Deep space network support of the manned space flight network for Apollo, volume 2 Technical memorandum, 1969 - 1970

Deep Space Network support activities for Apollo 9 through 13 flights and associated equipmen

Bridging the gap : intergenerational programs (2009)

Reviewed June 2009

Talking it through: using specialist coaching to enhance teachers’ knowledge from speech and language sciences

Teachers’ knowledge for effective pedagogies can be enhanced by drawing on a range of specific expertise held by those working in other disciplines or professions. In this article, we explore this potential through a focus on enhancing research-informed communication rich pedagogies in primary and early years’ settings. The specific example is that of speech and language therapists using video-based coaching with teachers. Our research provides case study evidence and demonstrates that this professional development approach brings speech and language therapy research and expertise into the practice domain of teachers. This is a dynamic, reciprocal and co-constructive relationship between the participants. The focus on this paper is on how it can enable teachers to extend their understanding and develop a more nuanced understanding of specialist evidence of speech, language and communication for, and in, practice

Prospects for observing the magnetorotational instability in the Plasma Couette Experiment

Many astrophysical disks, such as protoplanetary disks, are in a regime where non-ideal, plasma-specific magnetohydrodynamic (MHD) effects can significantly influence the behavior of the magnetorotational instability (MRI). The possibility of studying these effects in the Plasma Couette Experiment (PCX) is discussed. An incompressible, dissipative global stability analysis is developed to include plasma-specific two-fluid effects and neutral collisions, which are inherently absent in analyses of Taylor-Couette flows (TCFs) in liquid metal experiments. It is shown that with boundary driven flows, a ion-neutral collision drag body force significantly affects the azimuthal velocity profile, thus limiting the flows to regime where the MRI is not present. Electrically driven flow (EDF) is proposed as an alternative body force flow drive in which the MRI can destabilize at more easily achievable plasma parameters. Scenarios for reaching MRI relevant parameter space and necessary hardware upgrades are described.Comment: 18 pages, 13 figures, 1 table, under review for JPP special edition: Experiments at the Frontier of Fundamental Plasma Physic

Is the squeezing of relic gravitational waves produced by inflation detectable?

Grishchuk has shown that the stochastic background of gravitational waves produced by an inflationary phase in the early Universe has an unusual property: it is not a stationary Gaussian random process. Due to squeezing, the phases of the different waves are correlated in a deterministic way, arising from the process of parametric amplification that created them. The resulting random process is Gaussian but non-stationary. This provides a unique signature that could in principle distinguish a background created by inflation from stationary stochastic backgrounds created by other types of processes. We address the question: could this signature be observed with a gravitational wave detector? Sadly, the answer appears to be "no": an experiment which could distinguish the non-stationary behavior would have to last approximately the age of the Universe at the time of measurement. This rules out direct detection by ground and space based gravitational wave detectors, but not indirect detections via the electromagnetic Cosmic Microwave Background Radiation (CMBR).Comment: 17 pages, 4 Postscript figures, uses revtex, psfig, to be submitted to PRD, minor revisions - appendix B clarified, corrected typos, added reference

Bridging the gap : intergenerational programs (1994)

"Information from Human Environmental Sciences Extension."New 12/94/5M

Data analysis strategies for the detection of gravitational waves in non-Gaussian noise

In order to analyze data produced by the kilometer-scale gravitational wave detectors that will begin operation early next century, one needs to develop robust statistical tools capable of extracting weak signals from the detector noise. This noise will likely have non-stationary and non-Gaussian components. To facilitate the construction of robust detection techniques, I present a simple two-component noise model that consists of a background of Gaussian noise as well as stochastic noise bursts. The optimal detection statistic obtained for such a noise model incorporates a natural veto which suppresses spurious events that would be caused by the noise bursts. When two detectors are present, I show that the optimal statistic for the non-Gaussian noise model can be approximated by a simple coincidence detection strategy. For simulated detector noise containing noise bursts, I compare the operating characteristics of (i) a locally optimal detection statistic (which has nearly-optimal behavior for small signal amplitudes) for the non-Gaussian noise model, (ii) a standard coincidence-style detection strategy, and (iii) the optimal statistic for Gaussian noise.Comment: 5 pages RevTeX, 4 figure

Quantum Weak Energy Inequalities for the Dirac field in Flat Spacetime

Quantum Weak Energy Inequalities (QWEIs) have been established for a variety of quantum field theories in both flat and curved spacetimes. Dirac fields are known (by a result of Fewster and Verch) to satisfy QWEIs under very general circumstances. However this result does not provide an explicit formula for the QWEI bound, so its magnitude has not previously been determined. In this paper we present a new and explicit QWEI bound for Dirac fields of arbitrary mass in four-dimensional Minkowski space. We follow the methods employed by Fewster and Eveson for the scalar field, modified to take account of anticommutation relations. A key ingredient is an identity for Fourier transforms established by Fewster and Verch. We also compare our QWEI with those previously obtained for scalar and spin-1 fields.Comment: 8 pages, REVTeX4, version to appear in Phys Rev