Kinetic Modeling of the Impact of Solar Wind Discontinuities on the Magnetopause

2021 ◽  
Author(s):  
Jean Berchem ◽  
Giovanni Lapenta ◽  
Robert L. Richard ◽  
Philippe Escoubet ◽  
Simon Wing
Keyword(s):  
Solar Wind ◽  
Kinetic Modeling ◽  
Large Scale ◽  
Scale Effects ◽  
Comprehensive Understanding ◽  
Global Simulation ◽  
Mhd Simulations ◽  
Dayside Magnetopause ◽  
Pic Code ◽  
The Impact

<p>An important step in comprehending the effects of solar wind structures on the magnetosphere is to develop an understanding of their impact on the dayside magnetopause.  While most of the time global magnetohydrodynamic (MHD) models describe adequately the large-scale effects of solar wind structures on the magnetopause, recent spacecraft observations in the near Earth solar wind indicate that solar wind discontinuities have plasma features that are often not accurately described by MHD.  In this presentation, we report our progress in gaining a comprehensive understanding of kinetic processes occurring at the magnetopause as solar wind structures impact the dayside magnetosphere. Our approach combines implicit PIC simulations with global MHD simulations of the solar wind-magnetosphere-ionosphere system. The global simulation sets the overall configuration of the magnetosphere, while fields and plasma moments of a sub-domain of the global simulation are used to set initial and boundary conditions of the PIC code. Results are discussed in the context of spacecraft observations.</p>

Multi-point Observations of Sudden Impulses and Implications for Signal Travel Time in the Magnetosphere

2020 ◽  
Author(s):  
Erin Flores ◽  
Peter Chi
Keyword(s):  
Solar Wind ◽  
Travel Time ◽  
Large Scale ◽  
Inhomogeneous Plasma ◽  
Interplanetary Shock ◽  
Mhd Waves ◽  
Propagation Time ◽  
Impulse Propagation ◽  
Dayside Magnetopause ◽  
The Impact

<p>The Earth’s magnetosphere occasionally experiences sudden movements from localized sources. For example, the impact of the interplanetary shock on the magnetosphere starts from a localized region on the dayside magnetopause, where the perturbations rapidly propagate inside the magnetosphere as the pressure front moves farther away from the Sun. The impulses generated from these sources propagate through the inhomogeneous plasma and can be detected in many corners of the magnetosphere. These impulses often mark the beginning of large-scale reconfigurations in the magnetosphere and the ionosphere, such as magnetic/ionospheric storms and substorms. The propagation of these impulses, such as that through MHD waves, is fast but not instantaneous. The propagation paths in the highly inhomogeneous magnetosphere may not be straightforward. Nonetheless, past studies have demonstrated that the impulse propagation in the dayside magnetosphere can be characterized by the Tamao model.</p><p>In this study, we examine the signatures of sudden impulses in the data from a network of spacecraft in the magnetosphere, including THEMIS, Van Allen Probes, MMS, Geotail, and GOES. The ACE and Wind data are also used for solar wind conditions. Observations from Polar, FAST, GOES, Cluster, Swarm, IMP-8, and ground-based magnetometers are also examined whenever they are available. The observations of impulse propagation time will be compared against the modeled Tamao travel time to understand how much the two agree with each other and how the comparison varies with the properties of the solar wind discontinuity.</p>

Interplanetary Shock-driven Magnetopause Compressions in Gorgon Global-MHD Simulations

2021 ◽  
Author(s):  
Ravindra Desai ◽  
Jonathan Eastwood ◽  
Joseph Eggington ◽  
Mervyn Freeman ◽  
Martin Archer ◽  
...  
Keyword(s):  
Solar Wind ◽  
Large Scale ◽  
Interplanetary Shock ◽  
Interplanetary Shocks ◽  
Pressure Balance ◽  
Interplanetary Coronal Mass Ejections ◽  
Corotating Interaction Regions ◽  
Mhd Simulations ◽  
Interaction Regions ◽  
Space Weather Event

<p>Fast-forward interplanetary interplanetary shocks, as occur at the forefront of interplanetary coronal mass ejections and at corotating interaction regions, can rapidly compress the magnetopause inside the drift paths of electrons and protons, and expose geosynchonous satellites directly to the solar wind.  Here, we use Gorgon Global-MHD simulations to study the response of the magnetopause to different fast-forward interplanetary shocks, with strengths extending from the median shocks observed during solar minimum up to that representing an extreme space weather event. The subsequent magnetopause response can be characterised by three distinct phases; an initial acceleration as inertial forces are overcome, a rapid compression well-represented by a power law, and large-scale damped oscillatory motion of the order of an Earth radius, prior to reaching pressure-balance equilibrium. The subsolar magnetopause is found to oscillate with notable frequencies in the range of 2–13 mHz over several periods of diminishing amplitudes.  These results provide an explanation for similar large-scale magnetopause oscillations observed previously during the extreme events of August 1972 and March 1991 and highlight why static magnetopause models break down during periods of strong solar wind driving.</p>

scholarly journals Mapping of host-parasite-microbiome interactions reveals metabolic determinants of tropism and tolerance in Chagas disease

2020 ◽  
Vol 6 (30) ◽  
pp. eaaz2015 ◽  
Author(s):  
E. Hossain ◽  
S. Khanam ◽  
D. A. Dean ◽  
C. Wu ◽  
S. Lostracco-Johnson ◽  
...  
Keyword(s):  
Chagas Disease ◽  
Large Scale ◽  
Scale Effects ◽  
Parasite Burden ◽  
Acute Stage ◽  
Metabolic Disturbances ◽  
Spatially Resolved ◽  
Cardiac Strain ◽  
Host Parasite ◽  
The Impact

Chagas disease (CD) is a parasitic disease caused by Trypanosoma cruzi protozoa, presenting with cardiomyopathy, megaesophagus, and/or megacolon. To determine the mechanisms of gastrointestinal (GI) CD tissue tropism, we systematically characterized the spatial localization of infection-induced metabolic and microbiome alterations, in a mouse model of CD. Notably, the impact of the transition between acute and persistent infection differed between tissue sites, with sustained large-scale effects of infection in the esophagus and large intestine, providing a potential mechanism for the tropism of CD within the GI tract. Infection affected acylcarnitine metabolism; carnitine supplementation prevented acute-stage CD mortality without affecting parasite burden by mitigating infection-induced metabolic disturbances and reducing cardiac strain. Overall, results identified a previously-unknown mechanism of disease tolerance in CD, with potential for new therapeutic regimen development. More broadly, results highlight the potential of spatially resolved metabolomics to provide insight into disease pathogenesis and infectious disease drug development.

scholarly journals The Impact of Neurofeedback on Effective Connectivity Networks in Chronic Stroke Patients

2020 ◽  
Author(s):  
Lioi Giulia ◽  
Veliz Adolfo ◽  
Coloigner Julie ◽  
Duché Quentin ◽  
Butet Simon ◽  
...  
Keyword(s):  
Neural Plasticity ◽  
Large Scale ◽  
Scale Effects ◽  
Self Regulation ◽  
Chronic Stroke ◽  
Causal Modeling ◽  
Stroke Recovery ◽  
Functional Improvement ◽  
Stroke Patients ◽  
The Impact

AbstractStroke is a complex motor disease that not only affects perilesional areas but also global brain networks in both hemispheres. Neurofeedback (NF) is a promising technique to enhance neural plasticity and support functional improvement after stroke by means of brain self-regulation. Most of the studies using NF or brain computer interfaces for stroke rehabilitation have assessed treatment effects focusing on motor outcomes and successful activation of targeted cortical regions. However, given the crucial role of large-scale networks reorganization for stroke recovery, it is now believed that assessment of brain connectivity is central to predict treatment response and to individualize rehabilitation therapies. In this study, we assessed the impact of EEG-fMRI NF training on connectivity strength and direction using a Dynamic Causal Modeling approach. We considered a motor network including both ipsilesional and contralesional premotor, supplementary and primary motor areas. Our results in nine chronic stroke patients indicate that NF upregulation of targeted areas (ipsilesional SMA and M1) not only modulated activation patterns, but also had a more widespread impact on fMRI bilateral motor networks. In particular, inter-hemispheric connectivity between premotor and primary motor regions decreased, and ipsilesional self-inhibitory connections were reduced in strength, indicating an increase in activation during the NF motor task. To the best of our knowledge, this is the first work that investigates fMRI connectivity changes elicited by training of localized motor targets in stroke. Our results open new perspectives in the understanding of large-scale effects of NF training and the design of more effective NF strategies, based on the pathophysiology underlying stroke-induced deficits.

scholarly journals Early galaxy formation and its large-scale effects

2019 ◽  
Vol 15 (S352) ◽  
pp. 43-43
Author(s):  
Pratika Dayal
Keyword(s):  
Dark Matter ◽  
Galaxy Formation ◽  
Large Scale ◽  
Cold Dark Matter ◽  
Scale Effects ◽  
High Redshift ◽  
Early Galaxies ◽  
First Galaxies ◽  
The Impact ◽  
Early Galaxy

AbstractGalaxy formation in the first billion years mark a time of great upheaval in the history of the Universe: the first galaxies started both the ‘metal age’ as well as the era of cosmic reionization. I will start by reviewing the dust production mechanisms and dust masses for high-redshift galaxies which will be revolutionized in the ALMA era. I will then show how the JWST will be an invaluable experiment to shed light on the impact of reionization feedback on early galaxy formation. As we look forward towards the era of 21cm cosmology, I will highlight the crucial and urgent synergies required between 21cm facilities (such as the SKA) and galaxy experiments (JWST, E-ELT and Subaru to name a few) to understand the physics of the epoch of reionization that remains a crucial frontier in the field of astrophysics and physical cosmology. Time permitting, I will try to give a flavour of how the assembly of early galaxies, accessible with the forthcoming JWST, can provide a powerful testbed for Dark Matter models beyond ‘Cold Dark Matter’.

scholarly journals Discovering the opposite shore: How did hominins cross sea straits?

PLoS ONE ◽  
2021 ◽  
Vol 16 (6) ◽  
pp. e0252885
Author(s):  
Ericson Hölzchen ◽  
Christine Hertler ◽  
Ana Mateos ◽  
Jesús Rodríguez ◽  
Jan Ole Berndt ◽  
...  
Keyword(s):  
Large Scale ◽  
Scale Effects ◽  
Small Scale ◽  
Behavioral Models ◽  
Comprehensive Understanding ◽  
Agent Based ◽  
Continental Scale ◽  
Water Barrier ◽  
Sea Straits ◽  
Scale Models

Understanding hominin expansions requires the comprehension of movement processes at different scales. In many models of hominin expansion these processes are viewed as being determined by large-scale effects, such as changes in climate and vegetation spanning continents and thousands or even millions of years. However, these large-scale patterns of expansions also need to be considered as possibly resulting from the accumulation of small-scale decisions of individual hominins. Moving on a continental scale may for instance involve crossing a water barrier. We present a generalized agent-based model for simulating the crossing of a water barrier where the agents represent the hominin individuals. The model can be configured to represent a variety of movement modes across water. Here, we compare four different behavioral scenarios in conjunction with a set of water barrier configurations, in which agents move in water by either paddling, drifting, swimming or rafting. We introduce the crossing-success-rate (CSR) to quantify the performance in water crossing. Our study suggests that more focus should be directed towards the exploration of behavioral models for hominins, as directionality may be a more powerful factor for crossing a barrier than environmental opportunities alone. A prerequisite for this is to perceive the opposite shore. Furthermore, to provide a comprehensive understanding of hominin expansions, the CSR allows for the integration of results obtained from small-scale simulations into large-scale models for hominin expansion.

Embedding particle-in-cell simulations in global magnetohydrodynamic simulations of the magnetosphere

2019 ◽  
Vol 85 (1) ◽  
Author(s):  
Raymond J. Walker ◽  
Giovanni Lapenta ◽  
Jean Berchem ◽  
Mostafa El-Alaoui ◽  
David Schriver
Keyword(s):  
Solar Wind ◽  
Mhd Simulation ◽  
Magnetospheric Substorm ◽  
Pic Simulation ◽  
Particle In Cell ◽  
Mhd Simulations ◽  
Dayside Magnetopause ◽  
Thin Current Sheet ◽  
Cell Simulation ◽  
Magnetohydrodynamic Simulations

We have combined global magnetohydrodynamic (MHD) simulations of the solar wind and magnetosphere interaction with an implicit particle-in-cell simulation (PIC) and used this approach to model magnetic reconnection at both the dayside magnetopause and in the magnetotail plasma sheet. In this approach, we first model the magnetospheric configuration driven by the solar wind using the MHD simulation. At a time of interest (usually when a thin current sheet has formed in the MHD simulation), we load a large particle-in-cell simulation with plasma and fields based on the MHD state. We use the MHD results to set the boundary conditions on the PIC simulation. The coupling between the two models is one way – the PIC results do not change the MHD results. In these calculations, we use the UCLA global MHD code and the iPic3D implicit particle-in-cell code. In this paper we describe this technique in detail. As an example of this approach, we present PIC results on reconnection in the magnetotail during a magnetospheric substorm.

scholarly journals Structural and Efficiency Effects of Land Transfers on Food Planting: A Comparative Perspective on North and South of China

2021 ◽  
Vol 13 (6) ◽  
pp. 3327
Author(s):  
Zhihua Leng ◽  
Yana Wang ◽  
Xinshuo Hou
Keyword(s):  
Large Scale ◽  
Scale Effects ◽  
Division Of Labour ◽  
Market Mechanism ◽  
Small Scale ◽  
Structural Effects ◽  
The South ◽  
Operating Income ◽  
The North ◽  
The Impact

This paper uses a multi-period PSM-DID model to explore the impact of land transfers on food production from a spatial perspective and analyses the income effects, scale effects, and structural effects of such transfers. The empirical results are as follows. (1) Land transfers have reduced the proportion of food crops planted by farmers, and the planting structure has shifted towards cash crops, which has obvious structural effects. (2) The impact of land transfers on the planting structure is spatially heterogeneous. Land transfers are more common in the south than in the north. Land transfers have reduced wheat planting in the north, while rice planting has been reduced in the south. (3) Land transfers have increased the operating income of farmers and have an income effect, but the income of farmers in the north is higher than that of farmers in the south. (4) Land transfers do not have scale effects. Current land transfers among farmers are mainly conducted on a small scale and do not improve farmers’ efficiency in planting food. The following suggestions are proposed. (1) A market mechanism for land transfers should be established to promote large-scale land transfers. (2) The trend towards non-grain cultivation due to land transfers should be halted to ensure food security. (3) The different impacts of urbanization in the northern and southern regions should be considered, and the division of labour in grain-producing areas should be strengthened. (4) Land transfer models should be developed, and the development of smart agriculture should be explored.

scholarly journals Magnetopause reconnection and interlinked flux tubes

2013 ◽  
Vol 31 (10) ◽  
pp. 1853-1866 ◽  
Author(s):  
F. R. Cardoso ◽  
W. D. Gonzalez ◽  
D. G. Sibeck ◽  
M. Kuznetsova ◽  
D. Koga
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Magnetic Reconnection ◽  
Large Scale ◽  
Time Dependent ◽  
Mhd Simulation ◽  
Flux Tubes ◽  
Magnetic Structures ◽  
Mhd Simulations ◽  
Magnetopause Reconnection

Abstract. Magnetic reconnection can be a continuous or a transient process. Global magnetohydrodynamics (MHD) simulations are important tools to understand the relevant magnetic reconnection mechanisms and the resulting magnetic structures. We have studied magnetopause reconnection using a global 3-D MHD simulation in which the interplanetary magnetic field (IMF) has been set to large positive By and large negative Bz components, i.e., a south-duskward direction. Flux tubes have been observed even during these constant solar wind conditions. We have focused on the interlinked flux tubes event resulting from time-dependent, patchy and multiple reconnection. At the event onset, two reconnection modes seem to occur simultaneously: a time-dependent, patchy and multiple reconnection for the subsolar region; and, a steady and large-scale reconnection for the regions far from the subsolar site.

scholarly journals WAVE LOADS ON EXPOSED JETTIES: DESCRIPTION OF LARGE SCALE EXPERIMENTS AND PRELIMINARY RESULTS

2011 ◽  
Vol 1 (32) ◽  
pp. 18 ◽  
Author(s):  
Luca Martinelli ◽  
Alberto Lamberti ◽  
Maria Gabriella Gaeta ◽  
Matteo Tirindelli ◽  
John Alderson ◽  
...  
Keyword(s):  
Large Scale ◽  
Research Team ◽  
Scale Effects ◽  
Wave Loads ◽  
Large Wave ◽  
Preliminary Results ◽  
Wave Flume ◽  
Air Content ◽  
Wave Induced ◽  
The Impact

The large scale experiments described in this paper were carried out at the Large Wave Flume (GWK, Große Wellenkanal) in Hanover (Germany). The research team included Universities of Bologna (IT), Edinburgh (UK), Southampton (UK), Plymouth (UK), HR Wallingford (UK) and Coast & Harbor Engineering Inc (USA). Wave-induced loads on close-to-prototype scale jetties were measured, with particular attention to scale effects due to air content in water. The aim of the paper is to present the tests, describe the impact process and give preliminary results concerning uplift loads.

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