2,436 research outputs found
Oppositional Defiant Disorder and Aggression in a Young Man with Mental Retardation: Long-Term Treatment in a Community-Based Setting
A longitudinal, intensive treatment program is described that was implemented over an 8-year period in a community-based setting for a young man with mental retardation and oppositional defiant disorder with severe physical aggression. The development of this disorder and its systematic treatment are described, with new components added based on improvement in the individual’s behavior. The individual made steady progress and has maintained good behavioral stability for the final three years of the treatment program. This paper highlights the inherent difficulties of applying empirically validated treatment strategies in community-based settings
Low temperature thermodynamic properties of precipitation-hardening copper-beryllium alloys
An unusual enhancement has been found in the ratios of the specific heats of copper-beryllium solid-solutions to the specific heat of pure copper. The magnitude of this effect represents an apparent 5% increase of the alloy specific heat, peaking near 20 K. Specific heat measurements from 1 K to 60 K on a Cu-1.92wt.% Be alloy and on the commercial alloy Berylco-25 show that the size of the enhancement is reduced by precipitation-hardening;Measurements of the linear thermal expansivity from 4 K to 300 K of CUBE-250, an alloy similar to Berylco-25, also show an enhance- ment effect. No unusual behavior was found in the electrical resis- tivity of Berylco-25 between 1 K and 80 K;It is suggested that the apparent enhancement of the Cu-Be specific heat is due to slight shifts of the phonon frequencies in the alloy with respect to pure copper. The Debye temperature of the Cu-Be solid-solution is nearly the same as that of copper (345 K). The electronic density of states at the Fermi level is slightly higher for the alloy;Precipitation-hardening is associated with formation of particles of the CuBe intermetallic phase within the solid-solution matrix. The apparent specific heat enhancement is reduced for the hardened condition due to depletion of the Be concentration in the matrix. With precipitation-hardening, the Debye temperature of the alloy;increases, and the electronic specific heat contribution approaches that of copper; *DOE Report IS-T-1108. This work was perfomed under contract No. W-7405-Eng-82 with the U.S. Department of Energy
Minimizing Communication in Linear Algebra
In 1981 Hong and Kung proved a lower bound on the amount of communication
needed to perform dense, matrix-multiplication using the conventional
algorithm, where the input matrices were too large to fit in the small, fast
memory. In 2004 Irony, Toledo and Tiskin gave a new proof of this result and
extended it to the parallel case. In both cases the lower bound may be
expressed as (#arithmetic operations / ), where M is the size
of the fast memory (or local memory in the parallel case). Here we generalize
these results to a much wider variety of algorithms, including LU
factorization, Cholesky factorization, factorization, QR factorization,
algorithms for eigenvalues and singular values, i.e., essentially all direct
methods of linear algebra. The proof works for dense or sparse matrices, and
for sequential or parallel algorithms. In addition to lower bounds on the
amount of data moved (bandwidth) we get lower bounds on the number of messages
required to move it (latency). We illustrate how to extend our lower bound
technique to compositions of linear algebra operations (like computing powers
of a matrix), to decide whether it is enough to call a sequence of simpler
optimal algorithms (like matrix multiplication) to minimize communication, or
if we can do better. We give examples of both. We also show how to extend our
lower bounds to certain graph theoretic problems.
We point out recently designed algorithms for dense LU, Cholesky, QR,
eigenvalue and the SVD problems that attain these lower bounds; implementations
of LU and QR show large speedups over conventional linear algebra algorithms in
standard libraries like LAPACK and ScaLAPACK. Many open problems remain.Comment: 27 pages, 2 table
Global Existence and Regularity for the 3D Stochastic Primitive Equations of the Ocean and Atmosphere with Multiplicative White Noise
The Primitive Equations are a basic model in the study of large scale Oceanic
and Atmospheric dynamics. These systems form the analytical core of the most
advanced General Circulation Models. For this reason and due to their
challenging nonlinear and anisotropic structure the Primitive Equations have
recently received considerable attention from the mathematical community.
In view of the complex multi-scale nature of the earth's climate system, many
uncertainties appear that should be accounted for in the basic dynamical models
of atmospheric and oceanic processes. In the climate community stochastic
methods have come into extensive use in this connection. For this reason there
has appeared a need to further develop the foundations of nonlinear stochastic
partial differential equations in connection with the Primitive Equations and
more generally.
In this work we study a stochastic version of the Primitive Equations. We
establish the global existence of strong, pathwise solutions for these
equations in dimension 3 for the case of a nonlinear multiplicative noise. The
proof makes use of anisotropic estimates, estimates on the
pressure and stopping time arguments.Comment: To appear in Nonlinearit
How Much Does Money Matter in a Direct Democracy?
The fine-structure splitting of quantum confined InxGa1-x Nexcitons is investigated using polarization-sensitive photoluminescence spectroscopy. The majority of the studied emission lines exhibits mutually orthogonal fine-structure components split by 100-340 mu eV, as measured from the cleaved edge of the sample. The exciton and the biexciton reveal identical magnitudes but reversed sign of the energy splitting.Original Publication:Supaluck Amloy, Y T Chen, K F Karlsson, K H Chen, H C Hsu, C L Hsiao, L C Chen and Per-Olof Holtz, Polarization-resolved fine-structure splitting of zero-dimensional InxGa1-xN excitons, 2011, PHYSICAL REVIEW B, (83), 20, 201307.http://dx.doi.org/10.1103/PhysRevB.83.201307Copyright: American Physical Societyhttp://www.aps.org
Existence Theory for the Radically Symmetric Contact Lens Equation
In this paper we present a variational formulation of the problem of determining the elastic stresses in a contact lens on an eye and the induced suction pressure distribution in the tear film between the eye and the lens. This complements the force-balance derivation that we used in earlier work [K. L. Maki and D. S. Ross, J. Bio. Sys., 22 (2014), pp. 235–248]. We investigate the existence of solutions of the relevant boundary value problem for the singular, second-order Euler–Lagrange equation. We prove that, for lenses of constant thickness, solutions exist. We present an example to show that in some cases in which the lens thickness increases with distance from the lens center no solution exists
Structured matrices, continued fractions, and root localization of polynomials
We give a detailed account of various connections between several classes of
objects: Hankel, Hurwitz, Toeplitz, Vandermonde and other structured matrices,
Stietjes and Jacobi-type continued fractions, Cauchy indices, moment problems,
total positivity, and root localization of univariate polynomials. Along with a
survey of many classical facts, we provide a number of new results.Comment: 79 pages; new material added to the Introductio
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