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Partner: UNT College of Arts and Sciences
Department: Physics
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### Control of chaos in a CO2 laser

Date: September 5, 1994
Creator: Pérez, José M.; Steinshnider, J.; Stallcup, Richard E. & Aviles, A. F.
Description: This article discusses the control of chaos in a CO2 laser. Abstract: We report the experimental control of chaos in an optically modulated CO2 laser. The CO2 laser was driven into chaos by injecting a feedback beam modulated by an electro-optical modulator. Control of chaos was achieved using a modified proportional feedback technique in which the control pulses were delayed by approximately one relaxation period. Using this technique, it was possible to control unstable periodic orbits up to period 6.
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### Controllable enhanced dragging of light in ultradispersive media

Date: July 5, 2012
Creator: Rostovtsev, Yuri V. & Davuluri, Sankar
Description: This article discusses controllable enhanced dragging of light in ultradispersive media. Abstract: We have theoretically demonstrated an enhanced Fizeau effect due to dragging the light that occurs when the group velocity of light is ultraslow. The proposed experiment can be done in a cell of atomic Rb vapor under conditions such that the group velocity of light is of the order of a few hundred meters per second. We show theoretically that higher-order dispersion can influence the Fizeau effect and can be observed experimentally. It has been shown that the change of phase is sensitive to the motion of the cell with the speed of the order of 10⁻³ cm/s and for possible displacements as small as 10 Å. The enhanced dragging effect can be applied for position control, detection of slow mechanical motion, and efficient modulators of light.
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### Controlled terahertz frequency response and transparency of Josephson chains and superconducting multilayers

Date: January 26, 2007
Creator: Yampol'skii, V. A.; Savel'ev, Sergey; Usatenko, O. V.; Mel'nik, S. S.; Kusmartsev, F. V.; Krokhin, Arkadii A. et al.
Description: This article discusses controlled terahertz frequency response and transparency of Josephson chains and superconducting multilayers. Abstract: A fundamental property of wave propagation is Anderson localization, which affects the transfer of information, energy, mass, and charge in disordered media. This localization can manifest itself via, e.g., the metal-insulator transition. We exactly map the behavior of a quantum particle moving in a potential with correlated disorder to teh sub-terahertz wave propagation in either Josephson chaines or superconducting multilayers. When the Josephson junction parameters vary randomly, the sub-THz electromagnetic waves cannot propagate through these Josephson structures due to localization. For parameter variations with long-range correlations, we predict sharp transitions from transparent to reflective frequency regions for Josephson plasma waves. With appropriate choices of the correlation function, frequency windows with targeted or designed transparencies for THz or sub-THz electromagnetic waves could be achieved. This could be useful for tailoring the electromagnetic wave spectrum of Josephson arrays within the THz frequency range, which is important for applications in physics, astronomy, chemistry, biology, and medicine.
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### Cooperation in neural systems: Bridging complexity and periodicity

Date: November 29, 2012
Creator: Zare, Marzieh & Grigolini, Paolo
Description: This article discusses cooperation in neural systems. Abstract: Inverse power law distributions are generally interpreted as a manifestation of complexity, and waiting time distributions with power index μ < 2 reflect the occurrence of ergodicity-breaking renewal events. In this paper we show how to combine these properties with the apparently foreign clocklike nature of biological processes. We use a two-dimensional regular network of leaky integrate-and-fire neurons, each of which is linked to its four nearest neighbors, to show that both complexity and periodicity are generated by locality breakdown: Links of increasing strength have the effect of turning local interactions into long-range interactions, thereby generating time complexity followed by time periodicity. Increasing the density of neuron firings reduces the influence of periodicity, thus creating a cooperation-induced renewal condition that is distinctly non-Poissonian.
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### Cooperation-induced topological complexity: a promising road to fault tolerance and Hebbian learning

Date: March 16, 2012
Creator: Turalska, Malgorzata; Geneston, Elvis L.; West, Bruce J.; Allegrini, Paolo & Grigolini, Paolo
Description: This article discusses cooperation-induced topological complexity and the emergence of intelligence.
Contributing Partner: UNT College of Arts and Sciences

### Correlation Function and Generalized Master Equation of Arbitrary Age

Date: June 10, 2005
Creator: Allegrini, Paolo; Aquino, Gerardo; Grigolini, Paolo; Palatella, Luigi; Rosa, Angelo & West, Bruce J.
Description: This article discusses correlation function and generalized master equation of arbitrary age using non-Poisson, Markovian, and Liouville methods.
Contributing Partner: UNT College of Arts and Sciences

### Criticality and Transmission of Information in a Swarm of Cooperative Units

Date: August 12, 2011
Creator: Vanni, Fabio; Lukovic, Mirko & Grigolini, Paolo
Description: This article discusses criticality and transmission of information in a swarm of cooperative units. Abstract: We show that the intelligence of a swarm of cooperative units (birds) emerges at criticality, as an effect of the joint action of frequent organizational collapses and of spatial correlation as extended as the flock size. The organizational collapses make the birds become independent of one another, thereby allowing the flock to follow the direction of the lookout birds. Long-range correlation violates the principle of locality, making the lookout birds transmit information on either danger or resources with a time delay determined by the time distance between two consecutive collapses.
Contributing Partner: UNT College of Arts and Sciences

### Decoherence, wave function collapses and non-ordinary statistical mechanics

Date: August 2003
Creator: Bologna, Mauro; Grigolini, Paolo; Pala, Marco G. & Palatella, Luigi
Description: Article discussing decoherence, wave function collapses, and non-ordinary statistical mechanics. Abstract: We consider a toy model of pointer interacting with a 1/2-spin system, whose $\sigma_{x}$ variable is \emph{measured} by the environment, according to the prescription of decoherence theory. If the environment measuring the variable $\sigma_{x}$ yields ordinary statistical mechanics, the pointer sensitive to the 1/2-spin system undergoes the same, exponential, relaxation regardless of whether real collapses or an entanglement with the environment, mimicking the effect of real collapses, occur. In the case of non-ordinary statistical mechanics the occurrence of real collapses make the pointer still relax exponentially in time, while the equivalent picture in terms of reduced density matrix generates an inverse power law relaxation.
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### Detection of invisible and crucial events: from seismic fluctuations to the war against terrorism

Date: October 28, 2003
Creator: Allegrini, Paolo; Fronzoni, Leone; Grigolini, Paolo; Latora, Vito; Mega, Mirko S.; Palatella, Luigi et al.
Description: Paper discussing the detection of invisible and crucial events. Abstract: We argue that the recent discovery of the non-Poissonian statistics of the seismic main-shocks is a special case of a more general approach to the detection of the distribution of the time increments between one crucial but invisible event and the next. We make the conjecture that the proposed approach can be applied to the analysis of terrorist network with significant benefits for the Intelligence Community.
Contributing Partner: UNT College of Arts and Sciences

### Diffusion Entropy and Waiting Time Statistics of Hard-X-Ray Solar Flares

Date: March 25, 2002
Creator: Grigolini, Paolo; Leddon, Deborah & Scafetta, Nicola
Description: This article discusses diffusion entropy and waiting time statistics of hard-x-ray solar flares.
Contributing Partner: UNT College of Arts and Sciences