The Deep Diffuse Extragalactic Radio Sky at 1.75 GHz

We present a study of diffuse extragalactic radio emission at $1.75\,$GHz from part of the ELAIS-S1 field using the Australia Telescope Compact Array. The resulting mosaic is $2.46\,$deg$^2$, with a roughly constant noise region of $0.61\,$deg$^2$ used for analysis. The image has a beam size of $150 \times60\,$arcsec and instrumental $\langle\sigma_{\rm n}\rangle= (52\pm5)\, \mu$Jy beam$^{-1}$. Using point-source models from the ATLAS survey, we subtract the discrete emission in this field for $S \ge 150\, \mu$Jy beam$^{-1}$. Comparison of the source-subtracted probability distribution, or \pd, with the predicted distribution from unsubtracted discrete emission and noise, yields an excess of $(76 \pm 23) \, \mu$Jy beam$^{-1}$. Taking this as an upper limit on any extended emission we constrain several models of extended source counts, assuming $\Omega_{\rm source} \le 2\,$arcmin. The best-fitting models yield temperatures of the radio background from extended emission of $T_{\rm b}=(10\pm7) \,$mK, giving an upper limit on the total temperature at $1.75\,$GHz of $(73\pm10)\,$mK. Further modelling shows that our data are inconsistent with the reported excess temperature of ARCADE2 to a source-count limit of $1\, \mu$Jy. Our new data close a loop-hole in the previous constraints, because of the possibility of extended emission being resolved out at higher resolution. Additionally, we look at a model of cluster halo emission and two WIMP dark matter annihilation source-count models, and discuss general constraints on any predicted counts from such sources. Finally, we report the derived integral count at $1.4\,$GHz using the deepest discrete count plus our new extended-emission limits, providing numbers that can be used for planning future ultra-deep surveys.Comment: 18 pages, 15 figures, 7 tables, Accepted by MNRA

A summary of research relating to first grade reading, 1932-1963

Thesis (Ed.M.)--Boston UniversityProblem: An attempt to compare the rate of learning of colorful and abstract words of children in grade one. Materials: 1. Thirty words were selected to be used in three groups of ten words each. Each list consisted of five colorful and five abstract words. Colorful words are those which have much meaning for children and abstract words are those with little meaning. The words were printed on 3 x 11 inch flash cards in lower case letters. 2. Check sheets were made with spaces for checking the retention of words at three different times and pictures were made to enrich the colorful words. 3. Directions were prepared and given to each teacher who participated in the study. 4. Kuhlmann-Anderson Intelligence Test: Battery A. 5. Detroit Word Recognition Test: Form A [TRUNCATED

A Large Blue Shift of the Biexciton State in Tellurium Doped CdSe Colloidal Quantum Dots

The exciton-exciton interaction energy of Tellurium doped CdSe colloidal quantum dots is experimentally investigated. The dots exhibit a strong Coulomb repulsion between the two excitons, which results in a huge measured biexciton blue shift of up to 300 meV. Such a strong Coulomb repulsion implies a very narrow hole wave function localized around the defect, which is manifested by a large Stokes shift. Moreover, we show that the biexciton blue shift increases linearly with the Stokes shift. This result is highly relevant for the use of colloidal QDs as optical gain media, where a large biexciton blue shift is required to obtain gain in the single exciton regime.Comment: 9 pages, 4 figure

U.S. Coast Guard Boat Recovery Simulation at NASA Ames Vertical Motion Simulator

The Boat Recovery Simulation was a collaboration between the U.S. Coast Guard and NASA. The experiment was conducted at the NASA Ames Vertical Motion Simulator (VMS). The goals were to (1) design a VMS experiment that can accurately simulate the motion of high sea conditions and to (2) collect data for the U.S. Coast Guard on human performance related to small boat recovery operations. The experiment setup included a software operation model designed around empirical boat position data; a replica boat section manufactured to incorporate real-world task elements; and the means to collect objective and subjective data from human participants. The VMS provided a viable testbed to assess certified U.S. Coast Guard crewmembers task performance while in motion

The Extended Methanol Maser Emission in W51

The European VLBI Network (EVN) has been used to make phase referenced, wide-field (several arcminute) spectral line observations of the 6.7-GHz methanol maser emission towards W51. In the W51main region, the bulk of the methanol is offset from an UCHII region. This probably indicates the methanol emission arises at the interface of the expanding UCHII region and not from an edge-on circumstellar disc, as previously suggested. Near the W51 IRS2 region, the methanol emission is associated with a very compact, extremely embedded source supporting the hypothesis that methanol masers trace the earliest stages of massive star formation. As well as these two previously well studied sites of star formation, many previously unknown regions star formation are detected, demonstrating that methanol masers are powerful means of detection young massive stars.Comment: 5 pages, 3 figure