693 research outputs found

    Ethno-Nationalistic and Religious-Nationalistic Components of Identity in Post-Soviet Georgia

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    Deep economic and democratic changes in Georgian society in last 20 years have conditioned the transformation of social environment in such a way that people had to change their views on society and their place in the new social environment. Changing attitudes on social reality affected and transformed the whole system of social identity. Transformation processes were characterized with reduced trust and tolerance among people and different social groups and with increase or weakening of different aspects of basic identities. Difficulties emerging from the process of formation of the identity system hinder the development of integration processes in the society. For a society in transition in the conditions of normative uncertainty and devaluation of values actuality of such problems as are the lack of trust on every level of relationship and disorientation of people, is of high importance. Our starting issue is that nowadays in the framework of construction of social identity basic identity encompasses civil, national, confessional, ideological elements which determine the state of a person in the system of social coordinates. The subject of this sociological research was to study the role of religion and ethnicity in the modern configuration of identity in Georgian society

    On the puzzling feature of the silence of precursory electromagnetic emissions

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    It has been suggested that fracture-induced MHz-kHz electromagnetic (EM) emissions, which emerge from a few days up to a few hours before the main seismic shock occurrence permit a real-time monitoring of the damage process during the last stages of earthquake preparation, as it happens at the laboratory scale. Despite fairly abundant evidence, EM precursors have not been adequately accepted as credible physical phenomena. These negative views are enhanced by the fact that certain 'puzzling features' are repetitively observed in candidate fracture-induced pre-seismic EM emissions. More precisely, EM silence in all frequency bands appears before the main seismic shock occurrence, as well as during the aftershock period. Actually, the view that 'acceptance of 'precursive' EM signals without convincing co-seismic signals should not be expected' seems to be reasonable. In this work we focus on this point. We examine whether the aforementioned features of EM silence are really puzzling ones or, instead, reflect well-documented characteristic features of the fracture process, in terms of: universal structural patterns of the fracture process, recent laboratory experiments, numerical and theoretical studies of fracture dynamics, critical phenomena, percolation theory, and micromechanics of granular materials. Our analysis shows that these features should not be considered puzzling.Comment: arXiv admin note: text overlap with arXiv:cond-mat/0603542 by other author

    Electromagnetic and mechanical control of slip: laboratory experiments with slider system

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    International audienceField and laboratory data reveal the possibility of a significant coupling of elastic and electromagnetic (EM) fields that affect (hamper or initiate) slip. In this work we try to prove experimentally the possibility of controlling the slip regime by relatively weak mechanical or EM impact, in the way it has been done in nonlinear dynamic experiments on the control of chaos. The experimental setup consisted of a system of two plates of roughly finished basalt, where a constant pulling force was applied to the upper (sliding) plate. In addition, the same plate was subjected to mechanical or electric periodic perturbations, which are much weaker when compared to the pulling force. Quite different regimes of slip were excited depending on the amplitude and the frequency of applied weak perturbations. The observed regimes of slip vary from perfect synchronization of slip events, recorded as acoustic emission bursts with the perturbing periodic mechanical or EM impact, to their complete desynchronization. We consider the obtained results as evidence that it is possible to control slip by the application of weak periodic perturbations. The phenomenon can be explained in terms of nonlinear dynamics and synchronization theory

    Phase synchronization of slip in laboratory slider system

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    International audienceIn the present study the character of slip regimes in laboratory spring-slider system under weak external periodical forcing has been investigated. We report the experimental evidence of phase synchronization (PS) in a slip dynamics, induced by the external periodic electromagnetic (EM) impact. The quality of synchronization depends on the intensity and frequency of the applied field; the corresponding Arnold's tongue region is constructed. Application of special techniques (measuring phase differences, phase diffusion coefficient, Shannon entropy, Recurrence Quantification Analysis) allows quantitative assessment of the strength of synchronization of microslips with EM impact. It is also shown that the character of power law relationship in acoustic emission amplitude (energy) distribution also undergoes significant changes at changing excitation intensity

    Investigation of the temporal fluctuations of the 1960–2010 seismicity of Caucasus

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    The time-clustering behaviour of the seismicity of the Caucasus spanning from 1960 to 2010 was investigated. The analysis was performed on the whole and aftershock-depleted catalogues by means of the method of Allan Factor, which permits the identification and quantification of time-clustering in point processes. The whole sequence is featured by two scaling regimes with the scaling exponent at intermediate timescales lower than that at high timescales, and a crossover that could be probably linked with aftershock time activiation. The aftershock-depleted sequence is characterized by higher time-clustering degree and the presence of a periodicity probably correlated with the cyclic earth surface load variations on regional and local scales, e.g. with snow melting in Caucasian mountains and large Enguri dam operations. The obtained results were corroborated by the application of two surrogate methods: the random shuffling and the generation of Poissonian sequences

    Re-examination of log-periodicity observed in the seismic precursors of the 1989 Loma Prieta earthquake

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    Based on several empirical evidence, a series of papers has advocated the concept that seismicity prior to a large earthquake can be understood in terms of the statistical physics of a critical phase transition. In this model, the cumulative Benioff strain (BS) increases as a power-law time-to-failure before the final event. This power law reflects a kind of scale invariance with respect to the distance to the critical point. A few years ago, on the basis of a fit of the cumulative BS released prior to the 1989 Loma Prieta earthquake, Sornette and Sammis [1995] proposed that this scale invariance could be partially broken into a discrete scale invariance (DSI). The observable consequence of DSI takes the form of log-periodic oscillations decorating the accelerating power law. They found that the quality of the fit and the predicted time of the event are significantly improved by the introduction of log-periodicity. Here, we present a battery of synthetic tests performed to quantify the statistical significance of this claim. We find that log-periodic oscillations with frequency and regularity similar to those of the Loma Prieta case are very likely to be generated by the interplay of the low pass filtering step due to the construction of cumulative functions together with the approximate power law acceleration. Thus, the single Loma Prieta case alone cannot support the initial claim and additional cases and further study are needed to increase the signal-to-noise ratio if any. The present study will be a useful methodological benchmark for future testing of additional events when the methodology and data to construct reliable Benioff strain function become available.Comment: LaTeX, JGR preprint with AGU++ v16.b and AGUTeX 5.0, use packages graphicx and psfrag, 23 eps figures, 17 pages. In press J. Geophys. Re

    Reliable Estimation of Minimum Embedding Dimension Through Statistical Analysis of Nearest Neighbors

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    False nearest neighbors (FNN) is one of the essential methods used in estimating the minimally sufficient embedding dimension in delay-coordinate embedding of deterministic time series. Its use for stochastic and noisy deterministic time series is problematic and erroneously indicates a finite embedding dimension. Various modifications to the original method have been proposed to mitigate this problem, but those are still not reliable for noisy time series. Here, nearest-neighbor statistics are studied for uncorrelated random time series and contrasted with the corresponding deterministic and stochastic statistics. New composite FNN metrics are constructed and their performance is evaluated for deterministic, correlates stochastic, and white random time series. In addition, noise-contaminated deterministic data analysis shows that these composite FNN metrics are robust to noise. All FNN results are also contrasted with surrogate data analysis to show their robustness. The new metrics clearly identify random time series as not having a finite embedding dimension and provide information about the deterministic part of correlated stochastic processes. These metrics can also be used to differentiate between chaotic and random time series

    Smooth Local Subspace Projection for Nonlinear Noise Reduction

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    Many nonlinear or chaotic time series exhibit an innate broad spectrum, which makes noise reduction difficult. Local projective noise reduction is one of the most effective tools. It is based on proper orthogonal decomposition (POD) and works for both map-like and continuously sampled time series. However, POD only looks at geometrical or topological properties of data and does not take into account the temporal characteristics of time series. Here, we present a new smooth projective noise reduction method. It uses smooth orthogonal decomposition (SOD) of bundles of reconstructed short-time trajectory strands to identify smooth local subspaces. Restricting trajectories to these subspaces imposes temporal smoothness on the filtered time series. It is shown that SOD-based noise reduction significantly outperforms the POD-based method for continuously sampled noisy time series
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