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  • 2012-2021
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  • Hal-Diderot
  • Mémoires en Sciences de l'Information et de la Communication
  • Social Science and Humanities

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  • Open Access English
    Authors: 
    Mathilde François; Philippe Crave; François Osiurak; Alexandra Fort; Jordan Navarro;
    Publisher: HAL CCSD
    Country: France
    Project: ANR | Avenir L.S.E. (ANR-11-IDEX-0007), ANR | CORTEX (ANR-11-LABX-0042)

    Existing literature does not draw conclusions as to which speedometer type is better for truck driving. A digital speedometer would be more beneficial when obtaining absolute and relative readings, while an analogue speedometer would be more efficient and less distracting when detecting dynamic speed changes. Redundant speedometers, which simultaneously present digital and analogue speedometers, appear increasingly in vehicles, but no information is available on their ergonomic qualities. This study compared three speedometers: digital speedometers, analogue speedometers, and redundant speedometers. This study compared the efficiency, usability and visual distraction measures for all three types of speedometers in a simulated truck driving setting. The task-dependant results were confirmed for the digital and analogue speedometer. The redundant speedometer combined the benefits of each type presented separately, which highlights interesting theoretical and applied implications.

  • Closed Access English
    Authors: 
    Muriel Bouttemy; Damien Aureau; Mathieu Frégnaux; Yasushi Shoji; Zacharie Jehl; Daniel Suchet; Jean-François Guillemoles; Arnaud Etcheberry; Yoshitaka Okada;
    Publisher: HAL CCSD
    Country: France

    III-V materials have yet proved to be promising candidates for photovoltaic applications. Solar cell technologies based on III-V semiconductors are competitive in term of fabrication cost but also have the potential to reach the highest photovoltaic efficiencies. To overcome the 30% conversion limitation established for a single junction, the Shockley Queisser limit [1], due to different losses that cannot be avoided (transmission, thermalization, emission…), different solar cell architectures have been proposed. One of them, multi-junctions, are using a stack of absorbing materials enabling to cover a wider part of the solar spectrum with high efficiency due to their optimized bang-gaps. Among other recent concepts, intermediate band solar cells have gained interest with predicted efficiency greater than 60% (under maximum concentration) and almost 48.2% under one sun [2], similar to the efficiency potential of a 3 material stack, but with a single material. By implementing quantum dots at the surface of a III-V single layer, an intermediate band can be generated [3, 4] and tuned by changing the quantum dots nature, size and shape. More complex structures with multi-stacked quantum dots have also been studied [5]. The present work focuses on the preparation of III-V quantum dots surfaces using wet chemistry. Not only dots evolution but also the development of a specific soaking to eliminate the wetting layer, detrimental for optoelectronic properties, will be shown. Numerous studies and formulation have been reported for chemical etching of III-V semiconductors [6]. Nevertheless, the remaining challenge concerns the implementation of this chemical engineering at nanometric scale [7], in consistency with the miniaturization trend and requirements of the materials, structures and devices. The study is carried out on InAs and InGaAs quantum dots grown by MBE on GaAs substrates. They present different surface densities. The structure of the samples is presented figure 1 where the wetting layer, essential for the quantum dots epitaxial growth, is illustrated. A multi-technique methodology combining XPS, AFM and nano-Auger is employed to precisely determine the surface chemical and morphologic modifications from micrometric to nanometric scale. Thanks to XPS, the evolutions of the fine chemistries of quantum dots and their surface are accessible, giving crucial information about the dissolution processes and enabling to re-adjust the experimental conditions. In Figure 1 b, the In3d photopeak evolution with the chemical treatment employed on a sample presenting only the wetting layer is shown. Indium atoms are only present in the wetting layer in this case. Thus it represents the tracking element indicative of the maintenance, thinning or elimination of this layer. The complementary use of AFM brings the evidence of the dots conservation or disappearance as illustrated Figure 1c. Nano-Auger provides additional information on local chemistry. Various formulations, in acidic or base media, are developed to enable a differential dissolution between the wetting layer and the quantum dots. Both oxidation-deoxidation cycling and direct dipping procedures were experimented and optimized taking account the differences in oxides solubility. The various scenarios likely to occur during deoxidation are presented Figure 1a, the elimination of QD being also possible by the dissolution of the wetting layer below. Finally, a comparison of capabilities for nano-etching and possible selectivity of the different solutions considered here will be presented. References [1] W. Shockley and H.J. Queisser, J. Appl. Phys. 32 (1961), 510. [2]A. Luque, A. Marti, Phys. Rev .Lett. 78 (1997) 5014-5017. [3] T. Sogabe, Y. Shoji, M. Ohba, K. Yoshida, R.Tamaki, H.-F. Hong, C.-H. Wu, C.-T. Kuo, S. Tomić, and Y. Okada, Scientific Reports (Nature Publishing Group), 4, (2014)/4/25. doi:10.1038/srep04792. [4] E. Lopez, A. Datas, I. Ramiro, P.G. Linares, E. Antolin, I. Artacho, A. Marti, A. Luque, Y. Shoji, T. Sogabe, A. Ogura, Y. Okada, Sol. Energy Mater Sol. Cells 149 (2016) 15-18. [5] T. Kada, S. Asahi, T. Kaizu, Y. Harada and T. Kita, Phys. Rev. B 91 (2015) 201303(R). [6] A.R. Clawson, Reports: a review journal, Mater. Sci. Eng. 31 (2001) 1-438. [7] D. H. van Dorp, S. Arnauts, M. Laitinen, T. Sajavaara, J. Meersschaut, T. Conard and John J. Kelly, Appl. Surf. Sci. 465, (2018), Pages 596-606. Figure 1

  • Open Access English
    Authors: 
    Léandre Gagné Lemieux; Martin Simoneau; Jean Francois Tessier; Maxime Billot; Jean Blouin; Normand Teasdale;
    Publisher: HAL CCSD
    Country: France
    Project: NSERC

    When tracing a template with mirror-reversed vision (or distorted vision), the sensory information arising from the movement does not match the expected sensory consequences. In such situations, participants have to learn a new visuomotor mapping in order to trace the template with an accuracy and speed approaching that observed when tracing with direct vision. There are several suggestions that such visuomotor learning requires lowering the gain of the proprioceptive inputs. Generally, subjects learn this task in a seated condition offering a stable postural platform. Adapting to the new visuomotor relationship in a standing condition could add complexity and even hinder sensorimotor adaptation because balance control and processing of additional information typically interfere with each other. To examine this possibility, older individuals and young adults (on average, 70 and 22 years of age, respectively) were assigned to groups that trained to trace a shape with mirror-reversed vision in a seated or a standing condition for two sessions. For a third session, the seated groups (young and elderly) transferred to the standing condition while the standing groups continued to perform the tracing task while standing. This procedure allowed comparing the tracing performance of all groups (with the same amount of practice) in a standing condition. The standing groups also did a fourth session in a seated condition. Results show that older participants initially exposed to the standing condition were much slower to trace the template than all other groups (including the older group that performed the tracing task while seated). This slowness did not result from a baseline general slowness but from a genuine interference between balance control and the visuomotor conflict resulting from tracing the pattern with mirror-reversed vision. Besides, the Standing-Old participants that transferred to a seated condition in the fourth session immediately improved their tracing by reducing the total displacement covered by the pen to trace the template. Interestingly, the results did not support a transfer-appropriate practice hypothesis which suggests that training in a standing condition (at the third session) should have benefited the performance of those individuals who initially learned to trace the mirror pattern in a standing condition. This has important clinical implications: training at adapting to new sensory contexts or environmental conditions in conditions that do not challenge balance control could be necessary if one desires to attenuate the detrimental consequences on the postural or motor performances brought up by the interference between maintaining balance and the sensory reweighing processes.

  • Open Access English
    Authors: 
    Radu Vranceanu; Damien Besancenot;
    Publisher: HAL CCSD
    Country: France

    This paper argues that in Euro-area economies, where the ECB cannot bail-out …nancially distressed governments, the …scal multiplier is adversely affected by the amount of public debt. A regression model on a panel of 26 EU countries over the period 1996-2011 shows that a 10 percentage point increase in the debt-to-GDP ratio is connected to a slowdown in annual growth rates of 0.28 percentage point. Furthermore, the e¤ectiveness of …scal spending is adversely affected by the amount of public debt; for a debt-to-GDP ratio above 150% the impact on growth of the …scal stimulus turns negative.

  • Closed Access English
    Authors: 
    Cécile Edlinger; Maxime Merli; Antoine Parent;
    Publisher: HAL CCSD
    Country: France

    International audience; The geographical distributions of French and British foreign investment portfolios differ markedly before World War I. Did French portfolios favor European investments just as British portfolios favored “New World” assets? Should economic rationality have encouraged investors to invest widely in the “New World” rather than in Europe? Combining Modern Portfolio Theory and a new data set comprising assets listed on the Paris and London Stock Exchanges, we show that investing in the “New World” did not yield higher returns than investing in Europe. The “European preference” of the Paris Bourse and, by extension, of French investors was not inefficient.

  • Open Access
    Authors: 
    Françoise Lavocat;
    Publisher: Wiley
    Country: France

    International audience; Can literature and the arts in general help to prevent catastrophes? In the article this question is entertained through examinationof the contrast between ancient cultural productions (comprising those legends and sermons which constitute ‘literature’in the larger sense) and contemporary fiction. The article shows, first of all, how ancient culture not only engaged inforward-looking thought when it came to catastrophes through the attribution of responsibility and by recommending moralreform but also by constituting a memory of catastrophes and in making practical suggestions. Our contemporary world hasbeen swamped with fictional treatments of catastrophes – treatments that might seem to have the power of heralding thesecatastrophes and certainly of nurturing an obsessive fear of them. But contemporary fiction (literary or filmic) principallyexpresses a consciousness of its own impotence; if literature can prepare people for catastrophes, it can only be along ethicallines.

  • Open Access English
    Authors: 
    Olivier Nocent; S Piotin; Aassif Benassarou; Maxime Jaisson; Laurent Lucas;
    Publisher: HAL CCSD
    Country: France

    International audience; A few years ago, the introduction of the WebGL API has allowed displaying 3D content in web browsers very efficiently by using the power of 3D accelerators. Nowadays, 3D web applications, from games to medical imaging, tend to compete with their desk-top counterparts. Among the main factors that can improve the feeling of presence in terms of impressiveness, immersion and natural interaction play a prominent role in enhancing the quality of the user experience. Both immersion and natural interaction rely on dedicated hardware like 3D displays and tracking devices. Unfortunately , browser makers do not supply JavaScript mechanisms for accessing hardware for security reasons. In this paper, we propose a plugin-free solution using the new features of HTML5 (WebGL and WebSockets) in order to handle autostereoscopic displays and widespread tracking devices like IR depth sensors for providing immersion and natural interaction within the web browser.

  • Open Access English
    Authors: 
    Ami Tsuchida; Alexandre Laurent; Fabrice Crivello; Laurent Petit; Antonietta Pepe; Naka Beguedou; Stéphanie Debette; Christophe Tzourio; B Mazoyer;
    Publisher: HAL CCSD
    Country: France

    AbstractHuman brain white matter undergoes a protracted maturation that continues well into adulthood. Recent advances in diffusion-weighted imaging (DWI) methods allow detailed characterizations of the microstructural architecture of white matter, and they are increasingly utilised to study white matter changes during development and ageing. However, relatively little is known about the late maturational changes in the microstructural architecture of white matter during post-adolescence. Here we report on regional changes in white matter volume and microstructure in young adults undergoing university-level education. As part of the MRi-Share multi-modal brain MRI database, multi-shell, high angular resolution DWI data were acquired in a unique sample of 1,713 university students aged 18 to 26. We assessed the age and sex dependence, as well as hemispheric asymmetry of diffusion metrics derived from diffusion tensor imaging (DTI) and neurite orientation dispersion and density imaging (NODDI), in the white matter regions as defined in the John Hopkins University (JHU) white matter labels atlas. We demonstrate that while regional white matter volume is relatively stable over the age range of our sample, the white matter microstructural properties show clear age-related variations. Globally, it is characterised by a robust increase in neurite density index (NDI), and to a lesser extent, orientation dispersion index (ODI). These changes are accompanied by a decrease in diffusivity. In contrast, there is minimal age-related variation in fractional anisotropy. There are regional variations in these microstructural changes: some tracts, most notably cingulum bundles, show a strong age-related increase in NDI coupled with decreases in radial and mean diffusivity, while others, mainly cortico-spinal projection tracts, primarily show an ODI increase and axial diffusivity decrease. These age-related variations are not different between males and females, but males show higher NDI and ODI and lower diffusivity than females across many tracts. We also report a robust hemispheric asymmetry in both the volume and microstructural properties in many regions. These findings emphasise the complexity of changes in white matter structure occurring in this critical period of late maturation in early adulthood.

  • Open Access English
    Authors: 
    Ilya Kalesnikau; Michal Pioro; Michael Poss; Dritan Nace; Artur Tomaszewski;
    Publisher: HAL CCSD
    Country: France
    Project: ANR | SUPER (ANR-11-IDEX-0004)

    International audience; Flow thinning (FT) is a traffic protection mechanism for communication networks with variable link capacities, for example wireless networks. With FT, end-to-end traffic demands use dedicated logical tunnels, for example MPLS tunnels, whose nominal capacity is subject to thinning in order to follow fluctuations in link capacities availability. Moreover, instantaneous traffic of each demand is throttled at its originating node accordingly to the current total capacity available on the demands dedicated tunnels so that the network is always capable of carrying the admitted traffic. In this paper we deal with efficient, implementable versions of FT, referred to as AFT (affine FT) and QFT (quadratic FT). By deriving appropriate link availability state and path generation algorithms, we show how real-life network dimen-sioning problems for AFT/QFT can be efficiently treated using a proper characterization of the network link availability states. Results of a numerical study illustrate tractability of the cost minimization problems, and assess efficiency of AFT/QFT as compared with other protection mechanisms.

  • Open Access French
    Authors: 
    Renaud Epstein;
    Publisher: HAL CCSD
    Country: France

    Les projets de territoire, qui se sont multipliés en France au cours des années 1980 et 1990 dans le cadre des politiques contractuelles développées par l'Etat, constituent des prismes utiles pour décrire et analyser les transformations de l'action publique infra-nationale et des relations entre niveaux de gouvernement. Ils permettent de saisir le basculement de la gestion publique des territoires d'un modèle hiérarchisé d'administration étatique des affaires locales, vers une forme de gouvernance territoriale pluraliste et horizontale au cours vingt dernières années du XXe siècle. Après avoir présenté cette transformation de la gestion publique des territoires et des relations entre pouvoir central et périphérique, dont les projets territoriaux sont tout à la fois des indices et des catalyseurs, on s'interrogera sur sa pérennité en considérant l'essor récent des appels à projets dans les politiques territoriales de l'Etat français ainsi que les effets de ces appels à projets concurrentiels, entre approfondissement et remise en cause de la logique de projet.

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