76 research outputs found

    Social and Nonsocial Decentration in Hearing-Impaired and Normal Hearing Children

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    Tweny-three hearing-impaired and 25 normally hearing children between 7 and 14 years of age were administered a social decentration task, a nonsocial decentration task (a set of conservation problems), and a test of nonverbal intelligence. Although the two groups did not differ with respect to nonverbal intelligence, the hearing-impaired children obtained significantlv lower scores than their normally hearing peers on both the social and nonsocial decentration measures. Within both groups, there was a significant positive correlation between social decentration and nonsocial decentration, which is consistent with Piaget\u27s contention that centration-decentration is a cognitive dimension underlying the structuring of both social and nonsocial content. Within the hearing-impaired sample, degree of hearing loss was not associated with either social or nonsocial decentration

    A Robust Solution Procedure for Hyperelastic Solids with Large Boundary Deformation

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    Compressible Mooney-Rivlin theory has been used to model hyperelastic solids, such as rubber and porous polymers, and more recently for the modeling of soft tissues for biomedical tissues, undergoing large elastic deformations. We propose a solution procedure for Lagrangian finite element discretization of a static nonlinear compressible Mooney-Rivlin hyperelastic solid. We consider the case in which the boundary condition is a large prescribed deformation, so that mesh tangling becomes an obstacle for straightforward algorithms. Our solution procedure involves a largely geometric procedure to untangle the mesh: solution of a sequence of linear systems to obtain initial guesses for interior nodal positions for which no element is inverted. After the mesh is untangled, we take Newton iterations to converge to a mechanical equilibrium. The Newton iterations are safeguarded by a line search similar to one used in optimization. Our computational results indicate that the algorithm is up to 70 times faster than a straightforward Newton continuation procedure and is also more robust (i.e., able to tolerate much larger deformations). For a few extremely large deformations, the deformed mesh could only be computed through the use of an expensive Newton continuation method while using a tight convergence tolerance and taking very small steps.Comment: Revision of earlier version of paper. Submitted for publication in Engineering with Computers on 9 September 2010. Accepted for publication on 20 May 2011. Published online 11 June 2011. The final publication is available at http://www.springerlink.co

    Analysis of and workarounds for element reversal for a finite element-based algorithm for warping triangular and tetrahedral meshes

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    We consider an algorithm called FEMWARP for warping triangular and tetrahedral finite element meshes that computes the warping using the finite element method itself. The algorithm takes as input a two- or three-dimensional domain defined by a boundary mesh (segments in one dimension or triangles in two dimensions) that has a volume mesh (triangles in two dimensions or tetrahedra in three dimensions) in its interior. It also takes as input a prescribed movement of the boundary mesh. It computes as output updated positions of the vertices of the volume mesh. The first step of the algorithm is to determine from the initial mesh a set of local weights for each interior vertex that describes each interior vertex in terms of the positions of its neighbors. These weights are computed using a finite element stiffness matrix. After a boundary transformation is applied, a linear system of equations based upon the weights is solved to determine the final positions of the interior vertices. The FEMWARP algorithm has been considered in the previous literature (e.g., in a 2001 paper by Baker). FEMWARP has been succesful in computing deformed meshes for certain applications. However, sometimes FEMWARP reverses elements; this is our main concern in this paper. We analyze the causes for this undesirable behavior and propose several techniques to make the method more robust against reversals. The most successful of the proposed methods includes combining FEMWARP with an optimization-based untangler.Comment: Revision of earlier version of paper. Submitted for publication in BIT Numerical Mathematics on 27 April 2010. Accepted for publication on 7 September 2010. Published online on 9 October 2010. The final publication is available at http://www.springerlink.co

    The Effects of Time Pressure on Social Cognitive Problem-Solving by Aggressive and Nonaggressive Boys

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    This study evaluated the effects of one potential source of arousal, namely time pressure, on the attributions made and the solutions generated in hypothetical social problem situations by aggressive and nonaggressive boys. It was predicted that time pressure would be more disruptive to the social information-processing of aggressive boys as compared to their nonaggressive peers. Thirty aggressive and 32 nonaggressive third- and fourth-grade boys were administered attribution and solution generation tasks under both untimed and time pressured conditions. Level of arousal in both conditions was assessed by experimenter observation and subject self-report. The time pressure condition re-suited in greater arousal than the untimed condition across all subjects. The predicted interaction between group and condition did not reach statistical significance; however, there was a trend suggesting that the aggressive group made more hostile attributions in the time pressured as compared to the untimed condition, whereas the nonaggressive group did not differ between the two conditions. On the solution generation measure, the time pressure condition resulted in all subjects producing a greater number of solutions overall, more types of solutions, and proportionally more aggressive solutions. Results are discussed in terms of the influence of arousal on social information-processing

    Research and Education in Computational Science and Engineering

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    Over the past two decades the field of computational science and engineering (CSE) has penetrated both basic and applied research in academia, industry, and laboratories to advance discovery, optimize systems, support decision-makers, and educate the scientific and engineering workforce. Informed by centuries of theory and experiment, CSE performs computational experiments to answer questions that neither theory nor experiment alone is equipped to answer. CSE provides scientists and engineers of all persuasions with algorithmic inventions and software systems that transcend disciplines and scales. Carried on a wave of digital technology, CSE brings the power of parallelism to bear on troves of data. Mathematics-based advanced computing has become a prevalent means of discovery and innovation in essentially all areas of science, engineering, technology, and society; and the CSE community is at the core of this transformation. However, a combination of disruptive developments---including the architectural complexity of extreme-scale computing, the data revolution that engulfs the planet, and the specialization required to follow the applications to new frontiers---is redefining the scope and reach of the CSE endeavor. This report describes the rapid expansion of CSE and the challenges to sustaining its bold advances. The report also presents strategies and directions for CSE research and education for the next decade.Comment: Major revision, to appear in SIAM Revie

    The Meaning of Body Experience Evaluation in Oncology

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    Evaluation of quality of life, psychic and bodily well-being is becoming increasingly important in oncology aftercare. This type of assessment is mainly carried out by medical psychologists. In this paper I will seek to show that body experience valuation has, besides its psychological usefulness, a normative and practical dimension. Body experience evaluation aims at establishing the way a person experiences and appreciates his or her physical appearance, intactness and competence. This valuation constitutes one’s ‘body image’. While, first, interpreting the meaning of body image and, second, indicating the limitations of current psychological body image assessment, I argue that the normative aspect of body image is related to the experience of bodily wholeness or bodily integrity. Since this experience is contextualized by a person’s life story, evaluation should also focus on narrative aspects. I finally suggest that the interpretation of body experience is not only valuable to assess a person’s quality of life after treatment, but that it can also be useful in counseling prior to interventions, since it can support patients in making decisions about interventions that will change their bodies. To apply this type of evaluation to oncology practice, a rich and tailored vocabulary of body experiences has to be developed

    Prediction of ventricular boundary evolutionin hydrocephalic brain via a combined level set and adaptive finite element mesh warping method

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    Hydrocephalus is a serious neurological disorder caused by abnormalities in cerebrospinal fluid (CSF) flow, resulting in large brain deformations and neuronal damage. Treatments drain the excess CSF from the ventricles either via a CSF shunt or an endoscopic third ventriculostomy. However, patients’responseto these treatments is poor. Mathematical models of hydrocephalus mechanics couldaid neurosurgeons in hydrocephalus treatment planning.Current models and corresponding computational simulations of hydrocephalus are still in their infancy, despitethis being a disease with serious long-term implications.We propose a novel geometriccomputational approach for tracking the evolution of hydrocephalic brain tissue –ventricular CSF interfacevia the level set method and an adaptive mesh warping technique. In our previous work [1], weevolved the ventricular boundary in 2D CT images which required a backtracking line search for obtaining valid intermediate meshes for use with FEMWARP, a finite element-based mesh warping method. In [2], we automatically evolved the ventricular boundary deformation for 2D CT imagesvia the level set method. To help surgeons determine where to implant a shunt, we also computed the brain ventricle volume evolution for 3D MR images using FEMWARP.In this work, we generalize the results from [1,2] and incorporate adaptive mesh refinement following mesh deformation. Based on the use of the solution gradientof the PDE in the mesh warping approach as an enrichment indicator, the mesh is refinedwhere the solution gradient islargeand is coarsened where it is small.We present computational simulations of the onset and treatment of pediatric hydrocephalus based on 2D CT images which demonstrate the success of our combined level set/adaptive finite element-based mesh warping approach
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