8,558 research outputs found
Using curriculum-based measures for assessing achievement in children who may have potential risk-factors for reading difficulty
Includes bibliographical references
High index top layer for multimaterial coatings
For application in future cryogenically cooled gravitational wave detectors, the thermal noise of low absorbing mirror coatings has to be reduced. The development of low mechanical and optical loss materials is challenging, but thermal noise reduction can be significantly supported by using a multimaterial coating design. We analyze the possible improvement of the total (optical and mechanical) loss of a three-material based coating obtained by optimizing the properties of the top layer of the coating stack. A top-layer material with sufficiently high refractive index could have a significantly higher optical and mechanical loss than currently used tantala, while still enabling reduction of the total coating loss. Restrictions on possible top-layer material properties are made, and the option of a crystalline top layer is discussed
Why is Long-Horizon Equity Less Risky? A Duration-Based Explanation of the Value Premium
This paper proposes a dynamic risk-based model that captures the high expected returns on value stocks relative to growth stocks, and the failure of the capital asset pricing model to explain these expected returns. To model the difference between value and growth stocks, we introduce a cross-section of long-lived firms distinguished by the timing of their cash flows. Firms with cash flows weighted more to the future have high price ratios, while firms with cash flows weighted more to the present have low price ratios. We model how investors perceive the risks of these cash flows by specifying a stochastic discount factor for the economy. The stochastic discount factor implies that shocks to aggregate dividends are priced, but that shocks to the time-varying price of risk are not. As long-horizon equity, growth stocks covary more with this time-varying price of risk than value stocks, which covary more with shocks to cash flows. When the model is calibrated to explain aggregate stock market behavior, we find that it can also account for the observed value premium, the high Sharpe ratios on value stocks relative to growth stocks, and the outperformance of value (and underperformance of growth) relative to the CAPM.
The Measure of Poverty: A Boston Indicators Project Special Report
Examines Boston's poverty rate by race/ethnicity, family structure, education, and geography; income inequality; demand for safety-net programs; and how the high cost of living and budget cuts affect vulnerable households and those below the poverty line
Fast solution of Cahn-Hilliard variational inequalities using implicit time discretization and finite elements
We consider the e�cient solution of the Cahn-Hilliard variational inequality using an implicit time discretization, which is formulated as an optimal control problem with pointwise constraints on the control. By applying a semi-smooth Newton method combined with a Moreau-Yosida regularization technique for handling the control constraints we show superlinear convergence in function space. At the heart of this method lies the solution of large and sparse linear systems for which we propose the use of preconditioned Krylov subspace solvers using an e�ective Schur complement approximation. Numerical results illustrate the competitiveness of this approach
City of Ideas: Reinventing Boston's Innovation Economy: The Boston Indicators Report 2012
Analyzes indicators of the city's economic, social, and technological progress; potential for creating innovative solutions to global and national challenges; and complexities, disparities, and weaknesses in the indicators and innovation economy paradigm
Beyond Chandra - the X-ray Surveyor
Over the past 16 years, NASA's Chandra X-ray Observatory has provided an
unparalleled means for exploring the universe with its half-arcsecond angular
resolution. Chandra studies have deepened our understanding of galaxy clusters,
active galactic nuclei, galaxies, supernova remnants, planets, and solar system
objects addressing almost all areas of current interest in astronomy and
astrophysics. As we look beyond Chandra, it is clear that comparable or even
better angular resolution with greatly increased photon throughput is essential
to address even more demanding science questions, such as the formation and
subsequent growth of black hole seeds at very high redshift; the emergence of
the first galaxy groups; and details of feedback over a large range of scales
from galaxies to galaxy clusters. Recently, NASA Marshall Space Flight Center,
together with the Smithsonian Astrophysical Observatory, has initiated a
concept study for such a mission named the X-ray Surveyor. This study starts
with a baseline payload consisting of a high resolution X-ray telescope and an
instrument set which may include an X-ray calorimeter, a wide-field imager and
a dispersive grating spectrometer and readout. The telescope would consist of
highly nested thin shells, for which a number of technical approaches are
currently under development, including adjustable X-ray optics, differential
deposition, and modern polishing techniques applied to a variety of substrates.
In many areas, the mission requirements would be no more stringent than those
of Chandra, and the study takes advantage of similar studies for other large
area missions carried out over the past two decades. Initial assessments
indicate that such an X-ray mission is scientifically compelling, technically
feasible, and worthy of a high rioritization by the next American National
Academy of Sciences Decadal Survey for Astronomy and Astrophysics.Comment: 6 pages, 6 figures, paper 9510-01 presented at SPIE Europe, Prague,
April 201
Fast Solvers for Cahn-Hilliard Inpainting
We consider the efficient solution of the modified Cahn-Hilliard equation for binary image inpainting using convexity splitting, which allows an unconditionally gradient stable time-discretization scheme. We look at a double-well as well as a double obstacle potential. For the latter we get a nonlinear system for which we apply a semi-smooth Newton method combined with a Moreau-Yosida regularization technique. At the heart of both methods lies the solution of large and sparse linear systems. We introduce and study block-triangular preconditioners using an efficient and easy to apply Schur complement approximation. Numerical results indicate that our preconditioners work very well for both problems and show that qualitatively better results can be obtained using the double obstacle potential
Language Revitalization: Strategies to Reverse Language Shift
Language shift, the process by which a language loses speakers until it becomes extinct, is occurring in speech communities all over the world. This process is influenced by internal and external political, social, and economic factors unique to each community. As its causes and effects are not uniform, a universal model for reversing language shift does not exist. However, several broad principles can be applied across multiple contexts and situations for successful language revitalization. It is essential for the speech community to be the primary decision maker in any program. A thorough assessment of the community’s current status, challenges, and resources will help in designing an effective strategy. It is also important for the community to set realistic goals and create or improve a language education program. Navajo is a local example of a community engaging in language revitalization. Using the Graded International Disruption Scale developed by Joshua Fishman, the current position of the Navajo language, as well as target areas for future goals, can be assessed. While speech communities face significant challenges to keep their languages alive, efforts to revitalize minority languages are worthwhile and success is possible with time, dedication, and access to needed resources
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