The stability of orbits of putative Earth-mass planets or satellites of giant planets within known exoplanetary systems.

The movement of the habitable zone of 55 stars from 0.5 to 1.5 Solar masses and 0.75% to 5% metallicity were modelled over their main sequence lifetimes. 156 stars known to have planetary systems had their mass and metallicity matched to their nearest model, giving approximate habitable zones, which were compared with their giant planet(s)’s orbital range and gravitational reach. Habitable zones lying outside a giant’s gravitational reach for one billion years (two billion years after star birth) could host an Earth-mass planet in a stable confined orbit long enough for life to develop. Low eccentricity giant orbits confined to the habitable zone could also host Earth-mass satellites. Results show 85 of 156 exosystems could house a habitable Earth-mass body over the last billion years, 113 could do so for at least a billion years at sometime during their main sequence lifetimes, excluding the heavy bombardment period. An orbital integrator computer program modelled orbits of Earth-mass planets in the habitable zones of x1 Gruis, HD 196050, HD 52265, 55 Cancri, and Earth-mass giant planet satellites in HD 23079 and HD 28185. The integrator’s predictions for satellite orbits were shown to comply with restricted three-body problem theory. ‘Earths’ were ‘launched’ at different distances from the star or planet and their orbital parameters monitored with time until the program concluded after either one billion years, 100 million years, or a cataclysmic event. Orbits lasting the full run time are assumed to remain stable for the star’s main sequence lifetime. Results reveal the possibility of habitable Earth-mass planets around HD 52265, 55 Cancri, and satellites around the giants of HD 23079 and HD 28185. The x1 Gruis system cannot host a habitable ‘Earth’ whereas HD 196050 could, provided the planet’s semimajor axis was at the inner 20% of the habitable zone width

The Stability of the orbits of Earth-mass planets in and near the habitable zones of known exoplanetary systems

We have shown that Earth-mass planets could survive in variously restricted regions of the habitable zones (HZs) of most of a sample of nine of the 93 main-sequence exoplanetary systems confirmed by May 2003. In a preliminary extrapolation of our results to the other systems, we estimate that roughly a third of the 93 systems might be able to have Earth-mass planets in stable, confined orbits somewhere in their HZs. Clearly, these systems should be high on the target list for exploration for terrestrial planets. We have reached this conclusion by launching putative Earth-mass planets in various orbits and following their fate with a mixed-variable symplectic integrator

Habitability of known exoplanetary systems based on measured stellar properties

At present, because of observational selection effects, we know of no exoplanetary systems with any planetary masses close to that of the Earth. We have therefore used computer models to see whether such planets could be dynamically stable in the presence of the more massive planets known to be present, and in particular whether planets with roughly an Earth mass could remain confined to the classical habitable zone (HZ) for long enough for life to have emerged. Measured stellar properties have been used to determine for each system the present location of the HZ. We have also determined the critical distances from the orbit of each giant planet within which an Earth-mass planet would suffer large orbital changes. We then evaluated the present habitability of each and every exoplanetary system by examining the penetration of these critical distances into the HZ. The critical distances can be obtained by extensive computer modelling of an exoplanetary system. This is far too time consuming to apply to all of the 150 or so systems already known, and to keep up with the latest discoveries. Therefore, in earlier work we studied a few systems in great detail, and developed a speedier means of obtaining the critical distances. We summarize this comparatively quick method here. We can then evaluate comparatively quickly the present habitability of each exoplanetary system by examining the penetration of the critical distance(s) into the HZ. The results are encouraging for astrobiology.Comment: Accepted for publication by The Astrophysical Journal. A few revisions have been made following suggestions by the refere

Fidelity in complex behaviour change interventions : a standardised approach to evaluate intervention integrity

Objectives: The aim of this study was to (1) demonstrate the development and testing of tools and procedures designed to monitor and assess the integrity of a complex intervention for chronic pain (COping with persistent Pain, Effectiveness Research into Self-management (COPERS) course); and (2) make recommendations based on our experiences. Design: Fidelity assessment of a two-arm randomised controlled trial intervention, assessing the adherence and competence of the facilitators delivering the intervention. Setting: The intervention was delivered in the community in two centres in the UK: one inner city and one a mix of rural and urban locations. Participants: 403 people with chronic musculoskeletal pain were enrolled in the intervention arm and 300 attended the self-management course. Thirty lay and healthcare professionals were trained and 24 delivered the courses (2 per course). We ran 31 courses for up to 16 people per course and all were audio recorded. Interventions: The course was run over three and a half days; facilitators delivered a semistructured manualised course. Outcomes: We designed three measures to evaluate fidelity assessing adherence to the manual, competence and overall impression. Results: We evaluated a random sample of four components from each course (n=122). The evaluation forms were reliable and had good face validity. There were high levels of adherence in the delivery: overall adherence was two (maximum 2, IQR 1.67–2.00), facilitator competence exhibited more variability, and overall competence was 1.5 (maximum 2, IQR 1.25–2.00). Overall impression was three (maximum 4, IQR 2.00–3.00). Conclusions: Monitoring and assessing adherence and competence at the point of intervention delivery can be realised most efficiently by embedding the principles of fidelity measurement within the design stage of complex interventions and the training and assessment of those delivering the intervention. More work is necessary to ensure that more robust systems of fidelity evaluation accompany the growth of complex interventions

Universal quantum computation by discontinuous quantum walk

Quantum walks are the quantum-mechanical analog of random walks, in which a quantum `walker' evolves between initial and final states by traversing the edges of a graph, either in discrete steps from node to node or via continuous evolution under the Hamiltonian furnished by the adjacency matrix of the graph. We present a hybrid scheme for universal quantum computation in which a quantum walker takes discrete steps of continuous evolution. This `discontinuous' quantum walk employs perfect quantum state transfer between two nodes of specific subgraphs chosen to implement a universal gate set, thereby ensuring unitary evolution without requiring the introduction of an ancillary coin space. The run time is linear in the number of simulated qubits and gates. The scheme allows multiple runs of the algorithm to be executed almost simultaneously by starting walkers one timestep apart.Comment: 7 pages, revte

Single-qubit unitary gates by graph scattering

We consider the effects of plane-wave states scattering off finite graphs, as an approach to implementing single-qubit unitary operations within the continuous-time quantum walk framework of universal quantum computation. Four semi-infinite tails are attached at arbitrary points of a given graph, representing the input and output registers of a single qubit. For a range of momentum eigenstates, we enumerate all of the graphs with up to $n=9$ vertices for which the scattering implements a single-qubit gate. As $n$ increases, the number of new unitary operations increases exponentially, and for $n>6$ the majority correspond to rotations about axes distributed roughly uniformly across the Bloch sphere. Rotations by both rational and irrational multiples of $\pi$ are found.Comment: 8 pages, 7 figure

Identifying potential moderators for response to treatment in low back pain : a systematic review

Background: Identifying which patients with non-specific low back pain are likely to gain the greatest benefit from different treatments is an important research priority. Few studies are large enough to produce data on sub-group effects from different treatments. Data from existing large studies may help identify potential moderators to use in future individual patient data meta-analyses. Objective: To systematically review papers of therapist delivered interventions for low back pain to identify potential moderators to inform an individual patient data meta-analysis. Data sources: We searched MEDLINE, EMBASE, Web of Science and Citation Index and Cochrane Register of Controlled Trials (CENTRALhttp://www.cochrane.org/editorial-and-publishing-policy-resource/cochrane-central-register-controlled-trials-central) for relevant papers. Data extraction and data synthesis: We screened for randomised controlled trials with ≥500 or more participants, and cohort studies of ≥1000 or more participants. We examined all publications related to these studies for any reported moderator analyses. Two reviewers independently did risk of bias assessment of main results and quality assessment of any moderator analyses. Results: We included four randomised trials (n=7208). Potential moderators with strong evidence (p<0.05) in one or more studies were age, employment status and type, back pain status, narcotic medication use, treatment expectations and education. Potential moderators with weaker evidence (0.05<p≤0.20) included gender, psychological distress, pain/disability and quality of life. Conclusion: There are insufficient robust data on moderators to be useful in clinical practice. This review has identified some important potential moderators of treatment effect worthy of testing in future confirmatory analyses

Intra-articular facet joint injections for low back pain : a systematic review

Purpose: Evidence supporting the use of therapeutic intra-articular facet joint injections for patients with suspected facet joint pain is sparse. A systematic review including a narrative synthesis was carried out to determine if intra-articular facet joint injections with active drug are more effective in reducing back pain and back pain-related disability than a sham procedure or a placebo/inactive injection. Secondly, to determine if intra-articular facet joint injections with active drug or placebo/inactive injection are more effective in reducing back pain and back pain-related disability than conservative treatment. Methods: Medline, EMBASE, CINAHL, CENTRAL, Index to Chiropractic Literature and the Cochrane Central Register of Controlled Trials were searched from inception through April 2015. Data were screened and single extraction with independent verification and risk of bias assessment was performed. Results: A total of 391 records were screened, and six trials were included. The trials included were small (range 18–109 participants) and overall in terms of pain and disability outcomes most were inconclusive. Only two of the trials report any significant between-group differences in pain (mean difference −1.0, 95 % CI −2.0 to −0.1) and (p = 0.032) or disability (mean difference −3.0, 95 % CI −6.2 to 0.2) and (p = 0.013) outcomes. Conclusions: The studies found here were clinically diverse and precluded any meta-analysis. A number of methodological issues were identified. The positive results, whilst interpreted with caution, do suggest that there is a need for further high-quality work in this area

Whole home exercise intervention for depression in older care home residents (the OPERA study) : a process evaluation

Background: The ‘Older People’s Exercise intervention in Residential and nursing Accommodation’ (OPERA) cluster randomised trial evaluated the impact of training for care home staff together with twice-weekly, physiotherapist-led exercise classes on depressive symptoms in care home residents, but found no effect. We report a process evaluation exploring potential explanations for the lack of effect. Methods: The OPERA trial included over 1,000 residents in 78 care homes in the UK. We used a mixed methods approach including quantitative data collected from all homes. In eight case study homes, we carried out repeated periods of observation and interviews with residents, care staff and managers. At the end of the intervention, we held focus groups with OPERA research staff. We reported our first findings before the trial outcome was known. Results: Homes showed large variations in activity at baseline and throughout the trial. Overall attendance rate at the group exercise sessions was low (50%). We considered two issues that might explain the negative outcome: whether the intervention changed the culture of the homes, and whether the residents engaged with the intervention. We found low levels of staff training, few home champions for the intervention and a culture that prioritised protecting residents from harm over encouraging activity. The trial team delivered 3,191 exercise groups but only 36% of participants attended at least 1 group per week and depressed residents attended significantly fewer groups than those who were not depressed. Residents were very frail and therefore most groups only included seated exercises. Conclusions: The intervention did not change the culture of the homes and, in the case study homes, activity levels did not change outside the exercise groups. Residents did not engage in the exercise groups at a sufficient level, and this was particularly true for those with depressive symptoms at baseline. The physical and mental frailty of care home residents may make it impossible to deliver a sufficiently intense exercise intervention to impact on depressive symptoms