Adhesive factor/rabbit 2, a new fimbrial adhesin and a virulence factor from Escherichia coli O103, a serogroup enteropathogenic for rabbits

Enteropathogenic Escherichia coli-like E. coli strains belonging to serovar O103:K-:H2 and rhamnose-negative biotypes are highly pathogenic diarrhea-inducing strains for weaned European rabbits. We describe here the cloning and sequencing of the major subunit gene of a new fimbrial adhesin, adhesive factor/rabbit 2 (AF/R2), which confers on these strains the ability to attach to rabbit enterocytes and to HeLa cells in a diffuse manner and which is associated with in vivo virulence. The chromosomal operon that encodes functional AF/R2 has been cloned from strain B10. The major subunit gene afr2G, as well as an adjacent open reading frame, afr2H, has been sequenced. The Afr2G protein shows homologies with FaeG and ClpG, which are the respective major subunits of fimbrial adhesin K88 (F4) and afimbrial adhesin CS31A. Plasmid carrying the operon transcomplements an AF/R2-negative TnphoA mutant for its ability to express AF/R2. As a whole, AF/R2 is a new member of the E. coli K88 adhesin family which is associated with virulence and which may serve in the design of vaccines

Effect of the over-ageing treatment on the mechanical properties of AA2024 aluminum alloy.

The evolution of the hardness of the over-ageing AA2024 alloy scale was followed by measurements of Vickers hardness. The nanoindentation is adapted to the determination of elastoplastic properties (hardness and Young’s modulus) of the matrix and also of coarse intermetallic precipitates. Influence of the artificial over-ageing time to hardness and to mechanical properties as the local scale was investigated

Using magnetic disturbances to improve IMU-based position estimation

International audienceWe address the problem of position estimation for a rigid body using an inertial measurement unit (IMU). In this paper, we present a Kalman filtering technique which takes advantage of the magnetic disturbances usually observed indoors. This is an important topic for military operations in urban areas where GPS is often unavailable. This approach yields significant improvements in estimation accuracy. We illustrate our technique with several experimental results obtained with a low cost IMU

Volumetric relief map for the cortical subarachnoid space analysis

Purpose: Medical image visualization is an important step in the medical diagnosis of hydrocephalus. In this paper, we present planar representations called volumetric relief maps that are generated from three-dimensional images of the cerebrospinal fluid within the cortical subarachnoid space. Such maps are visually interpreted at once and allow to automatically characterize fluid distributions. Consequently, they help specialists to provide a diagnosis and to monitor patients instantly. Methods: Volumetric relief maps are generated by enclosing the cortical subarachnoid space with a hemisphere, and using a ray tracing method and a map projection technique from a hemisphere to a plane. Results: Visualization of maps indicates that healthy adults have more balanced fluid distributions with well-filled sulci, unlike hydrocephalus patients who have more or less large fluid depletions in the posterior regions of the brain. We showed that a moment-based approach allows to efficiently characterize such fluid distributions from maps. In particular, the center of mass of a distribution is an efficient discriminant factor to distinguish between healthy adults and hydrocephalus patients, with resulting sensitivity and specificity of 100%. In addition, we have noted that asymmetry of the fluid distribution increases with depletion for hydrocephalus patients; such asymmetry is generally oriented towards the frontal part of the fissura longitudinalis cerebri. Conclusions: This paper describes an innovative visualization tool used to analyze fluid distribution within the cortical subarachnoid space. It allows to efficiently discriminate between healthy adults and pathological cases, and to monitor patients before and after surgery

Sex-biased dispersal promotes adaptive parental effects

<p>Abstract</p> <p>Background</p> <p>In heterogeneous environments, sex-biased dispersal could lead to environmental adaptive parental effects, with offspring selected to perform in the same way as the parent dispersing least, because this parent is more likely to be locally adapted. We investigate this hypothesis by simulating varying levels of sex-biased dispersal in a patchy environment. The relative advantage of a strategy involving pure maternal (or paternal) inheritance is then compared with a strategy involving classical biparental inheritance in plants and in animals.</p> <p>Results</p> <p>We find that the advantage of the uniparental strategy over the biparental strategy is maximal when dispersal is more strongly sex-biased and when dispersal distances of the least mobile sex are much lower than the size of the environmental patches. In plants, only maternal effects can be selected for, in contrast to animals where the evolution of either paternal or maternal effects can be favoured. Moreover, the conditions for environmental adaptive maternal effects to be selected for are more easily fulfilled in plants than in animals.</p> <p>Conclusions</p> <p>The study suggests that sex-biased dispersal can help predict the direction and magnitude of environmental adaptive parental effects. However, this depends on the scale of dispersal relative to that of the environment and on the existence of appropriate mechanisms of transmission of environmentally induced traits.</p

Volumetric relief map for intracranial cerebrospinal fluid distribution analysis

International audienceCerebrospinal fluid imaging plays a significant role in the clinical diagnosis of brain disorders, such as hydrocephalus and Alzheimer's disease. While three-dimensional images of cerebrospinal fluid are very detailed, the complex structures they contain can be time-consuming and laborious to interpret. This paper presents a simple technique that represents the intracranial cerebrospinal fluid distribution as a two-dimensional image in such a way that the total fluid volume is preserved. We call this a volumetric relief map, and show its effectiveness in a characterization and analysis of fluid distributions and networks in hydrocephalus patients and healthy adults

Similarities Between Proton and Neutron Induced Dark Current Distribution in CMOS Image Sensors

Several CMOS image sensors were exposed to neutron or proton beams (displacement damage dose range from 4 TeV/g to 1825 TeV/g) and their radiation-induced dark current distributions are compared. It appears that for a given displacement damage dose, the hot pixel tail distributions are very similar, if normalized properly. This behavior is observed on all the tested CIS designs (4 designs, 2 technologies) and all the tested particles (protons from 50 MeV to 500 MeV and neutrons from 14 MeV to 22 MeV). Thanks to this result, all the dark current distribution presented in this paper can be fitted by a simple model with a unique set of two factors (not varying from one experimental condition to another). The proposed normalization method of the dark current histogram can be used to compare any dark current distribution to the distributions observed in this work. This paper suggests that this model could be applied to other devices and/or irradiation conditions

Anomalies de surface et pêche thonière: SPOT et la détection de zones de pêche par l'inventaire des hauts-fonds

Par une analyse théorique et quelques exemples pratiques, il est montré que, dans une zone de pêche des thonidés, la présence de hauts-fonds est un facteur d'amélioration des rendements, et que, par l'utilisation des caractéristiques spécifiques de l'imagerie SPOT et par un traitement simple, la télédétection des hauts-fonds est réalisable. Une nouvelle stratégie d'exploitation de cette imagerie est proposée

Etude structurale de la Dihydroflavonol 4-Reductase, enzime clé de la biosynthèse des flavonoïdes chez Vitis Vinifera

Anthocyanes et tanins condensés constituent deux classes de flavonoïdes présentant des propriétés d’intérêt dans le domaine de la « vigne et du vin ». Non seulement, ils confèrent à la plante une forte résistance aux pathogènes mais ils sont de plus, très impliqués dans la qualité organoleptique du vin. Dans une première partie de ce mémoire, nous présentons une synthèse des connaissances se rapportant aux flavonoïdes. Nous décrivons les grandes classes de composés, leurs différentes propriétés ainsi que leur voie de biosynthèse. La seconde partie de ce travail est consacrée à l’étude tant fonctionnelle que structurale d’une enzyme, la dihydroflavonol 4-reductase de Vitis vinifera essentielle à la synthèse des anthocyanes et des tanins condensés. La structure 3D confirme l’importance du segment 131-156 qui délimite le site actif. Les résultats démontrent que le seul résidu 133 ne peut être tenu pour responsable de la spécificité de substrat. Ce travail ouvre la voie à une étude plus approfondie du rôle joué par les autres acides aminés appartenant au segment précédent.Anthocyanins and condensed tannins are two major classes of flavonoids presenting properties of interest in Viticulture and Oenology. Not only they are involved in relevant functions in the plant, such as protection against pathogens, but also they strongly influence the organoleptic properties of wine. In the first part of this manuscript, we present a review of what is known about flavonoids. We describe the different classes of compounds, their various properties, together with their biosynthetic pathway. The second part of the work deals with the functional and structural studies of dihydroflavonol 4-reductase from Vitis vinifera, a key enzyme in the anthocyanin and condensed tannin biosynthesis. The 3D structure confirms the importance of the 131-156 region which lines the substrate binding site. Results demonstrate that position 133 cannot be solely responsible for the substrate specificity. This work leads the way towards a more detailed investigation of the relevant functions of other amino acids included in the above region

Iterative calibration method for inertial and magnetic sensors

International audienceWe address the problem of three-axis sensor calibration. Our focus is on magnetometers. Usual errors (misalignment, non-orthogonality, scale factors, biases) are accounted for. We consider a method where no specific calibration hardware is required. We solely use the fact that the norm of the sensed field must remain constant irrespective of the sensors orientation. The proposed algorithm is iterative. Its convergence is studied. Experiments conducted with MEMS sensors (magnetometers) stress the relevance of the approach