The impact of nature of onset of pain and posttraumatic stress on adjustment to chronic pain and treatment outcome

Despite the demonstrated efficacy of cognitive-behavioural therapy for chronic pain, recent research has attempted to identify predictors of treatment outcome in order to improve the effectiveness of such treatments. This research has indicated that variables such as the nature of the onset of the pain and psychopathology are associated with poor adjustment to chronic pain. Accordingly, these variables might also be predictive of poor response to treatment. Individuals who experience a sudden onset of pain following an injury or accident, particularly when the instigating event is experienced as psychologically traumatic, may present for treatment with high levels of distress, including symptoms consistent with a posttraumatic stress response. The impact of this type of onset of pain and posttraumatic stress symptoms on adjustment to chronic pain and treatment outcome is the focus of this thesis. Three studies were conducted to clarify and extend earlier research findings in this area. Using 536 patients referred for treatment in a tertiary referral pain management centre, the first study examined the psychometric properties of a widely used self-report measure of posttraumatic stress symptoms (the PTSD Checklist, or PCL), modified for use in a chronic pain sample. This study provided preliminary support for the suitability of the PCL as a self-report measure of Posttraumatic Stress Disorder (PTSD) symptoms in chronic pain patients. However, the study also highlighted a number of issues with the use of self-report measures of posttraumatic stress symptoms in chronic pain patient samples. In particular, PCL items enquiring about symptoms which are a common aspect of the chronic pain experience (e.g. irritability, sleep problems) appeared to contribute to high mean scores on the PCL Avoidance and Arousal subscales. Furthermore, application of diagnostic cut-off scores and an algorithm recommended for the PCL in other trauma groups suggested that a much larger proportion of the sample was identified as potentially meeting diagnostic criteria for PTSD than would have been expected from previous research. The second study utilised the modified PCL to investigate the impact of different types of onset of pain (e.g. traumatic onset) and posttraumatic stress symptoms on adjustment to chronic pain in a sample of 196 chronic pain patients referred to the same centre. For patients who experienced the onset of pain related to a specific event, two independent experts in the field of PTSD determined whether these events satisfied the definition of a traumatic event according to DSM-IV diagnostic criteria. Adjustment was assessed through a number of validated measures of mood, disability, pain experience, and pain-related cognitions. Contrary to expectations, comparisons between patients who had experienced different types of onset of pain revealed few significant differences between them. That is, analyses comparing patients presenting with accident-related pain, or pain related to other specific events, to patients who had experienced spontaneous or insidious onset of pain revealed no significant differences between the groups on measures of pain severity, pain-related disability, and symptoms of affective distress after adjustment for age, pain duration, and compensation status. Similarly, comparisons between patients who had experienced a potentially traumatic onset of pain with those who had experienced a non-traumatic or spontaneous or insidious onset of pain also revealed no significant differences on the aforementioned variables. In contrast, compensation status, age, and a number of cognitive variables were significant predictors of pain severity, pain-related disability, and depression. The final study investigated the impact of type of pain onset and posttraumatic stress symptoms on response to a multidisciplinary cognitive-behavioural pain management program. Unlike the previous study, this treatment outcome study revealed a number of differences between onset groups. Most notably, patients who had experienced an insidious or spontaneous onset of pain reported greater improvements in pain severity and maintained these improvements more effectively over a one month period than patients who had experienced pain in the context of an accident or other specific incident. There was also limited evidence that improvements in depression favoured patients who had experienced an insidious or spontaneous and non-traumatic onset of pain. Consistent with this, posttraumatic stress symptoms were a significant predictor of treatment outcome, with higher levels of symptoms being associated with smaller improvements in pain-related disability and distress. Notably, this study also revealed that certain cognitive variables (i.e. catastrophising, self-efficacy, and fear-avoidance beliefs) were also significant predictors of treatment outcome, consistent with previous findings in the pain literature. This provided some perspective on the relative roles of both PTSD symptoms and cognitive variables in adjustment to persisting pain and treatment response. These findings were all consistent with expectations and with previous research. Implications for future research and for the assessment and treatment of chronic pain patients who present with posttraumatic stress symptoms are discussed

Black Hole Spin via Continuum Fitting and the Role of Spin in Powering Transient Jets

The spins of ten stellar black holes have been measured using the continuum-fitting method. These black holes are located in two distinct classes of X-ray binary systems, one that is persistently X-ray bright and another that is transient. Both the persistent and transient black holes remain for long periods in a state where their spectra are dominated by a thermal accretion disk component. The spin of a black hole of known mass and distance can be measured by fitting this thermal continuum spectrum to the thin-disk model of Novikov and Thorne; the key fit parameter is the radius of the inner edge of the black hole's accretion disk. Strong observational and theoretical evidence links the inner-disk radius to the radius of the innermost stable circular orbit, which is trivially related to the dimensionless spin parameter a_* of the black hole (|a_*| < 1). The ten spins that have so far been measured by this continuum-fitting method range widely from a_* \approx 0 to a_* > 0.95. The robustness of the method is demonstrated by the dozens or hundreds of independent and consistent measurements of spin that have been obtained for several black holes, and through careful consideration of many sources of systematic error. Among the results discussed is a dichotomy between the transient and persistent black holes; the latter have higher spins and larger masses. Also discussed is recently discovered evidence in the transient sources for a correlation between the power of ballistic jets and black hole spin.Comment: 30 pages. Accepted for publication in Space Science Reviews. Also to appear in hard cover in the Space Sciences Series of ISSI "The Physics of Accretion onto Black Holes" (Springer Publisher). Changes to Sections 5.2, 6.1 and 7.4. Section 7.4 responds to Russell et al. 2013 (MNRAS, 431, 405) who find no evidence for a correlation between the power of ballistic jets and black hole spi

Radio emission and jets from microquasars

To some extent, all Galactic binary systems hosting a compact object are potential `microquasars', so much as all galactic nuclei may have been quasars, once upon a time. The necessary ingredients for a compact object of stellar mass to qualify as a microquasar seem to be: accretion, rotation and magnetic field. The presence of a black hole may help, but is not strictly required, since neutron star X-ray binaries and dwarf novae can be powerful jet sources as well. The above issues are broadly discussed throughout this Chapter, with a a rather trivial question in mind: why do we care? In other words: are jets a negligible phenomenon in terms of accretion power, or do they contribute significantly to dissipating gravitational potential energy? How do they influence their surroundings? The latter point is especially relevant in a broader context, as there is mounting evidence that outflows powered by super-massive black holes in external galaxies may play a crucial role in regulating the evolution of cosmic structures. Microquasars can also be thought of as a form of quasars for the impatient: what makes them appealing, despite their low number statistics with respect to quasars, are the fast variability time-scales. In the first approximation, the physics of the jet-accretion coupling in the innermost regions should be set by the mass/size of the accretor: stellar mass objects vary on 10^5-10^8 times shorter time-scales, making it possible to study variable accretion modes and related ejection phenomena over average Ph.D. time-scales. [Abridged]Comment: 28 pages, 13 figures, To appear in Belloni, T. (ed.): The Jet Paradigm - From Microquasars to Quasars, Lect. Notes Phys. 794 (2009

General Relativistic MHD Jets

Magnetic fields connecting the immediate environs of rotating black holes to large distances appear to be the most promising mechanism for launching relativistic jets, an idea first developed by Blandford and Znajek in the mid-1970s. To enable an understanding of this process, we provide a brief introduction to dynamics and electromagnetism in the spacetime near black holes. We then present a brief summary of the classical Blandford-Znajek mechanism and its conceptual foundations. Recently, it has become possible to study these effects in much greater detail using numerical simulation. After discussing which aspects of the problem can be handled well by numerical means and which aspects remain beyond the grasp of such methods, we summarize their results so far. Simulations have confirmed that processes akin to the classical Blandford-Znajek mechanism can launch powerful electromagnetically-dominated jets, and have shown how the jet luminosity can be related to black hole spin and concurrent accretion rate. However, they have also shown that the luminosity and variability of jets can depend strongly on magnetic field geometry. We close with a discussion of several important open questions.Comment: 21 pages, 2 figures, To appear in Belloni, T. (ed.): The Jet Paradigm - From Microquasars to Quasars, Lect. Notes Phys. 794 (2009

Investigating the composition and recruitment of the mycobacterial ImuA'-ImuB-DnaE2 mutasome

A DNA damage-inducible mutagenic gene cassette has been implicated in the emergence of drug resistance in Mycobacterium tuberculosis during anti-tuberculosis (TB) chemotherapy. However, the molecular composition and operation of the encoded 'mycobacterial mutasome' - minimally comprising DnaE2 polymerase and ImuA ' and ImuB accessory proteins - remain elusive. Following exposure of mycobacteria to DNA damaging agents, we observe that DnaE2 and ImuB co-localize with the DNA polymerase III beta subunit (beta clamp) in distinct intracellular foci. Notably, genetic inactivation of the mutasome in an imuB(AAAAGG) mutant containing a disrupted beta clamp-binding motif abolishes ImuB-beta clamp focus formation, a phenotype recapitulated pharmacologically by treating bacilli with griselimycin and in biochemical assays in which this beta clamp-binding antibiotic collapses pre-formed ImuB-beta clamp complexes. These observations establish the essentiality of the ImuB-beta clamp interaction for mutagenic DNA repair in mycobacteria, identifying the mutasome as target for adjunctive therapeutics designed to protect anti-TB drugs against emerging resistance.Microscopic imaging and technolog

The ELFIN mission

The Electron Loss and Fields Investigation with a Spatio-Temporal Ambiguity-Resolving option (ELFIN-STAR, or heretoforth simply: ELFIN) mission comprises two identical 3-Unit (3U) CubeSats on a polar (∼93∘ inclination), nearly circular, low-Earth (∼450 km altitude) orbit. Launched on September 15, 2018, ELFIN is expected to have a >2.5 year lifetime. Its primary science objective is to resolve the mechanism of storm-time relativistic electron precipitation, for which electromagnetic ion cyclotron (EMIC) waves are a prime candidate. From its ionospheric vantage point, ELFIN uses its unique pitch-angle-resolving capability to determine whether measured relativistic electron pitch-angle and energy spectra within the loss cone bear the characteristic signatures of scattering by EMIC waves or whether such scattering may be due to other processes. Pairing identical ELFIN satellites with slowly-variable along-track separation allows disambiguation of spatial and temporal evolution of the precipitation over minutes-to-tens-of-minutes timescales, faster than the orbit period of a single low-altitude satellite (Torbit ∼ 90 min). Each satellite carries an energetic particle detector for electrons (EPDE) that measures 50 keV to 5 MeV electrons with Δ E/E 1 MeV. This broad energy range of precipitation indicates that multiple waves are providing scattering concurrently. Many observed events show significant backscattered fluxes, which in the past were hard to resolve by equatorial spacecraft or non-pitch-angle-resolving ionospheric missions. These observations suggest that the ionosphere plays a significant role in modifying magnetospheric electron fluxes and wave-particle interactions. Routine data captures starting in February 2020 and lasting for at least another year, approximately the remainder of the mission lifetime, are expected to provide a very rich dataset to address questions even beyond the primary mission science objective.Published versio