Static meta-object protocols : towards efficient reflective object-oriented languages

Reflection and extensibility in object-oriented programming languages can be supported by meta-object protocols (MOP) that define class-based interfaces over data representation and execution features. MOPs are typically dynamic in the sense that type-based dispatching is used to select between feature implementations at run time leading to a significant difference in execution speed compared to non-MOP-based languages. Defining a corresponding static-MOP would seem to be a solution whereby type-dispatching can occur at compile time. Such an approach requires the integration of a static type system with a MOP. This paper introduces a new reflective and extensible language called JMF written in Java that aims to generate efficient code through the use of a static-MOP. The contribution of this paper is to characterise a static-MOP and to show how it integrates with a type system for JMF

Liver fibrosis staging using supersonic shear imaging : a clinical study on 142 patients

International audienceI. Background, Motivation and ObjectiveFibrosis staging can be assessed by a rough estimation of the liver stiffness averaged along an ultrasonic A-line. Providing a complete 2D map of liver stiffness would thus be of great clinical interest for the diagnosis of hepatic fibrosis and help prevent upcoming cirrhosis. However, such measurement requires both a quantitative value of shear elasticity and a great precision to discriminate between different fibrosis levels. Beyond the scope of non-invasive fibrosis quantification, it is also envisioned that quantitative elasticity imaging of liver will have potential interest for liver cancer diagnosis. In this work, the Supersonic Shear Imaging technique (SSI) is proposed to map the in vivo viscoelastic parameters of liver on patients with hepatitis C and derive a mean elasticity of liver tissues. The results are compared to biological tests (Fib4, Apri, Forns) and Fibroscan® measurements. II. Statement of Contribution / MethodsThe SSI technique is based on the radiation force induced by a conventional ultrasonic probe to generate a planar shear wave deep into tissues. The shear wave propagation throughout the medium is caught in real time thanks to an ultrafast ultrasound scanner (up to 5000 frames/s). Using modified sequences and post-processing, this technique is implemented on curved arrays in order to get a larger field of view of liver tissues. A study on 150 HCV patients with different fibrosis stages F has been conducted in order to investigate the accuracy of the technique (F ϵ [0;4]). Quantitative maps of liver elasticity are produced for each volunteer with a linear and a curved array. III. ResultsB-mode images of 120x75 mm² and corresponding elasticity maps are obtained using a 2.5 MHz curved ultrasonic probe with a good reproducibility and accuracy. The shear wave phase velocity dispersion is also calculated. This study shows a good correlation between the values obtained by SSI and the fibrosis levels diagnosed by biological tests (p-index 0.9 for F>3 and Y> 0.8 for F>2). Results are also compared (r2 > 0.92) to the Fibroscan® elasticity measurement by fitting the velocity dispersion curves obtained by SSI at 50 Hz.IV. Discussion and ConclusionsThis real-time elasticity mapping using an ultrasonic curved probe offers better signal to noise ratio than linear arrays and a larger area in the patient's liver (13.3±2.8 cm² estimation area). This gives more confidence on the accuracy of the diagnosis of the fibrosis stage. Furthermore, the elasticity parameters obtained with SSI give access to the shear wave group velocity and the phase velocity. As a consequence, the SSI assessment of liver stiffness could potentially give more information on the viscoelasticity properties of the liver

A Flexible Approach To Interactive Runtime Inspection

Behavioral reflection is well-known approach enabling exhaustive querying of program state (introspection) as well as controlling its execution (intercession). It is hence an adequate foundation for runtime inspection. Partial behavioral reflection aims at making behavioral reflection more applicable by providing high levels of selectivity and configurability. We first outline the main features of partial behavioral reflection and of Reflex---our portable Java implementation. We then sketch how we plan to apply such an approach to provide an interactive environment for runtime inspection, which, in particular, could be used to assist in reflective and aspect-oriented programming