Analytical designs of a space-borne magnetically-focused klystron amplifier Final report

Design analysis for magnetically focused klystron of satellite television transmission syste

Supernova Resonance-Scattering Profiles in the Presence of External Illumination

We discuss a simple model for the formation of a supernova spectral line by resonance scattering in the presence of external illumination of the line-forming region by light from circumstellar interaction (toplighting). The simple model provides a clear understanding of the most conspicuous toplighting effect: a rescaling or, as we prefer, a ``muting'' of the line profile relative to the continuum. This effect would be present in more realistic models, but would be harder to isolate. An analytic expression for a muting factor for a P-Cygni line is derived that depends on the ratio E of the toplighting specific intensity to the specific intensity from the supernova photosphere. If E<1, the line profile is reduced in scale or ``muted''. If E=1, the line profile vanishes altogether. If E>1, the line profile flips vertically: then having an absorption component near the observer-frame line center wavelength and a blueshifted emission component.Comment: accepted for publication in PAS

Patterns of Failure in Texas Urban Improvement Required Schools: An Equity Audit Expansion

The achievement gap is a concept that has long been explored in education; students of color, low socioeconomic status, those who speak languages other than English, and students labeled as special education perform lower on student achievement tests and often receive less in terms of funding and resources (Harris & Hopson, 2008). Brown (2010) stated, As a result, these students, without realizing it, often fall into a predetermined mold designed for school failure and social inequity (p. 2)

Have You Paid Your Rent? Servant Leadership in Correctional Education

This article makes the case for servant leadership as a model and as a philosophy to guide correctional educationalists on how to interact with their students. This article begins with an introduction to identify the gap in the literature with regards to the relationship between servant leadership and adult and correctional education. It continues with a summary of the 10 characteristics of servant leadership that parallel some of the characteristics that educators exhibit in the prison classroom, and explores how those characteristics impact the student population. We conclude by providing a framework by which further research should explore the link between servant leadership and correctional education in order to enhance classroom practices

Standardised library instruction assessment: an institution-specific approach

Introduction We explore the use of a psychometric model for locally-relevant, information literacy assessment, using an online tool for standardised assessment of student learning during discipline-based library instruction sessions. Method A quantitative approach to data collection and analysis was used, employing standardised multiple-choice survey questions followed by individual, cognitive interviews with undergraduate students. The assessment tool was administered to five general education psychology classes during library instruction sessions. AnalysisDescriptive statistics were generated by the assessment tool. Results. The assessment tool proved a feasible means of measuring student learning. While student scores improved on every survey question, there was uneven improvement from pre-test to post-test for different questions. Conclusion Student scores showed more improvement for some learning outcomes over others, thus, spending time on fewer concepts during instruction sessions would enable more reliable evaluation of student learning. We recommend using digital learning objects that address basic research skills to enhance library instruction programmes. Future studies will explore different applications of the assessment tool, provide more detailed statistical analysis of the data and shed additional light on the significance of overall scores

The Joint Efficient Dark-energy Investigation (JEDI): Measuring the cosmic expansion history from type Ia supernovae

JEDI (Joint Efficient Dark-energy Investigation) is a candidate implementation of the NASA-DOE Joint Dark Energy Mission (JDEM). JEDI will probe dark energy in three independent methods: (1) type Ia supernovae, (2) baryon acoustic oscillations, and (3) weak gravitational lensing. In an accompanying paper, an overall summary of the JEDI mission is given. In this paper, we present further details of the supernova component of JEDI. To derive model-independent constraints on dark energy, it is important to precisely measure the cosmic expansion history, H(z), in continuous redshift bins from z \~ 0-2 (the redshift range in which dark energy is important). SNe Ia at z > 1 are not readily accessible from the ground because the bulk of their light has shifted into the near-infrared where the sky background is overwhelming; hence a space mission is required to probe dark energy using SNe. Because of its unique near-infrared wavelength coverage (0.8-4.2 microns), JEDI has the advantage of observing SNe Ia in the rest frame J band for the entire redshift range of 0 < z < 2, where they are less affected by dust, and appear to be nearly perfect standard candles. During the first year of JEDI operations, spectra and light curves will be obtained for ~4,000 SNe Ia at z < 2. The resulting constraints on dark energy are discussed, with special emphasis on the improved precision afforded by the rest frame near-infrared data.Comment: 8 pages, accepted for publication in SPIE proceeding

Computer programs for reduction of microphotometer data

Five computer programs for analyzing magnetic tape recordings of digital data from microphotomete

Function of Funnel-Shaped Coral Growth in a High-Sedimentation Environment

Advantages and disadvantages of a funnel-shaped growth in 2 coral species (Acropora clathrata, Turbinaria peltata) in a high-sedimentation environment (Natal, South Africa) were observed in the field and modeled in a flow tank. Funnel-shaped growth serves different purposes in different hydrographic settings. In calm waters with little currents (in our case deep reef areas, 18 to 25 m) funnel-shaped colonies served as \u27sacrificial sediment traps\u27: all sediment trapped inside the funnel was directed towards the centre, where it was concentrated. There, tissues underwent necroses, but all other tissues remained sediment free and healthy. In areas with high currents (in our case shallower reef areas with high surge, 8 to 14 m) funnels tended to be self-cleaning. By a process of vortex shedding, mass replacement of fluid within the funnel also led to the removal of all sediment. Current speeds between 30 and 90 cm s-1 were enough to clean the funnels of 3 experimental grain sizes (coarse, fine, medium sand)