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