Yiannis Contoyiannis

University of the West

Particle physicsMagnetic fieldQuantum chromodynamicsPhysicsStatistical physicsCriticalitySpontaneous symmetry breakingGeologyCritical point (thermodynamics)Phase transitionCritical exponentSeismologyField (physics)Critical phenomenaSymmetry breakingCondensed matter physicsIntermittencyMathematicsFracture (geology)Ising modelRenormalization groupGeophysicsPower law

67Publications

18H-index

710Citations

Publications 63

Statistical and Criticality Analysis of the Lower Ionosphere Prior to the 30 October 2020 Samos (Greece) Earthquake (M6.9), Based on VLF Electromagnetic Propagation Data as Recorded by a New VLF/LF Receiver Installed in Athens (Greece).

#1Dimitrios Z. Politis (UWest: University of the West)

#2Stelios M. Potirakis (UWest: University of the West)H-Index: 17

Last. Masashi Hayakawa (University of Electro-Communications)H-Index: 66

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In this work we present the statistical and criticality analysis of the very low frequency (VLF) sub-ionospheric propagation data recorded by a VLF/LF radio receiver which has recently been established at the University of West Attica in Athens (Greece). We investigate a very recent, strong (M6.9), and shallow earthquake (EQ) that occurred on 30 October 2020, very close to the northern coast of the island of Samos (Greece). We focus on the reception data from two VLF transmitters, located in Tur...

#1Yiannis Contoyiannis (UWest: University of the West)H-Index: 18

#2Stelios M. Potirakis (UWest: University of the West)H-Index: 17

Last. Efstratios K. Kosmidis (A.U.Th.: Aristotle University of Thessaloniki)H-Index: 15

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Abstract Combining concepts of artificial neural networks (ANNs) with the stochastic dynamics of Ising spin lattices we introduce a hybrid model, the hybrid spin model (HSM). We find that the HSM carries the critical/tricritical fluctuations of the 2D Ising model and allows for an accurate estimation of the isothermal critical/tricritical exponents of 2D Ising universality class. Our work clearly demonstrates that HSM launches a new category of models supporting alternative pathways for the real...

#1Fotis K. Diakonos (UoA: National and Kapodistrian University of Athens)H-Index: 26

#2Yiannis ContoyiannisH-Index: 18

Last. Stelios M. PotirakisH-Index: 17

view all 3 authors...

We show that the spontaneous symmetry breaking can be defined also for finite systems based on the properly defined jump probability between the ground states in the 2d and 3d Ising models on a square and a cubic lattice respectively. Our analysis reveals the existence of an interval in the temperature (control parameter) space within which the spontaneous symmetry breaking takes place. The upper limit of this region is the pseudocritical point where the symmetric vacuum bifurcates in energetica...

#1Yiannis ContoyiannisH-Index: 18

#2Stavros G. StavrinidesH-Index: 9

Last. Perikles G. PapadopoulosH-Index: 4

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In this brief, the spontaneous symmetry breaking (SSB) of the \varphi^4theory in phase space, is studied. This phase space results from the appropriate system of Poincare maps, produced in both the Minkowski and the Euclidean time. The importance of discretization in the creation of phase space, is highlighted. A series of interesting, novel, unknown behaviors are reported for the first time; among them the most characteristic is the change in stability. In specific, the stable fixed points o...

Post-spontaneous-symmetry-breaking power-laws after a very strong earthquake: Indication for the preparation of a new strong earthquake or not?

#1Stelios M. PotirakisH-Index: 17

#2Yiannis ContoyiannisH-Index: 18

Last. Constantinos NomicosH-Index: 21

view all 5 authors...

It has recently been found that the evolution of the preparation of a strong earthquake (EQ), as it is monitored through fracture-induced electromagnetic emissions (EME) in the MHz band, presents striking similarity with the evolution of a thermal system as temperature drops, since distinct steps of the evolution of the phenomenon of spontaneous symmetry breaking (SSB) can be identified. Here, the study of fracture-induced EME in the MHz band in analogy to thermal systems is extended to the phas...

#1Yiannis Contoyiannis (UWest: University of the West)H-Index: 18

#2Stavros G. Stavrinides (International Hellenic University)H-Index: 9

Last. E. K. Kosmidis (A.U.Th.: Aristotle University of Thessaloniki)

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Recently, it has been successfully shown that the temporal evolution of the fraction of COVID-19 infected people possesses the same dynamics as the ones demonstrated by a self-organizing diffusion model over a lattice, in the frame of universality. In this brief, the relevant emerging dynamics are further investigated. Evidence that this nonlinear model demonstrates critical dynamics is scrutinized within the frame of the physics of critical phenomena. Additionally, the concept of criticality ov...

#1Yiannis Contoyiannis (UoA: National and Kapodistrian University of Athens)H-Index: 18

#2Stelios M. PotirakisH-Index: 17

Last. Myron KampitakisH-Index: 1

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A device consisting of an array of coaxial, identical, circular rings behaves like a solenoid when the ratio of its radius and distance between two successive rings is higher than 1. As this ratio decreases, the device significantly deviates from the solenoid behavior. At the same time, a diffraction-like phenomenon for the magnetic field appears when currents of random direction flow through the rings. This phenomenon demonstrates critical behavior. Thus, an extension of the diffraction phenome...

#1Stelios M. Potirakis (UWest: University of the West)H-Index: 17

#2Yiannis Contoyiannis (UWest: University of the West)H-Index: 18

Last. Masashi Hayakawa (University of Electro-Communications)H-Index: 66

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A wide variety of electromagnetic phenomena possibly related with earthquake (EQ) preparation processes have been reported in the literature during the last few decades. An interesting aspect in their study is the time series analysis of the related observables aiming at the investigation of any embedded dynamics. In this review article we focus on the study of fracto-electromagnetic emissions (fracto-EME) at the MHz band, the ultra-low frequency (ULF) magnetic field variations (<3 Hz) and the s...

#1Yiannis Contoyiannis (UWest: University of the West)H-Index: 4

#1Yiannis Contoyiannis (UWest: University of the West)H-Index: 18

Last. Stelios M. PotirakisH-Index: 17

view all 7 authors...

The self-organizing mechanism is a universal approach that is widely followed in nature. In this work, a novel self-organizing model describing diffusion over a lattice is introduced. Simulation results for the model's active lattice sites demonstrate an evolution curve that is very close to those describing the evolution of infected European populations by COVID-19. The model was further examined against real data regarding the COVID-19 epidemic for seven European countries (with a total popula...

Solitons and Instantons in the inverse {\phi}4 theory of critical phenomena. A proposal for the violation of causality of tachyonic field

#1Yiannis ContoyiannisH-Index: 18

#1Y. ContoyiannisH-Index: 1

Last. Stavros G. Stavrinides (International Hellenic University)H-Index: 9

view all 5 authors...

We investigate about the existence of static solitons solutions in the inverse G-L free energy in phase transitions of {\phi}4 theory. We calculate all the characteristics of these solitons , like localized structure, finite energy and mass . We show that solitons appears in spontaneous symmetry breaking (SSB) phenomenon only if the critical point is in excited state. When the time is introduced we shown that the static solitons of SSB remain as solitons in Minkowski space-time while the static ...

Close Researchers

Konstantinos Eftaxias

H-index : 29

Stelios M. Potirakis

H-index : 17

Fotis K. Diakonos

H-index : 26

Constantinos Nomicos

H-index : 21

J. Kopanas

H-index : 13

G. Antonopoulos

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