7,650 research outputs found
Predicting Success, Preventing Failure: An Investigation of the California High School Exit Exam
Examines early indicators that identify fourth-grade students in San Diego who are at risk of failing the California High School Exit Exam, discusses implications for when and how to intervene to address those factors, and makes policy recommendations
Lessons in Reading Reform: Finding What Works
Evaluates elements of reforms designed to improve reading scores among students identified as lagging behind, including extended-length English classes and school years. Considers the role of teachers' experience, lessons learned, and policy implications
Passing the California High School Exit Exam: Have Recent Policies Improved Student Performance?
This report evaluates the effectiveness of three support services in helping struggling students pass the California High School Exit Examination (CAHSEE). The report highlights the need to help students before they first take the exam in grade 10 and introduces the CAHSEE Early Warning Model, a forecasting tool to identify at-risk students in earlier grades
Analytical sun synchronous low-thrust manoeuvres
Article describes analytical sun synchronous low-thrust manoeuvres
Carefully designed multiple choice tests can help teachers to quickly determine what students don't understand
Over the last 20 years, US schools have widely adopted annual student testing, a move which many researchers believe may have been of little benefit to students' educational outcomes. Julian R. Betts, Youjin Hahn and Andrew C. Zau examine the impact of a different type of mathematics testing - one which is aimed at determining students' strengths and weaknesses in math. They find that since 2000 the Mathematics Diagnostic Testing Project in Californiaâs second largest school district has increased studentâs state test score by up to 4 percentage points. They attribute these increases to the detailed information and insights into student performance the tests provide compared to more traditional examinations
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Effects of ADHD on writing composition product and process in school-age students
Objective: This study examined the relationship between ADHD and writing performance. Method: Students in Grades 3 to 7, 84 with ADHD and 135 age and gender-matched controls completed a writing task (including process logs), and measures of, working memory and attention. Results: Students with ADHD wrote texts of similar length but with poorer structure, coherence and ideation. 6.7% of the variance in writing quality was explained by whether or not the student had an ADHD diagnosis, after control for IQ and age-within-year, with students with ADHD producing text that was less coherent, well structured, and ideationally rich and to spend less time thinking about and reviewing their text. Half of the effect on text quality could be attributed to working memory and sustained attention effects. Conclusions: ADHD has some effect on writing performance which can, in part, be explained by working memory and attentional deficits
The spin-half Heisenberg antiferromagnet on two Archimedian lattices: From the bounce lattice to the maple-leaf lattice and beyond
We investigate the ground state of the two-dimensional Heisenberg
antiferromagnet on two Archimedean lattices, namely, the maple-leaf and bounce
lattices as well as a generalized - model interpolating between both
systems by varying from (bounce limit) to (maple-leaf
limit) and beyond. We use the coupled cluster method to high orders of
approximation and also exact diagonalization of finite-sized lattices to
discuss the ground-state magnetic long-range order based on data for the
ground-state energy, the magnetic order parameter, the spin-spin correlation
functions as well as the pitch angle between neighboring spins. Our results
indicate that the "pure" bounce () and maple-leaf () Heisenberg
antiferromagnets are magnetically ordered, however, with a sublattice
magnetization drastically reduced by frustration and quantum fluctuations. We
found that magnetic long-range order is present in a wide parameter range and that the magnetic order parameter varies only
weakly with . At a direct first-order transition to
a quantum orthogonal-dimer singlet ground state without magnetic long-range
order takes place. The orthogonal-dimer state is the exact ground state in this
large- regime, and so our model has similarities to the Shastry-Sutherland
model. Finally, we use the exact diagonalization to investigate the
magnetization curve. We a find a 1/3 magnetization plateau for and another one at 2/3 of saturation emerging only at large .Comment: 9 pages, 10 figure
Deformation effects in the Si+C and Si+Si reaction Search
The possible occurence of highly deformed configurations is investigated in
the Ca and Ni di-nuclear systems as formed in the
Si+C,Si reactions by using the properties of emitted light
charged particles. Inclusive as well as exclusive data of the heavy fragments
and their associated light charged particles have been collected by using the
{\sc ICARE} charged particle multidetector array. The data are analysed by
Monte Carlo CASCADE statistical-model calculations using a consistent set of
parameters with spin-dependent level densities. Significant deformation effects
at high spin are observed as well as an unexpected large Be cluster
emission of a binary nature.Comment: 3 pages latex, 2 eps figures, paper presented in "wokshop on physics
with multidetector array (pmda2000)Calcutta, India (to be published at
PRAMANA, journal of Physics, India
Generation of optimal trajectories for Earth hybrid pole sitters
A pole-sitter orbit is a closed path that is constantly above one of the Earth's poles, by means of continuous low thrust. This work proposes to hybridize solar sail propulsion and solar electric propulsion (SEP) on the same spacecraft, to enable such a pole-sitter orbit. Locally-optimal control laws are found with a semi-analytical inverse method, starting from a trajectory that satisfies the pole-sitter condition in the Sun-Earth circular restricted three-body problem. These solutions are subsequently used as first guess to find optimal orbits, using a direct method based on pseudospectral transcription. The orbital dynamics of both the pure SEP case and the hybrid case are investigated and compared. It is found that the hybrid spacecraft allows savings on propellant mass fraction. Finally, it is shown that for sufficiently long missions, a hybrid pole-sitter, based on mid-term technology, enables a consistent reduction in the launch mass for a given payload, with respect to a pure SEP spacecraft
Interaction effects and quantum phase transitions in topological insulators
We study strong correlation effects in topological insulators via the Lanczos
algorithm, which we utilize to calculate the exact many-particle ground-state
wave function and its topological properties. We analyze the simple,
noninteracting Haldane model on a honeycomb lattice with known topological
properties and demonstrate that these properties are already evident in small
clusters. Next, we consider interacting fermions by introducing repulsive
nearest-neighbor interactions. A first-order quantum phase transition was
discovered at finite interaction strength between the topological band
insulator and a topologically trivial Mott insulating phase by use of the
fidelity metric and the charge-density-wave structure factor. We construct the
phase diagram at as a function of the interaction strength and the
complex phase for the next-nearest-neighbor hoppings. Finally, we consider the
Haldane model with interacting hard-core bosons, where no evidence for a
topological phase is observed. An important general conclusion of our work is
that despite the intrinsic nonlocality of topological phases their key
topological properties manifest themselves already in small systems and
therefore can be studied numerically via exact diagonalization and observed
experimentally, e.g., with trapped ions and cold atoms in optical lattices.Comment: 13 pages, 12 figures. Published versio
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