2,520 research outputs found
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
Amniotic fluid is important for the maintenance of maternal responsiveness and the establishment of maternal selectivity in sheep
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 -dimensional helical
magnetic field in the presence of -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 . 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 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
B\"acklund transformation for non-relativistic Chern-Simons vortices
A B\"acklund transformation yielding the static non-relativistic Chern-Simons
vortices of Jackiw and Pi is presented.Comment: 7 pages plain Te
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