939 research outputs found
Dynamic testing of gifted and average-ability children's analogy problem solving: Does executive functioning play a role?
Article / Letter to editorInstituut Psychologie;Instituut Psychologie;Instituut Psychologie;Instituut Psychologi
Dynamic testing of gifted and average-ability children's analogy problem solving: Does executive functioning play a role?
Article / Letter to editorInstituut Psychologie;Instituut Psychologie;Instituut Psychologie;Instituut Psychologi
Dynamic testing of gifted and average-ability children's analogy problem solving: Does executive functioning play a role?
status: publishe
Dynamic testing of gifted and average-ability children's analogy problem solving: Does executive functioning play a role?
Article / Letter to editorInstituut Psychologie;Instituut Psychologie;Instituut Psychologie;Instituut Psychologi
Computerized process-oriented dynamic testing of children’s ability to reason by analogy using log data
The study investigated the value of process data obtained from a group-administered computerized dynamic test of analogical reasoning, consisting of a pretest-training-posttest design. We sought to evaluate the effects of training on processes and performance, and the relationships between process measures and performance on the dynamic test. Participants were N = 86 primary school children (Mage = 8.11 years, SD = 0.63). The test consisted of constructed-response geometrical analogy items, requiring several actions to construct an answer. Process data enabled scoring of the total time, the time taken for initial planning of the task, the time taken for checking the answer that was provided, and variation in solving time. Training led to improved performance compared to repeated practice, but this improvement was not reflected in task-solving processes. Almost all process measures were related to performance, but the effects of training or repeated practice on this relationship differed widely between measures. In conclusion, the findings seemed to indicate that investigating process indicators within computerized dynamic testing of analogical reasoning ability provided information about children’s learning processes, but that not all processes were affected in the same way by training.Education and Child Studie
Pre-Existing Superbubbles as the Sites of Gamma-Ray Bursts
According to recent models, gamma-ray bursts apparently explode in a wide
variety of ambient densities ranging from ~ 10^{-3} to 30 cm^{-3}. The lowest
density environments seem, at first sight, to be incompatible with bursts in or
near molecular clouds or with dense stellar winds and hence with the
association of gamma-ray bursts with massive stars. We argue that low ambient
density regions naturally exist in areas of active star formation as the
interiors of superbubbles. The evolution of the interior bubble density as a
function of time for different assumptions about the evaporative or
hydrodynamical mass loading of the bubble interior is discussed. We present a
number of reasons why there should exist a large range of inferred afterglow
ambient densities whether gamma-ray bursts arise in massive stars or some
version of compact star coalescence. We predict that many gamma-ray bursts will
be identified with X-ray bright regions of galaxies, corresponding to
superbubbles, rather than with blue localized regions of star formation.
Massive star progenitors are expected to have their own circumstellar winds.
The lack of evidence for individual stellar winds associated with the
progenitor stars for the cases with afterglows in especially low density
environments may imply low wind densities and hence low mass loss rates
combined with high velocities. If gamma-ray bursts are associated with massive
stars, this combination might be expected for compact progenitors with
atmospheres dominated by carbon, oxygen or heavier elements, that is,
progenitors resembling Type Ic supernovae.Comment: 14 pages, no figures, submitted to The Astrophysical Journa
The Fractal Dimension of Projected Clouds
The interstellar medium seems to have an underlying fractal structure which
can be characterized through its fractal dimension. However, interstellar
clouds are observed as projected two-dimensional images, and the projection of
a tri-dimensional fractal distorts its measured properties. Here we use
simulated fractal clouds to study the relationship between the tri-dimensional
fractal dimension (D_f) of modeled clouds and the dimension resulting from
their projected images. We analyze different fractal dimension estimators: the
correlation and mass dimensions of the clouds, and the perimeter-based
dimension of their boundaries (D_per). We find the functional forms relating
D_f with the projected fractal dimensions, as well as the dependence on the
image resolution, which allow to estimatethe "real" D_f value of a cloud from
its projection. The application of these results to Orion A indicates in a
self-consistent way that 2.5 < D_f < 2.7 for this molecular cloud, a value
higher than the result D_per+1 = 2.3 some times assumed in literature for
interstellar clouds.Comment: 27 pages, 13 figures, 1 table. Accepted for publication in ApJ. Minor
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Optimizing patient risk stratification for colonoscopy screening and surveillance of colorectal cancer: The role for linked data
No abstract available for this article
Constraining ^(26)Al+p resonances using ^(26)Al(^3He,d)^(27)Si
The ^(26)Al(^3He,d)^(27)Si reaction was measured from 0°≤θ_(c.m.)≤35° at E(^3He)=20 MeV using a quadrupole-dipole-dipole-dipole magnetic spectrometer. States in ^(27)Si were observed above the background at 7652 and 7741 keV and upper limits were set for the state at 7592 keV. Implications for the ^(26)Al(p,γ)^(27)Si stellar reaction rate are discussed
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