International perspectives on validity in action research: introduction to the special issue

This special issue has its roots in a series of meetings at the annual EGOS conferences held between 2001 and 2007. The Action Research sub-theme at these annual meetings has attracted almost 200 papers from authors on every continent. A particular focus of the group has been the socio-economic approach to action research developed by Henri Savall and the ISEOR team which discusses what Savall describes as "Generic Contingencies” and a “qualimetrics research methodology” (2003). The meetings have drawn together a truly international grouping of researchers who share a common interest in working closely with the world of practice to “make a difference.

Overcoming change fatigue: lessons from Glasgow's National Health Service

Structured Abstract Purpose of this paper This paper explores the practicalities of organizational change in complex settings where much change has already occurred. It therefore offers insights into tackling and overcoming change fatigue. Design/methodology/approach The paper uses a longitudinal study of change within a healthcare organization. The paper draws on interviews, focus groups and observations during a 2.5 year long action research project. Findings The paper reports findings on the speed at which change takes place, the importance of communication and the burden placed on senior officers during such communication and consultation processes, the use of appropriate external resources and expertise, the benefits of sharing best practice across sectors and the role of academic researchers in change processes. What is original/value of paper The paper offers valuable insights to those charged with effecting organizational change in change fatigued settings

'But I thought we were friends?' Life cycles and research relationships

This chapter is concerned with a relatively under-explored aspect of ‘engaged research’ – the nature of friendship relations between researchers and practitioners, and the ethical dilemmas that arise in such relationships. Attention has been paid to the relational aspects of research in the methodology literature, but this chapter focuses more closely on friendship in particular. The chapter is framed around two guiding concerns: how do friendships, formed in and around research, change over time; and in view of friendship conceived in this dynamic fashion, what ethical questions and dilemmas arise for the ‘friends’

Angular Differential Imaging: a Powerful High-Contrast Imaging Technique

Angular differential imaging is a high-contrast imaging technique that reduces quasi-static speckle noise and facilitates the detection of nearby companions. A sequence of images is acquired with an altitude/azimuth telescope while the instrument field derotator is switched off. This keeps the instrument and telescope optics aligned and allows the field of view to rotate with respect to the instrument. For each image, a reference PSF is constructed from other appropriately-selected images of the same sequence and subtracted to remove quasi-static PSF structure. All residual images are then rotated to align the field and are combined. Observed performances are reported for Gemini North data. It is shown that quasi-static PSF noise can be reduced by a factor \~5 for each image subtraction. The combination of all residuals then provides an additional gain of the order of the square root of the total number of acquired images. A total speckle noise attenuation of 20-50 is obtained for one-hour long observing sequences compared to a single 30s exposure. A PSF noise attenuation of 100 was achieved for two-hour long sequences of images of Vega, reaching a 5-sigma contrast of 20 magnitudes for separations greater than 8". For a 30-minute long sequence, ADI achieves 30 times better signal-to-noise than a classical observation technique. The ADI technique can be used with currently available instruments to search for ~1MJup exoplanets with orbits of radii between 50 and 300 AU around nearby young stars. The possibility of combining the technique with other high-contrast imaging methods is briefly discussed.Comment: 27 pages, 7 figures, accepted for publication in Ap

Studies on Molecular Sieve Crystallization and Heteroatomic Substitution

Molecular sieves have been scientifically and industrially important materials since their inception. These porous, crystalline networks of tetrahedrally coordinated atoms bridged by oxygen are known for their extremely high surface area and low density, making them excellent systems for catalysis. The framework of the AlPO4 family of molecular sieves is itself non-catalytic, but through heteroatomic substitution these materials can diversify into the catalytically active silicoaluminophosphate (SAPO) and metalloaluminophosphate (MAPO) families of heterogeneous acid and redox catalysts. Research into the methods by which these substitutions occur, and the effects therein on the crystallization of the sieves, is of great importance, as discoveries can lead to refined control over material property and function. To that end, this thesis is concerned with heteroatomic substitution in AlPO4 molecular sieves. SAPO-5 and MAPO-5 were chosen as model systems. Both the dry-gel conversion and hydrothermal synthesis methods were used to produce crystallization intermediates for study. Solid state NMR spectroscopy was used as the primary method of investigation. The SAPO-5 study determined that the dry-gel conversion methods of steam assisted conversion and vapour phase transport follow similar reaction pathways. After an initial divergence caused by the lack of organic structure directing agent in the gel in the VPT method, crystallization is similar between methods, and silicon incorporation results in two populations of silicon sites. One is well incorporated into the framework, while the other either represents reagent silica or dense silicon islands within the framework. The vapour phase silicon uptake method provides a contrast to this data, producing a uniquely well-incorporated silicon population (albeit with significantly less substitution). The MAPO-5 study, looking at manganese and iron substitution, showed that metal centers coordinate with phosphorous very early in the reaction, and are incorporated into the developing sieve before any channels or framework structure are formed. It showed that the use of the hydrothermal synthesis can be effective in capturing crystallization intermediates, and that the presence of paramagnetic materials does not exclude NMR from being a vital source of information

Sarcomere length-dependence of activity-dependent twitch potentiation in mouse skeletal muscle

BACKGROUND: It has been reported that potentiation of a skeletal muscle twitch response is proportional to muscle length with a negative slope during staircase, and a positive slope during posttetanic potentiation. This study was done to directly compare staircase and posttetanic responses with measurement of sarcomere length to compare their length-dependence. METHODS: Mouse extensor digitorum longus (EDL) muscles were dissected to small bundles of fibers, which permit measurement of sarcomere length (SL), by laser diffraction. In vitro fixed-end contractions of EDL fiber bundles were elicited at 22°C and 35°C at sarcomere lengths ranging from 2.35 μm to 3.85 μm. Twitch contractions were assessed before and after 1.5 s of 75 Hz stimulation at 22°C or during 10 s of 10 Hz stimulation at 22°C or 35°C. RESULTS: Staircase potentiation was greater at 35°C than 22°C, and the relative magnitude of the twitch contraction (P(t)*/P(t)) was proportional to sarcomere length with a negative slope, over the range 2.3 μm – 3.7 μm. Linear regression yielded the following: P(t)*/P(t )= -0.59·SL+3.27 (r(2 )= 0.74); P(t)*/P(t )= -0.39·SL+2.34 (r(2 )= 0.48); and P(t)*/P(t )= -0.50·SL+2.45 (r(2 )= 0.80) for staircase at 35°C, and 22°C and posttetanic response respectively. Posttetanic depression rather than potentiation was present at long SL. This indicates that there may be two processes operating in these muscles to modulate the force: one that enhances and a second that depresses the force. Either or both of these processes may have a length-dependence of its mechanism. CONCLUSION: There is no evidence that posttetanic potentiation is fundamentally different from staircase in these muscles

The Structure of High Strehl Ratio Point-Spread Functions

We describe the symmetries present in the point-spread function (PSF) of an optical system either located in space or corrected by an adaptive o to Strehl ratios of about 70% and higher. We present a formalism for expanding the PSF to arbitrary order in terms of powers of the Fourier transform of the residual phase error, over an arbitrarily shaped and apodized entrance aperture. For traditional unapodized apertures at high Strehl ratios, bright speckles pinned to the bright Airy rings are part of an antisymmetric perturbation of the perfect PSF, arising from the term that is first order in the residual phase error. There are two symmetric second degree terms. One is negative at the center, and, like the first order term, is modulated by the perfect image's field strength -- it reduces to the Marechal approximation at the center of the PSF. The other is non-negative everywhere, zero at the image center, and can be responsible for an extended halo -- which limits the dynamic range of faint companion detection in the darkest portions of the image. In regimes where one or the other term dominates the speckles in an image, the symmetry of the dominant term can be exploited to reduce the effect of those speckles, potentially by an order of magnitude or more. We demonstrate the effects of both secondary obscuration and pupil apodization on the structure of residual speckles, and discuss how these symmetries can be exploited by appropriate telescope and instrument design, observing strategies, and filter bandwidths to improve the dynamic range of high dynamic range AO and space-based observations. Finally, we show that our analysis is relevant to high dynamic range coronagraphy.Comment: Accepted for publication in ApJ; 20 pages, 4 figure

Direct Imaging of Multiple Planets Orbiting the Star HR 8799

Direct imaging of exoplanetary systems is a powerful technique that can reveal Jupiter-like planets in wide orbits, can enable detailed characterization of planetary atmospheres, and is a key step towards imaging Earth-like planets. Imaging detections are challenging due to the combined effect of small angular separation and large luminosity contrast between a planet and its host star. High-contrast observations with the Keck and Gemini telescopes have revealed three planets orbiting the star HR 8799, with projected separations of 24, 38, and 68 astronomical units. Multi-epoch data show counter-clockwise orbital motion for all three imaged planets. The low luminosity of the companions and the estimated age of the system imply planetary masses between 5 and 13 times that of Jupiter. This system resembles a scaled-up version of the outer portion of our Solar System.Comment: 30 pages, 5 figures, Research Article published online in Science Express Nov 13th, 200

Astrometric Monitoring of the HR 8799 Planets: Orbit Constraints from Self-Consistent Measurements

We present new astrometric measurements from our ongoing monitoring campaign of the HR 8799 directly imaged planetary system. These new data points were obtained with NIRC2 on the W.M. Keck II 10 meter telescope between 2009 and 2014. In addition, we present updated astrometry from previously published observations in 2007 and 2008. All data were reduced using the SOSIE algorithm, which accounts for systematic biases present in previously published observations. This allows us to construct a self-consistent data set derived entirely from NIRC2 data alone. From this dataset, we detect acceleration for two of the planets (HR 8799b and e) at $>$3$\sigma$. We also assess possible orbital parameters for each of the four planets independently. We find no statistically significant difference in the allowed inclinations of the planets. Fitting the astrometry while forcing coplanarity also returns $\chi^2$ consistent to within 1$\sigma$ of the best fit values, suggesting that if inclination offsets of $\lesssim$20$^{o}$ are present, they are not detectable with current data. Our orbital fits also favor low eccentricities, consistent with predictions from dynamical modeling. We also find period distributions consistent to within 1$\sigma$ with a 1:2:4:8 resonance between all planets. This analysis demonstrates the importance of minimizing astrometric systematics when fitting for solutions to highly undersampled orbits.Comment: 18 pages, 11 figures. Accepted for publication in A