Nuclear reactor descriptions for space power systems analysis

For the small, high performance reactors required for space electric applications, adequate neutronic analysis is of crucial importance, but in terms of computational time consumed, nuclear calculations probably yield the least amount of detail for mission analysis study. It has been found possible, after generation of only a few designs of a reactor family in elaborate thermomechanical and nuclear detail to use simple curve fitting techniques to assure desired neutronic performance while still performing the thermomechanical analysis in explicit detail. The resulting speed-up in computation time permits a broad detailed examination of constraints by the mission analyst

A latitudinal survey of hydroxyl airglow emissions Final report, 1 Apr. 1969 - 31 Mar. 1970

Airborne photometer instrumentation and measurement data on high latitude hydroxyl airglow emissio

Hedge Funds With Style

The popular perception is that hedge funds follow a reasonably well defined market-neutral investment style. While this long-short investment strategy may have characterized the first hedge funds, today hedge funds are a reasonably heterogeneous group. They are better defined in terms of their freedom from the constraints imposed by the Investment Company Act of 1940, than they are by the particular style of investment. We study the monthly return history of hedge funds over the period 1989 through to January 2000 and find that there are in fact a number of distinct styles of management. We find that differences in investment style contribute about 20 per cent of the cross sectional variability in hedge fund performance. This result is consistent across the years of our sample and is robust to the way in which we determine investment style. We conclude that appropriate style analysis and style management are crucial to success for investors looking to invest in this market.

Polarimetric variations of binary stars. II. Numerical simulations for circular and eccentric binaries in Mie scattering envelopes

We present numerical simulations of the periodic polarimetric variations produced by a binary star placed at the center of an empty spherical cavity inside a circumbinary ellipsoidal and optically thin envelope made of dust grains. Mie single-scattering is considered along with pre- and post-scattering extinction factors which produce a time-varying optical depth and affect the morphology of the periodic variations. We are interested in the effects that various parameters will have on the average polarization, the amplitude of the polarimetric variations, and the morphology of the variability. We show that the absolute amplitudes of the variations are smaller for Mie scattering than for Thomson scattering. Among the four grain types that we have studied, the highest polarizations are produced by grains with sizes in the range 0.1-0.2 micron. In general, the variations are seen twice per orbit. In some cases, because spherical dust grains have an asymmetric scattering function, the polarimetric curves produced also show variations seen once per orbit. Circumstellar disks produce polarimetric variations of greater amplitude than circumbinary envelopes. Another goal of these simulations is to see if the 1978 BME (Brown, McLean, & Emslie, ApJ, 68, 415) formalism, which uses a Fourier analysis of the polarimetric variations to find the orbital inclination for Thomson-scattering envelopes, can still be used for Mie scattering. We find that this is the case, if the amplitude of the variations is sufficient and the true inclinations is i_true > 45 deg. For eccentric orbits, the first-order coefficients of the Fourier fit, instead of second-order ones, can be used to find almost all inclinations.Comment: 23 pages, 5 figures, to be published in Astronomical Journa

TEXES Observations of M Supergiants: Dynamics and Thermodynamics of Wind Acceleration

We have detected [Fe II] 17.94 um and 24.52 um emission from a sample of M supergiants using TEXES on the IRTF. These low opacity emission lines are resolved at R = 50, 000 and provide new diagnostics of the dynamics and thermodynamics of the stellar wind acceleration zone. The [Fe II] lines, from the first excited term, are sensitive to the warm plasma where energy is deposited into the extended atmosphere to form the chromosphere and wind outflow. These diagnostics complement previous KAO and ISO observations which were sensitive to the cooler and more extended circumstellar envelopes. The turbulent velocities, Vturb is about 12 to 13 km/s, observed in the [Fe II] forbidden lines are found to be a common property of our sample, and are less than that derived from the hotter chromospheric C II] 2325 Angstrom lines observed in alpha Ori, where Vturb is about 17 to 19 km/s. For the first time, we have dynamically resolved the motions of the dominant cool atmospheric component discovered in alpha Ori from multi-wavelength radio interferometry by Lim et al. (1998). Surprisingly, the emission centroids are quite Gaussian and at rest with respect to the M supergiants. These constraints combined with model calculations of the infrared emission line fluxes for alpha Ori imply that the warm material has a low outflow velocity and is located close to the star. We have also detected narrow [Fe I] 24.04 um emission that confirms that Fe II is the dominant ionization state in alpha Ori's extended atmosphere.Comment: 79 pages including 10 figures and 2 appendices. Accepted by Ap

The embodied academic: Body work in teacher education

I am a lecturer in education, but entered academia because my experience in secondary school teaching was required for teacher education. As such I followed the traditional pathway of teacher educators transitioning from professional practice to become a lecturer in higher education (Boyd and Harris, 2010). Had I been asked two years ago if I considered myself an embodied academic, my answer would have been that I thought of myself as an embodied practitioner. This has more to do with my hesitation to identify as an academic than to describe myself as embodied. Even after several years in academia I would have considered myself a teacher and identified with that embodied teaching identity. Like the research participants in Boyd and Harris’s (2010) study, I clung on to my “identity and credibility as [a] school teacher” (p. 10). My motto at the time – “once a teacher, always a teacher” – is proof of that. I would not have called myself an academic, but I was definitely embodied

A New Approach to Black Hole Microstates

If one encodes the gravitational degrees of freedom in an orthonormal frame field there is a very natural first order action one can write down (which in four dimensions is known as the Goldberg action). In this essay we will show that this action contains a boundary action for certain microscopic degrees of freedom living at the horizon of a black hole, and argue that these degrees of freedom hold great promise for explaining the microstates responsible for black hole entropy, in any number of spacetime dimensions. This approach faces many interesting challenges, both technical and conceptual.Comment: 6 pages, 0 figures, LaTeX; submitted to Mod. Phys. Lett. A.; this essay received "honorable mention" from the Gravity Research Foundation, 199

Creativity and Playfulness in Higher Education Research

Due to the diversity of academics engaging with research into higher education, there is no single methodological approach or method that would embody higher education research. In this chapter, we put forward the case that this is a good thing and argue that higher education research can benefit from fusing existing methodological and theoretical paradigms with more creative, playful and artistic approaches, more commonly associated with sociological or anthropological research and performance-based disciplines. In order to frame this attitude of creativity, playfulness and openness, we start by providing a brief delineation of the research field and methods of higher education research. In this context we introduce the Deleuzoguattarian concept of rhizomes and assemblages to provide the grounding for what we mean by creativity and playfulness, which leads to our proposal of a renewed approach to research into higher education. We draw upon our own work on embodied academic identity and trainee teachers’ perceptions of their placement experiences in order to critically explore the benefits and potential pitfalls of incorporating this creativity and playfulness into higher education research