arXiv subjects

Y. Contoyiannis

Publications and source records attributed to Y. Contoyiannis.

12 recordsLinked to original sources

arXiv2025

On the recent seismic activity at Ioannina (Greece): Pre-earthquake electromagnetic emissions with critical and tricritical behavior

In this short paper we report that the dynamics of the earthquake (EQ) preparation processes, as embedded in the observed fracture-induced electromagnetic emissions (EME), were characterized by critical and then tricritical behavior a few days before the occurrence of the recent Ioannina (Greece) earthquake [($39.79^o N, 20.69^o E$), 15 October 2016, $M_L=5.3$]. Specifically, an excerpt of the MHz EME recorded by our remote telemetric station near the city of Ioannina five days before the EQ was found to possess critical characteristics, followed by an excerpt possessing tricritical characteristics. The analysis was performed by means of the method of critical fluctuations (MCF). Interestingly, spontaneous symmetry breaking was identified between critical and tricritical behavior.

physics.geo-ph↗

arXiv2023

New phenomena beyond Spontaneous Symmetry Breaking

It is known that in thermal systems of finite size that are subject to second order phase transitions and until the spontaneous symmetry breaking is completed, the fluctuations of the order parameter obey to the dynamics of critical intermittency. Beyond the SSB, critical intermittency does not hold. Thus, it is not expected that the distribution of the waiting times in the order parameter timeseries would hold any power law. However we reveal for the first time that right after the SSB, power laws still exist within a small zone of temperatures. These power laws emerge due to another form of intermittency that determines the dynamics of the order parameter fluctuations in the beginning of the tricritical crossover, without this crossover ever being completed in a first order phase transition. In the work pesented hereby, we present and explain this change of the dynamics of the order parameter fluctuations, as the temperature drops under the temperature of the SSB. Finally, it is mentioned that such a phenomenon has been already observed in preseismic processes.

cond-mat.stat-mech↗

arXiv2022

Biot-Savart type magnetic field quantization via prime number theory, applications to symbolic dynamics

In the present work we propose an algorithm based on the theory of prime numbers for the estimation of the magnetic field in a device of current carrying circular rings. Using the proposed algorithm, the magnetic field can be determined in a very good agreement with that resulting from an algorithm based on the Biot-Savart law. In addition, the prime-numbers-based algorithm gives quantized values of the magnetic field and reveals previously unknown behaviors such as special properties of the distribution of the waiting times at the quantized magnetic field values. Applications of the proposed prime-numbers-based algorithm to systems exhibiting symbolic dynamics is presented, proving its ability to provide a measure of the existence or not of dynamics in the system.

physics.gen-ph↗

arXiv2021

Spontaneous Symmetry Breaking in the Phase Space

In this brief, the spontaneous symmetry breaking (SSB) of the $φ^4$ theory 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 of the $φ^4$ potential appear as unstable ones, in phase space. Additionally, in the Euclidean-time phase space a unique instability in the position of the critical point, can be created. This instability is further proposed to host tachyonic field in Euclidean space.

cond-mat.stat-mech↗

arXiv2020

Solitons and Instantons in the inverse ϕ4 theory of critical phenomena. A proposal for the violation of causality of tachyonic field

We investigate about the existence of static solitons solutions in the inverse G-L free energy in phase transitions of ϕ4 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 solitons of inverse G-L free energy converted to instantons in Euclidean space. The violation of causality which appears in the tachyonic field could be faced passing from Minkowski solitons to Euclidean instantons.

nlin.PS↗

arXiv2020

On the effectiveness of imposing restrictive measures in a graded Self-Organized Criticality epidemic spread model The case of COVID-19

The scope of this work is to serve as a guiding tool against subjective estimations on real pandemic situations (mainly due to the inability to acquire objective real data over whole populations). The previously introduced model of closed self-organized criticality (SOC), is adapted in the case of a virus-induced epidemic. In this version this physical model can distinguish the virus spread according to the virus aggressiveness. The study presented, highlights the critical value of virus density over a population. For low values of the initial virus density (lower than the critical value) it is proved that the virus-diffusion behavior is safe and quantitatively similar to usual real epidemical data. However, it is revealed that very close to the critical point, the critical slowing-down (CSD) phenomenon, introduced by the theory of critical phenomena, emerges, leading to a tremendous increase of both the percentage of active carriers and the duration of the epidemic. A behavior of the epidemic obeying to a second order phase transition, also occurs. For virus density values higher than the critical value, the epidemic duration becomes extremely prolonged. Additionally, the effect of the closed system population size revealed interesting properties. All these results, together with an investigation of the effectiveness of applying physical contact restriction measures, document scientifically their worthiness, while they also demonstrate the limits for which herd immunity holds safely. Finally, the model has been compared against real epidemic data in the case of Greece, which imposed restrictive measures consistently and in time.

physics.soc-ph↗

arXiv2020

Diffraction of magnetic field in a device of circular rings

A device consisted of a set of circular rings, the centers of which lie on an axis, behaves like a solenoid when the ratio of its radius and distance between two successive rings is greater than one. As this ratio decreases, the device deviates a lot from the solenoid behavior.In the same way, a diffraction phenomenon for magnetic field appears when currents of random direction flow through the rings. This phenomenon demonstrates a critical behavior. Thus an extension of diffraction phenomenon can be done beyond the classical wave diffraction. A possible application of this device could be the diffraction of electronic beams.

physics.class-ph↗

arXiv2018

Preliminary results concerning the fracture-induced electromagnetic emissions recorded prior to the Mw 6.7 Earthquake on October 25, 2018 south of Zakynthos

In this letter we present preliminary results concerning precursors to the recent significant (Mw 6.7) earthquake (EQ) that took place in the region south of the Greek Island of Zakynthos (October 25, 2018). We show, in terms of fracture-induced electromagnetic emissions (EME), that the Earth system around the focal area was at critical state up to a few hours before the occurrence of the EQ. Importantly, departure from the critical state, in terms of the symmetry breaking phenomenon, was also identified in the EME recorded after the appearance of the last signatures of criticality. The analysis was performed by means of the method of critical fluctuations (MCF).

physics.geo-ph↗

arXiv2017

On the recent seismic activity at eastern Aegean Sea: Analysis of fracture-induced electromagnetic emissions in terms of critical fluctuations

In this letter we show, in terms of fracture-induced electromagnetic emissions (EME) that the Earth system around the focal areas came to critical condition a few days before the occurrence of recent significant (M>5) earthquakes (EQs) which happened in the region of the eastern Aegean Sea, between the Greek Islands of Lesvos (6-7, 12 February 2017 and 12 June 2017) and Kos (20 July 2017) and the Turkish Asia Minor coastline. Moreover, departure from the critical state in terms of a tricritical crossover was identified in the EME recorded prior to the 12 June main event as well as prior to the 20 July main event. The analysis was performed by means of the method of critical fluctuations (MCF).

physics.geo-ph↗

arXiv2014

On the recent seismic activity at Kefalonia island (Greece): Manifestations of an Earth system in critical state

In this paper we show, in terms of fracture-induced electromagnetic emissions (EME) that the Earth system around the focal areas came to critical condition a few days before the occurrence of each one of the two recent earthquakes of Kefalonia (Cephalonia), Greece. Specifically, EME were recorded two days prior to the first earthquake [(38.22o N, 20.53oE), 26 January 2014, M=6.1] & six days prior to the second one [(38.26o N, 20.39oE), 03 February 2014, M=6.0]. Specifically, the MHz EME recorded by the remote telemetric stations on the island of Kefalonia and the neighboring island of Zante came simultaneously to critical condition in both cases. The analysis was performed by means of the method of critical fluctuations (MCF) revealing critical features.

physics.geo-ph↗

arXiv2009

Unfolding the procedure of characterizing recorded ultra low frequency, kHZ and MHz electromagnetic anomalies prior to the L'Aquila earthquake as pre-seismic ones. Part II

Ultra low frequency-ULF (1 Hz or lower), kHz and MHz electromagnetic (EM) anomalies were recorded prior to the L'Aquila catastrophic earthquake (EQ) that occurred on April 6, 2009. The detected anomalies followed this temporal scheme. (i) The MHZ EM anomalies were detected on March 26, 2009 and April 2, 2009. The kHz EM anomalies were emerged on April, 4 2009. The ULF EM anomaly was continuously recorded from March 29, 2009 up to April 2, 2009. "Are EQs predictable?" is a question hotly debated in the science community. Its answer begs for another question: "Are there credible EQ precursors?". Despite fairly abundant circumstantial evidence pre-seismic EM signals have not been adequately accepted as real physical quantities. Therefore, the question effortlessly arises as to whether the observed anomalies before the L'Aquila EQ were seismogenic or not. The main goal of this work is to provide some insight into this issue.

physics.geo-ph↗

arXiv2009

Unfolding the procedure of characterizing recorded ultra low frequency, kHZ and MHz electromagetic anomalies prior to the L'Aquila earthquake as pre-seismic ones. Part I

Ultra low frequency, kHz and MHz electromagnetic anomalies were recorded prior to the L'Aquila catastrophic earthquake that occurred on April 6, 2009. The main aims of this contribution are: (i) To suggest a procedure for the designation of detected EM anomalies as seismogenic ones. We do not expect to be possible to provide a succinct and solid definition of a pre-seismic EM emission. Instead, we attempt, through a multidisciplinary analysis, to provide elements of a definition. (ii) To link the detected MHz and kHz EM anomalies with equivalent last stages of the L'Aquila earthquake preparation process. (iii) To put forward physically meaningful arguments to support a way of quantifying the time to global failure and the identification of distinguishing features beyond which the evolution towards global failure becomes irreversible. The whole effort is unfolded in two consecutive parts. We clarify we try to specify not only whether or not a single EM anomaly is pre-seismic in itself, but mainly whether a combination of kHz, MHz, and ULF EM anomalies can be characterized as pre-seismic one.

physics.geo-ph↗