSR J00382501, such as a
disrupted recycled pulsar (DRP) from a binary system or an orphaned central
compact object (CCO). Correcting the observed spin-down rate for the Shklovskii
effect suggests that this pulsar may have an unusually low space velocity,
which is consistent with expectations for DRPs. There is no X-ray emission
detected from PSR J00382501 in an archival swift observation, which suggests
that it is not a young orphaned CCO. The high dispersion measure of PSR
J1949+3426 suggests a distance of 12.3kpc. This distance indicates that PSR
J1949+3426 is among the most distant 7% of Galactic field pulsars, and is one
of the most luminous pulsars.Comment: 7 pages, 5 figure
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