News
Finding attractors of continuous-time systems by parameter switching
September 28, 2011
There are many different interactions in nature and systems could evolve according to more than one dynamics for short periods of time. Therefore, it is reasonable to think that the evolution of some natural processes could be explained by the alternation of different dynamics for relatively short periods of time. RIST's Marius F. Danca has found that if the control parameter p, of a continuous-time nonlinear system belonging to a large class of systems, is switched within a set of chosen values in a deterministic or even random manner, while the underlying model is numerically integrated, the obtained attractor is a numerical approximation of one of the existing attractors of the considered system. The numerically obtained trajectory is extremely similar to the trajectory obtained for p replaced with the averaged value of the switched parameters. The algorithm could be considered as an excellent alternative for control and anticontrol of chaos for continuous-time systems. Moreover, this kind of attractor synthesis resembles Parrondo's philosophy in a winning game: ''losing + losing = winning''. Thus, switching the control parameter within a set of values which generate e.g. chaotic attractors, one can obtain a stable periodic motion which, in Parondian terms this means: "chaos+chaos=order" (a kind of control like algorithm). Also one can have anticontrol: "order+order=chaos" or other possible combinations. The work leading to these results has been performed in the last four years, and has been documented through more than ten papers in nonlinear science journals. A review is presented in: Marius-F. Danca, M. Romera, G. Pastor, and F. Montoya, Finding Attractors of Continuous-Time Systems by Parameter Switching, Nonlinear Dynamics (2011), doi:10.1007/s11071-011-0172-6.
1st International Conference on Coping with Complexity
September 15, 2011
RIST co-organizes this conference which welcomes scientists and researchers over the vast field of complexity to exchange ideas in Cluj-Napoca, on October 19-20, 2011. Conference website.
Graduate student contest: Best PhD thesis project of the year in computational game theory
August 3, 2011
RIST will award a 1000 euros prize for the best PhD thesis project of the year in computational game theory. Applicants should submit a summary of their thesis by October 15, 2011, and the full-length thesis by November 15, 2011. The awards are sponsored by the John Templeton Foundation. More information is available at http://gametheory.rist.ro/phdcontest/.
The institute has received a grant from John Templeton Foundation
March 24, 2011
The USA foundation awarded a grant to the group led by prof. Dumitru Dumitrescu for a project entitled "Towards a conceptual integration of artificial intelligence, game theory and decision theory".
The brain's timescale correlates to the timescale of visual stimuli
February 8, 2011
An important problem in brain research deals with understanding how visual stimuli are processed by the brain to create our every-day visual experience. It is still unknown how multiple neurons work together in the visual system to accomplish the encoding of visual information that is sampled from the environment dynamically and effortlessly by our eyes. Our researchers have found a way to group the recorded activity of multiple neurons and to measure how quickly they react together to the ever-changing visual world. They have found that the internal timescale of the brain, i.e., the time window needed by neurons to encode a given aspect of the visual stimulus, is tightly correlated to the external timescale of the visual stimulus, i.e., the speed with which the visual image on the retina changes. This means that the brain is well adapted to the environment and the visual system may have been important for survival. For example, when quick responses are needed as a reaction to the attack of a predator, the rapid change in the field of vision can determine the brain to quickly respond with multiple neurons that convey information rapidly, on timescales of a few milliseconds. When the visual image evolves slowly, neurons can afford to be “lazy” and they encode the visual stimulus with slower activity patterns. These findings were published in PLoS ONE (Jurjuţ O.F., Nikolic D., Singer W., Yu S., Havenith M.N., Mureşan R.C., Timescales of Multineuronal Activity Patterns Reflect Temporal Structure of Visual Stimuli. PLoS ONE 6(2): e16758. doi:10.1371/journal.pone.0016758, 2011), a journal of the Public Library of Science from USA.
The Coneural – Max Planck Partner Group has been renewed
December 13, 2010
The partnership between the institute's Center for Cognitive and Neural Studies (Coneural) and the prestigious Max Plank Institute for Brain Research in Frankfurt, Germany, has been extended for another 2 years (2011-2013), after an evaluation of the work performed in the previous 3 years.
The Partner Group establishes a direct link between the lab of Dr. Raul Mureşan from Coneural and the Neurophysiology department led by Prof. Wolf Singer in the Max Planck Institute for Brain Research in Frankfurt am Main, Germany. This collaboration is very important because it connects our labs with top-level international scientists and offers a wide opening towards high-profile science in Europe. The Partner Group at Coneural is the only Max Planck partner group in Romania and among the few in Eastern Europe, being a recognition of the quality of the research performed at Coneural.
At the mid-term evaluation of the Coneural – Max Planck Partner Group, Peter
Gruss, the President of the Max Planck Society (Germany), stated in the renewal
letter: “It is with great pleasure that I take this opportunity to inform you
of the very successful outcome of the mid-term review of your Partner Group.
The review report points out the impressive scientific output of the Partner
Group during the first three years since its inception. I congratulate you
upon this success”.
Visualizing how the brain encodes information
October 15, 2009
The brain is one of the most complex systems known to man. It consists of thousands of billions of neurons that constantly interact by emitting electrical impulses called spikes. When trying to understand how these neurons encode information from the sensors (e.g., visual, auditory, tactile sense), one records their spikes and attempts to discover patterns that are associated to given stimuli. Unfortunately, it is very difficult for us to comprehend how multiple neurons fire spikes together to encode information because there is a vast amount of possible patterns. Scientists at the Center for Cognitive and Neural Studies (Coneural), that is part of RIST, have developed in collaboration with the Max Planck Institute for Brain Research in Frankfurt a special visualization technique to solve this difficult problem by representing the identity of firing patterns of multiple neurons with color sequences. Their method was published in Journal of Neurophysiology (Jurjuţ O.F., Nikolic D., Pipa G., Singer W., Metzler D., Mureşan R.C., A color-based visualization technique for multi-electrode spike trains. Journal of Neurophysiology 102: 3766-3778, 2009), a journal of the American Physiological Society. Color sequences prove versatile and efficient to discover firing patterns corresponding to different visual stimuli, across different timescales, and are useful to detect changes in the state of the brain, the so-called cortical-state changes.
