Eddy currents signal processing for stream generator inspection in PWR nuclear power plants

Steam generator tubes in nuclear power plants are periodically checked by means of eddy current probes . The output of a probe is composed of three types of signais : known events (rolling zone, support plates, U-bend part), noise (mainly metallurgical noise) and possible flaws . The latter are random transients, both in arrivai time and in shape : they have to be detected and then estimated, before to be fed to the high level stages of a diagnostics system . The objective of the study presented is to develop a semi-automatic system, which could manage and process more than 1 M-bytes of data per tube and provide an operator with reliable diagnostics proposais within, a few minutes . This can be achieved only by cooperation of severai digital signal processing techniques : detection, segmentation, estimation, noise subtraction, adoptive filtering, modelisation, pattern recognition . The paper describes some of these items .Les tubes des échangeurs de chaleur que sont les générateurs de vapeur des centrales nucléaires, sont contrôlés périodiquement à l'aide d'une sonde à Courants de Foucault. La sonde délivre un signal complexe (2 composantes), contenant à la fois des événements prévisibles (dudgeonnage, plaques, cintres...), du bruit (d'origine principalement métallurgique) et des signaux représentatifs de l'état du tube (défauts éventuels). Ces signaux transitoires, aléatoires en temps d'arrivée et en forme, doivent être détectés, puis caractérisés, avant d'alimenter les étages de haut niveau d'un système de diagnostic. Les exigences actuelles de qualité et d'efficacité économique conduisent à développer un système de contrôle largement automatique, capable de gérer environ 1 méga-octets de données par tube contrôlé et de proposer au contrôleur, en quelques minutes, des diagnostics fiable

The Prony's method for vibration analysis

Among the différent digital signal processing techniques based on modelization, the Prony's method is particularly suited to vibration analysis. We describe a straightforward application of this method to the analysis of the damped oscillations of an electrical transmission line. We emphasize the use of a modern spectral analysis technique in the industrial field.Les méthodes de traitement du signal fondées sur une modélisation, la méthode de Prony est particulièrement adaptée aux signaux de vibration. Présentation d'une application directe à l'analyse d'un signal transitoire d'oscillation de ligne électrique. Application industrielle des méthodes modernes d'analyse spectral

Expression and nuclear translocation of the rel/NF-kappa B-related morphogen dorsal during the immune response of Drosophila

The rel/NF-kappa B-related morphogen dorsal is a maternally expressed gene which is involved in the control of the dorso-ventral axis during early embryogenesis of Drosophila. We show that this gene is also expressed in the fat body of larvae and adults of Drosophila as well as in a tumorous blood cell line: its expression is noticeably enhanced upon bacterial (or lipopolysaccharide) challenge. This challenge also induces within 15-30 min a nuclear translocation of the dorsal protein. The genes encoding inducible antibacterial peptides in Drosophila contain kappa B-related nucleotide sequences and we show that the dorsal protein can bind to such motifs and sequence-specifically transactivate a reporter gene in co-transfection experiments with a Drosophila cell line. However, in dl1 mutants, in the absence of dorsal protein, the genes encoding antibacterial peptides retain their inducibility, suggesting a multifactorial control. The results indicate that in addition to its role in embryogenesis, dorsal is involved in the immune response of Drosophila. They also strengthen the analogy between the mammalian acute phase response and the insect immune response

Insect immunity: the diptericin promoter contains multiple functional regulatory sequences homologous to mammalian acute-phase response elements

We are using the diptericin gene as a model system to study the control of expression of the genes encoding antibacterial peptides during the Drosophila immune reaction. In order to investigate the putative regulatory regions in the diptericin promoter, we performed DNaseI footprinting experiments combined with gel-shift assays in two inducible systems: the larval fat body and a tumorous Drosophila blood cell line. Our results confirm the importance of kappa B-like elements previously described in the immune response of insects and reveal for the first time the involvement of other regions containing sequences homologous to mammalian acute-phase response elements

Functional analysis and regulation of nuclear import of dorsal during the immune response in Drosophila

In addition to its function in embryonic development, the NF-kappa B/rel-related gene dorsal (dl) of Drosophila is expressed in larval and adult fat body where its RNA expression is enhanced upon injury. Injury also leads to a rapid nuclear translocation of dl from the cytoplasm in fat body cells. Here we present data which strongly suggest that the nuclear localization of dl during the immune response is controlled by the Toll signaling pathway, comprising gene products that participate in the intracellular part of the embryonic dorsoventral pathway. We also report that in mutants such as Toll or cactus, which exhibit melanotic tumor phenotypes, dl is constitutively nuclear. Together, these results point to a potential link between the Toll signaling pathway and melanotic tumor induction. Although dl has been shown previously to bind to kappa B-related motifs within the promoter of the antibacterial peptide coding gene diptericin, we find that injury-induced expression of diptericin can occur in the absence of dl. Furthermore, the melanotic tumor phenotype of Toll and cactus is not dl dependent. These data underline the complexity of the Drosophila immune response. Finally, we observed that like other rel proteins, dl can control the level of its own transcription

Activation of Human Stearoyl-Coenzyme A Desaturase 1 Contributes to the Lipogenic Effect of PXR in HepG2 Cells

The pregnane X receptor (PXR) was previously known as a xenobiotic receptor. Several recent studies suggested that PXR also played an important role in lipid homeostasis but the underlying mechanism remains to be clearly defined. In this study, we found that rifampicin, an agonist of human PXR, induced lipid accumulation in HepG2 cells. Lipid analysis showed the total cholesterol level increased. However, the free cholesterol and triglyceride levels were not changed. Treatment of HepG2 cells with rifampicin induced the expression of the free fatty acid transporter CD36 and ABCG1, as well as several lipogenic enzymes, including stearoyl-CoA desaturase-1 (SCD1), long chain free fatty acid elongase (FAE), and lecithin-cholesterol acyltransferase (LCAT), while the expression of acyl:cholesterol acetyltransferase(ACAT1) was not affected. Moreover, in PXR over-expressing HepG2 cells (HepG2-PXR), the SCD1 expression was significantly higher than in HepG2-Vector cells, even in the absence of rifampicin. Down-regulation of PXR by shRNA abolished the rifampicin-induced SCD1 gene expression in HepG2 cells. Promoter analysis showed that the human SCD1 gene promoter is activated by PXR and a novel DR-7 type PXR response element (PXRE) response element was located at -338 bp of the SCD1 gene promoter. Taken together, these results indicated that PXR activation promoted lipid synthesis in HepG2 cells and SCD1 is a novel PXR target gene. © 2013 Zhang et al

A recessive mutation, immune deficiency (imd), defines two distinct control pathways in the Drosophila host defense

In this paper we report a recessive mutation, immune deficiency (imd), that impairs the inducibility of all genes encoding antibacterial peptides during the immune response of Drosophila. When challenged with bacteria, flies carrying this mutation show a lower survival rate than wild-type flies. We also report that, in contrast to the antibacterial peptides, the antifungal peptide drosomycin remains inducible in a homozygous imd mutant background. These results point to the existence of two different pathways leading to the expression of two types of target genes, encoding either the antibacterial peptides or the antifungal peptide drosomycin

Evolving neural network optimization of cholesteryl ester separation by reversed-phase HPLC

Cholesteryl esters have antimicrobial activity and likely contribute to the innate immunity system. Improved separation techniques are needed to characterize these compounds. In this study, optimization of the reversed-phase high-performance liquid chromatography separation of six analyte standards (four cholesteryl esters plus cholesterol and tri-palmitin) was accomplished by modeling with an artificial neural network–genetic algorithm (ANN-GA) approach. A fractional factorial design was employed to examine the significance of four experimental factors: organic component in the mobile phase (ethanol and methanol), column temperature, and flow rate. Three separation parameters were then merged into geometric means using Derringer’s desirability function and used as input sources for model training and testing. The use of genetic operators proved valuable for the determination of an effective neural network structure. Implementation of the optimized method resulted in complete separation of all six analytes, including the resolution of two previously co-eluting peaks. Model validation was performed with experimental responses in good agreement with model-predicted responses. Improved separation was also realized in a complex biological fluid, human milk. Thus, the first known use of ANN-GA modeling for improving the chromatographic separation of cholesteryl esters in biological fluids is presented and will likely prove valuable for future investigators involved in studying complex biological samples