Mission Concept for the Single Aperture Far-Infrared (SAFIR) Observatory

The Single Aperture Far-InfraRed (SAFIR) Observatory's science goals are driven by the fact that the earliest stages of almost all phenomena in the universe are shrouded in absorption by and emission from cool dust and gas that emits strongly in the far-infrared and submillimeter. Over the past several years, there has been an increasing recognition of the critical importance of this spectral region to addressing fundamental astrophysical problems, ranging from cosmological questions to understanding how our own Solar System came into being. The development of large, far-infrared telescopes in space has become more feasible with the combination of developments for the James Webb Space Telescope and of enabling breakthroughs in detector technology. We have developed a preliminary but comprehensive mission concept for SAFIR, as a 10 m-class far-infrared and submillimeter observatory that would begin development later in this decade to meet the needs outlined above. Its operating temperature (<4K) and instrument complement would be optimized to reach the natural sky confusion limit in the far-infrared with diffraction-limited peformance down to at least 40 microns. This would provide a point source sensitivity improvement of several orders of magnitude over that of Spitzer or Herschel, with finer angular resolution, enabling imaging and spectroscopic studies of individual galaxies in the early universe. We have considered many aspects of the SAFIR mission, including the telescope technology, detector needs and technologies, cooling method and required technology developments, attitude and pointing, power systems, launch vehicle, and mission operations. The most challenging requirements for this mission are operating temperature and aperture size of the telescope, and the development of detector arrays.Comment: 36 page

A pain science education and walking program to increase physical activity in people with symptomatic knee osteoarthritis: A feasibility study

Introduction: Nine of 10 people with knee osteoarthritis are inactive. Unhelpful pain beliefs may negatively influence physical activity levels. Targeting these unhelpful pain beliefs, through contemporary pain science education (PSE), may provide benefit. Objectives: To evaluate the feasibility of conducting a clinical trial to determine the effect of adding PSE (vs adding sham ultrasound) to an individualised, physiotherapist-led education and walking program in people with painful knee osteoarthritis. Methods: Twenty participants were randomised (1:1) into the PSE group or Control group, each receiving 4 in-person weekly treatments, then 4 weeks of at-home activities (weekly telephone check-in). Clinical outcomes and physical activity (7 days of wristworn accelerometry) were assessed at baseline, 4 (clinical outcomes only), 8, and 26 weeks. A priori feasibility criteria for recruitment, intervention adherence, viability of wrist-based accelerometry, and follow-up retention were set. Perceived intervention credibility, acceptability, and usefulness from participants and clinicians were assessed (ratings, written/verbal feedback). Results: Most feasibility criteria were met. On average, 7 adults/wk were eligible, with 70% recruited. Treatment compliance was high (in-person: 80% PSE; 100% Control; at-home: 78% PSE; 75% Control). Wrist-based accelerometry had .75% valid weartime. Sufficient follow-up rates were not achieved (26 weeks: 65%). Participant and clinician feedback highlighted that PSE was too complex and did not match patient expectations of “physiotherapy”, that sham ultrasound was problematic (clinician), but that both treatments had high credibility, acceptability, and usefulness. Conclusions: Progression to a full trial is warranted. Strategies to increase participant retention, refine the PSE content/delivery, and replace/remove the sham intervention are required.Tasha R. Stanton, Emma L. Karran, David S. Butler, Melissa J. Hull, Sarah N. Schwetlik, Felicity A. Braithwaite, Hannah G. Jones, G. Lorimer Moseley, Catherine L. Hill, Christy Tomkins-Lane, Carol Maher, Kim Bennel

Social learning in LEADER: Exogenous, endogenous and hybrid evaluation in rural development

This paper considers the relationship between the centralised exogenous, institutions and the embedded, endogenous institutions of rural governance in Europe through an examination the evaluation procedures of the European LEADER programme. LEADER is presented in the literature as progressive in terms of innovation and stakeholder engagement. Yet while the planning and management of LEADER embraces heterogeneity and participation, programmatic evaluation is centralised and held at arms length from delivery organisations. The paper reviews previous efforts to improve evaluation in LEADER and considers alternative strategies for evaluation, contrasting LEADER practice with participatory evaluation methodologies in the wider international context. Can evaluation in itself be valuable as a mode of social learning and hence a driver for endogenous development in rural communities in Europe? The paper concludes by examining the challenges in producing a hybrid form of evaluation which accommodates endogenous and exogenous values

Dust in Supernovae and Supernova Remnants II: Processing and survival

Observations have recently shown that supernovae are efficient dust factories, as predicted for a long time by theoretical models. The rapid evolution of their stellar progenitors combined with their efficiency in precipitating refractory elements from the gas phase into dust grains make supernovae the major potential suppliers of dust in the early Universe, where more conventional sources like Asymptotic Giant Branch (AGB) stars did not have time to evolve. However, dust yields inferred from observations of young supernovae or derived from models do not reflect the net amount of supernova-condensed dust able to be expelled from the remnants and reach the interstellar medium. The cavity where the dust is formed and initially resides is crossed by the high velocity reverse shock which is generated by the pressure of the circumstellar material shocked by the expanding supernova blast wave. Depending on grain composition and initial size, processing by the reverse shock may lead to substantial dust erosion and even complete destruction. The goal of this review is to present the state of the art about processing and survival of dust inside supernova remnants, in terms of theoretical modelling and comparison to observations

Whole-body vibration and visual performance: An examination of spatial filtering and time-dependency

Two experiments have examined the effects of whole-body vibration on visual performance. The first experiment concerned alphanumeric reading performance and contrast thresholds for gratings subtending 7-5, 10 and 12-5 cycles per degree (c deg-1. Seated subjects were exposed to vertical sinusoidal whole-body vibration (4 Hz, 2-5ms-2 r.m.s.). Greatest reading errors occurred with characters exhibiting a high spatial complexity in their vertical axis. Reductions in contrast sensitivity due to vibration increased with increasing spatial frequency, the greatest loss occurring with horizontally orientated gratings. In the second experiment, contrast thresholds for horizontally orientated gratings subtending 1-5 and 12-5cdeg-1 were obtained from ten subjects at five-minute intervals during a 60-minute whole-body vibration exposure (20 Hz 1.7 ms-2 r.m.s.), a 20-minute pre-exposure and a 60-minute post-exposure period. There were no significant changes in contrast thresholds for gratings subtending 1-5cdeg-1 during or after vibration exposure. A large variation was found in the effect of vibration upon performance with the higher spatial frequency grating both during and after vibration exposure. Significant correlations between vertical head motion and contrast sensitivity were obtained with five of the ten subjects, suggesting that time-dependent changes in seat-to-head transmissibility were partly responsible for the results. Other time-dependent changes were found with the high spatial frequency grating. Possible explanations are discussed.</p

The effects of vibration on visual performance and display legibility

The research programme described in this thesis examines the theoretical and practical aspects of visual degradation caused by vibration. Initially, the published literature was reviewed in two areas: the effects of vibration on visual performance and the influence of display parameters on legibility under normal and vibration-degraded viewing conditions. A series of eight experiments were then conducted to assess visual performance and display legibility with reading and threshold detection tasks presented on cathode ray tube displays. The first experiment compared the visual degradation caused by sinusoidal and narrow-band random vibration in the frequency range 2.5 to 31.5 Hz. Random vibration produced a significantly smaller reading performance decrement than sinusoidal vibration. This finding was attributed to the greater probability of low image velocity with the random vibration stimuli and, in a follow-up experiment, velocity-based predictions accounted for the visual performance decrements due to laboratory-simulated aircraft vibration. A comparison of the effects of whole-body, display and simultaneous whole-body and display vibration showed that at frequencies below 4 Hz, vibration of the display resulted in the largest performance decrement and simultaneous vibration of observer and display, the least. In a second series of experiments, display parameters (horizontal and vertical character separation, contrast, font and symbol definition) were manipulated during static and vibration-degraded viewing conditions. Vertical separation was found to be a more significant variable than horizontal separation and tentative guidelines for character separation were stated. The relationship between contrast and legibility was shown to be quadratic during static and vibration-degraded viewing conditions. Optimum legibility occurred in the contrast range 60 to 88% . The determination of font and symbol definition requirements showed that for characters of equal subtense, 7x9 dot-matrix characters were significantly more legible than 5x7 characters during whole-body vibration. Differences between two frequently recommended fonts, the Huddleston and Lincoln Mitre, were not apparent at 7x9 definition although at 5x7 definition the Huddleston font was responsible for significantly fewer reading errors. In the final experiment, the spatial filtering characteristics of vibration were examined. In addition to an alphanumeric reading task, contrast thresholds for sinusoidally modulated grating patterns were determined during whole-body vibration. It was shown that the effects of vibration could be conceived as low-pass spatial filtering and the implications of this finding for simulating the effects of vibration were discussed. The overall findings of the experimental programme have been summarised and areas for future research discussed

Sinusoidal and random whole-body vibration: comparative effects on visual performance

An experimental comparison of the effect of whole-body sinusoidal and one-third octave-band random vibration on the performance of a display reading task is described. The findings indicate that one-third octave-band random vibration has significantly less effect on performance. Subsequent measurements of rotational head motion demonstrated that this finding may be due to differences in the velocity probability density distributions produced by the different motions. Subjects also performed the visual task during exposure to several broad-band random motions. Predicted error values were obtained by averaging the frequency weighted time histories of these motions. It was found that both R.M.S. and R.M.Q. averaging procedures applied to the broad-band frequency weighted time histories gave accurate error predictions when compared with the measured error scores. Practical implications of the experimental findings and recommendations for future research are discussed.</p