Video signal processing system uses gated current mode switches to perform high speed multiplication and digital-to-analog conversion

Video signal processor uses special-purpose integrated circuits with nonsaturating current mode switching to accept texture and color information from a digital computer in a visual spaceflight simulator and to combine these, for display on color CRT with analog information concerning fading

Constructions and Enumeration Methods for Cubic Graphs and Trees

The goal of this thesis is to study two related problems that, in the broadest terms, lie in a branch of mathematics called graph theory. The first problem examines some new techniques for constructing a Hamilton graph of least possible order and having a preassigned girth, and the second concerns the enumeration of a certain type of graphs called trees

Operation instructions for the cold electron source Final report, part II

Operation and maintenance procedures for cold electron accelerato

Faint, moving objects in the Hubble Deep Field: components of the dark halo?

The deepest optical image of the sky, the Hubble Deep Field (HDF), obtained with the Hubble Space Telescope (HST) in December 1995, has been compared to a similar image taken in December 1997. Two very faint, blue, isolated and unresolved objects are found to display a substantial apparent proper motion, 23+/-5 mas/yr and 26+/-5 mas/yr; a further three objects at the detection limit of the second epoch observations may also be moving. Galactic structure models predict a general absence of stars in the color-magnitude range in which these objects are found. However, these observations are consistent with recently-developed models of old white dwarfs with hydrogen atmospheres, whose color, contrary to previous expectations, has been shown to be blue. If these apparently moving objects are indeed old white dwarfs with hydrogen atmospheres and masses near 0.5 M_Sun, they have ages of approximately 12 Gyr, and a local mass density that is sufficient, within the large uncertainties arising from the small size of the sample, to account for the entire missing Galactic dynamical mass.Comment: 6 pages, using emulateapj, including 2 colour figures, accepted for publication in ApJ Letter

Revision of Earth-sized Kepler Planet Candidate Properties with High Resolution Imaging by Hubble Space Telescope

We present the results of our Hubble Space Telescope program and describe how our analysis methods were used to re-evaluate the habitability of some of the most interesting Kepler planet candidates. Our program observed 22 Kepler Object of Interest (KOI) host stars, several of which were found to be multiple star systems unresolved by Kepler. We use our high-resolution imaging to spatially resolve the stellar multiplicity of Kepler-296, KOI-2626, and KOI-3049, and develop a conversion to the Kepler photometry (Kp) from the F555W and F775W filters on WFC3/UVIS. The binary system Kepler-296 (5 planets) has a projected separation of 0.217" (80AU); KOI-2626 (1 planet candidate) is a triple star system with a projected separation of 0.201" (70AU) between the primary and secondary components and 0.161" (55AU) between the primary and tertiary; and the binary system KOI-3049 (1 planet candidate) has a projected separation of 0.464" (225AU). We use our measured photometry to fit the separated stellar components to the latest Victoria-Regina Stellar Models with synthetic photometry to conclude that the systems are coeval. The components of the three systems range from mid-K dwarf to mid-M dwarf spectral types. We solved for the planetary properties of each system analytically and via an MCMC algorithm using our independent stellar parameters. The planets range from ~1.6R_Earth to ~4.2R_Earth, mostly Super Earths and mini-Neptunes. As a result of the stellar multiplicity, some planets previously in the Habitable Zone are, in fact, not, and other planets may be habitable depending on their assumed stellar host.Comment: 16 pages, 10 figures, ApJ, 804, 9

A Framework for Thinking About Transferring Teaching Innovations into New Settings

As a result of health science educators’ shift to more active formats of teaching and learning, many educators are implementing innovative teaching strategies that were designed in other educational contexts. In some cases, this transfer from one context to another is smooth and unproblematic, but in others, educators must make informed decisions about how to adjust the innovation or incoming context to fit their needs. This paper presents a framework that draws on principles of design-based research to guide educators in analyzing and adapting teaching tools to fit new contexts

Hubble Space Telescope High Resolution Imaging of Kepler Small and Cool Exoplanet Host Stars

High resolution imaging is an important tool for follow-up study of exoplanet candidates found via transit detection with the Kepler Mission. We discuss here HST imaging with the WFC3 of 23 stars that host particularly interesting Kepler planet candidates based on their small size and cool equilibrium temperature estimates. Results include detections, exclusion of background stars that could be a source of false positives for the transits, and detection of physically-associated companions in a number of cases providing dilution measures necessary for planet parameter refinement. For six KOIs, we find that there is ambiguity in which star hosts the transiting planet(s), with potentially strong implications for planetary characteristics. Our sample is evenly distributed in G, K, and M spectral types. Albeit with a small sample size, we find that physically-associated binaries are more common than expected at each spectral type, reaching a factor of 10 frequency excess at M. We document the program detection sensitivities, detections, and deliverables to the Kepler follow-up program archive.Comment: Accepted for the Astronomical Journal; 13 pages with 9 figure