2,051 research outputs found
Time Segmentation Approach Allowing QoS and Energy Saving for Wireless Sensor Networks
Wireless sensor networks are conceived to monitor a certain application or
physical phenomena and are supposed to function for several years without any
human intervention for maintenance. Thus, the main issue in sensor networks is
often to extend the lifetime of the network by reducing energy consumption. On
the other hand, some applications have high priority traffic that needs to be
transferred within a bounded end-to-end delay while maintaining an energy
efficient behavior. We propose MaCARI, a time segmentation protocol that saves
energy, improves the overall performance of the network and enables quality of
service in terms of guaranteed access to the medium and end-to-end delays. This
time segmentation is achieved by synchronizing the activity of nodes using a
tree-based beacon propagation and allocating activity periods for each cluster
of nodes. The tree-based topology is inspired from the cluster-tree proposed by
the ZigBee standard. The efficiency of our protocol is proven analytically, by
simulation and through real testbed measurements
Lessons Learned from Designing the Montium - a Coarse-Grained Reconfigurable Processing Tile
In this paper we describe in retrospective the main results of a four year project, called Chameleon. As part of this project we developed a coarse-grained reconfigurable core for DSP algorithms in wirelessdevices denoted MONTIUM. After presenting the main achievements within this project we present the lessons learned from this project
The largest reservoir of mitochondrial introns is a relic of an ancestral split gene
In eukaryotes, introns are located in nuclear and organelle genes from several kingdoms (ref. 1-4). Large introns (0.1 to 5 kbp) are frequent in mitochondrial genomes of plant and fungi (ref. 1,5) but scarce in Metazoa, despite these organisms are grouped with fungi among Opisthokonts. Introns are classified in two main groups (I and II) according to their RNA secondary structure involved in the intron self-splicing mechanism (ref. 5,6). Most of the group I introns carry a "Homing Endonuclease Gene" (ref. 7-9) encoding a DNA endonuclease acting in the transfer and site specific integration "homing") and allowing the intron spreading and gain after lateral transfer even between species from different kingdoms (ref. 10,11). Opposite to this "late intron" paradigm, the "early intron" theory indicates that introns, which would have been abundant in the ancestral genes, would mainly evolve by loss (ref. 12,13).

Here we report the sequence of the cox1 gene of the button mushroom _Agaricus bisporus_, the most worldwide cultivated mushroom. This gene is both the longest mitochondrial gene (29,902 nt) and the largest Group I intron reservoir reported to date. An analysis of the group I introns available in _cox1_ genes shows that they are ancestral mobile genetic elements, whose frequent events of loss (according to the "late theory") and gain by lateral transfer ("early theory") must be combined to explain their wide and patchy distribution extending on several kingdoms. This allows the conciliation of the "early" and "late intron" paradigms, which are still matters of much debate (ref. 14,15). The overview of the intron distribution indicates that they evolve towards elimination. In such a landscape of eroded and lost intron sequences, the _A. bisporus_ largest intron reservoir, by its singular dynamics of intron keeping and catching, constitutes the most fitted relic of an early split gene
Mapping Applications to an FPFA Tile
This paper introduces a transformational design method which can be used to map code written in a high level source language, like C, to a coarse grain reconfigurable architecture. The source code is first translated into a control data flow graph (CDFG), which is minimized using a set of behaviour preserving transformations, such as dependency analysis, common subexpression elimination, etc. After applying graph clustering, scheduling and allocation transformations on this minimized graph, it can be mapped onto the target architecture
Exciton photon strong-coupling regime for a single quantum dot in a microcavity
We report on the observation of the strong coupling regime between a single
GaAs quantum dot and a microdisk optical mode. Photoluminescence is performed
at various temperatures to tune the quantum dot exciton with respect to the
optical mode. At resonance, we observe an anticrossing, signature of the strong
coupling regime with a well resolved doublet. The Vacuum Rabi splitting amounts
to 400 μeV and is twice as large as the individual linewidths.Comment: submitted on November 7th 200
Giant Optical Non-linearity induced by a Single Two-Level System interacting with a Cavity in the Purcell Regime
A two-level system that is coupled to a high-finesse cavity in the Purcell
regime exhibits a giant optical non-linearity due to the saturation of the
two-level system at very low intensities, of the order of one photon per
lifetime. We perform a detailed analysis of this effect, taking into account
the most important practical imperfections. Our conclusion is that an
experimental demonstration of the giant non-linearity should be feasible using
semiconductor micropillar cavities containing a single quantum dot in resonance
with the cavity mode.Comment: 40 pages, 16 figures, accepted in Phys. Rev.
Dynamical ultrafast all-optical switching of planar GaAs/AlAs photonic microcavities
The authors study the ultrafast switching-on and -off of planar GaAs/AlAs
microcavities. Up to 0.8% refractive index changes are achieved by optically
exciting free carriers at 1720 nm and a pulse energy of 1.8 micro Joules. The
cavity resonance is dynamically tracked by measuring reflectivity versus time
delay with tunable laser pulses, and is found to shift by as much as 3.3
linewidths within a few picoseconds. The switching-off occurs with a decay time
of around 50 ps. The authors derive the dynamic behavior of the carrier density
and of the complex refractive index. They propose that the inferred 10 GHz
switching rate may be tenfold improved by optimized sample growth.Comment: 1.) Replaced figure 1 (linear reflectivity) with a more recent and
improved measurement 2.) Included a Figure of Merit for switching and
compared to other recent contributions 3.) Explained more precisely the
effect of embedded Quantum Dots (namely no effect on measurement) 4.) Changed
wording in a few place
LA DYADE MANAGER – SUPERIEUR : UNE DIMENSION OUBLIEE DU CONTRÔLE DE GESTION
Les termes paradoxe, tension, contradiction ou encore dilemme reviennent régulièrement dans la littérature en management et en contrôle. La forte présence de ces thèmes marque leur importance pour appréhender la complexité de ces activités. Cependant, ces concepts sont souvent utilisés sinon de façon inappropriée, tout du moins avec peu de clarté dans leur définition. Par ailleurs, si les études en management traitent souvent des systèmes et des acteurs, elles s'intéressent rarement à la dyade manager-supérieur. Cette dernière est pourtant l'un des noeuds les plus importants où se forment et se gèrent oppositions, contradictions, paradoxes etc. Ceci nous amène à proposer certaines pistes afin de clarifier le concept de dualité et à étudier dans deux entreprises un exemple de contradiction dans les relations entre managers et supérieurs, celui de l'autonomie et de la direction par le sens. Nous mettons ainsi en évidence le besoin d'une compréhension plus fine des dynamiques interpersonnelles, et non seulement des systèmes de contrôle et des styles de management, dans les problématiques de contrôle.Contradiction; Dyades manager–supérieur hiérarchique; Coadaptation; Management; Contrôle de gestion
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