21 research outputs found
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Helping Children Master the Tricks and Avoid the Traps of Standardized Tests
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GJ 3236: a new bright, very low-mass eclipsing binary system discovered by the MEarth observatory
We report the detection of eclipses in GJ 3236, a bright (I = 11.6) very low
mass binary system with an orbital period of 0.77 days. Analysis of light- and
radial velocity curves of the system yielded component masses of 0.38 +/- 0.02
and 0.28 +/- 0.02 Msol. The central values for the stellar radii are larger
than the theoretical models predict for these masses, in agreement with the
results for existing eclipsing binaries, although the present 5% observational
uncertainties limit the significance of the larger radii to approximately 1
sigma. Degeneracies in the light curve models resulting from the unknown
configuration of surface spots on the components of GJ 3236 currently dominate
the uncertainties in the radii, and could be reduced by obtaining precise,
multi-band photometry covering the full orbital period. The system appears to
be tidally synchronized and shows signs of high activity levels as expected for
such a short orbital period, evidenced by strong Halpha emission lines in the
spectra of both components. These observations probe an important region of
mass-radius parameter space around the predicted transition to fully-convective
stellar interiors, where there are a limited number of precise measurements
available in the literature.Comment: 14 pages, 5 figures, 10 tables, emulateapj format. Accepted for
publication in Ap
Teachers as writers: a systematic review
This paper is a critical literature review of empirical work from 1990-2015 on teachers as writers. It interrogates the evidence on teachers’ attitudes to writing, their sense of themselves as writers and the potential impact of teacher writing on pedagogy or student outcomes in writing. The methodology was carried out in four stages. Firstly, educational databases keyword searches located 438 papers. Secondly, initial screening identified 159 for further scrutiny, 43 of which were found to specifically address teachers’ writing identities and practices. Thirdly, these sources were screened further using inclusion/exclusion criteria. Fourthly, the 22 papers judged to satisfy the criteria were subject to in-depth analysis and synthesis. The findings reveal that the evidence base in relation to teachers as writers is not strong, particularly with regard to the impact of teachers’ writing on student outcomes. The review indicates that teachers have narrow conceptions of what counts as writing and being a writer and that multiple tensions exist, relating to low self-confidence, negative writing histories, and the challenge of composing and enacting teacher and writer positions in school. However, initial training and professional development programmes do appear to afford opportunities for reformulation of attitudes and sense of self as writer
LSPM J1112+7626: detection of a 41-day M-dwarf eclipsing binary from the MEarth transit survey
We report the detection of eclipses in LSPM J1112+7626, which we find to be a
moderately bright (I_C = 12.14 +/- 0.05) very low-mass binary system with an
orbital period of 41.03236 +/- 0.00002 days, and component masses M_1 = 0.395
+/- 0.002 Msol and M_2 = 0.275 +/- 0.001 Msol in an eccentric (e = 0.239 +/-
0.002) orbit. A 65 day out of eclipse modulation of approximately 2%
peak-to-peak amplitude is seen in I-band, which is probably due to rotational
modulation of photospheric spots on one of the binary components. This paper
presents the discovery and characterization of the object, including radial
velocities sufficient to determine both component masses to better than 1%
precision, and a photometric solution. We find that the sum of the component
radii, which is much better-determined than the individual radii, is inflated
by 3.8 +0.9 -0.5 % compared to the theoretical model predictions, depending on
the age and metallicity assumed. These results demonstrate that the
difficulties in reproducing observed M-dwarf eclipsing binary radii with
theoretical models are not confined to systems with very short orbital periods.
This object promises to be a fruitful testing ground for the hypothesized link
between inflated radii in M-dwarfs and activity.Comment: 23 pages, 11 figures, 12 tables, emulateapj format. Accepted for
publication in Ap
Rationale and design for the Predictors of Arrhythmic and Cardiovascular Risk in End Stage Renal Disease (PACE) study
The art of teaching writing
A partir de los conocimientos obtenidos a lo largo de ocho años de investigación sobre el desarrollo de la escritura en los niños, este libro se centra en la enseñanza de ésta en la escuela primaria. A lo largo de los capÃtulos, se ocupa de varios temas: la creación de un aula para fomentar y apoyar la escritura, las conexiones lectura-escritura, las primeras incursiones en la escritura por los alumnos más pequeños hasta los problemas y éxitos en la adolescencia, el equilibrio entre contenido y forma, redacción de documentos.SCBiblioteca de Educación del Ministerio de Educación, Cultura y Deporte; Calle San AgustÃn, 5 - 3 planta; 28014 Madrid; Tel. +34917748000; [email protected]