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Relecture de la frontière à travers les activités quotidiennes. Le cas des travailleurs frontaliers de la région métropolitaine luxembourgeoise.
No full textLa présence d’une frontière administrative dans le bassin de vie d’actifs frontaliers entraine l’émergence d’un mode de vie articulant opportunités et contraintes (rémunérations plus attractives, législation etc.) se traduisant dans les comportements spatiaux quotidiens. Nous proposons de montrer que malgré l’intégration européenne la frontière influence les pratiques et les comportements de mobilité des frontaliers et qu’il existe un « effet frontière » plus ou moins important sur les choix de localisation et les durées d’activités quotidiennes des frontaliers (H1). Pour répondre à cette hypothèse générale, nous proposons une démarche originale de comparaison des comportements spatiaux d’actifs frontaliers et d'actifs non frontaliers se déplaçant sur des faisceaux de mobilité comparables : Thionville-Luxembourg et Voiron-Grenoble. Cette comparaison s’appuie sur deux « concepts outils » issus de la Time Geography (Hägerstrand, 1970, Lenntorp, 1976) et de l’approche de la mobilité par les activités (Jones et al, 1983) : les « patrons d’activités » (Vilhelmson, 1999) qui témoignent de la succession et de l’organisation des activités par rapport aux lieux structurants, domicile et travail ; les « espaces d’activités » (Schönfelder et Axhausen, 2010) qui permettent d’analyser la dispersion spatiale des activités quotidiennes tout en prenant en considération la durée de celles-ci. Les « patrons d’activités » des frontaliers présenteraient une succession d’activités organisée autour du domicile, alors que les actifs non frontaliers déploieraient davantage d’activités à partir de leur lieu de travail (H2). D’autre part, la mesure des espaces d'activités témoignerait d’un nombre d’activités, ainsi qu’un temps de présence plus important à proximité du domicile que du lieu de travail dans le cas des frontaliers. Inversement, les non frontaliers concentreraient davantage d’activités (et donc plus de temps) non loin de leur travail (H3). Les différences observées entre les deux populations d’actifs, au niveau des comportements spatiaux, permettraient ainsi de révéler un effet frontière selon une méthodologie liée à l’analyse spatio-temporelle de la mobilité et des activités quotidiennes (Klein, 2007).LASU
Dot trajectories in the superposition of random screens: Analysis and synthesis
No full textMoire effects that occur in the superposition of aperiodic layers such as correlated random dot screens are known as Glass patterns. One of the most interesting properties of such moire effects, which clearly distinguish them from their periodic counterparts, is undoubtedly the appearence in the superposition of intriguing microstructure dot alignments, also known as dot trajectories. These dot trajectories may have different geometric shapes, depending on the transformations undergone by the superposed layers. In the case of simple linear transformations such as layer rotations or layer scalings, the resulting dot trajectories are rather simple (circular, radial, spiral, elliptic, hyperbolic, linear, etc.); but in more complex layer transformations the dot trajectories can have much more interesting and surprising shapes. A full mathematical analysis of the dot trajectories, their morphology, and their various properties is provided. Furthermore, it is shown how the approach also allows us to synthesize correlated random screens that give in their superposition dot trajectories having any desired geometric shapes. Finally, it is also explained why such dot trajectories are visible only in superpositions of aperiodic screens but not in superpositions of periodic screens. © 2004 Optical Society of America.LS
Oxygen assisted focused electron beam induced deposition of Si-containing materials: Growth dynamics
No full textThe growth dynamics of oxygen assisted focused electron beam induced deposition of Si-containing materials (from SiOxCy to SiO2) were investigated as a function of relevant process parameters. The results obtained from organosilanes of different families (alkoxy, alkyl, and isocyanatosilanes) are compared. Residual water molecules in the SEM chamber were found to be responsible for side reactions leading to carbon etching and oxygen incorporation in focused electron beam induced deposition (FEBID) materials and ruled the deposition process during conventional FEBID. Depending on the precursor reactivity to oxygen, the material growth rate either increased or decreased with increasing additional O-2 until it remained constant from 1 SCCM. Accounting for the FEBID material density, oxygen always increased the deposition efficiency in terms of Si atoms deposited per second. Less carbon residues in the deposits were obtained at large replenishment times (above 50 mu s) and low dwell times (below 15 mu s), which hint to relatively slow process steps in the complex deposition mechanism in our deposition equipment. O-2 assisted FEBID showed to be insensitive to electron density variations, and secondary electrons were demonstrated to have sufficient energy to initiate the oxidation reaction and achieve 90% of the deposition process. (c) 2007 American Vacuum Society.IM
Raman-based distributed optical fiber temperature sensors: industrial applications and future developments
No full textThis book chapter describes Raman Based Distributed Optical Fiber Sensors and their main industrial applications. In particular, after a brief introduction on the basic physical mechanisms, and a theoretical description of distributed optical fiber sensors based on spontaneous Raman scattering, we have focused our attention on the most attractive applications in terms of market opportunity: fire detection in tunnels and industrial plants and leakage detection in pipelines. We show that in order to achieve long sensing distances with high temperature resolution and good reliability, most standard Raman based distributed temperature sensors make use of graded-index multi-mode fibers, in double-ended or looped configuration. Advanced pulse coding techniques can however be effectively applied to make Raman sensors based on standard single mode fibers competitive with respect to other distributed optical fiber sensing technologies, such as Brillouin-based optical fiber sensors. Future developments of Raman based distributed temperature sensors will likely exploit standard single mode fibers, achieving meter-scale spatial resolutions over ultra-long distances, with high temperature resolution, fast response time, high robustness and reliability.IE
Gestion des connaissances et apprentissages en matière de mobilité quotidienne: quelles évaluations ?
No full textLASU
Asymmetric dark matter and baryogenesis from pseudoscalar inflation
No full textWe show that both the baryon asymmetry of the Universe and the dark matter abundance can be explained within a single framework that makes use of maximally helical hypermagnetic fields produced during pseudoscalar inflation and the chiral anomaly in the Standard Model. We consider a minimal asymmetric dark matter model free from anomalies and constraints. We find that the observed baryon and the dark matter abundances are achieved for a wide range of inflationary parameters, and the dark matter mass ranges between 7-15 GeV. The novelty of our mechanism stems from the fact that the same source of CP violation occurring during inflation explains both baryonic and dark matter in the Universe with two inflationary parameters, hence addressing all the initial condition problems in an economical way.LPP
Band Gap of Atomically Precise Graphene Nanoribbons as a Function of Ribbon Length and Termination
No full textWe study the band gap of finite NA=7 armchair graphene nanoribbons (7-AGNRs) on Au(111) through scanning tunneling microscopy/spectroscopy combined with density functional theory calculations. The band gap of 7-AGNRs with lengths of 8 nm and more is converged to within 50 meV of its bulk value of approximate to 2.3eV, while the band gap opens by several hundred meV in very short 7-AGNRs. We demonstrate that even an atomic defect, such as the addition of one hydrogen atom at the termini, has a significant effect - in this case, lowering the band gap. The effect can be captured in terms of a simple analytical model by introducing an effective "electronic length".THEO
Perseveration in left spatial neglect: drawing and cancellation tasks
No full textPerseveration in target cancellation tasks and in drawing by copy and from memory was investigated in 21 right-brain-damaged patients, seven with no evidence of left visuo-spatial neglect, and 14 with neglect. Eight such neglect patients showed perseveration in both cancellation and drawing tasks, although no correlation was found with the severity of neglect. Patients with perseveration were not disproportionately impaired in tasks assessing executive (fluency, Stroop colour-word interference, and Weigl's sorting test), and visuo-spatial short-term memory function. In the context of a two-component hypothesis, graphic perseveration (the first component) is a specific disorder that manifests in a variety of tasks, particularly those requiring serial graphic production. Unilateral spatial neglect (the second component) may trigger and facilitate the production of perseveration errors, with a contra-ipsilateral gradient of increasing severity.BM