Highlights of Findings - San Diego: Aesthetic Development and Creative and Critical Thinking Skills Study

This summary will share some of the highlights from the study conducted from Winter 2000 through Spring 2002 by Visual Understanding in Education with the support of the San Antonio Independent School District (SAISD), Artpace, and the San Antonio Museum of Art. The study was designed to measure the impact of the multi-year Visual Thinking Strategies(VTS) program on students in gradesthreethrough five.VTS is a student-centered curriculum in which students examine and discuss worksof art, prompted by questions selected to support careful, evidentiary looking. The three basic VTS questions are: "What's going on in this picture?" "What do you see that makes you say that?" when an interpretative comment is made, and "What more can we find?" Classroom teachers facilitate the discussions by asking the questions, pointing, paraphrasing and linking responses. There are ten lessons each year, the last of which is a museum visit.Data was collected twice a year for three years, before the first yearly VTS lesson and after the last VTS lesson of the year, to follow the growth of aesthetic and more general critical thinking skills of an initialsample of 25 experimental and 25 control students. Pre- and post-VTS aesthetic development interviews(ADIs), demographic questionnaires, museum biographies, material object interviews(MOIs), and writing samples were collected from experimental and control groups

Frame-constrained Total Variation Regularization for White Noise Regression

Despite the popularity and practical success of total variation (TV) regularization for function estimation, surprisingly little is known about its theoretical performance in a statistical setting. While TV regularization has been known for quite some time to be minimax optimal for denoising one-dimensional signals, for higher dimensions this remains elusive until today. In this paper we consider frame-constrained TV estimators including many well-known (overcomplete) frames in a white noise regression model, and prove their minimax optimality w.r.t. $L^q$-risk ($1\leq q<\infty$) up to a logarithmic factor in any dimension $d\geq 1$. Overcomplete frames are an established tool in mathematical imaging and signal recovery, and their combination with TV regularization has been shown to give excellent results in practice, which our theory now confirms. Our results rely on a novel connection between frame-constraints and certain Besov norms, and on an interpolation inequality to relate them to the risk functional.Comment: 27 pages main text, 7 pages appendix, 2 figures. In this updated version we have simplied the proof of the upper bound and extended the convergence to the complete range $q\in[1,\infty)$ of $L^q$ risks, rather than the range $q\in(1,1+2/d]$ that we had in the first version. Further, the rates in the extended range are shown to be minimax optima

Crater size estimates for large-body terrestrial impact

Calculating the effects of impacts leading to global catastrophes requires knowledge of the impact process at very large size scales. This information cannot be obtained directly but must be inferred from subscale physical simulations, numerical simulations, and scaling laws. Schmidt and Holsapple presented scaling laws based upon laboratory-scale impact experiments performed on a centrifuge (Schmidt, 1980 and Schmidt and Holsapple, 1980). These experiments were used to develop scaling laws which were among the first to include gravity dependence associated with increasing event size. At that time using the results of experiments in dry sand and in water to provide bounds on crater size, they recognized that more precise bounds on large-body impact crater formation could be obtained with additional centrifuge experiments conducted in other geological media. In that previous work, simple power-law formulae were developed to relate final crater diameter to impactor size and velocity. In addition, Schmidt (1980) and Holsapple and Schmidt (1982) recognized that the energy scaling exponent is not a universal constant but depends upon the target media. Recently, Holsapple and Schmidt (1987) includes results for non-porous materials and provides a basis for estimating crater formation kinematics and final crater size. A revised set of scaling relationships for all crater parameters of interest are presented. These include results for various target media and include the kinematics of formation. Particular attention is given to possible limits brought about by very large impactors

Luis Salazar ou la tectonique des plaques

Présentation de l'oeuvre de Luis Salazar, et particulièrement d'une peinture murale au restaurant universitaire du Sart-Tilman

Aggregated motion estimation for real-time MRI reconstruction

Real-time magnetic resonance imaging (MRI) methods generally shorten the measuring time by acquiring less data than needed according to the sampling theorem. In order to obtain a proper image from such undersampled data, the reconstruction is commonly defined as the solution of an inverse problem, which is regularized by a priori assumptions about the object. While practical realizations have hitherto been surprisingly successful, strong assumptions about the continuity of image features may affect the temporal fidelity of the estimated images. Here we propose a novel approach for the reconstruction of serial real-time MRI data which integrates the deformations between nearby frames into the data consistency term. The method is not required to be affine or rigid and does not need additional measurements. Moreover, it handles multi-channel MRI data by simultaneously determining the image and its coil sensitivity profiles in a nonlinear formulation which also adapts to non-Cartesian (e.g., radial) sampling schemes. Experimental results of a motion phantom with controlled speed and in vivo measurements of rapid tongue movements demonstrate image improvements in preserving temporal fidelity and removing residual artifacts.Comment: This is a preliminary technical report. A polished version is published by Magnetic Resonance in Medicine. Magnetic Resonance in Medicine 201