Application of the morphological ultimate opening to the detection of microaneurysms on eye fundus images from a clinical database

International audienceDiabetic Retinopathy (DR) is a severe disease which can cause blindness. OPHDIAT is a telemedicine network for DR mass screening, which has gathered thousands of clinical high resolution color eye fundus images. The TELEOPHTA project has been launched in order to develop a computer aided diagnosis system of DR, which aims at performing a preliminary analysis of the OPHDIAT images in order to filter most images corresponding to healthy eyes. Microaneurysms (MAs) are likely to be the lesions present at the earliest stage of the disease. In this paper, a new method of MAs detection, using the recently proposed ultimate opening, is presented. The proposed method does not use any supervised classification, while provides a competitive and efficient way to detect MAs, especially for our clinical database. Further improvements may be brought through the accurate detection of the retinal elements and other retinal diseases, or through the estimation of the image quality

Effect of spray cooling on heat transfer in a two-phase helium flow

International audienceIn this paper, we describe an experimental study of the phenomenon of spray cooling in the case of liquid helium, either normal or superfluid, and its relationship to the heat transfer between an atomized diphasic flow contained in a long pipe, and the pipe walls. This situation is discussed in the context of the cooling of the superconducting magnets of the Large Hadron Collider (LHC). Experiments were conducted in a test loop reproducing the LHC cooling system, in which the vapor velocity and temperature could be varied in a large range. Shear induced atomization results in the generation of a droplet mist which was characterized by optical means. The thin liquid film deposited on the walls by the mist was measured using interdigitated capacitors. The cooling power of the mist was measured using thermal probes, and correlated to the local mist density. Analysis of the results shows that superfluidity has only a limited influence on both the film thickness and the mist cooling power. Using a simple model, we show that the phenomenon of spray cooling accounts for the measured non linearity of the global heat transfer. Finally, we discuss the relevance of our results for cooling the final focus magnets (inner triplets) in an upgraded version of the LHC

Visualization in cryogenic environment: Application to two-phase studies

11 pagesInternational audienceThis paper reviews recent technical developments devoted to the study of cryogenic two-phase fluids. These techniques span from simple flow visualization to quantitative measurements of light scattering. It is shown that simple flow pattern configurations are obtained using classical optical tools (CCD cam- eras, endoscopes), even in most severe environments (high vacuum, high magnetic field). Quantitative measurements include laser velocimetry, particle sizing, and light scattering analysis. In the case of mag- netically compensated gravity boiling oxygen, optical access is used to control the poistioning of a bubble subject to buoyancy forces in an experimental cell. Flow visualization on a two-phase superfluid helium pipe-flow, performed as a support of LHC cooldown studies, leads to flow pattern characterization. Visu- alization includes stratified and atomized flows. Thanks to the low refractive index contrast between the liquid and its vapor, quantitative results on droplet densities can be obtained even in a multiple scatter- ing regime

A brick in the wall: Staggered orientable infills for additive manufacturing

International audienceAdditive manufacturing is typically conducted in a layer-by-layer fashion. A key step of the process is to define, within each planar layer, the trajectories along which material is deposited to form the final shape. The direction of these trajectories triggers an anisotropy in the fabricated parts, which directly affects their properties, from their mechanical behavior to their appearance. Controlling this anisotropy paves the way to novel applications, from stronger parts to controlled deformations and surface patterning.This work introduces a method to generate trajectories that precisely follow an input direction field while simultaneously avoiding intra- and inter-layer defects. Our method results in spatially coherent trajectories - all follow the specified direction field throughout the layers - while providing precise control over their inter-layer arrangement. This allows us to generate a staggered layout of trajectories across layers, preventing unavoidable tiny gaps from forming tunnel-shaped voids throughout a part volume.Our approach is simple, robust, easy to implement, and scales linearly with the input volume. It builds upon recent results in procedural generation of oscillating patterns, generating a signal in the 3D domain that oscillates with a frequency matching the deposition beads width while following the input direction field. Trajectories are extracted with a process akin to a marching square

Tuning, Impedance Matching, and Temperature Regulation during High-Temperature Microwave Sintering of Ceramics

International audienceOver the years, microwave radiation has emerged as an efficient source of energy for material processing. This technology provides a rapid and a volumetric heating of material. However, the main issues that prevent microwave technology from being widespread in material processing are temperature control regulation and heating distribution within the sample. Most of the experimental works are usually manually monitored, and their reproducibility is rarely evaluated and discussed. In this work, an originally designed 915MHz microwave single-mode applicator for high-temperature processing is presented. The overall microwave system is described in terms of an equivalent electrical circuit. This circuit has allowed to point out the different parameters which need to be adjusted to get a fully controlled heating process. The basic principle of regulation is then depicted in terms of a block function diagram. From it, the process has been developed and tested to sinter zirconia-and spinel-based ceramics. It is clearly shown that the process can be successfully used to program multistep temperature cycles up to similar to 1550 degrees C, improving significantly the reproducibility and the ease of use of this emerging high-temperature process technology

Bio accessibility of tire-associated organic chemicals in fish gut (Oncorhynchus mykiss): insights from an in vitro digestion model

Tire and Road Wear Particles (TRWP) account for an important part of the anthropogenic particles released into the environment. There are scientific knowledge gaps as to the potential bio accessibility of chemicals associated with TRWP to aquatic organisms. This study aimed to investigate the solubilization of five tire-associated chemicals into fish gut using an in vitro digestion model (Oncorhynchus mykiss). Our results show that the targeted compounds were partly and rapidly solubilized into simulated fluids (SF) present in the gastrointestinal tract within a typical gut transit time for fish (3h in SFGASTRIC and 24h in SFINTESTINAL). The effects of food co-ingestion on the solubilization of tire-associated chemicals was compound-specific and either lowered or stimulated their solubilization into the gut fluids. Therefore, the uptake of the tire associated chemicals by the epithelial cells and related toxicity to fish need to be investigated

Quantum control of exciton wavefunctions in 2D semiconductors

Excitons -- bound electron-hole pairs -- play a central role in light-matter interaction phenomena, and are crucial for wide-ranging applications from light harvesting and generation to quantum information processing. A long-standing challenge in solid-state optics has been to achieve precise and scalable control over the quantum mechanical state of excitons in semiconductor heterostructures. Here, we demonstrate a technique for creating tailored and tunable potential landscapes for optically active excitons in 2D semiconductors that enables in-situ wavefunction shaping at the nanoscopic lengthscale. Using nanostructured gate electrodes, we create localized electrostatic traps for excitons in diverse geometries such as quantum dots and rings, and arrays thereof. We show independent spectral tuning of multiple spatially separated quantum dots, which allows us to bring them to degeneracy despite material disorder. Owing to the strong light-matter coupling of excitons in 2D semiconductors, we observe unambiguous signatures of confined exciton wavefunctions in optical reflection and photoluminescence measurements. Our work introduces a new approach to engineering exciton dynamics and interactions at the nanometer scale, with implications for novel optoelectronic devices, topological photonics, and many-body quantum nonlinear optics

A focus reduction neutralization assay for hepatitis C virus neutralizing antibodies

BACKGROUND/AIM: The role of humoral immunity in hepatitis C virus (HCV) infection is poorly understood. Nevertheless, there is increasing interest in characterizing the neutralizing antibodies in the serum of HCV-infected patients. Focus reduction assays have been widely used to evaluate neutralizing antibody responses against a range of non-cytopathic viruses. Based on the recent development of a HCV cell culture system using the genotype 2 JFH-1-strain, we developed a focus reduction assay for HCV-neutralizing antibodies. METHODS: The focus reduction assay was based on a standard microneutralization assay in which immunostained foci on tissue culture plates are counted. The neutralizing anti-HCV antibodies titers of purified serum immunoglobulin samples from seventy-seven individuals were determined using a 50% focus reduction neutralization assay. Each titer was determined as the log value of the reciprocal antibody dilution that reduced the number of viral foci by 50%. IgG antibodies were first purified from each serum in order to avoid the facilitating effect of HDL on HCV entry. RESULTS: The assay's cut-off using an ELISA and RNA HCV-negative samples was found to be 1.25 log, corresponding to a dilution of 1:18. The assay was compared with a commercial HCV ELISA and exhibited specificity and sensitivity values of 100% and 96.5%, respectively, and good reproducibility (with intra-assay and inter-assay coefficients of variation of 6.7% and 12.6%, respectively). The assay did not show any cross-reactivity with anti-HIV, anti-HBs or heterophile antibody-positive samples. The neutralizing antibodies titers were 2.13 log (1:134) for homologous samples from HCV genotype 2 infected patients harboring the same genotype as JFH-1 and 1.93 log (1:85) for heterologous samples from patients infected by genotypes other than type 2. These results confirm the presence of broadly cross-neutralizing antibodies already reported using the HCV pseudoparticles system. CONCLUSION: This study presents a simple, specific and reproducible cell culture-based assay for determination of HCV-neutralizing antibodies in human sera. The assay should be an important tool for gauging the relationship between the neutralizing antibodies response and viral load kinetics in acutely or chronically infected patients and for investigating the possible eradication or prevention of HCV infection by neutralizing antibodies