Science & Mathematics

An experimental study of the viscoelastic behaviour of a composite explosive material with an octogen content of almost 95% is presented. The addition of a plastic binder results in a material that, following isostatic compaction, exhibits a quasi-brittle behaviour that is strongly dependent on the strain rate. Some mechanical spectrometry tests were carried out in order to characterise this behaviour. The measurements were analysed using a time–temperature equivalence method. We also propose possible explanations for the irreversible phenomenon observed during the tests.

L'émergence d'une littérature numérique pour le jeune public a encore été peu analysée sur un plan littéraire. L'émergence de nouveaux formats s'écartant de l'imitation de l'album ou du livre illustré peut pourtant déstabiliser les repères habituels d'une éducation à la lecture par fréquentation de l'objet livre. Pour envisager ce que la prise en compte des possibilités technologiques transforme effectivement dans l'acte de lecture et l'implication du jeune lecteur, cinq applications pour le jeune public, primées ou reconnues par la communauté professionnelle, sont passées au crible d'une analyse, attentive autant aux bouleversements qu'aux filiations identifiables pour tous les amateurs de littérature jeunesse papier.

Le rôle du chirurgien-dentiste est primordial dans la prévention et le diagnostic précoce des cancers de la sphère oro-faciale. En effet, le taux de survie de ce type de cancers dépend grandement de son stade d'évolution au moment de son diagnostic. En outre, les traitements anti-cancéreux entraînent de nombreux effets indésirables au niveau de la sphère orale, dont certains sont irréversibles, et vont ainsi perdurer pendant toute la vie. Le chirurgien-dentiste en pratique de ville se doit d'être vigilant sur les précautions à prendre lors des soins bucco-dentaire et de la chirurgie orale chez des patients touchés ou ayant été touchés par des cancers de la sphère orofaciale. Il proposera également des traitements permettant d'atténuer les éventuel effets secondaires ressentis au niveau de la sphère orale, et améliorera ainsi à son échelle la qualité de vie du patient.

Root systems of host trees are known to establish ectomycorrhizae (ECM) interactions with rhizospheric fungi. This mutualistic association leads to dramatic developmental modifications in root architecture, with the formation of numerous short and swollen lateral roots ensheathed by a fungal mantle. Knowing that auxin plays a crucial role in root development, we investigated how auxin metabolism, signaling, and response are affected in poplar (Populus spp.)-Laccaria bicolor ECM roots. The plant-fungus interaction leads to the arrest of lateral root growth with simultaneous attenuation of the synthetic auxin response element DR5. Measurement of auxin-related metabolites in the free-living partners revealed that the mycelium of L. bicolor produces high concentrations of the auxin indole-3-acetic acid (IAA). Metabolic profiling showed an accumulation of IAA and changes in the indol-3-pyruvic acid-dependent IAA biosynthesis and IAA conjugation and degradation pathways during ECM formation. The global analysis of auxin response gene expression and the regulation of AUXIN SIGNALING F-BOX PROTEIN5, AUXIN/IAA, and AUXIN RESPONSE FACTOR expression in ECM roots suggested that symbiosis-dependent auxin signaling is activated during the colonization by L. bicolor. Taking all this evidence into account, we propose a model in which auxin signaling plays a crucial role in the modification of root growth during ECM formation.

Computational modelling approaches have been developed in the last decades to account for environment effects that can remarkably affect the spectroscopic features of organic dyes. With modern computing power, complex systems can be handled through hybrid QM/MM (Quantum Mechanics/Molecular Mechanics) simulations, which are nowadays commonly used to assist experiments in many different fields. We present here some of the latest advances made in our laboratory to develop and apply a Polarizable Embedding QM/MM based molecular dynamics methodology, and discussing applications where it is found useful. Then we report on the spectroscopic study of a ligand protein complex system, together with our perspective on the modelling of reactions in extreme conditions, illustrating our recent study on thermal Diels-Alder.

Cet article traite de la négociation des objectifs dans les entreprises

—The diversity of applications' types in Vehicular Ad hoc NETworks (VANETs) has spawned a large variety of messages that need to be efficiently disseminated between connected vehicles. The most critical messages are those dedicated for safety applications such as road hazardous warning, signal violation warning, etc. The dissemination of this sort of messages is considered as a challenging task in mobile networks where the topology changes dynamically. Indeed, transmitted messages should achieve a high data reachability within a limited transmission delay and an acceptable overhead in a Vehicle to Vehicle (V2V) communication mode. In this work, we focus on a special type of data dissemination protocols based on the delay strategy. The purpose of this paper is to compare two basic distinguished techniques, namely the slotted technique and the continuous technique, and study in depth their impact on the data dissemination performance. A proper selection of the convenient technique according to the application's requirements is consequently deduced. For a faithful and rigorous study, simulations are performed by means of ns-3 simulator under a realistic VANET environment in terms of map layout, mobility pattern and radio model. Simulation results show that contrary to the theoretical reflection, slotted technique is approved as the most appropriate one for safety message dissemination. This technique achieves the same packet data ratio and redundancy ratio, compared to the continuous one, while reducing the data transmission delay.

Background: Expression of several copies of the heat-inducible Hsp70.1Luciferase (LUC) transgene inserted at a single X chromosome locus of a bull (Bos taurus) was assessed in females after X-chromosome inactivation (XCI). Furthermore, impact of the chromosomal environment on the spontaneous expression of these transgene copies before XCI was studied during early development in embryos obtained after in vitro fertilization (IVF), when the locus was carried by the X chromosome inherited from the bull, and after somatic cell nuclear transfer (SCNT) cloning, when the locus could be carried by the inactive Xi or the active Xa chromosome in a female donor cell, or by the (active) X in a male donor cell. [br/] Findings: Transgene copies were mapped to bovine Xp22. In XXLUC female fibroblasts, i.e. after random XCI, the proportions of late-replicating inactive and early-replicating active XLUC chromosomes were not biased and the proportion of cells displaying an increase in the level of immunostained luciferase protein after heat-shock induction was similar to that in male fibroblasts. Spontaneous transgene expression occurred at the 8-16-cell stage both in transgenic (female) embryos obtained after IVF and in male and female embryos obtained after SCNT. [br/] Conclusions: The XLUC chromosome is normally inactivated but at least part of the inactivated X-linked Hsp70.1Luciferase transgene copies remains heat-inducible after random XCI in somatic cells. Before XCI, the profile of the transgenes' spontaneous expression is independent of the epigenetic origin of the XLUC chromosome since it is similar in IVF female, SCNT male and SCNT female embryos.

Cette étude rend compte d'un travail mené auprès de 11 formateurs en formation professionnelle pour adulte. Il vise à identifier comment se déclinent, en situation, les conditions d'emploi et de travail de cette population (connue dans la littérature comme " fragmentée ") et à décrire leurs incidences sur l'accomplissement des tâches, les possibilités de développement des compétences et la préservation de la santé. A l'aide d'entretiens semi-directifs et de relevés d'agendas de travail, il pointe la précarité des situations, les contraintes temporelles auxquelles font face les formateurs et les troubles de santé induits.

Cet article examine l’influence mutuelle et les interactions entre Philippe Égalité, duc d’Orléans, (1747-1793), et George, prince de Galles (1762-1830). Ce faisant, il évalue la possibilité pour les princes du sang d’agir comme chefs d’opposition à la fin du xviiie siècle dans les deux principales monarchies d’Europe occidentale. Alors que cela a souvent été sous-estimé, il souligne à quel point les convictions politiques de Philippe au sein de la vie constitutionnelle française furent façonnées par son contact avec les valeurs des whigs partisans de Charles James Fox. Cette étude se conclut par une réflexion sur ce qui, le cas échéant, a pu jouer un rôle dans ce lien réciproque au cours de cette année décisive de 1789 pour les deux princes.

Objective: To assess the influence of parental, friends', and teachers' smoking and tombak dipping on cigarette smoking and tombak dipping by school-going Sudanese adolescents. Design: A school-based cross-sectional survey was conducted in 2005-2006. Logistic regression was used for the analysis. Subjects: 4277 Sudanese school-going adolescents (aged 11-17 years) from 23 schools who completed an anonymous self-administered questionnaire on the use of tobacco products. Main outcome measures: Self-reported tobacco use during the previous month defined current tobacco use. Ever smoking, tombak (local smokeless tobacco) dipping, and other tobacco products were also considered as outcomes. Results: After adjusting for sex, age and school grade, adolescents' smoking habits were strongly associated with the habit in their parents and friends and, more weakly, with teachers' tombak dipping. When adjusted for each other, the association with smoking in friends was unaffected and remained significant (prevalence odds ratio [POR] of having ever smoked was 1.94, 95% confidence interval [CI] 1.64 to 2.29; OR of being current smoker was 3.77 (95% CI 2.80 to 5.07). Tobacco smoking in friends was positively associated with adolescents ever tombak dipping (POR 1.81, 95% CI 1.41 to 2.33) and current dipping (OR 3.33, 95% CI 2.20 to 5.05). The association with parental habits was reduced but still significantly elevated. Teachers' tombak dipping was only associated with adolescents ever tobacco smoking. Conclusion: Parental, teachers', and friends' tobacco use was associated with adolescents' tobacco habits. The influence of friends was the strongest. In developing programmes against adolescents' tobacco habits, there is need to target the influence of these ‘significant others'. Sudan needs to develop and implement comprehensive anti-smoking and anti-tombak dipping legislation to reduce the growing prevalence of the habits.

The warehousing industry experienced a period of rapid growth from 1998 to 2009. This paper compares how the geographic distribution of warehouses changed in both the Los Angeles and Seattle Metropolitan Areas over that time period. These two west coast cities were chosen due to their geographic spread and proximity to major ports as well as their difference in size. The phenomenon of logistics sprawl, or the movement of logistics facilities away from urban centers, which has been demonstrated in past research for the Atlanta and Paris regions, is examined for these two areas. The weighted geometric center of warehousing establishments was calculated for both areas for both years, along with the change in the average distance of warehouses to that center, an indicator of sprawl. We find that between 1998 and 2009, warehousing in Los Angeles sprawled considerably, with the average distance increasing from 25.91 to 31.96 miles, an increase of over 6 miles. However in Seattle, the region remained relatively stable, showing a slight decrease in average distance from the geographic center. Possible explanations for this difference are discussed.

Wire Arc Additive Manufacturing (WAAM) has the possibility to build metallic structures in 3D space. WAAM system is based on welding process to deposit metallic material and on a robot that moves the welding torch to add material at a given position. For large skeleton structures, it was chosen to deposit material point by point. Welding process induces uctuations.To be fully scalable, two main features must be taken into account. First, monitoring of the process is necessary. Local control on the geometry of the deposition must be used to reach the nal shape. Secondly, some deposition strategies must be implemented to manage branch intersections. To reach these two objectives, an adaptive and modular slicer and a process manager have been developed in order to implement this control. It allows us, if an error occurs during the deposition, to change the position of the eector. To obtain the desired geometry, the CAM software have to be able to, (i) do a slicing during the additive process of the part with a variable deposit height in order to take into account variation of the deposition process and (ii) manage the deposition strategy at intersection to output the position of the torch.