Science & Mathematics

In [35] Lichtenbaum conjectured the existence of a Weil-étale cohomology in order to describe the vanishing order and the special value of the Zeta function of an arithmetic scheme X at s = 0 in terms of Euler-Poincaré characteristics. Assuming the (conjectured) finite generation of some étale motivic cohomology groups we construct such a cohomology theory for regular schemes proper over Spec(Z). In particular, we obtain (unconditionally) the right Weil-étale cohomology for geometrically cellular schemes over number rings. We state a conjecture expressing the vanishing order and the special value up to sign of the Zeta function ⇣(X , s) at s = 0 in terms of a perfect complex of abelian groups R W,c(X , Z). Then we relate this conjecture to Soulé's conjecture and to the Tamagawa number conjecture of Bloch-Kato, and deduce its validity in simple cases.

L'ostéoporose cause environ 25 000 fractures par jour en Europe. Les méthodes utilisées en clinique pour établir son diagnostic sont basées sur des mesures densitométriques. Cependant, les résultats obtenus à l'aide de cette technique ne sont pas assez discriminant, 50% des femmes ayant subi une fracture ostéoporotique ne sont pas diagnostiquées comme atteintes d'ostéoporose selon les mesures densitométriques. Dans le but d'améliorer les prédictions sur le risque de fracture, de nouvelles méthodes sont envisagées, notamment le développement de modèles numériques simulant le comportement mécanique de l'os face à la fracture. Les données utilisées dans ces simulations ont été déterminées à partir d'essais mécaniques sous chargement quasi-statique. Or une fracture ostéoporotique est généralement la conséquence d'une chute du sujet, équivalent à un chargement rapide. L'os étant un matériau viscoélastique, l'objectif de cette étude est de mesurer la ténacité de l'os cortical humain sous chargement quasi-statique et sous chargement rapide pour simuler un cas de chute. Les résultats montrent que la ténacité de l'os cortical humain est plus faible pour une vitesse de chargement rapide.

In real scenes, dynamic background and moving cast shadow always make accurate moving object detection difficult. In this paper, a probabilistic framework for moving object segmentation in dynamic scenes is proposed. Under this framework, we deal with foreground detection and shadow removal simultaneously by constructing probability density functions (PDFs) of moving objects and non-moving objects. Here, these PDFs are constructed based on KDEGMMhybrid model (KGHM) which has advantages of KDE and GMM. This KGHM models the spatial dependencies of neighboring pixel colors to deal with highly dynamic scenes. Moreover, in this framework, tracking information is used to refine the PDF of moving objects. Experimental results demonstrate the effectiveness of our method.

This paper represents a repository for online laboratories, learning applications and Inquiry Learning Spaces (ILS) towards introducing Inquiry-Based Science Education (IBSE) in schools. In the first part, a classification scheme for online labs and a methodology for creating a federation of online labs are described. In the second part, technical implementation of the defined classification in the Go-Lab Repository is represented. In the third part, a usage scenario is described targeting science teachers of primary and secondary schools, who want to use online labs in their classroom activities. In sum, this paper aims at communicating the pedagogical background and advantages of the represented approach, as well as opportunities opened up by the Go-Lab Repository for teachers practicing inquiry-based learning activities in their classes.

The socialization of employees in companies has already been the subject of extensive research. However, knowledge on the subject still needs to be developed. In particular, little is known about the integration and retention of new and established SME employees. Based on an exploratory qualitative approach carried out in Cameroonian SMEs, we present the stakes of socialization practices on the loyalty of employees. This work, contributing to enrich the knowledge on the practices of organizational socialization (OS), emphasizes its preponderant role to the employees' loyalty, thus guaranteeing a better performance of the company by maintenance of the competent talents, a minimization of the recruitment costs and a reduction of social dysfunctions.

24x36 mm, film.

The pollution by persistent organic pollutants (POPs) in terrestrial and soil ecosystems pose a significant global threat, due to their long-term stability, widespread dissemination and detrimental effects on human health and ecological systems. In recent years, myco-remediation has emerged as a sustainable and cost-effective restoration technology, offering several advantages over bacteria, given the omnipresence of fungi, their capacity to tolerate and survive harsh environmental conditions, as well as their ability to oxidize a broader range of compounds, particularly those with high molecular weight and increased recalcitrance. This review explores past and recent advancements in fungal bioremediation of soil contaminated with 19 persistent organic pollutants (POPs) listed under the Stockholm Convention, including ten from the original "dirty dozen" and nine of the newly registered POPs. Fungal species which had demonstrated POP degradation capabilities are delved and their advantages, limitations, and degradation pathways are assessed. A comprehensive review of fungal species applied for POP bioremediation is provided, highlighting the most frequently employed strains. The review also highlights the need of agreeing on standardized approaches, including criteria to select truly effective fungal remediation strains as well as appropriate initial POP concentrations. To guide future research, it provides also insights on innovative fungal isolation approaches, and explores advancements in characterization strategies, to uncover promising candidates for soil bioremediation. Innovations in myco-remediation hold great promise for effectively mitigating POPs in soil environments. This review highlights the growing importance of sustainable solutions for persistent organic pollutants management.

Depuis la découverte de l'effet laser dans le rubis en 1960, un grand nombre de matériaux lasers ont été préparés. En se limitant aux monocristaux, on en recense actuellement environ 320 qui se partagent en deux familles selon que leur émission laser est constituée d'une série de longueurs d'onde discrètes, ou qu'elle est accordable continûment sur une certaine plage. Au premier type appartiennent les lasers activés à Nd3 + que le deuxième chapitre de l'article passe en revue, ainsi que ceux dopés à d'autres terres rares, notamment Pr3 +, Er3 +, Ho3 +, qui sont discutés au chapitre trois. Le chapitre quatre est consacré aux matériaux lasers accordables (aussi dénommés lasers vibroniques) qui peuvent être activés soit par des centres colorés, soit par des ions de transition (Cr3+ en particulier). En conclusion l'article suggère quelques axes de recherche et développement dans le domaine des matériaux pour lasers.

Outsourcing data to cloud environments can offer ease of access, provisioning, and cost benefits, but makes the data more vulnerable to disclosure. Loss of complete control over the data can be offset through encryption, but this approach requires an omniscient third party key authority to handle key management, increasing overhead complexity. We present the ZeroVis framework that provides confidentiality for data stored in a cloud environment without requiring a third party key manager. It combines fine-grained access control with the ability to search over encrypted data to allow existing applications to migrate to cloud environments with very minimal software changes, while maintaining data provider control over who can consume that data.

On s’intéresse à la simulation d’écoulements compressibles multi-matériaux et, notamment, aux interactions fluide/structure dans les régimes transitoires et en dynamique rapide. Le but est de pouvoir décrire l’évolution de matériaux de lois de comportement très différentes à l’aide d’un modèle unique. Les milieux sont seulement différenciés par leurs équations d’état et sont séparés par une interface dite sharp. Les matériaux peuvent être des fluides ou des solides élastiques et sont soumis à de grandes déformations. Le modèle est écrit dans le formalisme eulérien. Le schéma numérique est résolu sur des grilles cartésiennes pour des simulations en trois dimensions.Une extension du modèle permet de décrire les déformations plastiques des solides.

We address the problem of leader-follower formation control of nonholonomic vehicles with parametric uncertainty. The controller that we propose applies to diverse kinds of reference trajectories, including set-point stabilisation, persistently-exciting trajectories, and converging ones and ensures uniform global asymptotic stability in closed loop. In particular, for the first time in the literature, we establish uniform convergence of the parameter estimation errors in such context. Also, some original simulation results illustrate our theoretical findings.

Image JPEG compression leaves blocking artifact traces. This paper describes an algorithm that exploits those traces to locally recover the grid embedded in the image by the JPEG compression. The algorithm returns a list of grids associated with different parts of the image. The method uses Chen and Hsu's cross-difference to reveal the artifacts. Then, an a contrario validation step according to Desolneux, Moisan and Morel's theory delivers for each detected grid a Number of False Alarms (NFA) which tells how unlikely it is that the detection is due to chance. The only parameter is the step size of the windows used, which represents the exhaustiveness of the method. The application to image forgery detection is twofold: first, the presence of discrepant JPEG grids with low NFA is a strong forgery cue; second, knowledge of the grid is anyway required for further JPEG forensic analysis. Source Code The reviewed source code and documentation for this algorithm are available from the web page of this article 1. Compilation and usage instruction are included in the README.txt file of the archive.