5,554 research outputs found
Principals' sensemaking of coaching for ambitious reading instruction in a high-stakes accountability policy environment
In the present exploratory qualitative study we examine the contextual factors that influenced the implementation of a multi-year comprehensive literacy-coaching program (Content- Focused Coaching, CFC). We argue that principals' sensemaking of the dialogic instructional strategies promoted by the program in light of high-stakes accountability policies influenced coaches' work with teachers. Principals' views of the efficacy of the teaching strategies promoted by CFC for meeting accountability targets influenced how principals socially positioned coaches in schools (i.e., the degree to which they promoted coaches as sources of expertise to teachers), and the extent to which the coaching received by teachers focused on implementing dialogic teaching practices. Our results also suggest that principals' sensemaking of the program was for the most part consistent across years, even in the face of shifting accountability status and changes in district leadership. Implications of our findings for improving the implementation of coaching programs are discussed
Saving Planetary Systems: Dead Zones & Planetary Migration
The tidal interaction between a disk and a planet leads to the planet's
migration. A long-standing question regarding this mechanism is how to stop the
migration before planets plunge into their central stars. In this paper, we
propose a new, simple mechanism to significantly slow down planet migration,
and test the possibility by using a hybrid numerical integrator to simulate the
disk-planet interaction. The key component of the scenario is the role of low
viscosity regions in protostellar disks known as dead zones, which affect
planetary migration in two ways. First of all, it allows a smaller-mass planet
to open a gap, and hence switch the faster type I migration to the slower type
II migration. Secondly, a low viscosity slows down type II migration itself,
because type II migration is directly proportional to the viscosity. We present
numerical simulations of planetary migration by using a hybrid symplectic
integrator-gas dynamics code. Assuming that the disk viscosity parameter inside
the dead zone is (alpha=1e-4-1e-5), we find that, when a low-mass planet (e.g.
1-10 Earth masses) migrates from outside the dead zone, its migration is
stopped due to the mass accumulation inside the dead zone. When a low-mass
planet migrates from inside the dead zone, it opens a gap and slows down its
migration. A massive planet like Jupiter, on the other hand, opens a gap and
slows down inside the dead zone, independent of its initial orbital radius. The
final orbital radius of a Jupiter mass planet depends on the dead zone's
viscosity. For the range of alpha's noted above, this can vary anywhere from 7
AU, to an orbital radius of 0.1 AU that is characteristic of the hot Jupiters.Comment: 38 pages, 14 figures, some changes in text and figures, accepted for
publication in Ap
Dead Zones and the Origin of Planetary Masses
Protoplanets accrete material from their natal protostellar disks until they
are sufficiently massive to open a gap in the face of the disk's viscosity that
arises from the magneto-rotational instability (MRI). By computing the
ionization structure within observationally well-constrained disk models, we
demonstrate that poorly ionized, low viscosity "dead zones" stretch out to 12
AU within typical disks. We find that planets of terrestrial mass robustly form
within the dead zones while massive Jovian planets form beyond. Dead zones will
also halt the rapid migration of planets into their central stars. Finally, we
argue that the gravitational scattering of low mass planets formed in the dead
zone, to larger radii by a rapidly accreting Jupiter beyond, can explain the
distribution of planetary masses in our solar system.Comment: 10 pages, 4 figures, accepted for publication in ApJ
About multiplicities and applications to Bezout numbers
Let denote a local Noetherian ring and
an ideal such that for a
finitely generated -module . Let \au = a_1,\ldots,a_d denote a system
of parameters of such that for . It follows that \chi := e_0(\au;M)
- c \cdot e_0(\mathfrak{q};M) \geq 0, where .
The main results of the report are a discussion when resp. to
describe the value of in some particular cases. Applications concern
results on the multiplicity e_0(\au;M) and applications to Bezout numbers.Comment: 11 pages, to appear Springer INdAM-Series, Vol. 20 (2017
Assessing students' skills at writing analytically in response to texts
Despite the importance of writing analytically in response to texts, there are few assessments measuring students' mastery of this skill. This manuscript describes the development of a response-to-text assessment (RTA) intended for use in research. In a subsequent validity investigation we examined whether the RTA distinguished among classrooms in students' ability to write analytically in response to text and whether measures of teaching predicted this variation. We demonstrate that the RTA was correlated with the state standardized assessment, but did not overlap with this accountability test completely and, additionally, that more variation between classrooms existed on the RTA. Students' opportunities for reasoning and extended writing in the classroom were significantly associated with RTA scores. The findings suggest that the RTA can be a valuable tool for conducting research on students' attainment of analytic writing skills and for understanding how teaching relates to student achievement on these skills. © 2013 by The University of Chicago. All rights reserved
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
Collision-Energy-Resolved Penning Ionization Electron Spectroscopy of Toluene and Chlorotoluenes : Stereodynamics in Collisional Ionization and Anisotropic Interactions with He*(23S) atoms
Poor Childhood Dental Care: A Risk Factor for the Development of Coronary Artery Disease and Potential New Target for CAD Prevention
Gas disks to gas giants: Simulating the birth of planetary systems
The ensemble of now more than 250 discovered planetary systems displays a
wide range of masses, orbits and, in multiple systems, dynamical interactions.
These represent the end point of a complex sequence of events, wherein an
entire protostellar disk converts itself into a small number of planetary
bodies. Here, we present self-consistent numerical simulations of this process,
which produce results in agreement with some of the key trends observed in the
properties of the exoplanets. Analogs to our own solar system do not appear to
be common, originating from disks near the boundary between barren and (giant)
planet-forming.Comment: Science, August 8 issue. Published version and Supporting Online
material incl. movies are at
http://www.sciencemag.org/cgi/content/abstract/321/5890/81
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