Determinants of visual 2-D echo assessment of left ventricular wall motion: Comparison with myocardial thickening on cardiac magnetic resonance imaging

Background: left ventricular wall motion on 2d echo (2de) is usually scored visually. we sought to examine the determinants of visually assessed wall motion scoring on 2de by comparison with myocardial thickening quantified on MRI. Methods: using a 16 segment model, we studied 287 segments in 30 patients aged 61+/ -11 years (6 female), with ischaemic LV dysfunction (defined by at least 2 segments dysfunctional on 2de). 2de was performed in 5 views and wall motion scores (WMS) assigned: 1 (normal) 103 segments, 2 (hypokinetic) 93 segments, 3 (akinetic) 87 segments. MRI was used to measure end systolic wall thickness (ESWT), end diastolic wall thickness (EDWT) and percentage systolic wall thickening (SWT%) in the plane of the 2de and to assess WMS in the same planes visually. No patient had a clinical ischemic event between the tests. Results: visual assessment of wall motion by 2de and MRI showed moderate agreement (kappa = 0.425). Resting 2de wall motion correlated significantly (p

Eigen-Adaptation and Distributed Representation of 2-D Phase, Energy, Scale and Orientation in Spatial Vision

Distributed representations (DR) of cortical channels are pervasive in models of spatio-temporal vision. A central idea that underpins current innovations of DR stems from the extension of 1-D phase into 2-D images. Neurophysiological evidence, however, provides tenuous support for a quadrature representation in the visual cortex, since even phase visual units are associated with broader orientation tuning than odd phase visual units (J.Neurophys.,88,455–463, 2002). We demonstrate that the application of the steering theorems to a 2-D definition of phase afforded by the Riesz Transform (IEEE Trans. Sig. Proc., 49, 3136–3144), to include a Scale Transform, allows one to smoothly interpolate across 2-D phase and pass from circularly symmetric to orientation tuned visual units, and from more narrowly tuned odd symmetric units to even ones. Steering across 2-D phase and scale can be orthogonalized via a linearizing transformation. Using the tiltafter effect as an example, we argue that effects of visual adaptation can be better explained by via an orthogonal rather than channel specific representation of visual units. This is because of the ability to explicitly account for isotropic and cross-orientation adaptation effect from the orthogonal representation from which both direct and indirect tilt after-effects can be explained.

VLSI design and implementation of 2-D Inverse Discrete Wavelet Transform

This paper proposes a JPEG-2000 compliant architecture capable of computing the 2 -D Inverse Discrete Wavelet Transform. The proposed architecture uses a single processor and a row-based schedule to minimize control and routing complexity and to ensure that processor utilization is kept at 100%. The design incorporates the handling of borders through the use of symmetric extension. The architecture has been implemented on the Xilinx Virtex2 FPGA.

Contribuciones sobre métodos óptimos y subóptimos de aproximaciones poligonales de curvas 2-D

Esta tesis versa sobre el an álisis de la forma de objetos 2D. En visión articial existen numerosos aspectos de los que se pueden extraer información. Uno de los más usados es la forma o el contorno de esos objetos. Esta característica visual de los objetos nos permite, mediante el procesamiento adecuado, extraer información de los objetos, analizar escenas, etc. No obstante el contorno o silueta de los objetos contiene información redundante. Este exceso de datos que no aporta nuevo conocimiento debe ser eliminado, con el objeto de agilizar el procesamiento posterior o de minimizar el tamaño de la representación de ese contorno, para su almacenamiento o transmisión. Esta reducción de datos debe realizarse sin que se produzca una pérdida de información importante para representación del contorno original. Se puede obtener una versión reducida de un contorno eliminando puntos intermedios y uniendo los puntos restantes mediante segmentos. Esta representación reducida de un contorno se conoce como aproximación poligonal. Estas aproximaciones poligonales de contornos representan, por tanto, una versión comprimida de la información original. El principal uso de las mismas es la reducción del volumen de información necesario para representar el contorno de un objeto. No obstante, en los últimos años estas aproximaciones han sido usadas para el reconocimiento de objetos. Para ello los algoritmos de aproximaci ón poligonal se han usado directamente para la extracci ón de los vectores de caracter ísticas empleados en la fase de aprendizaje. Las contribuciones realizadas por tanto en esta tesis se han centrado en diversos aspectos de las aproximaciones poligonales. En la primera contribución se han mejorado varios algoritmos de aproximaciones poligonales, mediante el uso de una fase de preprocesado que acelera estos algoritmos permitiendo incluso mejorar la calidad de las soluciones en un menor tiempo. En la segunda contribución se ha propuesto un nuevo algoritmo de aproximaciones poligonales que obtiene soluciones optimas en un menor espacio de tiempo que el resto de métodos que aparecen en la literatura. En la tercera contribución se ha propuesto un algoritmo de aproximaciones que es capaz de obtener la solución óptima en pocas iteraciones en la mayor parte de los casos. Por último, se ha propuesto una versi ón mejorada del algoritmo óptimo para obtener aproximaciones poligonales que soluciona otro problema de optimización alternativo.

2 D game ediror on-line : A edição de videojogos em contexto web

Descreve-se, no presente trabalho, os esforços envidados no sentido de criar uma solução informática generalista, para os problemas mais recorrentes do processo de produção de videojogos 20, baseados em sprites, a correr em plataformas móveis. O sistema desenvolvido é uma aplicação web que está inserida no paradigma cloud­computing, usufruindo, portanto, de todas as vantagens em termos de acessibilidade, segurança da informação e manutenção que este paradigma oferece actualmente. Além das questões funcionais, a aplicação é ainda explorada do ponto de vista da arquitetura da implementação, com vista a garantir um sistema com implementação escalável, adaptável e de fácil manutenção. Propõe-se ainda um algoritmo que foi desenvolvido para resolver o problema de obter uma distribuição espacial otimizada de várias áreas retangulares, sem sobreposições nem restrições a nível das dimensões, quer do arranjo final, quer das áreas arranjadas. ABSTRACT: This document describes the efforts taken to create a generic computing solution for the most recurrent problems found in the production of two dimensional, sprite­based videogames, running on mobile platforms. The developed system is a web application that fits within the scope of the recent cloud-computing paradigm and, therefore, enjoys all of its advantages in terms of data safety, accessibility and application maintainability. In addition, to the functional issues, the system is also studied in terms of its internal software architecture, since it was planned and implemented in the perspective of attaining an easy to maintain application, that is both scalable and adaptable. Furthermore, it is also proposed an algorithm that aims to find an optimized solution to the space distribution problem of several rectangular areas, with no overlapping and no dimensinal restrictions, neither on the final arrangement nor on the arranged areas.

Spectral Splitting of Purely Magnetic Schrödinger Operator in 2-d

La tesi ripercorre i procedimenti utilizzati per il calcolo dell'asintotica dello splitting dell'operatore puramente magnetico di Schrödinger nel limite semiclassico (con campo magnetico costante) in un dominio aperto limitato e semplicemente connesso il cui bordo ha simmetria assiale ed esattamente due punti di curvatura massima non degeneri. Il punto di partenza è trovare stime a priori sulle sue autofunzioni, che permettono di dire che sono localizzate esponenzialmente vicino al bordo del dominio in oggetto, grazie a queste stime di riesce a modificare l'operatore in maniera tale che l'asintotica dello splitting rimanga equivalente. Si passa in seguito a coordinate tubulari, quindi si rettifica il borso del dominio, andando però a complicare il potenziale magnetico. Si ottengono nuove stime a priori per le autofunzioni. A questo punto si considera lo stesso operatore differenziale ma su un dominio modificato, in cui viene eliminato uno dei punti di curvatura massima. Per tale operatore si ha uno sviluppo asintotico delle autofunzioni (anche dette soluzioni WKB). Si utilizzano poi strumenti di calcolo pseudo-differenziale per studiare l'operatore nel nuovo dominio, ne si localizza la fase per renderlo limitato ed ottenere così una parametrice (anch'essa limitata) avente un simbolo esplicito. Se ne deducono stime di tipo ellittico che possono essere portate all'operatore senza la fase localizzata aggiungendo dei termini di errore. Grazie queste stime si riesce ad approssimare lo splitting (controllando sempre l'errore) che volevamo calcolare (quello dell'operatore sul dominio con due punti di curvatura massima) tramite le autofunzioni dell'operatore sul dominio con un solo punto di curvatura massima, e per queste autofunzioni abbiamo lo sviluppo asintotico (WKB). Considerando l'ordine principale di questi sviluppi si riesce a calcolare esplicitamente il termine dominante dello splitting, ottenendone così l'asintotica nel limite semiclassico.

Digital signal processing implementation for near real-time wavelet transformation system for binary images

Communication has become an essential function in our civilization. With the increasing demand for communication channels, it is now necessary to find ways to optimize the use of their bandwidth. One way to achieve this is by transforming the information before it is transmitted. This transformation can be performed by several techniques. One of the newest of these techniques is the use of wavelets. Wavelet transformation refers to the act of breaking down a signal into components called details and trends by using small waveforms that have a zero average in the time domain. After this transformation the data can be compressed by discarding the details, transmitting the trends. In the receiving end, the trends are used to reconstruct the image. In this work, the wavelet used for the transformation of an image will be selected from a library of available bases. The accuracy of the reconstruction, after the details are discarded, is dependent on the wavelets chosen from the wavelet basis library. The system developed in this thesis takes a 2-D image and decomposes it using a wavelet bank. A digital signal processor is used to achieve near real-time performance in this transformation task. A contribution of this thesis project is the development of DSP-based test bed for the future development of new real-time wavelet transformation algorithms.

The Study of Sonar for Imaging of the Solid-Liquid Interface Inside Large Tanks

Retrieval, treatment, and disposal of high-level radioactive waste (HLW) is expected to cost between 100 and 300 billion dollars. The risk to workers, public health, and the environment are also a major area of concern for HLW. Visualization of the interface between settled solids and the optically opaque liquid is needed for retrieval of the waste from underground storage tanks. A Profiling sonar selected for this research generates 2-D image of the interface. Multiple experiments were performed to demonstrate the effectiveness of sonar in real-time monitoring the interface inside HLW tanks. First set of experiments demonstrated that objects shapes could be identified even when 30% of solids entrained in liquid, thereby mapping the interface. Simulation of sonar system validated these results. Second set of experiments confirmed the sonar’s ability in detecting the solids with density similar to the immersed liquid. Third set of experiments determined the affects of near by objects on image resolution. Final set of experiments proved the functional and chemical capabilities of sonar in caustic solution.

[37 vues et types d'Islande, dont une phot. de l'lndre, corvette de guerre, en rade de Reykjavik, qui transportait l'expédition française et le phot. H. Labonne en 1886, don du phot. en 1887. Il y a aussi, du même phot., 2 phot. du voyageur A. Cotteau et du paléontologiste B. Cotteau devant leur maison de Châtelcensoir (Yonne), s.d]

Donateur : Labonne, Henry (1853-1936?)