Critical slowing down associated with critical transition and risk of collapse in cryptocurrency

The year 2017 saw the rise and fall of the crypto-currency market, followed by high variability in the price of all crypto-currencies. In this work, we study the abrupt transition in crypto-currency residuals, which is associated with the critical transition (the phenomenon of critical slowing down) or the stochastic transition phenomena. We find that, regardless of the specific crypto-currency or rolling window size, the autocorrelation always fluctuates around a high value, while the standard deviation increases monotonically. Therefore, while the autocorrelation does not display signals of critical slowing down, the standard deviation can be used to anticipate critical or stochastic transitions. In particular, we have detected two sudden jumps in the standard deviation, in the second quarter of 2017 and at the beginning of 2018, which could have served as early warning signals of two majors price collapses that have happened in the following periods. We finally propose a mean-field phenomenological model for the price of crypto-currency to show how the use of the standard deviation of the residuals is a better leading indicator of the collapse in price than the time series' autocorrelation. Our findings represent a first step towards a better diagnostic of the risk of critical transition in the price and/or volume of crypto-currencies.Comment: 14 pages, 5 figures, 1 tabl

THE ASTROPHYSICAL JOURNAL, 565 696719, 2002 February 1

We have detected in high-resolution spectra of the quasar Q0347[3819 obtained with the UV-Visual Echelle Spectrograph (UVES) at the VLT/Kueyen telescope over 80 absorption features in the Lyman and Werner bands at the redshift of a damped Lya (DLA) system at At the same red- H \ 3.025

THE ASTROPHYSICAL JOURNAL, 549 9099, 2001 March 1

The UV resonance transitions of neutral argon, Ar I j1066, and of singly ionized phosphorus, P II j963, originated in the damped Lya system (DLA) at toward QSO 0000[2620, have been z \ 3.3901 detected by means of the Ultraviolet-Visual Echelle Spectrograph (UVES) spectrograph at the 8.2 m ESO KUEYEN telescope. So far, this is the rst measurement of Ar I and the second of P II ever performed in damped galaxies and in high-redshift objects. This DLA is well known for having one of the lowest metal abundances and dust content and the lowest fractional abundance of molecular hydrogen The measured Ar abundance is [Ar/H] \[1.91^ 0.09, which is equal to the abundances of the H