Biopsychosocial Factors in Chronic Spine-Related Pain: Contributions to Pain Intensity and Perceived Disability

Psychological and contextual factors play an important role in the development and maintenance of chronic spine-related pain, and effective treatment of pain-related conditions requires an understanding of how these factors contribute to pain and disability. The present study examined the relative contributions of spine pathology, psychological complications, and demographic factors to perceived pain intensity and disability in patients with chronic spine-related pain. Because most patients were assessed in the context of a compensable injury, exaggeration of symptoms and disability was systematically controlled for using multiple validity indicators. A high prevalence of psychological complications was observed in the present sample. Analysis indicated that psychological factors were not significantly related to pain intensity, but were significantly related to reported pain-related disability. Further, psychological factors were found to predict pain-related disability beyond demographics, medical findings, and pain intensity. Clinical implications of these findings are discussed

Biopsychosocial Factors in Chronic Spine-Related Pain: Contributions to Pain Intensity and Perceived Disability

Psychological and contextual factors play an important role in the development and maintenance of chronic spine-related pain, and effective treatment of pain-related conditions requires an understanding of how these factors contribute to pain and disability. The present study examined the relative contributions of spine pathology, psychological complications, and demographic factors to perceived pain intensity and disability in patients with chronic spine-related pain. Because most patients were assessed in the context of a compensable injury, exaggeration of symptoms and disability was systematically controlled for using multiple validity indicators. A high prevalence of psychological complications was observed in the present sample. Analysis indicated that psychological factors were not significantly related to pain intensity, but were significantly related to reported pain-related disability. Further, psychological factors were found to predict pain-related disability beyond demographics, medical findings, and pain intensity. Clinical implications of these findings are discussed

Evidence for alignment of the rotation and velocity vectors in pulsars. II. Further data and emission heights

We have conducted observations of 22 pulsars at frequencies of 0.7, 1.4 and 3.1 GHz and present their polarization profiles. The observations were carried out for two main purposes. First we compare the orientation of the spin and velocity vectors to verify the proposed alignment of these vectors by Johnston et al. (2005). We find, for the 14 pulsars for which we were able to determine both vectors, that 7 are plausibly aligned, a fraction which is lower than, but consistent with, earlier measurements. Secondly, we use profiles obtained simultaneously at widely spaced frequencies to compute the radio emission heights. We find, similar to other workers in the field, that radiation from the centre of the profile originates from lower in the magnetosphere than the radiation from the outer parts of the profile.Comment: Accepted by MNRAS. 14 page

Interferometric Imaging with the 32 Element Murchison Wide-Field Array

The Murchison Wide-Field Array (MWA) is a low-frequency radio telescope, currently under construction, intended to search for the spectral signature of the epoch of reionization (EOR) and to probe the structure of the solar corona. Sited in western Australia, the full MWA will comprise 8192 dipoles grouped into 512 tiles and will be capable of imaging the sky south of 40° declination, from 80 MHz to 300 MHz with an instantaneous field of view that is tens of degrees wide and a resolution of a few arcminutes. A 32 station prototype of the MWA has been recently commissioned and a set of observations has been taken that exercise the whole acquisition and processing pipeline. We present Stokes I, Q, and U images from two ~4 hr integrations of a field 20° wide centered on Pictoris A. These images demonstrate the capacity and stability of a real-time calibration and imaging technique employing the weighted addition of warped snapshots to counter extreme wide-field imaging distortions

A Study of Giant Pulses from PSR J1824-2452A

We have searched for microsecond bursts of emission from millisecond pulsars in the globular cluster M28 using the Parkes radio telescope. We detected a total of 27 giant pulses from the known emitter PSR J1824-2452A. At wavelengths around 20 cm the giant pulses are scatter-broadened to widths of around 2 microseconds and follow power-law statistics. The pulses occur in two narrow phase-windows which correlate in phase with X-ray emission and trail the peaks of the integrated radio pulse-components. Notably, the integrated radio emission at these phase windows has a steeper spectral index than other emission. The giant pulses exhibit a high degree of polarization, with many being 100% elliptically polarized. Their position angles appear random. Although the integrated emission of PSR J1824-2452A is relatively stable for the frequencies and bandwidths observed, the intensities of individual giant pulses vary considerably across our bands. Two pulses were detected at both 2700 and 3500 MHz. The narrower of the two pulses is 20 ns wide at 3500 MHz. At 2700 MHz this pulse has an inferred brightness temperature at maximum of 5 x 10^37 K. Our observations suggest the giant pulses of PSR J1824-2452A are generated in the same part of the magnetosphere as X-ray emission through a different emission process to that of ordinary pulses.Comment: Accepted by Ap

Self-consistency of relativistic observables with general relativity in the white dwarf-neutron star binary pulsar PSR J1141-6545

Here we report timing measurements of the relativistic binary pulsar PSR J1141-6545 that constrain the component masses and demonstrate that the orbital period derivative \dot Pb = (-4+/-1)x10^-13 is consistent with gravitational wave emission as described by the general theory of relativity. The mass of the neutron star and its companion are 1.30+/-0.02 Mo and 0.986+/-0.020 Mo respectively, suggesting a white dwarf companion, and extending the range of systems for which general relativity provides a correct description. On evolutionary grounds, the progenitor mass of PSR J1141-6545 should be near the minimum for neutron star production. Its mass is two standard deviations below the mean of the other neutron stars, suggesting a relationship between progenitor and remnant masses.Comment: 10 pages, 2 figures, revised version to Ap J Letter

PSR J1909-3744, a Binary Millisecond Pulsar with a Very Small Duty Cycle

We report the discovery of PSR J1909-3744, a 2.95 millisecond pulsar in a nearly circular 1.53 day orbit. Its narrow pulse width of 43 microseconds allows pulse arrival times to be determined with great accuracy. We have spectroscopically identified the companion as a moderately hot (T = 8500 K) white dwarf with strong absorption lines. Radial velocity measurements of the companion will yield the mass ratio of the system. Our timing data suggest the presence of Shapiro delay; we expect that further timing observations, combined with the mass ratio, will allow the first accurate determination of a millisecond pulsar mass. We have measured the timing parallax and proper motion for this pulsar which indicate a transverse velocity of 140 (+80/-40) km/s. This pulsar's stunningly narrow pulse profile makes it an excellent candidate for precision timing experiments that attempt to detect low frequency gravitational waves from coalescing supermassive black hole binaries.Comment: 12 pages, 4 figures. Accepted for publication in ApJ