Universal scaling of thin current sheets in space plasma

2021 ◽  
Author(s):  
Helmi Malova ◽  
Lev Zelenyi ◽  
Elena Grigorenko ◽  
Victor Popov ◽  
Eduard Dubinin
Keyword(s):  
Hybrid Approach ◽  
Russian Science ◽  
Current Sheets ◽  
Scale Free ◽  
Universal Scaling ◽  
Magnetic Field Profile ◽  
Electron Sheet ◽  
Nonlinear Character ◽  
Drift Orbits ◽  
Universal Expression

<p>Thin current sheets (TCSs) with thicknesses about ion Larmor radii can play the key role in space; particularly they can store and then explosively release the accumulated free energy. The dynamics of ions moving along quasi-adiabatic trajectories in TCSs is different from one of magnetized electrons following guiding center drift orbits. Due to this property TCSs can be described in a frame of a hybrid approach. The thickness of the super-thin embedded electron sheet remains uncertain because of the scale-free character of magnetized electron motion. We propose a new analytical approach to describe the multilayer TCS and provide the universal expression describing the embedded electron sheet as a function of the cross-sheet transversal coordinate z characterizing TCS. We demonstrated that the unique property of the electron sheet is the nonlinear character of magnetic field profile:  <em>B(z) ~ z <sup>1/3 </sup></em>which conforms excellently with MAVEN observations in the Martian magnetotail. </p><p>This work was supported by the Russian Science Foundation (grant # 20-42-04418).</p><p> </p>

scholarly journals Universal scaling relations in scale-free structure formation

2018 ◽  
Vol 477 (4) ◽  
pp. 5139-5149 ◽  
Author(s):  
Dávid Guszejnov ◽  
Philip F Hopkins ◽  
Michael Y Grudić
Keyword(s):  
Structure Formation ◽  
Scaling Relations ◽  
Scale Free ◽  
Universal Scaling

Multi-year statistical analysis of properties of current sheets at 1 AU

2021 ◽  
Author(s):  
Olga Khabarova ◽  
Timothy Sagitov ◽  
Roman Kislov ◽  
Gang Li
Keyword(s):  
Solar Wind ◽  
Solar Wind Speed ◽  
Background Level ◽  
Scientific Activity ◽  
Solar Cycles ◽  
Russian Science ◽  
Current Sheets ◽  
Daily Rate ◽  
Interaction Regions ◽  
The One

<p>We use the multi-year open acees database of current sheets identified at 1 AU with the one-second resolution from ACE data (https://csdb.izmiran.ru ) to study properties of current sheets in the solar wind. We find that the CS daily rate (the number of CSs per day) <em>R</em> correlates with the solar wind temperature <em>T </em>rather than with the solar wind speed <em>V</em> and is proportional to the sum of the kinetic and thermal energy density. The main statistical results preliminary obtained in the study are as follows:</p><ul><li>There is clustering of CSs.</li> <li>Maxima of <em>R </em>are associated with stream/corotating interaction regions (SIRs/CIRs) and interplanetary mass ejection (ICME) sheaths.</li> <li>On average, one-three thousands of CSs are detected daily at the Earth’s orbit. The best-fit parameter is (<em>V </em><sup>2 </sup>(<em>N</em>+5 <em>N </em>' ) + 10( <em>N</em>+ <em>N </em>' )<em>T </em>)/5000 if <em>V </em>is given in km/s, <em>T </em>- in K, <em>N</em> is given in cm<sup>-3</sup>,  and <em>N </em>' =2 cm<sup>-3 </sup>is the background level of the solar wind density. The correlation coefficient between the parameter and <em>R</em>  is ~0.8.</li> <li>There is no obvious connection between the daily CS rate and the solar cycle. However, this preliminary conclusion should be reconsidered after the expansion of the CS database to several solar cycles.</li> </ul><p>O.K. and R.K. are supported by Russian Science Foundation grant No. 20-42-04418. T.S. acknowledges the HSE’s general support and encouragement of student’s scientific activity.</p>

Thin current sheets as key structures in space plasma

2021 ◽  
Author(s):  
Helmi Malova ◽  
Lev Zelenyi ◽  
Victor Popov ◽  
Elena Grigorenko
Keyword(s):  
Field Component ◽  
Space Plasma ◽  
Transverse Size ◽  
Tearing Mode ◽  
Russian Science ◽  
Current Sheets ◽  
Oxygen Ions ◽  
Proton Dynamics ◽  
Normal Magnetic Field ◽  
Mode Stabilization

<p>Plasma structures with extremely small transverse size (named thin current sheets or TCSs) have been discovered and investigated by spacecraft observations in the Earth's magnetotail, then in other planetary magnetospheres and the solar wind. Their formation is related with complicated dynamic processes in collisionless space plasma near the magnetic reconnection regions. The proposed models describing TCSs in space plasma, based on the assumption of a quasi-adiabatic proton dynamics and magnetized electrons were successful. Various modifications of the initial equilibrium allowed describing such current sheets as the system of current sheets where the central sheet is supported by magnetized electron drifts, and the external sheets are supported by quasi-adiabatic protons and sometimes oxygen ions. Such current configurations are shown to have properties that are completely different from the well-known Harris model, particularly the multiscale structure, embedding and metastability. The structure and evolution of TCSs under the tearing mode as well as the related paradox of complete tearing mode stabilization in configurations with a nonzero normal magnetic field component is highlighted.</p><p>This work is supported by the Russian Science Foundation grant № 20-42-04418.</p>

scholarly journals Direction-Optimizing Breadth-First Search

2013 ◽  
Vol 21 (3-4) ◽  
pp. 137-148 ◽  
Author(s):  
Scott Beamer ◽  
Krste Asanović ◽  
David Patterson
Keyword(s):  
Social Networks ◽  
Shared Memory ◽  
Hybrid Approach ◽  
Graph Processing ◽  
Breadth First Search ◽  
Top Down ◽  
Bottom Up ◽  
Scale Free

Breadth-First Search is an important kernel used by many graph-processing applications. In many of these emerging applications of BFS, such as analyzing social networks, the input graphs are low-diameter and scale-free. We propose a hybrid approach that is advantageous for low-diameter graphs, which combines a conventional top-down algorithm along with a novel bottom-up algorithm. The bottom-up algorithm can dramatically reduce the number of edges examined, which in turn accelerates the search as a whole. On a multi-socket server, our hybrid approach demonstrates speedups of 3.3–7.8 on a range of standard synthetic graphs and speedups of 2.4–4.6 on graphs from real social networks when compared to a strong baseline. We also typically double the performance of prior leading shared memory (multicore and GPU) implementations.

Universal Scaling of Thin Current Sheets

2020 ◽  
Vol 47 (14) ◽  
Author(s):  
L. M. Zelenyi ◽  
H. V. Malova ◽  
E. E. Grigorenko ◽  
V. Yu Popov ◽  
E. M. Dubinin
Keyword(s):  
Current Sheets ◽  
Universal Scaling

Scale-free architectures support representational diversity

2020 ◽  
Vol 43 ◽  
Author(s):  
Chris Fields ◽  
James F. Glazebrook
Keyword(s):  
Cognitive Architecture ◽  
Levels Of Abstraction ◽  
Scale Free ◽  
Abstract Representations ◽  
Computational Architecture ◽  
Architectural Models ◽  
Cognition Scale

Abstract Gilead et al. propose an ontology of abstract representations based on folk-psychological conceptions of cognitive architecture. There is, however, no evidence that the experience of cognition reveals the architecture of cognition. Scale-free architectural models propose that cognition has the same computational architecture from sub-cellular to whole-organism scales. This scale-free architecture supports representations with diverse functions and levels of abstraction.

Surgical and endovascular hybrid approach in peripheral arterial disease of the lower limbs

VASA ◽  
2016 ◽  
Vol 45 (5) ◽  
pp. 417-422 ◽  
Author(s):  
Anouk Grandjean ◽  
Katia Iglesias ◽  
Céline Dubuis ◽  
Sébastien Déglise ◽  
Jean-Marc Corpataux ◽  
...  
Keyword(s):  
Mortality Rate ◽  
Peripheral Arterial Disease ◽  
Limb Salvage ◽  
Hybrid Approach ◽  
Arterial Disease ◽  
Early Mortality ◽  
Secondary Patency ◽  
Limb Salvage Rate ◽  
Peripheral Arterial ◽  
Salvage Rate

Abstract. Background: Multilevel peripheral arterial disease is frequently observed in patients with intermittent claudication or critical limb ischemia. This report evaluates the efficacy of one-stage hybrid revascularization in patients with multilevel arterial peripheral disease. Patients and methods: A retrospective analysis of a prospective database included all consecutive patients treated by a hybrid approach for a multilevel arterial peripheral disease. The primary outcome was the patency rate at 6 months and 1 year. Secondary outcomes were early and midterm complication rate, limb salvage and mortality rate. Statistical analysis, including a Kaplan-Meier estimate and univariate and multivariate Cox regression analyses were carried out with the primary, primary assisted and secondary patency, comparing the impact of various risk factors in pre- and post-operative treatments. Results: 64 patients were included in the study, with a mean follow-up time of 428 days (range: 4 − 1140). The technical success rate was 100 %. The primary, primary assisted and secondary patency rates at 1 year were 39 %, 66 % and 81 %, respectively. The limb-salvage rate was 94 %. The early mortality rate was 3.1 %. Early and midterm complication rates were 15.4 % and 6.4 %, respectively. The early mortality rate was 3.1 %. Conclusions: The hybrid approach is a major alternative in the treatment of peripheral arterial disease in multilevel disease and comorbid patients, with low complication and mortality rates and a high limb-salvage rate.

The Scale-free Property in Emotion: Associated Word Networks

2010 ◽  
Author(s):  
Takuma Takehara ◽  
Tumio Ochiai ◽  
Kosuke Tamiguchi ◽  
Naoto Suzuki
Keyword(s):  
Scale Free

APPLICATION OF THE MAGNETIC FLUX PLASMA TRAP TO GENERATION OF CURRENT SHEETS IN A RAREFIED PLASMA

1979 ◽  
Vol 40 (C7) ◽  
pp. C7-507-C7-510
Author(s):  
N. A. Koshilev ◽  
N. A. Strokin ◽  
A. A. Shisko ◽  
A. V. Mikhalev
Keyword(s):  
Magnetic Flux ◽  
Current Sheets ◽  
Plasma Trap
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