18,067 research outputs found

    A process-oriented language for describing aspects of reading comprehension

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    Includes bibliographical references (p. 36-38)The research described herein was supported in part by the National Institute of Education under Contract No. MS-NIE-C-400-76-011

    Challenging Behaviors in Young Children: The Father\u27s Role

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    In this study, the authors examined the parenting practices, developmental expectations, and stress levels of 136 fathers and the challenging and prosocial behaviors of their 1- to 5-year-old children. In addition, the authors systematically addressed fathers\u27 qualitative concerns about their parenting. The authors divided the participants into 4 groups and controlled for family socioeconomic status (SES) and the focus child\u27s gender. Results showed a significantly higher use of corporal and verbal punishment and parenting stress among lower income fathers. Secondary analyses demonstrated a significant effect of paternal disciplinary practices that emphasized the frequent use of corporal and verbal punishment on child behavior problems, regardless of SES level. On a positive note, fathers from both lower and higher SES groups had reasonable developmental expectations for their boys and girls, and they reported similar frequencies of their children\u27s prosocial behavior. The authors discuss the need for early parent education programs that include fathers and that teach specific strategies to address child behavior problems

    Probing the Upper Limit of Nonclassical Rotational Inertia

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    We study the effect of confinement on solid 4-He's nonclassical rotational inertia (NCRI) in a torsional oscillator by constraining it to narrow annular cells of various widths. The NCRI exhibits a broad maximum value of 20% for annuli of approximately 100 micrometer width. Samples constrained to porous media or to larger geometries both have smaller NCRI, mostly below about 1%. In addition, we extend Kim and Chan's blocked annulus experiment to solid samples with large supersolid fractions. Blocking the annulus suppresses the nonclassical decoupling from 17.1% below the limit of our detection of 0.8%. This result demonstrates the nonlocal nature of the supersolid phenomena. At 20 mK, NCRI depends on velocity history showing a closed hysteresis loop in different thin annular cells.Comment: 5 pages, 4 figure

    A potential library for primary MFL pedagogy: the case of Young Pathfinders

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    As readers of this journal will know very well, 2010 will see all KS2 (ages 7-11) pupils in England entitled to learn a modern foreign language in normal curriculum time. This development of the commitment to primary language learning should provide an excellent opportunity and experience for pupils, whilst at the same time requiring some radical changes for many teachers, schools and much of the wider language learning community. Recent research has indicated general trends suggesting an increase in primary languages already, in anticipation of this development and even beforehand. One of the most recent studies indicates that 43% of primary children currently learn a foreign language at KS2, either in class or as an extra-curricular activity, although the extent of this learning varies considerably (Driscoll, Jones and Macrory, 2004). It has also been suggested (Muijs et al, 2005) that there are certain aspects of the process that will be particularly demanding if the challenge of providing this entitlement are to be met

    Absence of Pressure-Driven Supersolid Flow at Low Frequency

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    An important unresolved question in supersolid research is the degree to which the non-classical rotational inertia (NCRI) phenomenon observed in the torsional oscillator experiments of Kim and Chan, is evidence for a Bose-condensed supersolid state with superfluid-like properties. In an open annular geometry, Kim and Chan found that a fraction of the solid moment of inertia is decoupled from the motion of the oscillator; however, when the annulus is blocked by a partition, the decoupled supersolid fraction is locked to the oscillator being accelerated by an AC pressure gradient generated by the moving partition. These observations are in accord with superfluid hydrodynamics. We apply a low frequency AC pressure gradient in order to search for a superfluid-like response in a supersolid sample. Our results are consistent with zero supersolid flow in response to the imposed low frequency pressure gradient. A statistical analysis of our data sets a bound, at the 68% confidence level, of 9.6×104\times 10^{-4} nm/s for the mass transport velocity carried by a possible supersolid flow. In terms of a simple model for the supersolid, an upper bound of 3.3×106\times 10^{-6} is set for the supersolid fraction at 25 mK, at this same confidence level. These findings force the conclusion that the NCRI observed in the torsional oscillator experiments is not evidence for a frequency independent superfluid-like state. Supersolid behavior is a frequency-dependent phenomenon, clearly evident in the frequency range of the torsional oscillator experiments, but undetectably small at frequencies approaching zero.Comment: 6 pages, 5 figure

    A Collision of Subclusters in Abell 754

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    We present direct evidence of a collision of subclusters in the galaxy cluster Abell 754. Our comparison of new optical data and archival ROSAT PSPC X-ray data reveal three collision signatures predicted by n-body/hydrodynamical simulations of hierarchical cluster evolution. First, there is strong evidence of a non-hydrostatic process; neither of the two major clumps in the galaxy distribution lies on the off-center peak of the X-ray emission from the intracluster gas. Second, the peak of the X-ray emission is elongated perpendicular to the collision axis defined by the centroids of the two galaxy clumps. Third, there is evidence of compression-heated gas; one of A754's two X-ray temperature components (Henry & Briel 1995) is among the hottest observed in any cluster and hotter than that inferred from the velocity dispersion of the associated galaxy clump. These signatures are consistent with the qualitative features of simulations (Evrard 1990a,b) in which two subclusters have collided in the plane of the sky during roughly the last Gyr. The detection of such collisions is crucial for understanding both the dynamics of individual clusters and the underlying cosmology. First, for systems like A754, estimating the cluster X-ray mass from assumptions of hydrostatic equilibrium and isothermality is incorrect and may produce the discrepancies sometimes found between X-ray masses and those derived from gravitational lens models (Babul & Miralda-Escude 1994). Second, the fraction of nearby clusters in which subclusters have collided in the last Gyr is especially sensitive to the mean mass density parameter Omega_0 (cf. Richstone et al. 1992; Evrard et al. 1993; Lacey & Cole 1993). With a large, well-defined cluster sample, it will be possible to place a new and powerful constraint on cosmological models.Comment: 4 pages + 1 color figure (Postscript). Accepted for Publication in ApJ Letter
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