Noise Feedback Coding Revisited： Refurbished Legacy Codecs and New Coding Models

Noise feedback coding(NFC) has attracted renewed interest with the recent standardization of backward-compatible enhancements for ITU-T G.711 and G.722.It has also been revisited with the emergence of proprietary speech codecs,such as BV16,BV32,and SILK,that have structures different from CELP coding.In this article,we review NFC and describe a novel coding technique that optimally shapes coding noise in embedded pulse-code modulation(PCM) and embedded adaptive differential PCM(ADPCM).We describe how this new technique was incorporated into the recent ITU-T G.711.1,G.711 App.III,and G.722 Annex B(G.722B) speech-coding standards.     

A Non-local Topology-Preserving Segmentation-Guided Registration Model

In this paper, we address the issue of designing a theoretically well-motivated segmentation-guided registration method capable of handling large and smooth deformations. The shapes to be matched are viewed as hyperelastic materials and more precisely as Saint Venant–Kirchhoff ones and are implicitly modeled by level set functions. These are driven in order to minimize a functional containing both a nonlinear-elasticity-based regularizer prescribing the nature of the deformation, and a criterion that forces the evolving shape to match intermediate topology-preserving segmentation results. Theoretical results encompassing existence of minimizers, existence of a weak viscosity solution of the related evolution problem and asymptotic results are given. The study is then complemented by the derivation of the discrete counterparts of the asymptotic results provided in the continuous domain. Both a pure quadratic penalization method and an augmented Lagrangian technique (involving a related dual problem) are investigated with convergence results.     

Spectral analysis of electrograms during ventricular tachycardia in a canine model: relation with epicardial isochronal maps

The purpose of this study was to assess the capability of magnitude-squared coherence and bicoherence to differentiate monomorphic ventricular tachycardia (MVT) and polymorphic ventricular tachycardia (PVT) in a canine model and to relate these results to the epicardial isochronal maps on a beat-to-beat basis. Unipolar electrograms were simultaneously recorded from the surface of both ventricles with a 127-lead sock electrode array in 12 open-chest anesthetized dogs. The sampling frequency was 500 Hz. Atrioventricular block was induced by formaldehyde injection into the atrioventricular node. The left anterior descending coronary artery was occluded for 60 minutes under ventricular pacing (140 beats/min). During reperfusion, 12 MVT episodes lasting more than 42 seconds were recorded. Left stellate ganglion stimulation induced five PVT episodes lasting more than 42 seconds. Each of these recordings was divided into seven segments of 3,072 points (6.144 seconds). After visual selection, 104 segments were extracted and classified as 73 MVT and 31 PVT segments. Magnitude-squared coherence was estimated as the cross-spectrum from two epicardial signals (on the right and left ventricles, respectively), normalized with the respective autopower spectrum. Bicoherence was estimated as the bispectrum normalized with the autopower spectrum. Magnitude-squared coherence correctly identified 96% of MVT and 81% of PVT segments for a total accuracy of 91%. Bicoherence estimated with the left ventricular lead correctly identified 100% of MVT and 77% of PVT segments with an accuracy of 93%. Beat-to-beat epicardial maps of MVT displayed a cluster of sites of origin close to the reperfusion area, while the sites of origin from beats during PVT were much more dispersed over both ventricles. A strong and significant correlation was found between the number of electrodes with the earliest epicardial activation and coherence (r = .76, P < .0001) and bicoherence (r = .68, P < .0001), respectively. A high and significant correlation was also found between both spectral estimators (r = .74, P < .0001). Coherence and bicoherence discriminated accurately between MVT and PVT. Coherence achieved better results compared with bicoherence. Coherence and bicoherence measurements showed a quantitative relation with the spatial dispersion of the sites of origin. Both spectral techniques seemed powerful enough to be used in the development of implantable devices.     

Acoustic modeling of light and non-cohesive poro-granular materials with a fluid/fluid model

Summary Poro-granular materials are studied, and a model adapted to characterize their acoustic behaviour is presented. Biot’s theory is used to obtain this model but a great simplification is brought to classical formulation. Indeed, a solid phase being made of a non-cohesive poro-granular material, a specific continuum constitutive model is used to characterize its behaviour. The macroscopic coefficient of friction that takes into account friction and collision phenomena is then neglected under specific conditions. This strong assumption does not apply for all kinds of granular materials and for any solicitations: its validity is discussed for particular materials. The solid/fluid model of Biot’s theory is then transformed to an equivalent fluid/fluid model. The complexity of the classical formulation is significantly reduced since only two degrees of freedom are used: the solid and fluid pressures. A 1D case is then treated to present the simplicity of the formulation, and applied to a poro-granular material made of expanded polystyrene beads. Intrinsic parameters of this material are adjusted thanks to surface impedances measured with a stationary waves tube. Finally, a study on thermal and viscous dissipations is realized and associated with a study on pressure and velocity distribution in the sample. Dedicated to Professor Franz Ziegler on the occasion of his 70th birthday     

Norovirus contamination on French marketed oysters

Contaminated shellfish have been implicated in gastroenteritis outbreaks in different countries. As no regulation has been set up yet regarding viral contamination of food, very few data are available on the prevalence of contaminated products on the market. This study presents data obtained from oysters collected on the French market in one producing area over a 16 month period of time. Noroviruses were detected in 9% of samples with a seasonal impact and influence of climatic events. Contamination levels were low and, surprisingly, oysters sampled directly from the producer were found to have less contamination than oysters from supermarkets.     

Randomized controlled trial for hepatocellular carcinoma with portal vein thrombosis: intra-arterial iodine-131-iodized oil versus medical support

Portal vein thrombosis is a poor prognostic factor in patients with hepatocellular carcinoma (HCC) and a contraindication for chemoembolization. Intra-arterial injection of 131I-iodized oil which does not modify arterial flow, is feasible in this condition. The aim of this prospective randomized controlled trial was to compare the efficacy of treatment with radiolabeled oil (treated group) versus medical support (control group) in patients with stage I or II HCC (classification of Okuda) with portal vein thrombosis. METHODS: Twenty-seven HCC patients (26 males, 1 female), aged 53-79 yr, with portal vein thrombosis were randomly assigned to Lipiocis group (n = 14) or Control group (n = 13). Additional injections of radiolabeled oil were given 2, 5, 8 and 12 mo after initial therapy. Medical support treatment consisted of: tamoxifen (n = 5), 5 FU intravenously (n = 1), NSAIDs or corticosteroids (n = 5). Efficacy was evaluated according to survival rate (Kaplan-Meier method; log rank test), AFP serum values (measured at 2, 5, 8 and 12 mo) and angiography. RESULTS: The two groups were comparable (Child's classification, Okuda's classification, liver function tests, location of the thrombus). Tolerance was excellent in the Treated group. The actuarial survival curves were significantly different (p < 0.01) between the two groups, the survival rates (Cl 95%) at 3, 6 and 9 mo being 71% (48%-95%), 48% (12%-55%), 7% (1%-31%) for the Treated group; and 10% (1%-33%), 0% and 0% for the Control group. CONCLUSION: Intra-arterial hepatic injection of 131I-labeled iodized oil is a safe and effective palliative treatment of HCC with portal vein thrombosis.     

Sewage impact on shellfish microbial contamination.

Coastal areas are frequently contaminated by microorganisms of human origin, due to high population density and low seawater renewal. To evaluate the impact of wastewater input on shellfish quality, a study was conducted in Brittany (France) over a period of 20 months. A hydrodynamic model was used to simulate wastewater impact on microbial water quality. To validate the model, wastewater from the three main sewage treatment plants and shellfish from three sites were sampled monthly. Bacterial indicators (E. coli), F-RNA phages were searched for by culture and noroviruses by RT-PCR and hybridisation. These microorganisms were detected in the three effluents and clams, with no marked seasonal variation. The microbial concentrations in the two oyster beds, distant from the effluent outfall, were low, and only three of the samples were positive for norovirus. For simulation, the winter wastewater inputs of E. coli and phages were calculated and an estimation for norovirus flux was made from the epidemic situation in the population. The microbial behaviour was included in the model by a decay-rate factor. Results from the model calculations were found to be very similar to E. coli and phage concentrations observed in shellfish. For noroviruses, the model indicated that shellfish distant from the wastewater input were under the detection limit of the RT-PCR method. This study demonstrated the use of modelisation to interpret norovirus contamination in various areas.     

In situ contacting and current-injection into samples in photoemission electron microscopes

Studying the interaction of spin-polarized currents with the magnetization configuration is of high interest due to the possible applications and the novel physics involved. High-resolution magnetic imaging is one of the key techniques necessary for a better understanding of these effects. Here, we present an extension to a magnetic microscope that allows for in situ current injection into the structure investigated, and furthermore for the study of current induced magnetization changes during pulsed current injection. The developed setup is highly flexible and can be used for a wide range of investigations. Examples of current-induced domain wall motion and vortex core displacements measured using this setup are presented.     

Self-repelling snakes for topology-preserving segmentation models.

The implicit framework of the level-set method has several advantages when tracking propagating fronts. Indeed, the evolving contour is embedded in a higher dimensional level-set function and its evolution can be phrased in terms of a Eulerian formulation. The ability of this intrinsic method to handle topological changes (merging and breaking) makes it useful in a wide range of applications (fluid mechanics, computer vision) and particularly in image segmentation, the main subject of this paper. Nevertheless, in some applications, this topological flexibility turns out to be undesirable: for instance, when the shape to be detected has a known topology, or when the resulting shape must be homeomorphic to the initial one. The necessity of designing topology-preserving processes arises in medical imaging, for example, in the human cortex reconstruction. It is known that the human cortex has a spherical topology so throughout the reconstruction process this topological feature must be preserved. Therefore, we propose in this paper a segmentation model based on an implicit level-set formulation and on the geodesic active contours, in which a topological constraint is enforced.