896 research outputs found
Synchronization Properties of Network Motifs
We address the problem of understanding the variable abundance of 3-node and
4-node subgraphs (motifs) in complex networks from a dynamical point of view.
As a criterion in the determination of the functional significance of a n-node
subgraph, we propose an analytic method to measure the stability of the
synchronous state (SSS) the subgraph displays. We show that, for undirected
graphs, the SSS is correlated with the relative abundance, while in directed
graphs the correlation exists only for some specific motifs.Comment: 7 pages, 3 figure
Relay synchronization in multiplex networks
Relay (or remote) synchronization between two not directly connected
oscillators in a network is an important feature allowing distant coordination.
In this work, we report a systematic study of this phenomenon in multiplex
networks, where inter-layer synchronization occurs between distant layers
mediated by a relay layer that acts as a transmitter. We show that this
transmission can be extended to higher order relay configurations, provided
symmetry conditions are preserved. By first order perturbative analysis, we
identify the dynamical and topological dependencies of relay synchronization in
a multiplex. We find that the relay synchronization threshold is considerably
reduced in a multiplex configuration, and that such synchronous state is mostly
supported by the lower degree nodes of the outer layers, while hubs can be
de-multiplexed without affecting overall coherence. Finally, we experimentally
validated the analytical and numerical findings by means of a multiplex of
three layers of electronic circuits.the analytical and numerical findings by
means of a multiplex of three layers of electronic circuits
Searching for sub-stellar companion into the LkCa15 proto-planetary disk
Recent sub-millimetric observations at the Plateau de Bure interferometer
evidenced a cavity at ~ 46 AU in radius into the proto-planetary disk around
the T Tauri star LkCa15 (V1079 Tau), located in the Taurus molecular cloud.
Additional Spitzer observations have corroborated this result possibly
explained by the presence of a massive (>= 5 MJup) planetary mass, a brown
dwarf or a low mass star companion at about 30 AU from the star. We used the
most recent developments of high angular resolution and high contrast imaging
to search directly for the existence of this putative companion, and to bring
new constraints on its physical and orbital properties. The NACO adaptive
optics instrument at VLT was used to observe LkCa15 using a four quadrant phase
mask coronagraph to access small angular separations at relatively high
contrast. A reference star at the same parallactic angle was carefully observed
to optimize the quasi-static speckles subtraction (limiting our sensitivity at
less than 1.0). Although we do not report any positive detection of a faint
companion that would be responsible for the observed gap in LkCa15's disk
(25-30 AU), our detection limits start constraining its probable mass,
semi-major axis and eccentricity. Using evolutionary model predictions, Monte
Carlo simulations exclude the presence of low eccentric companions with masses
M >= 6 M Jup and orbiting at a >= 100 AU with significant level of confidence.
For closer orbits, brown dwarf companions can be rejected with a detection
probability of 90% down to 80 AU (at 80% down to 60 AU). Our detection limits
do not access the star environment close enough to fully exclude the presence
of a brown dwarf or a massive planet within the disk inner activity (i.e at
less than 30 AU). Only, further and higher contrast observations should unveil
the existence of this putative companion inside the LkCa15 disk.Comment: 6 pages, 4 figures, accepted for publication in A&
Synchronization of Chaotic Oscillators due to Common Delay Time Modulation
We have found a synchronization behavior between two identical chaotic
systems^M when their delay times are modulated by a common irregular signal. ^M
This phenomenon is demonstrated both in two identical chaotic maps whose
delay times are driven by a common^M chaotic or random signal and in two
identical chaotic oscillators whose delay times are driven by^M a signal of
another chaotic oscillator. We analyze the phenomenon by using^M the Lyapunov
exponents and discuss it in relation with generalized synchronization.^MComment: 5 pages, 4 figures (to be published in PRE
Generalized Synchronization in Ginzburg-Landau Equations with Local Coupling
The establishment of generalized chaotic synchronization in Ginzburg-Landau
equations unidirectionally coupled at discrete points of space (local coupling)
has been studied. It is shown that generalized syn-chronization regimes are
also established with this type of coupling, but the necessary intensity of
coupling issignificantly higher than that in the case of a spatially
homogeneous couplingComment: 4 pages, 2 figure
Familial Uncombable Hair Syndrome: Ultrastructural Hair Study and Response toBiotin
Abstract: We report a family affected to the fourth generation by uncombable
hair syndrome. This syndrome is characterized by unruly, dry,
blond hair with a tangled appearance. The family pedigree strongly supports
the hypothesis of autosomal dominant inheritance; some members of the
family had, apart from uncombable hair, minor signs of atopy and ectodermal
dysplasia, such as abnormalities of the nails. The diagnosis was confirmed
by means of extensive scanning electron microscopy. A trial with oral biotin
5 mg/daywas started on two young patients with excellent results as regards
the hair appearance, although scanning electron microscopy did not show
structural changes in the hair. After a 2-year-period of follow-up, hair normality
was maintained without biotin, while nail fragility still required biotin
supplementation for control
- …