Combining Multiple Measures of Students' Opportunities to Develop Analytic, Text-Based Writing Skills

Guided by evidence that teachers contribute to student achievement outcomes, researchers have been reexamining how to study instruction and the classroom opportunities teachers create for students. We describe our experience measuring students' opportunities to develop analytic, text-based writing skills. Utilizing multiple methods of data collection-writing assignment tasks, daily logs, and an annual survey-we generated a composite that was used in prediction models to examine multivariate outcomes, including scores on a state accountability test and a project-developed response-to-text assessment. Our findings demonstrate that students' opportunities to develop analytic, text-based writing skills predicted classroom performance on the project-developed response-to-text assessment. We discuss the importance of considering the measure(s) of learning when examining teaching-learning associations as well as implications for combining multiple measures for purposes of better construct representation. © 2012 Copyright Taylor and Francis Group, LLC

The StEllar Counterparts of COmpact high velocity clouds (SECCO) survey. II. Sensitivity of the survey and an Atlas of Synthetic Dwarf Galaxies

SECCO is a survey devoted to the search for stellar counterparts within Ultra Compact High Velocity Clouds. In this contribution we present the results of a set of simulations aimed at the quantitative estimate of the sensitivity of the survey as a function of the total luminosity, size and distance of the stellar systems we are looking for. For all our synthetic galaxies we assumed an exponential surface brightness profile and an old and metal-poor population. The synthetic galaxies are simulated both on the images and on the photometric catalogs, taking into account all the observational effects. In the fields where the available observational material is of the top quality we detect synthetic galaxies as >=5 sigma over-densities of resolved stars down to muV,h=30.0 mag/arcsec2, for D<=1.5 Mpc, and down to muV,h~29.5 mag/arcsec2, for D<=2.5 Mpc. In the field with the worst observational material of the whole survey we detect synthetic galaxies with muV,h<=28.8 mag/arcsec2 out to D<=1.0 Mpc, and those with muV,h<=27.5 mag/arcsec2 out to D<=2.5 Mpc. Dwarf galaxies with MV=-10, with sizes in the range spanned by known dwarfs, are detected by visual inspection of the images up to D=5 Mpc independently of the image quality. In the best quality images dwarfs are partially resolved into stars up to D=3.0 Mpc, and completely unresolved at D=5 Mpc. As an independent test of the sensitivity of our images to low surface brightness galaxies we report on the detection of several dwarf spheroidal galaxies probably located in the Virgo cluster with MV<=-8.0 and muV,h<=26.8 mag/arcsec2. The nature of the previously discovered SECCO 1 stellar system, also likely located in the Virgo cluster, is re-discussed in comparison with these dwarfs. While specific for the SECCO survey, our study may also provide general guidelines for detection of faint stellar systems with 8m class telescopes.Comment: accepted for publication on A&

Investigating the effectiveness of a comprehensive literacy coaching program in schools with high teacher mobility

Teacher mobility is a factor that impacts schoolwide implementation of professional development programs. In this article, we present interim results of a longitudinal randomized field trial of a comprehensive literacy coaching program (Content-Focused Coaching, CFC) for improving instruction and learning in schools with high teacher mobility.Weinvestigate program effects on 73 new treatment and comparison teachers recruited to replace the large proportion of teachers who left their schools during the first year of the program. HLM analyses indicated that the CFC program predicted significantly higher school-level gains on the state standardized test for English language learners (N=496, ES=.51). By spring, the quality of teachers' self-reported and observed instruction in the CFC schools exceeded that of comparison teachers. Implications for accommodating new teachers into an ongoing and established coaching program to improve instruction and student learning, and conducting randomized trials in schools with high teacher turnover, are discussed. Copyright © 2010 by The University of Chicago

The quality of writing tasks and students' use of academic language in Spanish

This study investigates the quality of the writing tasks assigned to native Spanish speakers in bilingual (Spanish-English) contexts, and the relationship between task quality and students' use of an academic register in their native language. Fifty-six language arts tasks were collected from 26 grade 4 and 5 teachers, and four student writing samples were collected in response to each task (N = 224). Multilevel modeling revealed that variation in students' use of key features of academic language in their writing was associated with the cognitive demand of writing tasks. Findings suggest that students' opportunities to respond to challenging tasks when writing in their native language are rare and that the rigor of writing tasks may relate to students' production and development of academic language. © 2012 by The University of Chicago. All rights reserved

Stemness Features in Liver Cancer

Heterogeneity is a cardinal hallmark of cancer, including primary liver cancer (PLC), and occurs at different layers including putative cell-of-origin. Current evidence suggests that within cellular subpopulations in PLC there are stem-like cells, the cancer stem cells (CSCs). The CSC concept has been recently proposed as an explanation of such intra-tumor heterogeneity. According to this model, CSCs are responsible for tumor initiation, recurrence, metastasis as well as drug-resistance. However, although the CSC hypothesis is intriguing and supported by a large number of experimental studies, there are still open questions regarding the origin of putative CSCs. Since chemo-resistance and recurrence represent major issues in PLC treatment, the development of new therapeutic strategies is needed, for which a good understanding of tumor behavior and in particular of CSCs biology is an imperative prerequisite. In this review we summarize the regulatory pathways that support CSC features in PLC. Moreover, we highlight the key features of hepatic CSC, in terms of enhanced drug-resistance, increased metastatic potential and metabolic rearrangement. Knowledge of the molecular mechanisms underlying CSC biology may provide novel options for PLC combination therapies

The Northern wraps of the Sagittarius Stream as traced by Red Clump stars: distances, intrinsic widths and stellar densities

We trace the tidal Stream of the Sagittarius dwarf spheroidal galaxy (Sgr dSph) using Red Clump stars from the catalog of the Sloan Digital Sky Survey - Data Release 6, in the range 150{\deg} < RA < 220{\deg}, corresponding to the range of orbital azimuth 220{\deg} < Lambda < 290{\deg}. Substructures along the line of sight are identified as significant peaks in the differential star count profiles (SCP) of candidate Red Clump stars. A proper modeling of the SCPs allows us to obtain: (a) <10% accurate, purely differential distances with respect to the main body of Sgr, (b) estimates of the FWHM along the line of sight, and (c) estimates of the local density, for each detected substructure. In the range 255{\deg} < Lambda < 290{\deg} we cleanly and continuously trace various coherent structures that can be ascribed to the Stream, in particular: the well known northern portion of the leading arm, running from d~43 kpc at Lambda ~ 290{\deg} to d ~ 30 kpc at Lambda ~ 255{\deg}, and a more nearby coherent series of detections lying at constant distance d ~ 25 kpc, that can be identified with a wrap of the trailing arm. The latter structure, predicted by several models of the disruption of Sgr dSph, was never traced before; comparison with existing models indicates that the difference in distance between these portions of the leading and trailing arms may provide a powerful tool to discriminate between theoretical models assuming different shapes of the Galactic potential. A further, more distant wrap in the same portion of the sky is detected only along a couple of lines of sight.[abridged]Comment: 31 pages, 28 figures, accepted for publication in the Astrophysical Journal, a version with figures at full resolution can be downloaded at the following URL: http://www.bo.astro.it/SGR

HII regions within a compact high velocity cloud. A nearly star-less dwarf galaxy?

Within the SECCO survey we identified a candidate stellar counterpart to the Ultra Compact High Velocity Cloud (UCHVC) HVC274.68+74.70-123, that was suggested by Adams et al. (2013) as a possible mini-halo within the Local Group of galaxies. The spectroscopic follow-up of the brightest sources within the candidate reveals the presence of two HII regions whose radial velocity is compatible with physical association with the UVHVC. The available data does not allow us to give a definite answer on the nature of the newly identified system. A few alternative hypotheses are discussed. However, the most likely possibility is that we have found a new faint dwarf galaxy residing in the Virgo cluster of galaxies, which we name SECCO-1. Independently of its actual distance, SECCO-1 displays a ratio of neutral hydrogen mass to V luminosity of M_{HI}/L_V>= 20, by far the largest among local dwarfs. Hence, it appears as a nearly star-less galaxy and it may be an example of the missing links between normal dwarfs and the dark mini halos that are predicted to exist in large numbers according to the currently accepted cosmological model.Comment: Accepted for publication in ApJ Letters. Pdflatex, emulateapj.cls. 6 pages, 3 figures, 2 table

Detection of a population gradient in the Sagittarius Stream

We present a quantitative comparison between the Horizontal Branch morphology in the core of the Sagittarius dwarf spheroidal galaxy (Sgr) and in a wide field sampling a portion of its tidal stream (Sgr Stream), located tens of kpc away from the center of the parent galaxy. We find that the Blue Horizontal Branch (BHB) stars in that part of the Stream are five times more abundant than in the Sgr core, relative to Red Clump stars. The difference in the ratio of BHB to RC stars between the two fields is significant at the 4.8 sigma level. This indicates that the old and metal-poor population of Sgr was preferentially stripped from the galaxy in past peri-Galactic passages with respect to the intermediate-age metal rich population that presently dominates the bound core of Sgr, probably due to a strong radial gradient that was settled within the galaxy before its disruption. The technique adopted in the present study allows to trace population gradients along the whole extension of the Stream.Comment: 4 pages, 3 .ps figures (fig. 1 at low resolution); Accepted for publication by A&A Letter

The StEllar Counterparts of COmpact high velocity clouds (SECCO) survey. I. Photos of ghosts

We present an imaging survey aimed at searching for the stellar counterparts of recently discovered ultra-compact high-velocity HI clouds (UCHVC). Adams et al. (2013) proposed these clouds to be candidate mini-haloes in the Local Group and/or its surroundings, within a distance range of 0.25-2.0 Mpc. Using the Large Binocular Telescope we obtain wide-field (~ 23' X 23') g- and r-band images of the twenty-five most promising and most compact clouds among the fifty-nine identified by Adams et al. Careful visual inspection of all the images does not reveal any stellar counterpart even slightly resembling LeoP, the only local dwarf galaxy that was found as a counterpart to a previously detected high velocity cloud. Only a possible distant (D>3.0 Mpc) counterpart to HVC274.68+74.70-123 has been identified on our images. The point source photometry in the central 17.3' X 7.7' chips reaches r<= 26.5, and is expected to contain most of the stellar counterparts to the UCHVCs. However, no obvious stellar over-density is detected in any of our fields, in marked contrast to our comparison LeoP field in which the dwarf galaxy is detected at a >30 sigma significance level. Only HVC352.45+59.06+263 may be associated with a weak over-density, whose nature cannot be ascertained with our data. Sensitivity tests shows that our survey would have detected any dwarf galaxy dominated by an old stellar population, with an integrated absolute magnitude M_V<= -8.0, a half-light radius r_h<= 300 pc, and lying within 1.5 Mpc from us, thereby confirming that it is unlikely that the observed UCHVCs are associated with stellar counterparts typical of known Local Group dwarf galaxies.Comment: Accepted for publication by A&A. PdfLaTex. 24 pages, 27 figures. Minor changes; A&A language editin