Self-organized evolution in socio-economic environments

We propose a general scenario to analyze social and economic changes in modern environments. We illustrate the ideas with a model that incorporating the main trends is simple enough to extract analytical results and, at the same time, sufficiently complex to display a rich dynamic behavior. Our study shows that there exists a macroscopic observable that is maximized in a regime where the system is critical, in the sense that the distribution of events follow power-laws. Computer simulations show that, in addition, the system always self-organizes to achieve the optimal performance in the stationary state.Comment: 4 pages RevTeX; needs epsf.sty and rotate.sty; submitted to Phys Rev Let

Control of synchronization regimes in networks of mobile interacting agents

We investigate synchronization in a population of mobile pulse-coupled agents with a view towards implementations in swarm robotics systems and mobile sensor networks. Previous theoretical approaches dealt with range and nearest neighbor interactions. In the latter case, a synchronization-hindering regime for intermediate agent mobility was found. In the present work, we investigate the robustness of this intermediate regime under practical scenarios. We show that synchronization in the intermediate regime can be predicted by means of a suitable metric of the phase response curve. Furthermore, we study more realistic K-nearest neighbors and cone of vision interactions, showing that it is possible to control the extent of the synchronization-hindering region by appropriately tuning the size of the neighborhood. To assess the effect of noise, we analyze the propagation of perturbations over the network and draw an analogy between the response in the hindering regime and stable chaos. Our findings reveal the conditions for the control of clock or activity synchronization of agents with intermediate mobility. In addition, the emergence of the intermediate regime is validated experimentally using a swarm of physical robots interacting with cone of vision interactions

On the ongoing multiple blowout in NGC 604

Several facts regarding the structure of NGC 604 are examined here. The three main cavities, produced by the mechanical energy from massive stars which in NGC 604 are spread over a volume of 10$^6$ pc$^3$, are shown here to be undergoing blowout into the halo of M33. High resolution long slit spectroscopy is used to track the impact from massive stars while HST archive data is used to display the asymmetry of the nebula. NGC 604 is found to be a collection of photoionized filaments and sections of shells in direct contact with the thermalized matter ejected by massive stars. The multiple blowout events presently drain the energy injected by massive stars and thus the densest photoionized gas is found almost at rest and is expected to suffer a slow evolution.Comment: 15 pages (11 text), 4 figures. To be published in Ap

High spatial resolution and high contrast optical speckle imaging with FASTCAM at the ORM

In this paper, we present an original observational approach, which combines, for the first time, traditional speckle imaging with image post-processing to obtain in the optical domain diffraction-limited images with high contrast (1e-5) within 0.5 to 2 arcseconds around a bright star. The post-processing step is based on wavelet filtering an has analogy with edge enhancement and high-pass filtering. Our I-band on-sky results with the 2.5-m Nordic Telescope (NOT) and the lucky imaging instrument FASTCAM show that we are able to detect L-type brown dwarf companions around a solar-type star with a contrast DI~12 at 2" and with no use of any coronographic capability, which greatly simplifies the instrumental and hardware approach. This object has been detected from the ground in J and H bands so far only with AO-assisted 8-10 m class telescopes (Gemini, Keck), although more recently detected with small-class telescopes in the K band. Discussing the advantage and disadvantage of the optical regime for the detection of faint intrinsic fluxes close to bright stars, we develop some perspectives for other fields, including the study of dense cores in globular clusters. To the best of our knowledge this is the first time that high contrast considerations are included in optical speckle imaging approach.Comment: Proceedings of SPIE conference - Ground-based and Airborne Instrumentation for Astronomy III (Conference 7735), San Diego 201

Modular Hydraulic Propulsion: A Robot that Moves by Routing Fluid Through Itself

This paper introduces the concept of Modular Hydraulic Propulsion, in which a modular robot that operates in a fluid environment moves by routing the fluid through itself. The robot’s modules represent sections of a hydraulics network. Each module can move fluid between any of its faces. The modules (network sections) can be rearranged into arbitrary topologies. We propose a decentralized motion controller, which does not require modules to communicate, compute, nor store information during run-time. We use 3-D simulations to compare the performance of this controller to that of a centralized controller with full knowledge of the task. We also detail the design and fabrication of six 2-D prototype modules, which float in a water tank. Results of systematic experiments show that the decentralized controller, despite its simplicity, reliably steers modular robots towards a light source. Modular Hydraulic Propulsion could offer new solutions to problems requiring reconfigurable systems to move precisely in 3-D, such as inspection of pipes, vascular systems or other confined spaces

Decontamination of Diesel particles from air by using the Counterfog (R) system

The existence of particles with diameter under 10m in air is strongly correlated with respiratory diseases. These particles are profusely produced by heating systems, traffic, and Diesel engines creating a serious problem to modern cities. Natural mechanisms removing particles from the atmosphere are too slow to deal with the huge amount of particles daily released by human activity. The objective of this work is to measure the effectiveness of a new technology called Counterfog (R) to eliminate airborne particles. The results show that Counterfog (R) is able to wash out PM10, PM5, and PM2.5 Diesel-generated airborne particles quite efficiently.This work has been funded by the FP7-SEC-2012-1 program of the EU Commission under grant number 312804