Space shuttle orbit maneuvering engine reusable thrust chamber program

Tests were conducted on the regenerative cooled thrust chamber of the space shuttle orbit maneuvering engine. The conditions for the tests and the durations obtained are presented. The tests demonstrated thrust chamber operation over the nominal ranges of chamber pressure mixture ratio. Variations in auxiliary film coolant flowrate were also demonstrated. High pressure tests were conducted to demonstrate the thrust chamber operation at conditions approaching the design chamber pressure for the derivative space tug application

Incorporating Student Response Systems in mathematics classes

In the past decade, Student Response Systems (SRS) have been used more widely in higher education as advancement in technology makes them more affordable, easier to use and of compact design. This technology shows potential in enhancing the student experience, especially in traditionally hard subjects like mathematics. Major reasons for introducing the technology into classrooms include positive student perception, anonymity, active teaching and learning and providing a natural break from straight content delivery. There remain issues related to the integration of the technology within mathematics courses - in particular related to the time required during lectures to successfully embed SRS without impinging too greatly on the delivery of the syllabus. In this study the appropriate number of questions that should be posed during a lecture is investigated, as is the time interval that should be permitted per question and when each question is posed. It has been suggested that SRS are not utilized effectively unless questions used provoke deep learning but this can be problematic and impact on endemic math anxiety regardless of anonymity. It is proposed that questions involving higher order thinking may be better explored within a tutorial environment using a Team Base Learning approach

Symplectic No-core Shell-model Approach to Intermediate-mass Nuclei

We present a microscopic description of nuclei in an intermediate-mass region, including the proximity to the proton drip line, based on a no-core shell model with a schematic many-nucleon long-range interaction with no parameter adjustments. The outcome confirms the essential role played by the symplectic symmetry to inform the interaction and the winnowing of shell-model spaces. We show that it is imperative that model spaces be expanded well beyond the current limits up through fifteen major shells to accommodate particle excitations that appear critical to highly-deformed spatial structures and the convergence of associated observables.Comment: 9 pages, 8 figure

The identification of a novel, high frequency variant in the Cytochrome b gene in an isolated population of a rare fish, Spined Loach Cobitis taenia, in England: A population worth protecting?

The spined loach Cobitis taenia, is listed as a protected species under Appendix 3 of the Bern Convention and Annex II of the European Council Directive (92/43/EEC) on the conservation of natural habitats and of wild fauna and flora. It is desirable therefore to understand the genetic diversity within European populations. In a molecular genetic analysis of the cytochrome b gene in Cobitis taenia from three sites in the upper reaches of the River Trent catchment, a novel high frequency variant was identified which has not been previously reported in any European or Non-European population

Crisis, climate change and comitology : policy dismantling via the backdoor?

The European Union (EU) is reputed to be a climate pioneer. However, the EU has been beset by crises, with potentially negative consequences for climate ambition. Analysis and coding of EU climate legislation between 1998 and 2015 reveal that while the rate of climate policy creation has increased since the onset of the crisis, the ambition of these policies has waned. Technical policy instruments (comitology) at the EU level – ‘Delegated and Implementing Acts’ (DIA) – are analysed alongside legislation adopted under the ‘Ordinary Legislative Procedure’ (OLP). If applied as indicated in the treaties, technical DIA measures should not influence policy ambition, but in fact during the crisis era, DIA measures were used more frequently, and used in three out of the four cases of policy weakening, suggesting that minor dismantling of climate policy is taking place at EU level, but via the backdoor

EU environmental policy in times of crisis

The European Union (EU) has been buffeted by a range of crises since 2007, not least the economic and financial crisis. One potential victim of this economic malaise is environmental policy ambition. It is well-established that during economic crises environmental policy slips down the agenda with long term consequences for environmental quality. The EU has sought to cast itself as a global environmental leader but that leadership has in large part rested upon its ability to set ambitious policy goals at home. The future environmental policy trajectory and leadership of the EU may be under threat as the Union struggles to emerge from the economic crisis. This article presents a comprehensive and robust analysis of all environmental policy outputs adopted by the EU over a ten-year period covering the crisis. This legislative analysis is supplemented by interviews with policy stakeholders. The article finds evidence of waning ambition over the period under analysis but a range of explanatory variables emerges from the interviews, which suggests that the diminution in EU environmental policy ambition is driven by a mix of factors and maybe likely to persist over the longer term

High efficiency GaAs-Ge tandem solar cells grown by MOCVD

High conversion efficiency and low weight are obviously desirable for solar cells intended for space applications. One promising structure is GaAs on Ge. The advantages of using Ge wafers as substrates include the following: they offer high efficiency by forming a two-junction tandem cell; low weight combined with superior strength allows usage of thin (3 mil) wafers; and they are a good substrate for GaAs, being lattice matched, thermal expansion matched, and available as large-area wafers