Critical phenomena at a firstorder phase transition in a lattice of glow lamps: Experimental findings and analogy to neural activity
Abstract
Networks of nonlinear electronic oscillators have shown potential as physical models of neural dynamics. However, two properties of brain activity, namely, criticality and metastability, remain underinvestigated with this approach. Here, we present a simple circuit that exhibits both phenomena. The apparatus consists of a twodimensional square lattice of capacitively coupled glow (neon) lamps. The dynamics of lamp breakdown (flash) events are controlled by a DC voltage globally connected to all nodes via fixed resistors. Depending on this parameter, two phases having distinct event rate and degree of spatiotemporal order are observed. The transition between them is hysteretic, thus a firstorder one, and it is possible to enter a metastability region, wherein, approaching a spinodal point, critical phenomena emerge. Avalanches of events occur according to powerlaw distributions having exponents ≈3/2 for size and ≈2 for duration, and fractal structure is evident as powerlaw scaling of the Fano factor. These critical exponents overlap observations in biological neural networks; hence, this circuit may have value as building block to realize corresponding physical models.
 Authors:
 Center for Mind/Brain Sciences, University of Trento, 38123 Mattarello (Italy)
 (Poland)
 Department of Physics “E. Pancini,” University of Naples “Federico II,” Napoli (Italy)
 (Italy)
 INFN Gr. Coll. Salerno, Unità di Napoli, Napoli (Italy)
 Publication Date:
 OSTI Identifier:
 22596641
 Resource Type:
 Journal Article
 Resource Relation:
 Journal Name: Chaos (Woodbury, N. Y.); Journal Volume: 26; Journal Issue: 7; Other Information: (c) 2016 Author(s); Country of input: International Atomic Energy Agency (IAEA)
 Country of Publication:
 United States
 Language:
 English
 Subject:
 71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; 97 MATHEMATICAL METHODS AND COMPUTING; FANO FACTOR; LIGHT BULBS; NONLINEAR PROBLEMS; OSCILLATORS; RESISTORS; TETRAGONAL LATTICES
Citation Formats
Minati, Ludovico, Email: lminati@ieee.org, Email: ludovico.minati@unitn.it, Email: ludovico.minati@ifj.edu, Complex Systems Theory Department, Institute of Nuclear Physics, Polish Academy of Sciences, Kraków, Candia, Antonio de, INFN Gr. Coll. Salerno, Unità di Napoli, Napoli, Scarpetta, Silvia, and Department of Physics “E.R.Caianiello,” University of Salerno, Napoli. Critical phenomena at a firstorder phase transition in a lattice of glow lamps: Experimental findings and analogy to neural activity. United States: N. p., 2016.
Web. doi:10.1063/1.4954879.
Minati, Ludovico, Email: lminati@ieee.org, Email: ludovico.minati@unitn.it, Email: ludovico.minati@ifj.edu, Complex Systems Theory Department, Institute of Nuclear Physics, Polish Academy of Sciences, Kraków, Candia, Antonio de, INFN Gr. Coll. Salerno, Unità di Napoli, Napoli, Scarpetta, Silvia, & Department of Physics “E.R.Caianiello,” University of Salerno, Napoli. Critical phenomena at a firstorder phase transition in a lattice of glow lamps: Experimental findings and analogy to neural activity. United States. doi:10.1063/1.4954879.
Minati, Ludovico, Email: lminati@ieee.org, Email: ludovico.minati@unitn.it, Email: ludovico.minati@ifj.edu, Complex Systems Theory Department, Institute of Nuclear Physics, Polish Academy of Sciences, Kraków, Candia, Antonio de, INFN Gr. Coll. Salerno, Unità di Napoli, Napoli, Scarpetta, Silvia, and Department of Physics “E.R.Caianiello,” University of Salerno, Napoli. Fri .
"Critical phenomena at a firstorder phase transition in a lattice of glow lamps: Experimental findings and analogy to neural activity". United States.
doi:10.1063/1.4954879.
@article{osti_22596641,
title = {Critical phenomena at a firstorder phase transition in a lattice of glow lamps: Experimental findings and analogy to neural activity},
author = {Minati, Ludovico, Email: lminati@ieee.org, Email: ludovico.minati@unitn.it, Email: ludovico.minati@ifj.edu and Complex Systems Theory Department, Institute of Nuclear Physics, Polish Academy of Sciences, Kraków and Candia, Antonio de and INFN Gr. Coll. Salerno, Unità di Napoli, Napoli and Scarpetta, Silvia and Department of Physics “E.R.Caianiello,” University of Salerno, Napoli},
abstractNote = {Networks of nonlinear electronic oscillators have shown potential as physical models of neural dynamics. However, two properties of brain activity, namely, criticality and metastability, remain underinvestigated with this approach. Here, we present a simple circuit that exhibits both phenomena. The apparatus consists of a twodimensional square lattice of capacitively coupled glow (neon) lamps. The dynamics of lamp breakdown (flash) events are controlled by a DC voltage globally connected to all nodes via fixed resistors. Depending on this parameter, two phases having distinct event rate and degree of spatiotemporal order are observed. The transition between them is hysteretic, thus a firstorder one, and it is possible to enter a metastability region, wherein, approaching a spinodal point, critical phenomena emerge. Avalanches of events occur according to powerlaw distributions having exponents ≈3/2 for size and ≈2 for duration, and fractal structure is evident as powerlaw scaling of the Fano factor. These critical exponents overlap observations in biological neural networks; hence, this circuit may have value as building block to realize corresponding physical models.},
doi = {10.1063/1.4954879},
journal = {Chaos (Woodbury, N. Y.)},
number = 7,
volume = 26,
place = {United States},
year = {Fri Jul 15 00:00:00 EDT 2016},
month = {Fri Jul 15 00:00:00 EDT 2016}
}

We study the orderdisorder transition of a p(2 x 2) ordered state on a honeycomb lattice using Monte Carlo calculations of the structure factor. We observe a correlation length which gets large as the transition is approached; the effective critical exponents are close to the exponents characterizing a discontinuity fixed point and similar to those we observe for the firstorder transition of the eightstate Potts model. We also discuss how observation of the outer integralorder diffraction beams gives information about the relevance of the field which distinguishes the two triangular sublattices of the honeycomb lattice.

FirstOrder VortexLattice Melting Transition in YBa{sub 2}Cu{sub 3}O{sub 7{ital {minus}{delta}}} near the Critical Temperature Detected by Magnetic Torque
Highresolution magnetictorque studies on an untwinned YBa{sub 2}Cu {sub 3}O{sub 7{minus}{delta}} single crystal near its critical temperature T{sub c} reveal that the firstorder vortexlattice melting transition (VLMT) persists at least up to 0.5thinspthinspK below T{sub c} . The associated sharp discontinuity in magnetization is detectable even at temperatures where the torque signal deviates from meanfield behavior due to fluctuations. The magnetic irreversibility at the VLMT can be suppressed by applying a weak transverse ac magnetic field. This offers the possibility of separating the irreversibility line from the melting line near T{sub c} . {copyright} {ital 1998} {ital The American Physicalmore » 
Paramagnetic ac susceptibility at the firstorder vortexlattice phase transition
A sharp paramagnetic peak in the local ac susceptibility {chi}{sup {prime}} at the firstorder vortexlattice phase transition in Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8} crystals is found. Observation of this peak establishes the thermodynamic nature of the transition and allows accurate evaluation of the equilibrium magnetization step height. The associated estimated entropy change {Delta}{ital s} reaches values in excess of 6{ital k}{sub {ital B}} per pancake vortex close to {ital T}{sub {ital c}}. The local {chi}{sup {double_prime}} shows two independent dissipation peaks. The broader one is caused by the onset of irreversible magnetization, whereas the narrow one is due to hysteresismore » 
Angular dependence of the firstorder vortexlattice phase transition in Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8}
The paramagnetic peak in the local ac susceptibility {chi}{sup {prime}} is used to identify the firstorder vortexlattice phase transition in Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8} at various tilt angles {theta} of the dc magnetic field with respect to the c axis. The transition field H{sub m} follows roughly the twodimensional scaling function H{sub dc}cos({theta}). The scaling fails for field orientations close to the ab plane. The amplitude of the paramagnetic peak, which is proportional to the jump in magnetization {Delta}B, does not depend on the tilt angle up to configurations very close to the ab plane ({plus_minus}1{degree}). From this wemore »