Preservice Teachers\u27 Use of Frustration to Enhance Communication

Pre-service teaching, a required component of accredited teacher education programs across the United States, provides the opportunity for pre-service teachers to not only teach in their specific fields, but also to work with specific populations of students, such as English Language Learners (ELLs). Rarely, however, do pre-service teachers from the U.S. have the opportunity to teach ELLs in contexts where languages other than English and cultures other than American are dominant. This presentation reports how pre-service teachers teaching ELLs in just such situations dealt with frustrations common to pre-service teachers and also frustrations due to situational contexts. Through self-reporting, these pre-service teachers describe how they used these frustrations to inform their conceptual knowledge, to make changes in their own English while teaching English to others, and to improve their teaching skills

Optimising Spectroscopic and Photometric Galaxy Surveys: Efficient Target Selection and Survey Strategy

The next generation of spectroscopic surveys will have a wealth of photometric data available for use in target selection. Selecting the best targets is likely to be one of the most important hurdles in making these spectroscopic campaigns as successful as possible. Our ability to measure dark energy depends strongly on the types of targets that we are able to select with a given photometric data set. We show in this paper that we will be able to successfully select the targets needed for the next generation of spectroscopic surveys. We also investigate the details of this selection, including optimisation of instrument design and survey strategy in order to measure dark energy. We use color-color selection as well as neural networks to select the best possible emission line galaxies and luminous red galaxies for a cosmological survey. Using the Fisher matrix formalism we forecast the efficiency of each target selection scenario. We show how the dark energy figures of merit change in each target selection regime as a function of target type, survey time, survey density and other survey parameters. We outline the optimal target selection scenarios and survey strategy choices which will be available to the next generation of spectroscopic surveys.Comment: 16 pages, 22 figures, accepted to MNRAS in dec 201

The Dust Content of Galaxy Clusters

We report on the detection of reddening toward z ~ 0.2 galaxy clusters. This is measured by correlating the Sloan Digital Sky Survey cluster and quasar catalogs and by comparing the photometric and spectroscopic properties of quasars behind the clusters to those in the field. We find mean E(B-V) values of a few times 10^-3 mag for sight lines passing ~Mpc from the clusters' center. The reddening curve is typical of dust but cannot be used to distinguish between different dust types. The radial dependence of the extinction is shallow near the cluster center suggesting that most of the detected dust lies at the outskirts of the clusters. Gravitational magnification of background z ~ 1.7 sources seen on Mpc (projected) scales around the clusters is found to be of order a few per cent, in qualitative agreement with theoretical predictions. Contamination by different spectral properties of the lensed quasar population is unlikely but cannot be excluded.Comment: 4 pages, 3 figure

The Mean and Scatter of the Velocity Dispersion-Optical Richness Relation for maxBCG Galaxy Clusters

The distribution of galaxies in position and velocity around the centers of galaxy clusters encodes important information about cluster mass and structure. Using the maxBCG galaxy cluster catalog identified from imaging data obtained in the Sloan Digital Sky Survey, we study the BCG-galaxy velocity correlation function. By modeling its non-Gaussianity, we measure the mean and scatter in velocity dispersion at fixed richness. The mean velocity dispersion increases from 202+/-10 km/s for small groups to more than 854+/-102 km/s for large clusters. We show the scatter to be at most 40.5+/-3.5%, declining to 14.9+/-9.4% in the richest bins. We test our methods in the C4 cluster catalog, a spectroscopic cluster catalog produced from the Sloan Digital Sky Survey DR2 spectroscopic sample, and in mock galaxy catalogs constructed from N-body simulations. Our methods are robust, measuring the scatter to well within one-sigma of the true value, and the mean to within 10%, in the mock catalogs. By convolving the scatter in velocity dispersion at fixed richness with the observed richness space density function, we measure the velocity dispersion function of the maxBCG galaxy clusters. Although velocity dispersion and richness do not form a true mass-observable relation, the relationship between velocity dispersion and mass is theoretically well characterized and has low scatter. Thus our results provide a key link between theory and observations up to the velocity bias between dark matter and galaxies.Comment: 25 pages, 15 figures, 2 tables, published in Ap

Limits on Dust in Rich Clusters of Galaxies from the Color of Background Quasars

I measure the V-I color distribution of two samples of radio-selected quasars. Quasars from one sample are projected on the sky within 1 degree of a rich foreground Abell cluster of galaxies, while quasars from the other sample are more than 3 degrees from any such cluster . There is no significant difference between the color distributions of the two samples. The 90\% upper limit on the relative reddening between the two samples is E(B-V)=0.05 mag. This result limits the allowed quantity of smoothly distributed dust in rich clusters, and contradicts previous indications for the existence of such a component.Comment: Submitted to ApJ Letters. 14 pages incl. 2 figures, uuencoded, compressed postscript. Also available by anonymous ftp to ftp://wise3.tau.ac.il/pub/dani/dust.ps.

A Systematic Search for High Surface Brightness Giant Arcs in a Sloan Digital Sky Survey Cluster Sample

We present the results of a search for gravitationally-lensed giant arcs conducted on a sample of 825 SDSS galaxy clusters. Both a visual inspection of the images and an automated search were performed and no arcs were found. This result is used to set an upper limit on the arc probability per cluster. We present selection functions for our survey, in the form of arc detection efficiency curves plotted as functions of arc parameters, both for the visual inspection and the automated search. The selection function is such that we are sensitive only to long, high surface brightness arcs with g-band surface brightness mu_g 10. Our upper limits on the arc probability are compatible with previous arc searches. Lastly, we report on a serendipitous discovery of a giant arc in the SDSS data, known inside the SDSS Collaboration as Hall's arc.Comment: 34 pages,8 Fig. Accepted ApJ:Jan-200

Weak-lensing calibration of a stellar mass-based mass proxy for redMaPPer and Voronoi Tessellation clusters in SDSS Stripe 82

We present the first weak lensing calibration of $\mu_{\star}$, a new galaxy cluster mass proxy corresponding to the total stellar mass of red and blue members, in two cluster samples selected from the SDSS Stripe 82 data: 230 redMaPPer clusters at redshift $0.1\leq z<0.33$ and 136 Voronoi Tessellation (VT) clusters at $0.1 \leq z < 0.6$. We use the CS82 shear catalog and stack the clusters in $\mu_{\star}$ bins to measure a mass-observable power law relation. For redMaPPer clusters we obtain $M_0 = (1.77 \pm 0.36) \times 10^{14}h^{-1} M_{\odot}$, $\alpha = 1.74 \pm 0.62$. For VT clusters, we find $M_0 = (4.31 \pm 0.89) \times 10^{14}h^{-1} M_{\odot}$, $\alpha = 0.59 \pm 0.54$ and $M_0 = (3.67 \pm 0.56) \times 10^{14}h^{-1} M_{\odot}$, $\alpha = 0.68 \pm 0.49$ for a low and a high redshift bin, respectively. Our results are consistent, internally and with the literature, indicating that our method can be applied to any cluster finding algorithm. In particular, we recommend that $\mu_{\star}$ be used as the mass proxy for VT clusters. Catalogs including $\mu_{\star}$ measurements will enable its use in studies of galaxy evolution in clusters and cluster cosmology.Comment: Updated to be consistent with the published versio

A High-resolution Scintillating Fiber Tracker With Silicon Photomultiplier Array Readout

We present prototype modules for a tracking detector consisting of multiple layers of 0.25 mm diameter scintillating fibers that are read out by linear arrays of silicon photomultipliers. The module production process is described and measurements of the key properties for both the fibers and the readout devices are shown. Five modules have been subjected to a 12 GeV/c proton/pion testbeam at CERN. A spatial resolution of 0.05 mm and light yields exceeding 20 detected photons per minimum ionizing particle have been achieved, at a tracking efficiency of more than 98.5%. Possible techniques for further improvement of the spatial resolution are discussed.Comment: 31 pages, 27 figures, pre-print version of an article published in Nuclear Instruments and Methods in Physics Research Section A, Vol. 62

Ddt Resistance in Anopheles Koliensis (Diptera: Culicidae) From Northeastern Irian Jaya, Indonesia

Nyamuk Anopheles koliensis, adalah perantara (vektor) penyakit malaria yang penting di daerah pedalaman Irian Jaya, Indonesia, yang telah dievaluasi kerentanannya terhadap DDT dengan menggunakan test kit diagnostik dan kertas yang telah diresapi sesuai dengan standar WHO. Serangkaian tes telah dilakukan di ARSO PIR I, yang merupakan tempat pemukiman para transmigran yang terletak 60 km sebelah selatan Jayapura. Pemeriksaan tersebut dilakukan mulai bulan Januari 1988 sampai dengan Mei 1989. DDT telah diuji pada dosis diagnostik yang telah direkomendasikan untuk jangka waktu tertentu pula. Daya tahan terhadap DDT diamati baik pada populasi nyamuk An koliensis maupun nyamuk Culex quinquefasciatus. Kira-kira 30% dari populasi nyamuk An. koliensis (sejumlah 468) ternyata tahan terhadap 4% DDT dalam kurun waktu 1 dan 2 jam paparan. Penemuan ini menunjukkan bahwa penggunaan DDT secara rutin di ARSO PIR I untuk penyemprotan di dalam mmah diperkirakan efektivitasnya terbatas, antara lain disebabkan oleh daya tahan fisiologik. Walaupun demikian, penggunaan insektisida alternatif ini akan lebih mahal dan mungkin terbukti sama tidak efektifnya karena sifat eksofilik dari jenis nyamuk tersebut. Makalah ini merupakan laporan pertama yang diperkuat dengan pengamatan yang dilakukan secara berulang-ulang mengenai kerentanan nyamuk Anopheles koliensis asal Indonesia terhadap DDT