Natural time analysis of critical phenomena: The case of pre-fracture electromagnetic emissions

2013 ◽  
Vol 23 (2) ◽  
pp. 023117 ◽  
Author(s):  
S. M. Potirakis ◽  
A. Karadimitrakis ◽  
K. Eftaxias
Keyword(s):  
Critical Phenomena ◽  
Time Analysis ◽  
Natural Time ◽  
Natural Time Analysis ◽  
Electromagnetic Emissions

Natural-time analysis of critical phenomena: The case of seismicity

2010 ◽  
Vol 92 (2) ◽  
pp. 29002 ◽  
Author(s):  
P. A. Varotsos ◽  
N. V. Sarlis ◽  
E. S. Skordas ◽  
S. Uyeda ◽  
M. Kamogawa
Keyword(s):  
Critical Phenomena ◽  
Time Analysis ◽  
Natural Time ◽  
Natural Time Analysis

scholarly journals Natural time analysis of critical phenomena

2011 ◽  
Vol 108 (28) ◽  
pp. 11361-11364 ◽  
Author(s):  
P. Varotsos ◽  
N. V. Sarlis ◽  
E. S. Skordas ◽  
S. Uyeda ◽  
M. Kamogawa
Keyword(s):  
Critical Phenomena ◽  
Time Analysis ◽  
Natural Time ◽  
Natural Time Analysis

scholarly journals On the Statistical Significance of the Variability Minima of the Order Parameter of Seismicity by Means of Event Coincidence Analysis

2020 ◽  
Vol 10 (2) ◽  
pp. 662 ◽  
Author(s):  
Stavros-Richard G. Christopoulos ◽  
Efthimios S. Skordas ◽  
Nicholas V. Sarlis
Keyword(s):  
Critical Phenomena ◽  
Order Parameter ◽  
Eastern Mediterranean ◽  
Statistical Significance ◽  
Time Analysis ◽  
Strong Earthquakes ◽  
Natural Time ◽  
Natural Time Analysis ◽  
Recent Method ◽  
Global Seismicity

Natural time analysis has led to the introduction of an order parameter for seismicity when considering earthquakes as critical phenomena. The study of the fluctuations of this order parameter has shown that its variability exhibits minima before strong earthquakes. In this paper, we evaluate the statistical significance of such minima by using the recent method of event coincidence analysis. Our study includes the variability minima identified before major earthquakes in Japan and Eastern Mediterranean as well as in global seismicity.

Remote sensing natural time analysis of heartbeat data by means of a portable photoplethysmography device

2020 ◽  
Vol 42 (6) ◽  
pp. 2292-2302
Author(s):  
G. Baldoumas ◽  
D. Peschos ◽  
G. Tatsis ◽  
V. Christofilakis ◽  
S. K. Chronopoulos ◽  
...  
Keyword(s):  
Remote Sensing ◽  
Time Analysis ◽  
Natural Time ◽  
Natural Time Analysis

Natural Time Analysis of Seismic Time Series

2018 ◽  
pp. 199-235 ◽  
Author(s):  
Nicholas V. Sarlis ◽  
Efthimios S. Skordas ◽  
Panayiotis A. Varotsos
Keyword(s):  
Time Series ◽  
Time Analysis ◽  
Natural Time ◽  
Natural Time Analysis

scholarly journals Natural Time Analysis: The Area under the Receiver Operating Characteristic Curve of the Order Parameter Fluctuations Minima Preceding Major Earthquakes

Entropy ◽  
2020 ◽  
Vol 22 (5) ◽  
pp. 583 ◽  
Author(s):  
Nicholas V. Sarlis ◽  
Efthimios S. Skordas ◽  
Stavros-Richard G. Christopoulos ◽  
Panayiotis A. Varotsos
Keyword(s):  
Order Parameter ◽  
Characteristic Curve ◽  
Activity Patterns ◽  
Space Physics ◽  
Operating Characteristics ◽  
Time Analysis ◽  
Natural Time ◽  
Natural Time Analysis ◽  
Electric Signals ◽  
Receiver Operating

It has been reported that major earthquakes are preceded by Seismic Electric Signals (SES). Observations show that in the natural time analysis of an earthquake (EQ) catalog, an SES activity starts when the fluctuations of the order parameter of seismicity exhibit a minimum. Fifteen distinct minima—observed simultaneously at two different natural time scales and deeper than a certain threshold—are found on analyzing the seismicity of Japan from 1 January 1984 to 11 March 2011 (the time of the M9 Tohoku EQ occurrence) 1 to 3 months before large EQs. Six (out of 15) of these minima preceded all shallow EQs of magnitude 7.6 or larger, while nine are followed by smaller EQs. The latter false positives can be excluded by a proper procedure (J. Geophys. Res. Space Physics 2014, 119, 9192–9206) that considers aspects of EQ networks based on similar activity patterns. These results are studied here by means of the receiver operating characteristics (ROC) technique by focusing on the area under the ROC curve (AUC). If this area, which is currently considered an effective way to summarize the overall diagnostic accuracy of a test, has the value 1, it corresponds to a perfectly accurate test. Here, we find that the AUC is around 0.95 which is evaluated as outstanding.

scholarly journals A Prototype Photoplethysmography Electronic Device that Distinguishes Congestive Heart Failure from Healthy Individuals by Applying Natural Time Analysis

Electronics ◽  
2019 ◽  
Vol 8 (11) ◽  
pp. 1288 ◽  
Author(s):  
George Baldoumas ◽  
Dimitrios Peschos ◽  
Giorgos Tatsis ◽  
Spyridon K. Chronopoulos ◽  
Vasilis Christofilakis ◽  
...  
Keyword(s):  
Heart Failure ◽  
Congestive Heart Failure ◽  
Electronic Device ◽  
Low Cost ◽  
Prototype System ◽  
Healthy Individuals ◽  
Time Analysis ◽  
Clear Separation ◽  
Natural Time ◽  
Natural Time Analysis

In this paper, a prototype photoplethysmography (PPG) electronic device is presented for the distinction of individuals with congestive heart failure (CHF) from the healthy (H) by applying the concept of Natural Time Analysis (NTA). Data were collected simultaneously with a conventional three-electrode electrocardiography (ECG) system and our prototype PPG electronic device from H and CHF volunteers at the 2nd Department of Cardiology, Medical School of Ioannina, Greece. Statistical analysis of the results show a clear separation of CHF from H subjects by means of NTA for both the conventional ECG system and our PPG prototype system, with a clearly better distinction for the second one which additionally inherits the advantages of a low-cost portable device.

scholarly journals Natural time analysis in financial markets

2016 ◽  
Vol 5 (1-2) ◽  
pp. 37-46 ◽  
Author(s):  
A. Mintzelas ◽  
K. Kiriakopoulos
Keyword(s):  
Financial Markets ◽  
Time Analysis ◽  
Natural Time ◽  
Natural Time Analysis
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