Origin of coherent structures in a discrete chaotic medium

Using as an example a large lattice of locally interacting Hindmarsh-Rose chaotic neurons, we disclose the origin of ordered structures in a discrete nonequilibrium medium with fast and slow chaotic oscillations. The origin of the ordering mechanism is related to the appearance of a periodic average dynamics in the group of chaotic neurons whose individual slow activity is significantly synchronized by the group mean field. Introducing the concept of a "coarse grain" as a cluster of neuron elements with periodic averaged behavior allows consideration of the dynamics of a medium composed of these clusters. A study of this medium reveals spatially ordered patterns in the periodic and slow dynamics of the coarse grains that are controlled by the average intensity of the fast chaotic pulsation

Cooperative tasks between humans and robots in industrial environments

Collaborative tasks between human operators and robotic manipulators can improve the performance and flexibility of industrial environments. Nevertheless, the safety of humans should always be guaranteed and the behaviour of the robots should be modified when a risk of collision may happen. This paper presents the research that the authors have performed in recent years in order to develop a human-robot interaction system which guarantees human safety by precisely tracking the complete body of the human and by activating safety strategies when the distance between them is too small. This paper not only summarizes the techniques which have been implemented in order to develop this system, but it also shows its application in three real human-robot interaction tasks.The research leading to these results has received funding from the European Communityʹs Seventh Framework Programme (FP7/2007‐2013) under Grant Agreement no. 231640 and the project HANDLE. This research has also been supported by the Spanish Ministry of Education and Science through the research project DPI2011‐22766

Safe cooperation between human operators and visually controlled industrial manipulators

Industrial tasks can be improved substantially by making humans and robots collaborate in the same workspace. The main goal of this chapter is the development of a human-robot interaction system which enables this collaboration and guarantees the safety of the human operator. This system is composed of two subsystems: the human tracking system and the robot control system. The human tracking system deals with the precise real-time localization of the human operator in the industrial environment. It is composed of two systems: an inertial motion capture system and an Ultra-WideBand localization system. The robot control system is based on visual servoing. A safety behaviour which stops the normal path tracking of the robot is performed when the robot and the human are too close. This safety behaviour has been implemented through a multi-threaded software architecture in order to share information between both systems. Thereby, the localization measurements obtained by the human tracking system are processed by the robot control system to compute the minimum human-robot distance and determine if the safety behaviour must be activated.Spanish Ministry of Science and Innovation and the Spanish Ministry of Education through the projects DPI2005-06222 and DPI2008-02647 and the grant AP2005-1458

Enhancing neural-network performance via assortativity

The performance of attractor neural networks has been shown to depend crucially on the heterogeneity of the underlying topology. We take this analysis a step further by examining the effect of degree-degree correlations -- or assortativity -- on neural-network behavior. We make use of a method recently put forward for studying correlated networks and dynamics thereon, both analytically and computationally, which is independent of how the topology may have evolved. We show how the robustness to noise is greatly enhanced in assortative (positively correlated) neural networks, especially if it is the hub neurons that store the information.Comment: 9 pages, 7 figure

APOBEC3G mRNA expression in exposed seronegative and early stage HIV infected individuals decreases with removal of exposure and with disease progression

<p>Abstract</p> <p>Background</p> <p>APOBEC3G is an antiretroviral factor that acts by inducing G to A mutations. In this study, we examined the expression of APOBEC3G in uninfected HIV-1 exposed individuals at the time of their partner's diagnosis and one year later. We then compared this expression with that of infected individuals at different disease stages. APOBEC3G mRNA was measured in PBMCs from three groups: healthy controls with no known risk factor to HIV infection (n = 26), exposed uninfected individuals who had unprotected sex with their HIV+ partners for at least 3 months (n = 37), and HIV infected patients at various disease stages (n = 45), including 8 patients with low HIV viral loads < 10,000 copies/mL (LVL) for at least 3 years. Additionally, we obtained sequences from the env, gag, pol, nef, vif and the LTR of the patients' virus.</p> <p>Results</p> <p>Exposed uninfected individuals expressed higher APOBEC3G than healthy controls (3.86 vs. 1.69 relative expression units), and their expression significantly decreased after a year from the HIV diagnosis and subsequent treatment of their partners. Infected individuals showed a positive correlation (Rho = 0.57, p = 0.00006) of APOBEC3G expression with CD4+ T cell count, and a negative correlation with HIV viremia (Rho = -0.54, p = 0.00004). The percentage of G to A mutations had a positive correlation (Rho = 0.43, p = 0.0226) with APOBEC3G expression, and it was higher in LVL individuals than in the other patients (IQR 8.27 to 9.64 vs. 7.06 to 8.1, p = 0.0084). Out of 8 LVLs, 3 had hypermutations, and 4 had premature stop codons only in viral <it>vif</it>.</p> <p>Conclusion</p> <p>The results suggest that exposure to HIV may trigger APOBEC3G expression in PBMCs, in the absence of infection. Additionally, cessation of exposure or advanced disease is associated with decreased APOBEC3G expression.</p

Confocal microscopy: a valid approach to evaluate the three-dimensional characteristics of root-end cavities

Objective: To analyze, using confocal microscope, the three-dimensional characteristics of the root-end cavity preparations completed in root apices of extracted teeth determining their area, perimeter, circularity and cavo-surface angle. Study design: Thirty-two single-rooted extracted teeth underwent endodontic treatment and apical resection. Root-end cavities were prepared according to 4 protocols, as follows: Group1, stainless steel ultrasonic tips (SST) at 33 KHz power; Group 2, SST at 30 KHz power; Group 3, diamond-coated ultrasonic tips (DCT) at 30 KHz power; and Group 4, DCT at 33 KHz power. Finally, root-end cavity was evaluated using a confocal microscope, recording its area, perimeter, circularity and cavo-surface angle. Results: The largest cavity perimeter was found in the Group 2 (4.8 ± 1.6 mm) (p > 0.05). Root-end cavities performed using SST showed larger areas than those performed with DCT (p = 0.03). The power of vibration or the tip type did not show correlation with the perimeter, circularity and cavo-surface angle of the root-end cavity (p > 0.05). Conclusions: Confocal microscopy is a useful approach to study the three-dimensional characteristics of the root- end cavit