A new Edge Detector Based on Parametric Surface Model: Regression Surface Descriptor

In this paper we present a new methodology for edge detection in digital images. The first originality of the proposed method is to consider image content as a parametric surface. Then, an original parametric local model of this surface representing image content is proposed. The few parameters involved in the proposed model are shown to be very sensitive to discontinuities in surface which correspond to edges in image content. This naturally leads to the design of an efficient edge detector. Moreover, a thorough analysis of the proposed model also allows us to explain how these parameters can be used to obtain edge descriptors such as orientations and curvatures. In practice, the proposed methodology offers two main advantages. First, it has high customization possibilities in order to be adjusted to a wide range of different problems, from coarse to fine scale edge detection. Second, it is very robust to blurring process and additive noise. Numerical results are presented to emphasis these properties and to confirm efficiency of the proposed method through a comparative study with other edge detectors.Comment: 21 pages, 13 figures and 2 table

Optimal selection on two quantitative trait loci with linkage

A mathematical approach to optimize selection on multiple quantitative trait loci (QTL) and an estimate of residual polygenic effects was applied to selection on two linked or unlinked additive QTL. Strategies to maximize total or cumulative discounted response over ten generations were compared to standard QTL selection on the sum of breeding values for the QTL and an estimated breeding value for polygenes, and to phenotypic selection. Optimal selection resulted in greater response to selection than standard QTL or phenotypic selection. Tight linkage between the QTL (recombination rate 0.05) resulted in a slightly lower response for standard QTL and phenotypic selection but in a greater response for optimal selection. Optimal selection capitalized on linkage by emphasizing selection on favorable haplotypes. When the objective was to maximize total response after ten generations and QTL were unlinked, optimal selection increased QTL frequencies to fixation in a near linear manner. When starting frequencies were equal for the two QTL, equal emphasis was given to each QTL, regardless of the difference in effects of the QTL and regardless of the linkage, but the emphasis given to each of the two QTL was not additive. These results demonstrate the ability of optimal selection to capitalize on information on the complex genetic basis of quantitative traits that is forthcoming

The invasion process of bovine erythrocyte by Babesia divergens: knowledge from an in vitro assay

Babesia divergens is a tick-transmitted apicomplexan parasite for which asexual multiplication in its vertebrate hosts is restricted to erythrocytes. Current knowledge of invasion of these target cells is limited. An efficient in vitro invasion assay was set up to gain access to this information. Parasites prepared from infected RBC, lysed by electroporation, and mixed with bovine RBC in a selected synthetic medium (RPMI 1640 supplemented with calcium) were able to establish subsequent cultures with parasitemia ranging from 6 to 14%. Free parasites remaining in the invasion medium could be eliminated by Percoll gradient and culture could be pursued with the freshly invaded erythrocytes. In this way, the invasion time window could be shortened to obtain a synchronised start of the culture or to study the kinetics of invasion. With this assay we demonstrate that 1) erythrocyte invasion by B. divergens is a rapid process since 70% of the invasion-competent parasites invaded the RBC in less than 45 s; 2) all invasion-competent parasites achieved invasion within 10 min of contact; 3) one erythrocyte could be invaded concomitantly by two merozoites; 4) despite a synchronous start, the parasite population evolved heterogeneously resulting in a progressive loss of synchronisation. Western blot analysis of proteins collected from invasion medium were performed with sera from animals experimentally infected with B. divergens and highlighted several proteins. The dose-dependent, inhibitory effects of these sera on B. divergens invasion suggest that these proteins might be involved in the invasion process. Further investigations are required for their characterisation

Individual heterogeneity in erythrocyte susceptibility to Babesia divergens is a critical factor for the outcome of experimental spleen-intact sheep infections

Susceptibility of sheep erythrocytes to Babesia divergens was investigated in vitro and a high inter-individual variability in their ability to support parasite population development was demonstrated, with some individuals having refractory red blood cells (RBC). As neither changes in growth conditions nor the use of different B. divergens strains influenced the level of susceptibility, the main factor postulated for this variability is the erythrocyte itself. Sheep therefore represent an excellent in vitro model to study the parasite-erythrocyte interaction. In addition, the existence of refractory RBC should help in the identification of the erythrocyte components required for B. divergens development. Experimental infections were carried out on spleen-intact sheep characterized by refractory or fully susceptible erythrocyte types. These differences translated into the successful infection of only those animals with susceptible erythrocytes: infected animals showed no clinical signs, but maintained an asymptomatic persistent infection, as usually observed in the natural bovine host. Sheep therefore represent model organisms that can allow us to study interactions between B. divergens and its vertebrate host at different levels of biological organisation, from the target cell to the intact animal, and represent an experimental infection model of concomitant immunity. Only a low percentage (13%) of the sheep population tested possessed susceptible erythrocytes and the potential role of sheep as a natural host or reservoir of B. divergens is discussed

Results of a whole genome scan targeting QTL for growth and carcass traits in a Piétrain × Large White intercross

We herein report the results of a whole genome scan performed in a Piétrain × Large White intercross counting 525 offspring to map QTL influencing economically important growth and carcass traits. We report experiment-wide significant lod scores (> 4.6 for meatiness and fat deposition on chromosome SSC2, and for average daily gain and carcass length on chromosome SSC7. Additional suggestive lod scores (> 3.3) for fat deposition are reported on chromosomes SSC1, SSC7 and SSC13. A significant dominance deviation was found for the QTL on SSC1, while the hypothesis of an additive QTL could not be rejected for the QTL on SSC7 and SSC13. No evidence for imprinted QTL could be found for QTL other than the one previously reported on SSC2

Défis 2025

International audienceNew paradigms, languages, modeling, verification, testing approaches and new tools in the field of programming and software should be created in the next 10 years, whether to make life easier for designers and maintainers of computer systems, to model and reliable software or to anticipate technological change. This text summarizes the challenges in the Programming and Software Engineering field on the horizon 2025. This work has been presented and discussed during the national days of the Research Group on Programming and Software Engineering in June 2014 and in September 2014 in Paris.De nouveaux paradigmes, de nouveaux langages, de nouvelles approches de modélisation, de vérification, de tests et de nouveaux outils dans le domaine de la programmation et du logiciel devraient voir le jour dans les dix ans à venir, que ce soit pour faciliter la vie des concepteurs et mainteneurs de systèmes informatiques, pour modéliser et fiabiliser les logiciels ou encore pour devancer l’évolution technologique. Ce texte résume les travaux menés sur les défis du Génie de la Programmation et du Logiciel à l’horizon 2025. Ces travaux ont été l’occasion de présentations et d’échanges lors des journées nationales du Groupe de Recherche Génie de la Programmation et du Logiciel en juin 2014 et lors d’une journée en septembre 2014 à Paris

Babesia and its hosts: adaptation to long-lasting interactions as a way to achieve efficient transmission

Babesia, the causal agent of babesiosis, are tick-borne apicomplexan protozoa. True babesiae (Babesia genus sensu stricto) are biologically characterized by direct development in erythrocytes and by transovarial transmission in the tick. A large number of true Babesia species have been described in various vertebrate and tick hosts. This review presents the genus then discusses specific adaptations of Babesia spp. to their hosts to achieve efficient transmission. The main adaptations lead to long-lasting interactions which result in the induction of two reservoirs: in the vertebrate host during low long-term parasitemia and throughout the life cycle of the tick host as a result of transovarial and transstadial transmission. The molecular bases of these adaptations in vertebrate hosts are partially known but few of the tick-host interaction mechanisms have been elucidated

Annotation fonctionnelle de corpus arborés avec des Champs Aléatoires Conditionnels

National audienceL'objectif de cet article est d'évaluer dans quelle mesure les "fonctions syntaxiques" qui figurent dans une partie du corpus arboré de Paris 7 sont apprenables à partir d'exemples. La technique d'apprentissage automatique employée pour cela fait appel aux "Champs Aléatoires Conditionnels" (Conditional Random Fields ou CRF), dans une variante adaptée à l'annotation d'arbres. Les expériences menées sont décrites en détail et analysées. Moyennant un bon paramétrage, elles atteignent une F1-mesure de plus de 80%

A Review of Pneumatic Actuators Used for the Design of Medical Simulators and Medical Tools

International audienc