7,047 research outputs found
Reconstructing directed and weighted topologies of phase-locked oscillator networks
The formalism of complex networks is extensively employed to describe the
dynamics of interacting agents in several applications. The features of the
connections among the nodes in a network are not always provided beforehand,
hence the problem of appropriately inferring them often arises. Here, we
present a method to reconstruct directed and weighted topologies (REDRAW) of
networks of heterogeneous phase-locked nonlinear oscillators. We ultimately
plan on using REDRAW to infer the interaction structure in human ensembles
engaged in coordination tasks, and give insights into the overall behavior
Effects of variations of load distribution on network performance
This paper is concerned with the characterization of the relationship between
topology and traffic dynamics. We use a model of network generation that allows
the transition from random to scale free networks. Specifically, we consider
three different topological types of network: random, scale-free with \gamma =
3, scale-free with \gamma = 2. By using a novel LRD traffic generator, we
observe best performance, in terms of transmission rates and delivered packets,
in the case of random networks. We show that, even if scale-free networks are
characterized by shorter characteristic-path- length (the lower the exponent,
the lower the path-length), they show worst performances in terms of
communication. We conjecture this could be explained in terms of changes in the
load distribution, defined here as the number of shortest paths going through a
given vertex. In fact, that distribu- tion is characterized by (i) a decreasing
mean (ii) an increas- ing standard deviation, as the networks becomes
scale-free (especially scale-free networks with low exponents). The use of a
degree-independent server also discriminates against a scale-free structure. As
a result, since the model is un- controlled, most packets will go through the
same vertices, favoring the onset of congestion.Comment: 4 pages, 4 figures, included in conference proceedings ISCAS 2005,
Kobe Japa
Heterogeneity induces emergent functional networks for synchronization
We study the evolution of heterogeneous networks of oscillators subject to a
state-dependent interconnection rule. We find that heterogeneity in the node
dynamics is key in organizing the architecture of the functional emerging
networks. We demonstrate that increasing heterogeneity among the nodes in
state-dependent networks of phase oscillators causes a differentiation in the
activation probabilities of the links. This, in turn, yields the formation of
hubs associated to nodes with larger distances from the average frequency of
the ensemble. Our generic local evolutionary strategy can be used to solve a
wide range of synchronization and control problems
Communication models with distributed transmission rates and buffer sizes
The paper is concerned with the interplay between network structure and
traffic dynamics in a communications network, from the viewpoint of end-to-end
performance of packet transfer. We use a model of network generation that
allows the transition from random to scale-free networks. Specifically, we are
able to consider three different topologycal types of networks: (a) random; (b)
scale-free with \gamma=3; (c) scale free with \gamma=2. We also use an LRD
traffic generator in order to reproduce the fractal behavior that is observed
in real world data communication. The issue is addressed of how the traffic
behavior on the network is influenced by the variable factors of the
transmission rates and queue length restrictions at the network vertices. We
show that these factors can induce drastic changes in the throughput and
delivery time of network performance and are able to counter-balance some
undesirable effects due to the topology.Comment: 4 pages, 5 figures, IEEE Symposium on Circuits and Systems, Island of
Kos, Greece, 200
Management of cluster headache in the emergency department
Although cluster headache (CH) is considered one of the most distinctive and painful primary headache disorders in clinical practice because of the brevity of each attack, its management is not always ergonomic or possible in the Emergency Department. In case of a previously competent diagnosis, the Emergency Department's team should send the patient to a headache centre where specialists in the management of CH can handle the pathology in the best way. In our headache centre we treat patients with CH attacks with a hyperbaric chamber, confirming the effectiveness of hyperbaric oxygen in CH patients. © Springer-Verlag Italia 2005
Can User Experience affect buying intention? A case study on the evaluation of exercise equipment.
Treadmills are increasingly loaded with digital technology for assisting the
individual during the workout sessions by providing information for tracking
relevant training parameters. Also, this technology makes exercise more pleasurable
by keeping the user connected to her/his digital ecosystem (e.g. social networking,
access to multimedia content). Although there is an increasing interest in digital
technologies to be used in fitness, a cursory literature search shows that the interest
towards gym equipment is currently limited to the hardware component, thus
making biomechanics the focus of the investigation. Other types of contributions are
very rare and mostly focused on the design of tools for special populations (e.g.
elderly, disabilities) as well as for promoting physical activity monitoring (eHealth).
In the present study information on the perceived usability of the interface was
collected and analysed along with opinions about buying intention and estimated
pricing. Twenty-three individuals were tested after using a treadmill (Technogym
S.p.A.) equipped with an interface allowing equipment and training management,
activity monitoring and user entertainment. Results indicated a significant influence
of perceived usability of the interface on the intention of buying the whole system,
thus suggesting the existence of a ROI of Human-Centred Design strategies
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