Low-density resin impregnated ceramic article and method for making the same

A low-density resin impregnated ceramic article advantageously employed as a structural ceramic ablator comprising a matrix of ceramic fibers. The fibers of the ceramic matrix are coated with an organic resin film. The organic resin can be a thermoplastic resin or a cured thermosetting resin. In one embodiment, the resin is uniformly distributed within the ceramic article. In a second embodiment, the resin is distributed so as to provide a density gradient along at least one direction of the ceramic article. The resin impregnated ceramic article is prepared by providing a matrix of ceramic fibers; immersing the matrix of ceramic fibers in a solution of a solvent and an organic resin infiltrant; and removing the solvent to form a resin film on the ceramic fibers

Low Density Resin Impregnated Ceramic Article Having an Average Density of 0.15 to 0.40 G/CC

A low-density resin impregnated ceramic article advantageously employed as a structural ceramic ablator comprising a fired preform of ceramic fibers. The fibers of the ceramic preform are coated with an organic resin film. The organic resin can be a thermoplastic resin or a cured thermosetting resin. In one embodiment, the resin is uniformly distributed within the ceramic article. In a second embodiment, the resin is distributed so as to provide a density gradient along at least one direction of the ceramic article. The resin impregnated ceramic article is prepared by providing a fired preform of ceramic fibers; immersing the preform of ceramic fibers in a solution of a solvent and an organic resin infiltrant; and removing the solvent to form a resin film on the ceramic fibers

Working through whiteness, race and (anti) racism in physical education teacher education

Background: The persistent gaps between a largely white profession and ethnically diverse school populations have brought renewed calls to support teachers' critical engagement with race. Programmes examining the effects of racism have had limited impact on practice, with student teachers responding with either denial, guilt or fear; they also contribute to a deficit view of racialised students in relation to an accepted white ‘norm’, and position white teachers ‘outside’ of race. Recent calls argue for a shift in focus towards an examination of the workings of the dominant culture through a critical engagement with whiteness, positioning white teachers within the processes of racialisation. Teacher educators' roles are central, and yet, while we routinely expect student teachers to reflect critically on issues of social justice, we have been less willing to engage in such work ourselves. This is particularly the case within physical education teacher education (PETE), an overwhelmingly white, embodied space, and where race and racism as professional issues are largely invisible. Purpose: This paper examines the operation of whiteness within PETE through a critical reflection on the three co-authors' careers and experiences working for social justice. The research questions were twofold: How are race, (anti) racism and whiteness constructed through everyday experiences of families, schooling and teacher education? How can collective biography be used to excavate discourses of race, racism and whiteness as the first step towards challenging them? In beginning the process of reflecting on what it means for us ‘to do own work’ in relation to (anti) racism, we examine some of the tensions and challenges for teacher educators in PE attempting to work to dismantle whiteness. Methodology: As co-authors, we engaged in collective biography work – a process in which we reflected upon, wrote about and shared our embodied experiences and memories about race, racism and whiteness as educators working for social justice. Using a critical whiteness lens, these narratives were examined for what they reveal about the collective practices and discourses about whiteness and (anti)racism within PETE. Results: The narratives reveal the ways in which whiteness operates within PETE through processes of naturalisation, ex-denomination and universalisation. We have been educated, and now work within, teacher education contexts where professional discourse about race at best focuses on understanding the racialised ‘other’, and at worse is invisible. By drawing on a ‘racialised other’, deficit discourse in our pedagogy, and by ignoring race in own research on inequalities in PETE, we have failed to disrupt universalised discourses of ‘white-as-norm’, or addressed our own privileged racialised positioning. Reflecting critically on our biographies and careers has been the first step in recognising how whiteness works in order that we can begin to work to disrupt it. Conclusion: The study highlights some of the challenges of addressing (anti)racism within PETE and argues that a focus on whiteness might offer a productive starting point. White teacher educators must critically examine their own role within these processes if they are to expect student teachers to engage seriously in doing the same

Value-Driven Analysis of New Paradigms in Space Architectures: An Ilities-Based Approach

Current commercial, civil, and military space architecture designs perform exquisitely and reliably. However, today’s architecture paradigms are also characterized by expensive launches, large and expensive high-performance spacecraft, long development cycles, and wide variations in ground architectures. While current assets provide high-quality services, and future assets are slated to improve performance within the same design frameworks, proposed future architectures may not be capitalizing on technology improvements, system innovations, or policy alternatives explored during the last two decades. This paper identifies five “trends” along which space architectures may develop, aimed at granting systems several “ilities,” such as resiliency, robustness, flexibility, scalability, and affordability. The trends examined include: commercialization of space, significant reductions in launch costs and the development of hybrid or reusable launch systems, development of on-orbit infrastructure and servicing, aggregation or disaggregation of orbital assets, and the automation and standardization of ground architectures. Further refinement of these key technological and system trends could result in major paradigm shifts in the development and fielding of space operations as well as lead to space architecture designs in the future that are radically different from those today. Within the framework of systems engineering ilities and risk management, this paper reviews current literature surrounding these new change trends and justifies their potential to cause significant paradigm shifts. By examining the work and research conducted so far through an ilities-based approach, systems engineers can more fully appreciate the value being offered by these trends

A comparison of two methods for estimating odds ratios: Results from the National Health Survey

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A new Late Agenian (MN2a, Early Miocene) fossil assemblage from Wallenried (Molasse Basin, Canton Fribourg, Switzerland)

Excavations of two fossiliferous layers in the Wallenried sand- and marl pit produced a very diversified vertebrate fauna. New material allows the reassessment of the taxonomic position of the ruminant taxa Andegameryx andegaviensis and endemic Friburgomeryx wallenriedensis. An emended diagnosis for the second species is provided and additional material of large and small mammals, as well as ectothermic vertebrates, is described. The recorded Lagomorpha show interesting morphological deviations from other Central European material, and probably represent a unique transitional assemblage with a co-occurrence of Titanomys, Lagopsis and Prolagus. Rodentia and Eulipotyphla belong to typical and well-known species of the Agenian of the Swiss Molasse Basin. Abundant small mammal teeth have allowed us to pinpoint the biostratigraphic age of Wallenried to late MN2a. The biostratigraphic age conforms to data derived from the charophyte assemblages and confirms the oldest occurrence of venomous snake fangs. The palaeoenvironmental context is quite complex. Sedimentary structures and fauna (fishes, frogs, salamanders, ostracods) are characteristic for a humid, lacustrine environment within a flood plain system

Lunar COTS Mission Concept: Using the Moon's Resources to Enable an Economical and Sustainable Pathway to Mars and Beyond

To support and enable future human missions to the surface of the Moon, a new plan was formulated to gradually develop an economical, evolvable and sustainable lunar infrastructure using a public/private partnerships between NASA and industry to share cost and risk in the development phase and ultimately transfer operation of these infrastructure services to its industry owners. These infrastructure services may include but are not limited to the following: lunar cargo transportation, power stations, energy storage devices, communication towers and relay satellites, and resource extraction operations. The plan is called the Commercial Orbital Transfer Services (COTS) Program, using NASA's well-proven Commercial Orbital Transportation Services (COTS) Program acquisition model