8,217 research outputs found
Scintillation Caustics in Planetary Occultation Light Curves
We revisit the GSC5249-01240 light curve obtained during its occultation by
Saturn's North polar region. In addition to refractive scintillations, the
power spectrum of intensity fluctuations shows an enhancement of power between
refractive and diffractive regimes. We identify this excess power as due to
high amplitude spikes in the light curve and suggest that these spikes are due
to caustics associated with ray crossing situations. The flux variation in
individual spikes follows the expected caustic behavior, including diffraction
fringes which we have observed for the first time in a planetary occultation
light curve. The presence of caustics in scintillation light curves require an
inner scale cut off to the power spectrum of underlying density fluctuations
associated with turbulence. Another possibility is the presence of gravity
waves in the atmosphere. While occultation light curves previously showed the
existence of refractive scintillations, a combination of small projected
stellar size and a low relative velocity during the event have allowed us to
identify caustics in this occultation. This has led us to re-examine previous
data sets, in which we have also found likely examples of caustics.Comment: 4 pages, 3 figures; ApJL submitte
TVET Teacher Education: A Vision Beyond Tradition
This paper identifies some basic information about brain based learning, which includes some technical information presented in terms that all may understand. Two major psychological notions, which underpin all we know about the teaching and learning process, will be identified and described. Further, this paper will focus upon best practice strategies that have been identified in the research on student achievement and will provide specific suggestions on how to implement them. It will demonstrate why the vocational education model is the premier educational delivery system for all of education and will aid in the developing of a vision beyond tradition
Achievement goals, self-handicapping, and performance: A 2 × 2 achievement goal perspective
Elliot and colleagues (2006) examined the effects of experimentally induced achievement goals, proposed by the
trichotomous model, on self-handicapping and performance in physical education. Our study replicated and extended the
work of Elliot et al. by experimentally promoting all four goals proposed by the 262 model (Elliot & McGregor, 2001),
measuring the participants’ own situational achievement goals, using a relatively novel task, and testing the participants in a group setting. We used a randomized experimental design with four conditions that aimed to induce one of the four goals advanced by the 262 model. The participants (n¼138) were undergraduates who engaged in a dart-throwing task. The results pertaining to self-handicapping partly replicated Elliot and colleagues’ findings by showing that experimentally promoted performance-avoidance goals resulted in less practice. In contrast, the promotion of mastery-avoidance goals did
not result in less practice compared with either of the approach goals. Dart-throwing performance did not differ among the four goal conditions. Personal achievement goals did not moderate the effects of experimentally induced goals on selfhandicapping and performance. The extent to which mastery-avoidance goals are maladaptive is discussed, as well as the interplay between personal and experimentally induced goals
The Hubble Space Telescope high speed photometer
The Hubble Space Telescope will provide the opportunity to perform precise astronomical photometry above the disturbing effects of the atmosphere. The High Speed Photometer is designed to provide the observatory with a stable, precise photometer with wide dynamic range, broad wavelenth coverage, time resolution in the microsecond region, and polarimetric capability. Here, the scientific requirements for the instrument are examined, the unique design features of the photometer are explored, and the improvements to be expected over the performance of ground-based instruments are projected
Neural Architecture Search as Program Transformation Exploration
Improving the performance of deep neural networks (DNNs) is important to both
the compiler and neural architecture search (NAS) communities. Compilers apply
program transformations in order to exploit hardware parallelism and memory
hierarchy. However, legality concerns mean they fail to exploit the natural
robustness of neural networks. In contrast, NAS techniques mutate networks by
operations such as the grouping or bottlenecking of convolutions, exploiting
the resilience of DNNs. In this work, we express such neural architecture
operations as program transformations whose legality depends on a notion of
representational capacity. This allows them to be combined with existing
transformations into a unified optimization framework. This unification allows
us to express existing NAS operations as combinations of simpler
transformations. Crucially, it allows us to generate and explore new tensor
convolutions. We prototyped the combined framework in TVM and were able to find
optimizations across different DNNs, that significantly reduce inference time -
over 3 in the majority of cases.
Furthermore, our scheme dramatically reduces NAS search time. Code is
available
at~\href{https://github.com/jack-willturner/nas-as-program-transformation-exploration}{this
https url}
A reduced subduction graph and higher multiplicity in S_n transformation coefficients
Transformation coefficients between {\it standard} bases for irreducible
representations of the symmetric group and {\it split} bases adapted to
the subgroup () are
considered. We first provide a \emph{selection rule} and an \emph{identity
rule} for the subduction coefficients which allow to decrease the number of
unknowns and equations arising from the linear method by Pan and Chen. Then,
using the {\it reduced subduction graph} approach, we may look at higher
multiplicity instances. As a significant example, an orthonormalized solution
for the first multiplicity-three case, which occurs in the decomposition of the
irreducible representation of into
of , is presented and discussed.Comment: 12 pages, 1 figure, iopart class, Revisited version (several
typographical errors have been corrected). Accepted for publication in J.
Phys. A: Math. Ge
Assessing direct contributions of morphological awareness and prosodic sensitivity to children’s word reading and reading comprehension
We examined the independent contributions of prosodic sensitivity and morphological awareness to word reading, text reading accuracy, and reading comprehension. We did so in a longitudinal study of English-speaking children (N = 70). At 5 to 7 years of age, children completed the metalinguistic measures along with control measures of phonological awareness and vocabulary. Children completed the reading measures two years later. Morphological awareness, but not prosodic sensitivity made a significant independent contribution to word reading, text reading accuracy and reading comprehension. The effects of morphological awareness on reading comprehension remained after controls for word reading. These results suggest that morphological awareness needs to be considered seriously in models of reading development and that prosodic sensitivity might have primarily indirect relations to reading outcomes.
Keywords: Morphological Awareness; Prosody; Word Reading; Reading Comprehension
Spectral Signatures of the Diffusional Anomaly in Water
Analysis of power spectrum profiles for various tagged particle quantities in
bulk SPC/E water is used to demonstrate that variations in mobility associated
with the diffusional anomaly are mirrored in the exponent of the \onebyf\
region. Monitoring of \onebyf behaviour is shown to be a simple and direct
method for linking phenomena on three distinctive length and time scales: the
local molecular environment, hydrogen bond network reorganisations and the
diffusivity. The results indicate that experimental studies of supercooled
water to probe the density dependence of spectral features, or
equivalent stretched exponential behaviour in time-correlation functions, will
be of interest.Comment: 5 Pages, 4 Figure
Spectral Geometry of Heterotic Compactifications
The structure of heterotic string target space compactifications is studied
using the formalism of the noncommutative geometry associated with lattice
vertex operator algebras. The spectral triples of the noncommutative spacetimes
are constructed and used to show that the intrinsic gauge field degrees of
freedom disappear in the low-energy sectors of these spacetimes. The quantum
geometry is thereby determined in much the same way as for ordinary superstring
target spaces. In this setting, non-abelian gauge theories on the classical
spacetimes arise from the K-theory of the effective target spaces.Comment: 14 pages LaTe
Systematic and Causal Corrections to the Coherent Potential Approximation
The Dynamical Cluster Approximation (DCA) is modified to include disorder.
The DCA incorporates non-local corrections to local approximations such as the
Coherent Potential Approximation (CPA) by mapping the lattice problem with
disorder, and in the thermodynamic limit, to a self-consistently embedded
finite-sized cluster problem. It satisfies all of the characteristics of a
successful cluster approximation. It is causal, preserves the point-group and
translational symmetry of the original lattice, recovers the CPA when the
cluster size equals one, and becomes exact as . We use the DCA to
study the Anderson model with binary diagonal disorder. It restores sharp
features and band tailing in the density of states which reflect correlations
in the local environment of each site. While the DCA does not describe the
localization transition, it does describe precursor effects of localization.Comment: 11 pages, LaTeX, and 11 PS figures, to appear in Phys. Rev. B.
Revised version with typos corrected and references adde
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