Formation flying for a Fresnel lens observatory mission

The employment of a large area Phase Fresnel Lens (PFL) in a gamma-ray telescope offers the potential to image astrophysical phenomena with micro-arcsecond angular resolution. In order to assess the feasibility of this concept, two detailed studies have been conducted of formation flying missions in which a Fresnel lens capable of focussing gamma-rays and the associated detector are carried on two spacecraft separated by up to 10$^6$ km. These studies were performed at the NASA Goddard Space Flight Center Integrated Mission Design Center (IMDC) which developed spacecraft, orbital dynamics, and mission profiles. The results of the studies indicated that the missions are challenging but could be accomplished with technologies available currently or in the near term. The findings of the original studies have been updated taking account of recent advances in ion thruster propulsion technology.Comment: Presented at GammaWave05: "Focusing Telescopes in Nuclear Astrophysics", Bonifacio, Corsica, September 2005, to be published in Experimental Astronomy, 7 page

Development of Ground-testable Phase Fresnel Lenses in Silicon

Diffractive/refractive optics, such as Phase Fresnel Lenses (PFL's), offer the potential to achieve excellent imaging performance in the x-ray and gamma-ray photon regimes. In principle, the angular resolution obtained with these devices can be diffraction limited. Furthermore, improvements in signal sensitivity can be achieved as virtually the entire flux incident on a lens can be concentrated onto a small detector area. In order to verify experimentally the imaging performance, we have fabricated PFL's in silicon using gray-scale lithography to produce the required Fresnel profile. These devices are to be evaluated in the recently constructed 600-meter x-ray interferometry testbed at NASA/GSFC. Profile measurements of the Fresnel structures in fabricated PFL's have been performed and have been used to obtain initial characterization of the expected PFL imaging efficiencies.Comment: Presented at GammaWave05: "Focusing Telescopes in Nuclear Astrophysics", Bonifacio, Corsica, September 2005, to be published in Experimental Astronomy, 8 pages, 3 figure

Fresnel lenses for X-ray and Gamma-ray Astronomy

Phase Fresnel lenses have the same imaging properties as zone plates, but with the possibility of concentrating all of the incident power into the primary focus, increasing the maximum theoretical efficiency from 11% to close to 100%. For X-rays, and in particular for gamma-rays, large, diffraction-limited phase Fresnel lenses can be made relatively easily. The focal length is very long - for example up to a million kms. However, the correspondingly high `plate-scale' of the image means that the ultra-high (sub-micro-arc-second) angular resolution possible with a diffraction limited gamma-ray lens a few metres in diameter can be exploited with detectors having \~mm spatial resolution. The potential of such systems for ultra-high angular resolution astronomy, and for attaining the sensitivity improvements desperately needed for certain other studies, are reviewed and the advantages and disadvantages vis-a-vis alternative approaches are discussed. We report on reduced-scale 'proof-of-principle tests' which are planned and on mission studies of the implementation of a Fresnel telescope on a space mission with lens and detector on two spacecraft separated by one million km. Such a telescope would be capable of resolving emission from super-massive black holes on the scale of their event horizons and would have the sensitivity necessary to detect gamma-ray lines from distant supernovae. We show how diffractive/refractive optics leads to a continuum of possible system designs between filled aperture lenses and wideband interferometric arrays.Comment: To be published in "Proceedings of the SPIE conference 5168 : Optics for EUV, X-ray and Gamma-Ray Astronomy", San Diego, August 200

The impact of positional leadership on secondary school captains

This article examines the impact of positional leadership on secondary school captains in a group of ‘like schools’ in Queensland, Australia. Through six studies, using document analysis, interviews, observations and focus groups, with school captains, parents and teachers, a number of perceived areas of impact on the students holding these positions emerged. These impacts involve relationships, roles and responsibilities, personal well-being, learning skills and learning management, self-management and self-confidence. The study suggests that through the status and responsibilities associated with the position and the self-awareness that grows during school captaincy, the young person is likely to experience deepening maturity more quickly than might otherwise be the case

Expectations of successful female small school principals

This paper forms part of a larger study investigating the experiences of twelve female teaching principals in small rural and isolated schools in their first year as school principal. The schools to which they were appointed had student enrolments ranging from 12 to 86 and were in geographic areas with no township, where the school building was the only structure, to small towns of less than 500. This study sought to discover the expectations stakeholders in small schools had of successful female teaching principals and the expectations teaching principals had of themselves. Interviews with both cohorts indicated a shared expectation that the teaching principal would come equipped with excellent communication skills, sound teaching knowledge and the ability to establish and maintain community relationships. Additional expectations from teaching principals related to their leaders hip, meeting systemic administrative requirements and balancing their work and personal lives. For stakeholders additional expectations included being organised in relation to isolation and having positive personal characteristics

Draft Genome Sequence of Rhodococcus sp. Strain ATCC 49988, a Quinoline-Degrading Bacterium.

We report here the 4.9-Mb genome sequence of a quinoline-degrading bacterium, Rhodococcus sp. strain ATCC 49988. The draft genome data will enable the identification of genes and future genetic modification to enhance traits relevant to heteroaromatic compound degradation

The contributions of research design and process facilitation in accessing adolescent views of leadership

This article reports an investigation into young people’s understanding of ‘good’ and ‘bad’ leadership in school and sporting club contexts. Four discussion methods (open ended or structured discussions of either a person or situation based scenario) were trialled by 40 adolescents (aged 14 to 16) in a structured focus group format. Particular attention was given to positioning participants as collaborators and establishing trusting and open communication in the focus groups. Both qualitative and quantitative evaluation supported the efficacy of all discussion methods. Importantly, participants attributed the efficacy of the research process less to the use of specific research designs and more to the engaging and respectful quality of the interpersonal and group processes established for the discussions in which the students acted as co-researchers. Preliminary findings on the content of young people’s leadership conceptions are also presented. Considerable consistency in young people’s ideas was evident across context (school or sporting club) and gender. From a methodological perspective, the findings have implications for the design and conduct of research seeking a valid understanding of young people’s experiences of leadership. From an educational perspective, the findings indicate the key engagement processes that should be incorporated into adolescent leadership program

The role of manufacturing and market managers in strategy development:lessons from three companies

According to researchers and managers, there is a lack of agreement between marketing and manufacturing managers on critical strategic issues. However, most of the literature on the subject is anecdotal and little formal empirical research has been done. Three companies are investigated to study the extent of agreement/disagreement between manufacturing and marketing managers on strategy content and process. A novel method permits the study of agreement between the two different functional managers on the process of developing strategy. The findings consistently show that manufacturing managers operate under a wider range of strategic priorities than marketing managers, and that manufacturing managers participate less than marketing managers in the strategy development process. Further, both marketing and manufacturing managers show higher involvement in the strategy development process in the latter stages of the Hayes and Wheelwright four-stage model of manufacturing’s strategic role