Micro-embolic signatures detection through GARCH parameters

International audienceDetection of micro-emboli is of great clinical importance to prevent cerebro-vascular events. Standard detection techniques implemented in the most commonly used systems are generally based on the comparison between a decision information (energy) and a threshold. The value of this threshold can be set just above the statistically highest detected energy of a blood Doppler signal. This choice of threshold consequently prevents all detection of micro-emboli events whose energy might be lower than the systolic energy. In this study three detectors were tested and compared: i) a standard energy detector, ii) a detector based on AR parameters and iii) a detector based on GARCH parameters. From in vivo signals and for a detection rate set to 100%, the false alarm rates were of 33%, 5% and 3% for the standard energy detector, for the detector based on a AR(2) model and for the proposed detector based on the GARCH(1,1) model, respectively. This study demonstrates that GARCH technique detects micro-emboli which did not identified by classical methods. Large micro-emboli are all detected, but small micro-emboli are only detected with parametric techniques. The new detector opens up new prospects to detect small emboli, despite the need for further studies to incorporate technique "on line"

Early assessment of mixed sessile and pedunculate stands at 3 plantation sites in France

En France, la plantation séparée des Chênes pédonculé et sessile est recommandée ; ces deux espèces n'ont pas les mêmes exigences stationnelles et des sylvicultures différentes leur sont appliquées. Cependant, elles se rencontrent fréquemment en mélange et peuvent s'hybrider. A l'automne 1993, le Cemagref a réalisé des lots mélangés des deux espèces, en proportions connues, pour étudier l'évolution de leur composition spécifique en pépinière puis après plantation. Les résultats obtenus quatre ans après plantation sur trois sites sont analysés. Comme en pépinière, la proportion relative de Chêne pédonculé tend à augmenter au sein des mélanges au détriment du Chêne sessile. Le Chêne pédonculé allie un meilleur taux de survie à la reprise à une croissance stimulée par le mélange interspécifique. Ces résultats sont obtenus sur les trois stations étudiées, même en présence de sécheresse estivale

Détection automatique de micro-emboles cérébraux grâce à un nouveau détecteur de variance conditionnelle

Version 2 includes an English translationInternational audienceThe detection of precursor signs of cerebrovascular accidents is a problem of public health since cerebrovascular accidents correspond to the second leading cause of death worldwide. The transcranial Doppler system is used to detect micro-emboli signals. To date, the commercial devices used by clinician did not permit to detect all micro-emboli. New detectors are expected to reduce the false negative rate. We propose a novel detector based on the conditional variance. This detector outperforms the conventionnal detector by a factor 10. Consequently, it will allow a more efficient detection of precursor signs of cerebrovascular accidents and a reducing of the risk for patients.La détection des signes précurseurs d'un accident vasculaire cérébral est un problème de santé publique puisque les accidents vasculaires cérébraux correspondent à la deuxième cause de mortalité dans le monde. Le système Doppler transcrânien est le seul dispositif permettant de détecter les micro-emboles cérébraux. Toutefois, les appareils du commerce existants ne permettent pas encore de détecter automatiquement tous les micro-emboles. Nous proposons alors un nouveau détecteur basé sur un modèle à variance conditionnelle. À partir d'enregistrements obtenus grâce à un système Doppler transcrânien, le nouveau détecteur permet de réduire, d'un facteur 10, le taux de faux négatif affiché par le détecteur d'énergie conventionnel. Ces très bons résultats sont de bonnes augures et ils permettront sans aucun doute une détection plus efficace des signes précurseurs d'un accident vasculaire cérébral et une réduction du risque pour les patients

La espacialidad colonial en las plantaciones de azucar de Martinica en 1770, a través del prisma de la mapa de Moreau du Temple

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Targeting Class I-II-III PI3Ks in Cancer Therapy: Recent Advances in Tumor Biology and Preclinical Research

Phosphatidylinositol-3-kinase (PI3K) enzymes, producing signaling phosphoinositides at plasma and intracellular membranes, are key in intracellular signaling and vesicular trafficking pathways. PI3K is a family of eight enzymes divided into three classes with various functions in physiology and largely deregulated in cancer. Here, we will review the recent evidence obtained during the last 5 years on the roles of PI3K class I, II and III isoforms in tumor biology and on the anti-tumoral action of PI3K inhibitors in preclinical cancer models. The dependency of tumors to PI3K isoforms is dictated by both genetics and context (e.g., the microenvironment). The understanding of class II/III isoforms in cancer development and progression remains scarce. Nonetheless, the limited available data are consistent and reveal that there is an interdependency between the pathways controlled by all PI3K class members in their role to promote cancer cell proliferation, survival, growth, migration and metabolism. It is unknown whether this feature contributes to partial treatment failure with isoform-selective PI3K inhibitors. Hence, a better understanding of class II/III functions to efficiently inhibit their positive and negative interactions with class I PI3Ks is needed. This research will provide the proof-of-concept to develop combination treatment strategies targeting several PI3K isoforms simultaneously

Targeting Class I-II-III PI3Ks in Cancer Therapy: Recent Advances in Tumor Biology and Preclinical Research

Phosphatidylinositol-3-kinase (PI3K) enzymes, producing signaling phosphoinositides at plasma and intracellular membranes, are key in intracellular signaling and vesicular trafficking pathways. PI3K is a family of eight enzymes divided into three classes with various functions in physiology and largely deregulated in cancer. Here, we will review the recent evidence obtained during the last 5 years on the roles of PI3K class I, II and III isoforms in tumor biology and on the anti-tumoral action of PI3K inhibitors in preclinical cancer models. The dependency of tumors to PI3K isoforms is dictated by both genetics and context (e.g., the microenvironment). The understanding of class II/III isoforms in cancer development and progression remains scarce. Nonetheless, the limited available data are consistent and reveal that there is an interdependency between the pathways controlled by all PI3K class members in their role to promote cancer cell proliferation, survival, growth, migration and metabolism. It is unknown whether this feature contributes to partial treatment failure with isoform-selective PI3K inhibitors. Hence, a better understanding of class II/III functions to efficiently inhibit their positive and negative interactions with class I PI3Ks is needed. This research will provide the proof-of-concept to develop combination treatment strategies targeting several PI3K isoforms simultaneously

Vessel segmentation in high-frequency 2D/3D ultrasound images

International audienc

A comparison of non-parametric segmentation methods

National audienceIn image segmentation, level-set methods discriminating regions with Parzen estimates of their intensity distributions have proven useful in a broad variety of contexts. A number of area cost terms have been proposed to achieve this goal, such as log-likelihood, Bhattacharyya coefficient, Kullback-Leibler divergence and several others. In this work we compare the performance of the most widespread criterions and show that log-likelihood and assimilated methods have a clear advantage in terms of robustness. In particular, the other methods tested suffer from a boundary instability due to small region/small initialization/hard to distinguish regions. We also give some theoretical arguments supporting our experimental results on synthetic and real images.Pour la segmentation d'images, différentes méthodes ont été proposées pour segmenter une image à partir d'estimateurs de Parzen des distributions d'intensités, par exemple la distance de Bhattacharyya, de Kullback-Leibler, ou la log-vraissemblance. Nous comparons plusieurs méthodes couramment utilisées et montrons que les méthodes basées sur la log-vraissemblance sont les plus robustes, et en particulier sont exemptes de problèmes de bords rencontrés dans toutes les autres méthodes testées. Ces résultats donnent des indications claires sur quelles méthodes doivent être préférées et nous avançons quelques arguments théoriques dans cette direction