Active ageing – Enhancing digital literacies in elderly citizens

Being digital and information literate is crucial in nowadays society, although not every citizen has the necessary means and resources to achieve these skills, especially the elderly ones. Therefore it is necessary to develop ways to help them to enhance their digital and information competences. In this paper we will present an ongoing project that was designed and implemented with the goal to provide elderly citizens with the necessary skills of a networked society, contributing for an active ageing. The methods used were based on a set of hands on workshops delivered by a team of voluntary students and teacher, with the help of collaborators from a nursing home. The workshops were developed accordingly with the detected needs of a group of elderly citizens, based on the answers of an implemented questionnaire.info:eu-repo/semantics/publishedVersio

Trois petites (nano) controverses et leurs morales

« Selon que vous serez puissant ou misérable, les juge-ments de cour vous rendront blanc ou noir » [1]. Ainsi s’achève la fable de La Fontaine Les animaux malades de la peste : le jugement de cour condamne à mort l’Âne, coupable d’avoir volé quelques brins d’herbes, tandis que le Lion et autres animaux puissants et coupables de crimes bien plus sérieux, ne reçoivent que louanges et flatteries. Il est tentant et réconfortant de penser que les jugements scientifiques sont d’une tout autre nature. Dans cette optique, la science se tiendrait en dehors des enjeux de pouvoirs et les quelques dérives (erreurs, fraudes, conflits d’intérêts) seraient rapidement corri-gées du simple fait que la réalité matérielle, à travers les résultats expérimentaux, viendrait rapidement se rappeler à nous si l’on venait à l’ignorer trop longtemps. La réa-lité est tout autre. Une très large fraction des résultats publiés n’est pas et ne peut pas être reproduite. Il ne s’agit pas de quelques dérives, mais de problèmes structuraux qui affectent les fondements de l’entreprise scientifique [2, 3]. L’évaluation par les pairs semble encourager la publication d’histoires extraordinaires dans des journaux à haut facteur d’impact plutôt que celle d’études expé-rimentales menées avec rigueur. Les résultats contradic-toires ou « négatifs » sont rarement publiés : les journaux ne sont pas vraiment intéressés et nous, scientifiques, ne sommes guère encouragés à communiquer publiquement nos doutes sur les travaux de ceux qui pourraient bien être les évaluateurs de notre prochaine publication ou demande de financement. Il est d’autant plus urgent de réparer notre système de production de connaissances que la science est au cœur de nombreux enjeux critiques pour l’avenir des hommes et de la planète. Les problèmes (réels) de reproductibilité sont d’ores et déjà exploités par les lobbys qui veulent attaquer la crédibilité des scientifiques [4]. Après l’élection à la tête de la première puissance scientifique et militaire du globe d’un homme qui nie l’existence du changement climatique, voit d’un très bon œil l’utilisation de l’arme atomique, et plus généralement mène une guerre contre la science et la vérité [5], nous avons grand besoin d’une science ouverte, robuste et capable de défendre son indépendance, son intégrité et ses valeurs universelles. Nous en sommes loin. La quasi-absence de discussions contradictoires dans la littérature scientifique contemporaine de nombreux domaines pourrait nous le faire oublier, mais les controverses sont un aspect essentiel du progrès de la connaissance permettant d’identifier les points faibles de tra-vaux et ainsi, de les renforcer ou les invalider de manière concluante [6]. Elles sont consubstantielles à l’exercice des sciences [7]. Leur analyse peut aussi être un moyen de « cartographier symétrique-ment » les acteurs pour mieux comprendre les individus et les pro-cessus sociaux qui entrent en jeu [8]. Dans ce forum, je décris trois controverses récentes dans mon domaine de recherche, les nanopar-ticules d’or appliquées à la biologie et à la médecine. Il ne s’agit pas d’une cartographie symétrique : je n’en suis pas un observateur neutre, mais un scientifique actif à divers degrés dans chacune d’entre elles. J’essaie néanmoins d’en tirer quelques enseignements et suggestions pratiques pour améliorer notre pratique de la science

Galilean Lee Model of the Delta Function Potential

The scattering cross section associated with a two dimensional delta function has recently been the object of considerable study. It is shown here that this problem can be put into a field theoretical framework by the construction of an appropriate Galilean covariant theory. The Lee model with a standard Yukawa interaction is shown to provide such a realization. The usual results for delta function scattering are then obtained in the case that a stable particle exists in the scattering channel provided that a certain limit is taken in the relevant parameter space. In the more general case in which no such limit is taken finite corrections to the cross section are obtained which (unlike the pure delta function case) depend on the coupling constant of the model.Comment: 7 pages, latex, no figure

Large deviations for the Yang-Mills measure on a compact surface

We prove the first mathematical result relating the Yang-Mills measure on a compact surface and the Yang-Mills energy. We show that, at the small volume limit, the Yang-Mills measures satisfy a large deviation principle with a rate function which is expressed in a simple and natural way in terms of the Yang-Mills energy

Sub-ballistic behavior in quantum systems with L\'evy noise

We investigate the quantum walk and the quantum kicked rotor in resonance subjected to noise with a L\'evy waiting time distribution. We find that both systems have a sub-ballistic wave function spreading as shown by a power-law tail of the standard deviation.Comment: 4 pages, 4 figure

Optimal target search on a fast folding polymer chain with volume exchange

We study the search process of a target on a rapidly folding polymer (`DNA') by an ensemble of particles (`proteins'), whose search combines 1D diffusion along the chain, Levy type diffusion mediated by chain looping, and volume exchange. A rich behavior of the search process is obtained with respect to the physical parameters, in particular, for the optimal search.Comment: 4 pages, 3 figures, REVTe

Charged particle dynamics in the presence of non-Gaussian L\'evy electrostatic fluctuations

Full orbit dynamics of charged particles in a $3$-dimensional helical magnetic field in the presence of $\alpha$-stable L\'evy electrostatic fluctuations and linear friction modeling collisional Coulomb drag is studied via Monte Carlo numerical simulations. The L\'evy fluctuations are introduced to model the effect of non-local transport due to fractional diffusion in velocity space resulting from intermittent electrostatic turbulence. The probability distribution functions of energy, particle displacements, and Larmor radii are computed and showed to exhibit a transition from exponential decay, in the case of Gaussian fluctuations, to power law decay in the case of L\'evy fluctuations. The absolute value of the power law decay exponents are linearly proportional to the L\'evy index $\alpha$. The observed anomalous non-Gaussian statistics of the particles' Larmor radii (resulting from outlier transport events) indicate that, when electrostatic turbulent fluctuations exhibit non-Gaussian L\'evy statistics, gyro-averaging and guiding centre approximations might face limitations and full particle orbit effects should be taken into account.Comment: 5 pages, 5 figures. Accepted as a letter in Physics of Plasma

Diamagnetic persistent currents for electrons in ballistic billiards subject to a point flux

We study the persistent current of noninteracting electrons subject to a pointlike magnetic flux in the simply connected chaotic Robnik-Berry quantum billiard, and also in an annular analog thereof. For the simply connected billiard we find a large diamagnetic contribution to the persistent current at small flux, which is independent of the flux and is proportional to the number of electrons (or equivalently the density since we keep the area fixed). The size of this diamagnetic contribution is much larger than mesoscopic fluctuations in the persistent current in the simply connected billiard, and can ultimately be traced to the response of the angular momentum $l=0$ levels (neglected in semiclassical expansions) on the unit disk to a pointlike flux at its center. The same behavior is observed for the annular billiard when the inner radius is much smaller than the outer one, while the usual fluctuating persistent current and Anderson-like localization due to boundary scattering are seen when the annulus tends to a one-dimensional ring. We explore the conditions for the observability of this phenomenon.Comment: 20 pages, 11 figures; added references for section

(In)finite extensions of algebras from their Inonu-Wigner contractions

The way to obtain massive non-relativistic states from the Poincare algebra is twofold. First, following Inonu and Wigner the Poincare algebra has to be contracted to the Galilean one. Second, the Galilean algebra is to be extended to include the central mass operator. We show that the central extension might be properly encoded in the non-relativistic contraction. In fact, any Inonu-Wigner contraction of one algebra to another, corresponds to an infinite tower of abelian extensions of the latter. The proposed method is straightforward and holds for both central and non-central extensions. Apart from the Bargmann (non-zero mass) extension of the Galilean algebra, our list of examples includes the Weyl algebra obtained from an extension of the contracted SO(3) algebra, the Carrollian (ultra-relativistic) contraction of the Poincare algebra, the exotic Newton-Hooke algebra and some others. The paper is dedicated to the memory of Laurent Houart (1967-2011).Comment: 7 pages, revtex style; v2: Minor corrections, references added; v3: Typos correcte