14,871 research outputs found
Unmotivated or motivated to fail? A cross-cultural study of achievement motivation, fear of failure, and student disengagement
A classic distinction in the literature on achievement and motivation is between fear of failure and success orientations. From the perspective of self-worth theory, these motives are not bipolar constructs but dimensions that interact in ways that make
Unmotivated or motivated to fail? A cross-cultural study of achievement motivation, fear of failure, and student disengagement
A classic distinction in the literature on achievement and motivation is between fear of failure and success orientations. From the perspective of self-worth theory, these motives are not bipolar constructs but dimensions that interact in ways that make some students particularly vulnerable to underachievement and disengagement from school. The current study employs the quadripolar model of need achievement (Covington, 1992; Covington & Omelich, 1988) to explore how these approach and avoidance orientations are related to self-handicapping, defensive pessimism, and helplessness in Eastern and Western settings. Although there have been numerous calls for research of this kind across cultures (Elliott & Bempechat, 2002; Jose & Kilburg, 2007; Pintrich, 2003), little exists in the field to date. In Study 1, with 1,423 Japanese high school students, helplessness and self-handicapping were found to be highest when students were low in success orientation and high in fear of failure. These findings were replicated in Study 2 with 643 Australian students and extended to measures of truancy, disengagement, and self-reported academic achievement. Consistent with self-worth theory, success orientation largely moderated the relationship between fear of failure and academic engagement in both cultures. These results suggest that in the absence of firm achievement goals, fear of failure is associated with a range of maladaptive self-protective strategies. The current project thus represents a unique application of self-worth theory to achievement dynamics and clarifies substantive issues relevant to self-handicapping and disengagement across cultures
Context-Aware Systems for Sequential Item Recommendation
Quizlet is the most popular online learning tool in the United States, and is
used by over 2/3 of high school students, and 1/2 of college students. With
more than 95% of Quizlet users reporting improved grades as a result, the
platform has become the de-facto tool used in millions of classrooms. In this
paper, we explore the task of recommending suitable content for a student to
study, given their prior interests, as well as what their peers are studying.
We propose a novel approach, i.e. Neural Educational Recommendation Engine
(NERE), to recommend educational content by leveraging student behaviors rather
than ratings. We have found that this approach better captures social factors
that are more aligned with learning. NERE is based on a recurrent neural
network that includes collaborative and content-based approaches for
recommendation, and takes into account any particular student's speed, mastery,
and experience to recommend the appropriate task. We train NERE by jointly
learning the user embeddings and content embeddings, and attempt to predict the
content embedding for the final timestamp. We also develop a confidence
estimator for our neural network, which is a crucial requirement for
productionizing this model. We apply NERE to Quizlet's proprietary dataset, and
present our results. We achieved an R^2 score of 0.81 in the content embedding
space, and a recall score of 54% on our 100 nearest neighbors. This vastly
exceeds the recall@100 score of 12% that a standard matrix-factorization
approach provides. We conclude with a discussion on how NERE will be deployed,
and position our work as one of the first educational recommender systems for
the K-12 space
Fingerprints of the hierarchical building up of the structure on the gas kinematics of galaxies
Recent observational and theoretical works have suggested that the
Tully-Fisher Relation might be generalised to include dispersion-dominated
systems by combining the rotation and dispersion velocity in the definition of
the kinematical indicator. Mergers and interactions have been pointed out as
responsible of driving turbulent and disordered gas kinematics, which could
generate Tully-Fisher Relation outliers. We intend to investigate the gas
kinematics of galaxies by using a simulated sample which includes both, gas
disc-dominated and spheroid-dominated systems. Cosmological hydrodynamical
simulations which include a multiphase model and physically-motivated Supernova
feedback were performed in order to follow the evolution of galaxies as they
are assembled. Both the baryonic and stellar Tully-Fisher relations for gas
disc-dominated systems are tight while, as more dispersion-dominated systems
are included, the scatter increases. We found a clear correlation between
and morphology, with dispersion-dominated systems
exhibiting the larger values (). Mergers and interactions can affect the
rotation curves directly or indirectly inducing a scatter in the Tully-Fisher
Relation larger than the simulated evolution since . Kinematical
indicators which combine rotation velocity and dispersion velocity can reduce
the scatter in the baryonic and the stellar mass-velocity relations. Our
findings also show that the lowest scatter in both relations is obtained if the
velocity indicators are measured at the maximum of the rotation curve.
Moreover, the rotation velocity estimated at the maximum of the gas rotation
curve is found to be the best proxy for the potential well regardless of
morphology.Comment: 16 pages, 10 figures, accepted for publication in A&
A thorough analysis of the short- and mid-term activity-related variations in the solar acoustic frequencies
The frequencies of the solar acoustic oscillations vary over the activity
cycle. The variations in other activity proxies are found to be well correlated
with the variations in the acoustic frequencies. However, each proxy has a
slightly different time behaviour. Our goal is to characterize the differences
between the time behaviour of the frequency shifts and of two other activity
proxies, namely, the area covered by sunspots and the 10.7cm flux. We define a
new observable that is particularly sensitive to the short-term frequency
variations. We then compare the observable when computed from model frequency
shifts and from observed frequency shifts obtained with the Global Oscillation
Network Group (GONG) for cycle 23. Our analysis shows that on the shortest
time-scales the variations in the frequency shifts seen in the GONG
observations are strongly correlated with the variations in the area covered by
sunspots. However, a significant loss of correlation is still found. We verify
that the times when the frequency shifts and the sunspot area do not vary in a
similar way tend to coincide with the times of the maxima of the quasi-biennial
variations seen in the solar seismic data. A similar analysis of the relation
between the 10.7cm flux and the frequency shifts reveals that the short-time
variations in the frequency shifts follow even more closely those of the 10.7cm
flux than those of the sunspot area. However, a loss of correlation between
frequency shifts and 10.7cm flux variations is still found around the same
times.Comment: 7 pages, 6 figures, accepted for publication in MNRA
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Absolute single photoionization cross-sections of Br3+: Experiment and theory
Absolute single photoionization cross section measurements for Br3+ ions are reported in the photon energy range 44.79-59.54 eV at a photon energy resolution of 21 ±3 meV. Measurements were performed at the Advanced Light Source at Lawrence Berkeley National Laboratory using the merged-beams technique. Numerous resonance features in the experimental spectrum are assigned and their energies and quantum defect values are tabulated. The cross-section measurements are also compared with Breit-Pauli R-matrix calculations with suitable agreement over the photon energy range investigated. Analysis of the measured spectrum including Rydberg resonance series identifications produced a new emperical determination of the ionizational potential of Br3+ of 46.977 ± 0.050 eV, which is 805 meV lower than the most recently published value of 47.782 eV. This disparity between our determination and the earlier published value is similar to an 843 meV shift in the accepted ionization potential published for iso-electronic Se2+ as part of this same research program
Understanding the Structural Scaling Relations of Early-Type Galaxies
We use a large suite of hydrodynamical simulations of binary galaxy mergers
to construct and calibrate a physical prescription for computing the effective
radii and velocity dispersions of spheroids. We implement this prescription
within a semi-analytic model embedded in merger trees extracted from the
Bolshoi Lambda-CDM N-body simulation, accounting for spheroid growth via major
and minor mergers as well as disk instabilities. We find that without disk
instabilities, our model does not predict sufficient numbers of intermediate
mass early-type galaxies in the local universe. Spheroids also form earlier in
models with spheroid growth via disk instabilities. Our model correctly
predicts the normalization, slope, and scatter of the low-redshift size-mass
and Fundamental Plane relations for early type galaxies. It predicts a degree
of curvature in the Faber-Jackson relation that is not seen in local
observations, but this could be alleviated if higher mass spheroids have more
bottom-heavy initial mass functions. The model also correctly predicts the
observed strong evolution of the size-mass relation for spheroids out to higher
redshifts, as well as the slower evolution in the normalization of the
Faber-Jackson relation. We emphasize that these are genuine predictions of the
model since it was tuned to match hydrodynamical simulations and not these
observations.Comment: Submitted to MNRA
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