scholarly journals Non-Extensive Statistical Analysis of Energetic Particle Flux Enhancements Caused by the Interplanetary Coronal Mass Ejection-Heliospheric Current Sheet Interaction

Entropy ◽  
2019 ◽  
Vol 21 (7) ◽  
pp. 648 ◽  
Author(s):  
Pavlos ◽  
Malandraki ◽  
Khabarova ◽  
Karakatsanis ◽  
Pavlos ◽  
...  

In this study we use theoretical concepts and computational-diagnostic tools of Tsallis non-extensive statistical theory (Tsallis q-triplet: qsen, qrel, qstat), complemented by other known tools of nonlinear dynamics such as Correlation Dimension and surrogate data, Hurst exponent, Flatness coefficient, and p-modeling of multifractality, in order to describe and understand Small-scale Magnetic Islands (SMIs) structures observed in Solar Wind (SW) with a typical size of ~0.01–0.001 AU at 1 AU. Specifically, we analyze ~0.5 MeV energetic ion time-intensity and magnetic field profiles observed by the STEREO A spacecraft during a rare, widely discussed event. Our analysis clearly reveals the non-extensive character of SW space plasmas during the periods of SMIs events, as well as significant physical complex phenomena in accordance with nonlinear dynamics and complexity theory. As our analysis also shows, a non-equilibrium phase transition parallel with self-organization processes, including the reduction of dimensionality and development of long-range correlations in connection with anomalous diffusion and fractional acceleration processes can be observed during SMIs events.

2020 ◽  
Author(s):  
Evgenios Pavlos ◽  
Olga Malandraki ◽  
Olga Khabarova ◽  
Leonidas P. Karakatsanis ◽  
George P. Pavlos ◽  
...  

<p>In this study we use theoretical concepts and computational-diagnostic tools of Tsallis non-extensive statistical theory (Tsallis q-triplet: qsen, qrel, qstat), complemented by other known tools of nonlinear dynamics such as Correlation Dimension and surrogate data, Hurst exponent, Flatness coefficient, and p-modeling of multifractality, in order to describe and understand Small-scale Magnetic Islands (SMIs) structures observed in Solar Wind (SW) with a typical size of ~0.01–0.001 AU at 1 AU. Specifically, we analyze ~0.5 MeV energetic ion time-intensity and magnetic field profiles observed by the STEREO A spacecraft during a rare, widely discussed event. Our analysis clearly reveals the non-extensive character of SW space plasmas during the periods of SMIs events, as well as significant physical complex phenomena in accordance with nonlinear dynamics and complexity theory. As our analysis also shows, a non-equilibrium phase transition parallel with self-organization processes, including the reduction of dimensionality and development of long-range correlations in connection with anomalous discussion and fractional acceleration processes can be observed during SMIs events.</p>


2009 ◽  
Vol 103 (14) ◽  
Author(s):  
M. Muraglia ◽  
O. Agullo ◽  
S. Benkadda ◽  
X. Garbet ◽  
P. Beyer ◽  
...  

2020 ◽  
Author(s):  
Olga Khabarova ◽  
Valentina Zharkova ◽  
Qian Xia ◽  
Olga Malandraki

<p>Recent observational and theoretical studies have shown that there is an unaccounted population of electrons and protons accelerated locally to suprathermal energies at reconnecting current sheets (RCSs) and 3-D dynamical plasmoids or 2-D magnetic islands (MIs) in the solar wind. The findings can be summarized as following: (i) RCSs are often subject to instabilities breaking those into 3D small-scale plasmoids/blobs or 2D magnetic islands (MIs) with multiple X- and O-nullpoints; (ii) RCSs and dynamical MIs can accelerate particles up to the MeV/nuc energies; (iii) accelerated particles may form clouds expanding far from a reconnecting region; and (iv) bi-directional(or counterstreaming) strahls observed in pitch-angle distributions (PADs) of suprathermal electrons may simply represent a signature of magnetic reconnection occurring at closed IMF structures (e.g., MIs), not necessarily connected to the Sun (Zharkova & Khabarova, 2012, 2015; Zank et al. 2014, 2015; Khabarova et al. 2015, 2016, 2017; 2018; le Roux 2016, 2017, 2018, 2019; Khabarova & Zank, 2017; Adhikari et al. 2019; Xia & Zharkova, 2018, 2020; Malandraki et al. 2019; Mingalev et al. 2019). We will briefly present an overview of the effects of local ion acceleration as observed at different heliocentric distances and focus on the impact of the locally-borne population of suprathermal electrons on typical patterns of PADs. </p><p>Suprathermal electrons with energies of ~70eV and above are observed at 1 AU as dispersionless halo and magnetic field-aligned beams of strahls. For a long time, it has been thought that both populations originate only from the solar corona. This view has consequently impacted interpretation of typical patterns of suprathermal electron PADs observed in the solar wind. We present multi-spacecraft observations of counterstreaming strahls and dropouts in PADs within a previously reported region filled with plasmoids and RCSs, comparing observed PAD features with those predicted by PIC simulations extended to heliospheric conditions. We show typical features of PADs determined by acceleration of the ambient thermal electrons up to suprathermal energies in single RCSs and dynamical plasmoids. Our study suggests that locally-accelerated suprathermal electrons co-exist with those of solar origin. Therefore, some heat flux dropout and bi-directional strahl events observed in the heliosphere can be explained by local dynamical processes involving magnetic reconnection. Possible implications of the results for the interpretation of the strahl/halo relative density change with heliocentric distance and puzzling features of suprathermal electrons observed at crossings of the heliospheric current sheet and cometary comas are also discussed.</p>


1994 ◽  
Vol 12 (12) ◽  
pp. 1127-1138 ◽  
Author(s):  
E. Marsch ◽  
C. Y. Tu

Abstract. The probability distributions of field differences ∆x(τ)=x(t+τ)-x(t), where the variable x(t) may denote any solar wind scalar field or vector field component at time t, have been calculated from time series of Helios data obtained in 1976 at heliocentric distances near 0.3 AU. It is found that for comparatively long time lag τ, ranging from a few hours to 1 day, the differences are normally distributed according to a Gaussian. For shorter time lags, of less than ten minutes, significant changes in shape are observed. The distributions are often spikier and narrower than the equivalent Gaussian distribution with the same standard deviation, and they are enhanced for large, reduced for intermediate and enhanced for very small values of ∆x. This result is in accordance with fluid observations and numerical simulations. Hence statistical properties are dominated at small scale τ by large fluctuation amplitudes that are sparsely distributed, which is direct evidence for spatial intermittency of the fluctuations. This is in agreement with results from earlier analyses of the structure functions of ∆x. The non-Gaussian features are differently developed for the various types of fluctuations. The relevance of these observations to the interpretation and understanding of the nature of solar wind magnetohydrodynamic (MHD) turbulence is pointed out, and contact is made with existing theoretical concepts of intermittency in fluid turbulence.


2003 ◽  
Vol 474 ◽  
pp. 299-318 ◽  
Author(s):  
JACQUES VANNESTE

The weakly nonlinear dynamics of quasi-geostrophic flows over a one-dimensional, periodic or random, small-scale topography is investigated using an asymptotic approach. Averaged (or homogenized) evolution equations which account for the flow–topography interaction are derived for both homogeneous and continuously stratified quasi-geostrophic fluids. The scaling assumptions are detailed in each case; for stratified fluids, they imply that the direct influence of the topography is confined within a thin bottom boundary layer, so that it is through a new bottom boundary condition that the topography affects the large-scale flow. For both homogeneous and stratified fluids, a single scalar function entirely encapsulates the properties of the topography that are relevant to the large-scale flow: it is the correlation function of the topographic height in the homogeneous case, and a linear transform thereof in the continuously stratified case.Some properties of the averaged equations are discussed. Explicit nonlinear solutions in the form of one-dimensional travelling waves can be found. In the homogeneous case, previously studied by Volosov, they obey a second-order differential equation; in the stratified case on which we focus they obey a nonlinear pseudodifferential equation, which reduces to the Peierls–Nabarro equation for sinusoidal topography. The known solutions to this equation provide examples of nonlinear periodic and solitary waves in continuously stratified fluid over topography.The influence of bottom topography on large-scale baroclinic instability is also examined using the averaged equations: they allow a straightforward extension of Eady's model which demonstrates the stabilizing effect of topography on baroclinic instability.


2000 ◽  
Vol 7 (12) ◽  
pp. 4983-4995 ◽  
Author(s):  
Richard Fitzpatrick ◽  
François L. Waelbroeck

2017 ◽  
Vol 32 (4) ◽  
pp. 227-234 ◽  
Author(s):  
Marianna E Kapsetaki ◽  
Charlie Easmon

PURPOSE: Previous literature on dancers and athletes has shown a large impact of eating disorders (EDs) on these individuals, but there is limited research on EDs affecting non-dance performing artists (i.e., musicians, actors, etc.). This systematic review aimed to identify and evaluate the literature on EDs in non-dance performing artists. METHODS: A systematic review of the literature was performed on 24 databases, using search terms related to EDs and non-dance performing artists. All results from the databases were systematically screened for inclusion and exclusion criteria. RESULTS: The initial search returned 86,383 total articles, which after screening and removal of duplicates and irrelevant papers yielded 129 results. After screening the 129 full-text results for eligibility, 10 studies met criteria for inclusion: 6 papers addressed EDs in musicians, and 4 papers addressed EDs in theatre performers. Most studies used questionnaires and body mass index (BMI) as diagnostic tools for EDs. Most were small-scale studies and participants were mostly students. Because of the studies’ heterogeneity and varying quality, the results obtained were often contradictory and questionable. CONCLUSIONS: Although there has been a lot of literature in dancers, we found relatively few studies associating EDs with other performing artists, and most were inconsistent in their information.


2019 ◽  
Vol 134 (2) ◽  
pp. 189-196 ◽  
Author(s):  
Carla L. DeSisto ◽  
Charlan D. Kroelinger ◽  
Cameron Estrich ◽  
Alisa Velonis ◽  
Keriann Uesugi ◽  
...  

Objectives: Implementation science provides useful tools for guiding and evaluating the integration of evidence-based interventions with standard practice. The objective of our study was to demonstrate the usefulness of applying an implementation science framework—the Consolidated Framework for Implementation Research (CFIR)—to increase understanding of implementation of complex statewide public health initiatives, using the example of Medicaid immediate postpartum long-acting reversible contraception (LARC) policies. Methods: We conducted semistructured telephone interviews with the 13 state teams participating in the Immediate Postpartum LARC Learning Community. We asked teams to describe the implementation facilitators, barriers, and strategies in 8 focus areas of the Learning Community. We audio-recorded and transcribed interviews and then coded each interview according to the domains and constructs (ie, theoretical concepts) of the CFIR. Results: Cosmopolitanism (ie, networking with external organizations) was the most frequently coded construct of the framework. A related construct was networks and communications (ie, the nature and quality of social networks and formal and informal communications in an organization). Within the construct of cost, state teams identified barriers that were often unable to be overcome. Trialability (ie, ability to test the intervention on a small scale) and engaging champions (ie, attracting and involving persons who dedicate themselves to supporting the intervention in an organization) were among the most salient constructs of the framework and were the sources of many implementation strategies. Conclusions: State leaders and program staff members may benefit from considering the CFIR domains and constructs in the planning, implementation, and evaluation of complex statewide public health initiatives.


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