694 research outputs found
Non-detection of a pulsar-powered nebula in Puppis A, and implications for the nature of the radio-quiet neutron star RX J0822-4300
We report on a deep radio search for a pulsar wind nebula associated with the
radio-quiet neutron star RX J0822-4300 in the supernova remnant Puppis A. The
well-determined properties of Puppis A allow us to constrain the size of any
nebula to less than 30 arcsec; however we find no evidence for such a source on
any spatial scale up to 30 arcmin. These non-detections result in an upper
limit on the radio luminosity of any pulsar-powered nebula which is three
orders of magnitude below what would be expected if RX J0822-4300 was an
energetic young radio pulsar beaming away from us, and cast doubt on a recent
claim of X-ray pulsations from this source. The lack of a radio nebula leads us
to conclude that RX J0822-4300 has properties very different from most young
radio pulsars, and that it represents a distinct population which may be as
numerous, or even more so, than radio pulsars.Comment: 5 pages, including 2 embedded EPS figures, uses emulateapj.sty.
Accepted to ApJ Letters (minor changes made following referee's report
A journey to client and therapist mutuality in person-centered psychotherapy: a case study
This aim of this case study was to build theory on the development of client–therapist mutuality in person-centered psychotherapy. A case study focusing on a 42-year-old female client who had presented for therapy following trauma within interpersonal relationships has been used. A reflective, theory-building, case study method was adopted that used data gathered from verbatim session notes and research interviews between the therapist (first author) and research supervisor (second author). Three primary therapeutic processes that contributed to the development of mutuality are discussed. First, the development of mutual empathy in the relationship; second, strategies for disconnection and staying out of relationship are identified. Third, client agency and mutuality is explored. In conclusion the study proposes that mutuality is a key construct within person-centered psychotherapy and develops as a natural consequence of the presence of Rogers’ therapeutic conditions
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
Limits on the Stochastic Gravitational Wave Background from the North American Nanohertz Observatory for Gravitational Waves
We present an analysis of high-precision pulsar timing data taken as part of
the North American Nanohertz Observatory for Gravitational waves (NANOGrav)
project. We have observed 17 pulsars for a span of roughly five years using the
Green Bank and Arecibo radio telescopes. We analyze these data using standard
pulsar timing models, with the addition of time-variable dispersion measure and
frequency-variable pulse shape terms. Sub-microsecond timing residuals are
obtained in nearly all cases, and the best root-mean-square timing residuals in
this set are ~30-50 ns. We present methods for analyzing post-fit timing
residuals for the presence of a gravitational wave signal with a specified
spectral shape. These optimally take into account the timing fluctuation power
removed by the model fit, and can be applied to either data from a single
pulsar, or to a set of pulsars to detect a correlated signal. We apply these
methods to our dataset to set an upper limit on the strength of the
nHz-frequency stochastic supermassive black hole gravitational wave background
of h_c (1 yr^-1) < 7x10^-15 (95%). This result is dominated by the timing of
the two best pulsars in the set, PSRs J1713+0747 and J1909-3744.Comment: To be submitted to Ap
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
Healing built-environment effects on health outcomes: environment–occupant–health framework
An investigation examined the structured scientific evidence on healthcare facilities (the healing built environment – HBE) and its impact on patients’ health outcomes under a holistic conceptual evaluative framework. The integrative review considered 127 papers (of which 59 were review papers). It found there was no adequate framework that could integrate existing research findings holistically. Such a holistic framework needs to demonstrate the cumulative and interactive effects of various HBE characteristics on patients’ health outcomes and wellbeing. An environment–occupant–health (E-O-H) framework is proposed, taking a holistic perspective to identify and evaluate different HBE characteristics. The E-O-H framework should support future research by (1) identifying the HBE characteristics that affect health outcomes; (2) defining appropriate future research designs; and (3) understanding the need for holistic analysis of the integrated effects of diverse HBE characteristics on health outcomes
Health, Health-Related Quality of Life, and Quality of Life: What is the Difference?
The terms health, health-related quality of life (HRQoL), and quality of life (QoL) are used interchangeably. Given that these are three key terms in the literature, their appropriate and clear use is important. This paper reviews the history and definitions of the terms and considers how they have been used. It is argued that the definitions of HRQoL in the literature are problematic because some definitions fail to distinguish between HRQoL and health or between HRQoL and QoL. Many so-called HRQoL questionnaires actually measure self-perceived health status and the use of the phrase QoL is unjustified. It is concluded that the concept of HRQoL as used now is confusing. A potential solution is to define HRQoL as the way health is empirically estimated to affect QoL or use the term to only signify the utility associated with a health state
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